56 results on '"Rainer Lenhardt"'
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2. Continuous positive airway pressure
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Rainer Lenhardt and Jerrad R. Businger
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business.industry ,Anesthesia ,medicine.medical_treatment ,Medicine ,Perioperative ,Continuous positive airway pressure ,business - Abstract
Given the increased risk prevalence of coronary artery disease, inflammatory disease, and cancer, morbidly obese patients are frequently scheduled for various types of surgery. In addition, the number of bariatric surgeries has risen almost exponentially. Therefore, the anaesthesiologist is more frequently challenged with providing general anaesthesia for this patient population. General anaesthesia comes with increased risks of events such as perioperative morbid cardiac events and postoperative respiratory failure. Postoperative respiratory failure is particularly common after cardiac, thoracic, and major abdominal surgery. Anaesthesiologists have a range of support mechanisms at their disposal to reduce postoperative respiratory failure including emergent reintubation. Apart from simple oxygen delivery via nasal cannulas or face masks, Venturi masks, and Mapleson circuits, there are various positive pressure systems available. These systems are commonly referred to as non-invasive ventilation (NIV) systems. NIV can be non-invasive continuous positive airway pressure or non-invasive intermittent positive pressure ventilation. Both types of NIV have been shown to improve oxygenation and hypercapnia in morbidly obese patients in the perioperative environment. This chapter presents the physiology and pathophysiology of the respiratory system in the morbidly obese patient. In addition, it illustrates the impact and implications of NIV systems on this patient population in the perioperative setting.
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- 2021
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3. Body temperature regulation and anesthesia
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Rainer Lenhardt
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Anesthetic gases ,business.industry ,Unconsciousness ,Perioperative ,Thermoregulation ,Hypothermia ,Pain sensation ,03 medical and health sciences ,0302 clinical medicine ,030202 anesthesiology ,Anesthesia ,medicine ,medicine.symptom ,business ,030217 neurology & neurosurgery ,Vasoconstriction - Abstract
General anesthesia is the induction and maintenance of a state of unconsciousness with the absence of pain sensation. General anesthesia is accomplished by the administration of a combination of inhaled anesthetic gases and intravenous drugs. These medications eliminate behavioral thermoregulatory compensations, leaving only autonomic defenses to offset environmental perturbations. Anesthetics inhibit thermoregulatory control in a dose-dependent fashion over the entire clinical range. Impairment of thermoregulatory control is observed by a change in thermoregulatory thresholds with the vasoconstriction threshold being affected about three times as much as the sweating threshold. Consequently, the zone between sweating and vasoconstriction thresholds, called interthreshold range, is widened dose-dependently. Impairment of thermoregulation, triggered by general anesthesia, typically causes inadvertent hypothermia. In febrile patients, general anesthesia reduces the magnitude of perioperative fever.
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- 2018
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4. Is Video Laryngoscope-Assisted Flexible Tracheoscope Intubation Feasible for Patients with Predicted Difficult Airway? A Prospective, Randomized Clinical Trial
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Rachana Sharma, Rainer Lenhardt, Sunitha Kanchi-Kandadai, Ozan Akca, Mary Tyler Burkhart, and Guy N. Brock
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Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Video laryngoscope ,Laryngoscopes ,Epiglottis ,Preoperative care ,law.invention ,Randomized controlled trial ,Interquartile range ,law ,Preoperative Care ,Intubation, Intratracheal ,medicine ,Humans ,Intubation ,Prospective Studies ,Airway Management ,Prospective cohort study ,Laryngoscopy ,business.industry ,Middle Aged ,Confidence interval ,Surgery ,Stylet ,Trachea ,Treatment Outcome ,Anesthesiology and Pain Medicine ,Data Interpretation, Statistical ,Anesthesia ,Cervical Vertebrae ,Female ,Larynx ,business - Abstract
Background Failed intubation may result in both increased morbidity and mortality. The combination of a video laryngoscope and a flexible tracheoscope used as a flexible video stylet may improve the success rate of securing a difficult airway. We tested the hypothesis that this combination is a feasible way to facilitate intubation in patients with a predicted difficult airway in that it will shorten intubation times and reduce the number of intubation attempts. Methods We conducted a randomized, prospective trial in 140 patients with anticipated difficult airways undergoing elective or urgent surgery. After insertion of video laryngoscope, patients were randomly assigned to either having their tube placed with the use of a preformed stylet (control group) or with a flexible tracheoscope (intervention group). The primary outcome measures were time to successful intubation and number of intubation attempts. Results The number of intubations requiring 2 or more intubation attempts was similar in the 2 groups (14% control vs 13% intervention, P = 1.0); the number of patients requiring 3 or more intubation attempts was not significantly different (8.6% control vs 1.4% intervention, P = 0.12). Distribution for time to intubation also did not differ between the control (median of 66 seconds, interquartile range 47-89) and the intervention group (median of 71 seconds, interquartile range 52-100; P = 0.35). In the control group, 4 patients, all with cervical spine pathology, had the trachea intubated successfully with the video laryngoscope plus flexible tracheoscope after 3 failed attempts with video laryngoscope and rigid stylet. For these 4 patients, time from the decision to change the intubation method to successful intubation with a flexible tracheoscope was 36 ± 14 seconds. Overall success probability for cervical spine patients was 100% (20/20) in the intervention group and 80% (16/20) in the control group, with an exact 95% confidence interval for the difference of 1.4% to 44%, P = 0.04. Conclusions Flexible tracheoscope-assisted video laryngoscopic intubation is a feasible alternative to video laryngoscope only intubation in patients with predicted difficult airways. A flexible tracheoscope used in combination with video laryngoscope may also further increase the success rate of intubation in select patients with a proven difficult airway, particularly when in-line stabilization is required.
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- 2014
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5. The Effect of Altering Skin-Surface Cooling Speeds on Vasoconstriction and Shivering Thresholds
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Daniel I. Sessler, Yoshie Taniguchi, Andrea Kurz, and Rainer Lenhardt
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Adult ,Time Factors ,Fingers ,Young Adult ,Oxygen Consumption ,Hypothermia, Induced ,Humans ,Medicine ,Forced-air ,Analysis of Variance ,Core (anatomy) ,business.industry ,Shivering ,Blood flow ,Hypothermia ,Confidence interval ,Anesthesiology and Pain Medicine ,Regional Blood Flow ,Vasoconstriction ,Anesthesia ,Analysis of variance ,medicine.symptom ,Skin Temperature ,business ,Blood Flow Velocity ,Switzerland - Abstract
BACKGROUND Both core and skin temperatures contribute to steady-state thermoregulatory control. Dynamic thermoregulatory responses trigger aggressive defenses against rapid thermal perturbations. These responses potentially complicate interpretation of thermoregulatory studies and could slow induction of therapeutic hypothermia. We thus tested the hypothesis that rapid external skin-cooling triggers vasoconstriction and shivering at higher mean skin temperatures than slow or moderate rates of skin cooling. METHODS Eleven healthy volunteers were cooled at 3 skin-cooling rates using forced air or/and conductive cooling in random order. One day volunteers received slow (≈2°C/h) skin cooling, and on another day, they received both medium (≈4°C/h) and fast (≈6°C/h) skin cooling. An endovascular heat-exchanging catheter maintained core temperature. Fingertip blood flow ≤0.25 mL/min defined onset of vasoconstriction; sustained ≥25% increase in oxygen consumption defined onset of shivering. Results were evaluated with repeated-measures analysis of variance, with P < 0.05 representing statistical significance. RESULTS Volunteers were 25 ± 5 years of age (mean ± SD), 175 ± 7 cm tall, and weighed 63 ± 10 kg. Core temperature remained constant (≈37°C) throughout each study day. At vasoconstriction, mean skin temperatures were 33.2°C (95% confidence interval [CI]: 32.0°C, 34.4°C), 33.5°C (95% CI: 32.3°C, 34.7°C), and 33.0°C (95% CI: 31.4°C, 34.6°C) at slow, medium, and fast skin-cooling rates, respectively. Mean skin temperatures at shivering were also comparable: 31.4°C (95% CI: 30.3°C, 32.5°C), 31.5°C (95% CI: 30.2°C, 32.8°C), and 30.7°C (95% CI: 28.9°C, 32.5°C), respectively. CONCLUSIONS Onset of vasoconstriction and shivering occurred at similar mean skin temperatures with all 3 cooling rates. Aggressive surface cooling can thus be used in thermoregulatory studies and for induction of therapeutic hypothermia without provoking dynamic thermoregulatory defenses.
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- 2011
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6. Suppression of Shivering during Hypothermia Using a Novel Drug Combination in Healthy Volunteers
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Yusuke Kasuya, Raghavendra Govinda, Daniel I. Sessler, Rainer Lenhardt, Anupama Wadhwa, Ryu Komatsu, and Mukadder Orhan-Sungur
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Mean arterial pressure ,animal structures ,business.industry ,Sedation ,Hypothermia ,Buspirone ,Anesthesiology and Pain Medicine ,Anesthesia ,Heart rate ,medicine ,Shivering ,medicine.symptom ,Respiratory system ,Dexmedetomidine ,business ,medicine.drug - Abstract
Background Hypothermia may be beneficial in stroke victims; however, it provokes vigorous shivering. Buspirone and dexmedetomidine each linearly reduce the shivering threshold with minimal sedation and no respiratory depression. This study tested the hypotheses that the combination of buspirone and dexmedetomidine would (1) synergistically reduce the shivering threshold, (2) synergistically reduce the gain and maximum intensity of shivering, and (3) produce sufficient inhibition to permit cooling to 34 degrees C without excessive hypotension or sedation. Methods Eight healthy men were randomly assigned on 4 days to (1) no drug, (2) buspirone (60 mg orally), (3) dexmedetomidine (intravenous infusion to target plasma concentration of 0.6 ng/ml), or (4) combination of buspirone and dexmedetomidine at same doses. Lactated Ringer's solution (approximately 3 degrees C) was infused intravenously to decrease tympanic membrane temperature by 1.5 degrees C/h. Shivering threshold was defined as an increase in oxygen consumption greater than 20%. Sedation was evaluated using the Observer's Assessment of Sedation/Alertness scale. Results Mean arterial pressure and heart rate were slightly lower on dexmedetomidine and combination days. Likewise, the level of sedation was statistically different on these 2 days but clinically unimportant. Buspirone reduced the shivering threshold from 36.6 degrees C +/- 0.4 degrees C to 35.9 degrees C +/- 0.4 degrees C, dexmedetomidine reduced it to 34.7 degrees C +/- 0.5 degrees C, and the combination to 34.1 +/- 0.4 degrees C. The interaction effect of 0.04 degrees C was not significant. The gain of shivering and maximum shivering intensity were similar on each day. Conclusions The combination of buspirone and dexmedetomidine additively reduced the shivering threshold. Thus, supplementing dexmedetomidine with buspirone blocks shivering and causes only minimal sedation.
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- 2009
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7. Magnesium sulphate only slightly reduces the shivering threshold in humans † †Data were presented in abstract form at the Annual Meeting of the American Society of Anesthesiologists, San Francisco, CA, 2003
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Ozan Akca, Anthony G. Doufas, Papiya Sengupta, Daniel I. Sessler, Jaleel Durrani, Rainer Lenhardt, and Anupama Wadhwa
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Magnesium ,business.industry ,Sedation ,chemistry.chemical_element ,Muscle weakness ,Hypothermia ,Thermoregulation ,Anesthesiology and Pain Medicine ,Bolus (medicine) ,chemistry ,Bispectral index ,Anesthesia ,medicine ,Shivering ,medicine.symptom ,business - Abstract
Background. Hypothermia may be an effective treatment for stroke or acute myocardial infarction; however, it provokes vigorous shivering, which causes potentially dangerous haemodynamic responses and prevents further hypothermia. Magnesium is an attractive anti-shivering agent because it is used for treatment of postoperative shivering and provides protection against ischaemic injury in animal models. We tested the hypothesis that magnesium reduces the threshold (triggering core temperature) and gain of shivering without substantial sedation or muscle weakness. Methods. We studied nine healthy male volunteers (18–40 yr) on two randomly assigned treatment days: (1) control and (2) magnesium (80 mg kg � 1 followed by infusion at 2 g h � 1 ). Lactated Ringer’s solution (4 � C) was infused via a central venous catheter over a period of approximately 2 h to decrease tympanic membrane temperature by � 1.5 � Ch � 1 . A significant and persistent increase in oxygen consumption identified the threshold. The gain of shivering was determined by the slope of oxygen consumption vs core temperature regression. Sedation was evaluated using a verbal rating score (VRS) from 0 to 10 and bispectral index (BIS) of the EEG. Peripheral muscle strength was evaluated using dynamometry and spirometry. Data were analysed using repeated measures ANOVA; P
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- 2005
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8. The Timing of Acupuncture Stimulation Does Not Influence Anesthetic Requirement
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Rainer Lenhardt, Papiya Sengupta, Edwin B. Liem, Daniel I. Sessler, Anthony G. Doufas, Ozan Akca, and Grigory V. Chernyak
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Adult ,Male ,medicine.medical_specialty ,Time Factors ,Adolescent ,Electroacupuncture ,medicine.medical_treatment ,Analgesic ,Stimulation ,Zusanli ,Article ,Body Temperature ,Desflurane ,medicine ,Acupuncture ,Humans ,Anesthetics ,Isoflurane ,business.industry ,Hemodynamics ,Electroencephalography ,Surgery ,Anesthesiology and Pain Medicine ,Anesthesia ,Anesthetics, Inhalation ,Anesthetic ,Female ,Anesthesia, Inhalation ,business ,medicine.drug - Abstract
Studies suggest that acupuncture is more effective when induced before the induction of general anesthesia than afterwards. We tested the hypothesis that electro-acupuncture initiated 30 min before the induction reduces anesthetic requirement more than acupuncture initiated after the induction. Seven volunteers were each anesthetized with desflurane on 3 study days. Needles were inserted percutaneously at four acupuncture points thought to produce analgesia in the upper abdominal area and provide generalized sedative and analgesic effects: Zusanli (St36), Sanyinjiao (Sp6), Liangqiu (Sp34), and Hegu (LI4). Needles were stimulated at 2 Hz and 10 Hz, with frequencies alternating at 2-s intervals. On Preinduction day, electro-acupuncture was started 30 min before the induction of anesthesia and maintained throughout the study. On At-induction day, needles were positioned before the induction of anesthesia, but electro-acupuncture stimulation was not initiated until after the induction. On Control day, electrodes were positioned near the acupoints, but needles were not inserted. Noxious electrical stimulation was administered via 25-gauge needles on the upper abdomen (70 mA; 100 Hz; 10 s). The desflurane concentration was increased 0.5% when movement occurred and decreased 0.5% when it did not. These up-and-down sequences continued until volunteers crossed from movement to no movement four times. The P(50) of logistic regression identified desflurane requirement. Desflurane requirement was similar on the Control (mean +/- sd; 5.2% +/- 0.6%), Preinduction (5.0% +/- 0.8%), and At-induction (4.7% +/- 0.3%; P = 0.125) days. This type of acupuncture is thus unlikely to facilitate general anesthesia or decrease the requirement for anesthetic drugs.
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- 2005
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9. Nitrous oxide increases the incidence of bowel distension in patients undergoing elective colon resection
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Oliver Kimberger, Robert Greif, Daniel I. Sessler, Ozan Akca, Tanja A. Treschan, Edith Fleischmann, Rainer Lenhardt, Andrea Kurz, and R. Fleischhackl
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Adult ,Male ,inorganic chemicals ,Adolescent ,Colon ,Nitrous Oxide ,chemistry.chemical_element ,Article ,Colon resection ,chemistry.chemical_compound ,Colon surgery ,Pressure ,medicine ,Humans ,In patient ,Aged ,Aged, 80 and over ,business.industry ,Incidence ,organic chemicals ,General Medicine ,Blood flow ,Nitrous oxide ,Middle Aged ,equipment and supplies ,Nitrogen ,Intestinal Diseases ,Anesthesiology and Pain Medicine ,chemistry ,Anesthesia ,Postoperative Nausea and Vomiting ,Bowel distension ,bacteria ,Female ,medicine.symptom ,business ,Postoperative nausea and vomiting - Abstract
Nitrous oxide has been used for more than 150 years and has been given to several billion patients. It justifiably remains a popular anaesthetic agent because it is inexpensive, analgesic, and extremely short acting. It reduces the need of maintenance anaesthetic, which has more significance when ventilators with larger fresh airflows are used. However, intestinal distension by nitrous oxide has been reported at least since the 1960’s (1), and it is well established that nitrous oxide inflates closed, gas-filled spaces (2). Nitrous oxide will move into air-filled cavities in the body that normally contain nitrogen; so as nitrous oxide transfers from the blood into the space, nitrogen transfers out. However, nitrous oxide is 34 times more soluble than nitrogen in blood. Thus, substantial quantities of nitrous oxide leave the blood and enter the bowel, but not much nitrogen can leave the bowel to enter the blood. The result is that during exposure to nitrous oxide, like in other compliant spaces, the volume of gas in the bowel increases. The amount of the increase depends on the alveolar partial pressure of nitrous oxide, the intestinal blood flow, and the duration of nitrous oxide administration. The evidence that nitrous oxide causes clinically important bowel distension is equivocal. Several studies have failed to identify any effect whatsoever of nitrous oxide on bowel distension(3–6) or postoperative intestinal function (6,7). In contrast, others have reported that nitrous oxide increases bowel distension in both animals (8) and humans (9). All of these studies were relatively small and some were seriously underpowered. We, therefore, tested the hypothesis that the use of nitrous oxide produces clinically important bowel distension in patients undergoing elective colon resection with isoflurane anaesthesia. We simultaneously quantified the magnitude of the effect by determining the number of patients in whom air must be substituted for nitrous oxide to avoid a single case of clinically important bowel distension (number-needed-to-harm).
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- 2004
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10. The New Perilaryngeal Airway (CobraPLA™) Is as Efficient as the Laryngeal Mask Airway (LMA™) but Provides Better Airway Sealing Pressures
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Anthony G. Doufas, Rainer Lenhardt, Papiya Sengupta, Anupama Wadhwa, Mary Wenke, Daniel I. Sessler, Ozan Akca, Keith Hanni, Yüksel Yücel, and Jaleel Durrani
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medicine.medical_specialty ,business.industry ,Mascara ,respiratory system ,respiratory tract diseases ,Surgery ,Laryngeal Masks ,Anesthesiology and Pain Medicine ,Insertion time ,Laryngeal mask airway ,Anesthesia ,Cuff ,Medicine ,Airway ,business ,Propofol ,Tidal volume ,medicine.drug - Abstract
The Laryngeal Mask Airway (LMA) is a frequently used efficient airway device, yet it sometimes seals poorly, thus reducing the efficacy of positive-pressure ventilation. The Perilaryngeal Airway (CobraPLA) is a novel airway device with a larger pharyngeal cuff (when inflated). We tested the hypothesis that the CobraPLA was superior to the LMA with regard to insertion time and airway sealing pressure and comparable to the LMA in airway adequacy and recovery characteristics. After midazolam and fentanyl administration, 81 ASA physical status I-II outpatients having elective surgery were randomized to receive an LMA or CobraPLA. Anesthesia was induced with propofol (2.5 mg/kg IV), and the airway was inserted. We measured 1) insertion time; 2) adequacy of the airway (no leak at 15-cm-H 2 O peak pressure or tidal volume of 5 mL/kg); 3) airway sealing pressure; 4) number of repositioning attempts; and 5) sealing quality (no leak at tidal volume of 8 mL/kg). At the end of surgery, gastric insufflation, postoperative sore throat, dysphonia, and dysphagia were evaluated. Data were compared with unpaired Student's t-tests, X 2 tests, or Fisher's exact tests; P < 0.05 was significant. Patient characteristics, insertion times, airway adequacy, number of repositioning attempts, and recovery were similar in each group. Airway sealing pressure was significantly greater with CobraPLA (23 ± 6 cm H 2 O) than LMA (18 ± 5 cm H 2 O, P < 0.001). The CobraPLA has insertion characteristics similar to the LMA but better airway sealing capabilities.
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- 2004
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11. Fever during anaesthesia
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Chiharu Negishi and Rainer Lenhardt
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Anesthesia, Epidural ,Narcotics ,Hyperthermia ,Fever ,Inflammation ,Anesthesia, General ,Postoperative Complications ,medicine ,Humans ,General anaesthesia ,Antipyretic ,business.industry ,Perioperative ,Analgesics, Non-Narcotic ,Thermoregulation ,medicine.disease ,Analgesics, Opioid ,Anesthesiology and Pain Medicine ,Opioid ,Surgical Procedures, Operative ,Anesthesia ,Etiology ,medicine.symptom ,business ,Adjuvants, Anesthesia ,medicine.drug - Abstract
Fever occurs when pyrogenic stimulation activates thermal control centres. Fever is common during the perioperative period, but rare during anaesthesia. Although only a limited number of studies are available to explain how anaesthesia affects fever, general anaesthesia seems to inhibit fever by decreasing the thermoregulatory-response thresholds to cold. Opioids also inhibit fever; however, the effect is slightly less than that of general anaesthesia. In contrast, epidural anaesthesia does not affect fever. This suggests that hyperthermia, which is often associated with epidural infusions during labour or in the post-operative period, may be a true fever caused by inflammatory activation. Accordingly, this fever might be diminished in patients who receive opioids for pain treatment. Post-operative fever is a normal thermoregulatory response usually of non-infectious aetiology. Fever may be important in the host defence mechanisms and should not be routinely treated lest the associated risks exceed the benefits.
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- 2003
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12. Monitoring and thermal management
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Rainer Lenhardt
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Clinical Trials as Topic ,Core (anatomy) ,Core cooling ,business.industry ,Hypothermia ,Perioperative ,Thermal management of electronic devices and systems ,Anesthesia, General ,Perioperative Care ,Body Temperature ,Anesthesiology and Pain Medicine ,Intravenous fluid ,Hypothermia, Induced ,Surgical Procedures, Operative ,Anesthesia ,medicine.artery ,Pulmonary artery ,medicine ,Humans ,Forced-air ,medicine.symptom ,business ,Monitoring, Physiologic - Abstract
Anaesthesia alters normal thermoregulatory control of the body, usually leading to perioperative hypothermia. Hypothermia is associated with a large number of serious complications. To assess perianaesthetic hypothermia, core temperature should be monitored vigorously. Pulmonary artery, tympanic membrane, distal oesophageal or nasopharyngeal temperatures reflect core temperature reliably. Core temperatures can be often estimated with reasonable accuracy using oral, axillary and bladder temperatures, except during extreme thermal perturbations. The body site for measurements should be chosen according to the surgical procedure. Unless hypothermia is specifically indicated, efforts should be made to maintain intraoperative core temperatures above 36 degrees C. Forced air is the most effective, commonly available, non-invasive warming method. Resistive heating electrical blankets and circulating water garment systems are an equally effective alternative. Intravenous fluid warming is also helpful when large volumes are required. In some patients, induction of mild therapeutic hypothermia may become an issue for the future. Recent studies indicate that patients suffering from neurological disease may profit from rapid core cooling.
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- 2003
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13. Dexmedetomidine and Meperidine Additively Reduce the Shivering Threshold in Humans
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Nobutada Morioka, Andrew R. Bjorksten, Ozan Akca, Edwin B. Liem, M. Suleman, Daniel I. Sessler, Chun-Ming Lin, Anthony G. Doufas, Rainer Lenhardt, and Yunus M. Shah
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Adult ,Male ,Tympanic Membrane ,Adolescent ,Meperidine ,Partial Pressure ,Sedation ,Receptors, Opioid, mu ,Hemodynamics ,Frisson ,Body Temperature ,Oxygen Consumption ,Hypothermia, Induced ,medicine ,Humans ,Wakefulness ,Dexmedetomidine ,Advanced and Specialized Nursing ,business.industry ,Respiration ,Shivering ,Drug Synergism ,Carbon Dioxide ,Hypothermia ,Pethidine ,Opioid ,Vasoconstriction ,Depression, Chemical ,Anesthesia ,Neurology (clinical) ,medicine.symptom ,Skin Temperature ,Cardiology and Cardiovascular Medicine ,business ,Adrenergic alpha-Agonists ,medicine.drug - Abstract
Background and Purpose— Hypothermia might prove to be therapeutically beneficial in stroke victims; however, even mild hypothermia provokes vigorous shivering. Meperidine and dexmedetomidine each linearly reduce the shivering threshold (triggering core temperature) with minimal sedation. We tested the hypothesis that meperidine and dexmedetomidine synergistically reduce the shivering threshold without producing substantial sedation or respiratory depression. Methods— We studied 10 healthy male volunteers (18 to 40 years) on 4 days: (1) control (no drug); (2) meperidine (target plasma level 0.3 μg/mL); (3) dexmedetomidine (target plasma level 0.4 ng/mL); and (4) meperidine plus dexmedetomidine (target plasma levels of 0.3 μg/mL and 0.4 ng/mL, respectively). Lactated Ringer’s solution (≈4°C) was infused through a central venous catheter to decrease tympanic membrane temperature by ≈2.5°C/h; mean skin temperature was maintained at 31°C. An increase in oxygen consumption >25% of baseline identified the shivering threshold. Sedation was evaluated by using the Observer’s Assessment of Sedation/Alertness scale. Two-way repeated-measures ANOVA was used to identify interactions between drugs. Data are presented as mean±SD; P Results— The shivering thresholds on the study days were as follows: control, 36.7±0.3°C; dexmedetomidine, 36.0±0.5°C ( P P P P =0.19). There was trivial sedation with either drug alone or in combination. Respiratory rate and end-tidal P co 2 were well preserved on all days. Conclusions— Dexmedetomidine and meperidine additively reduce the shivering threshold; in the small doses tested, the combination produced only mild sedation and no respiratory toxicity.
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- 2003
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14. Effects of supplemental oxygen and dexamethasone on surgical site infection: a factorial randomized trial‡
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Barbara Kabon, Endrit Bala, Donal J. Buggy, Raghavendra Govinda, Jagan Devarajan, Andrea Kurz, Ramatia Mahboobi, Ina Ratzenboeck, Friedrich Herbst, Karl Schebesta, Corinna Marschalek, E. Fleischmann, Ozan Akca, B. McGuire, Anton Stift, A. Kurz, Adrian Alvarez, Siun Burke, Ankit Maheshwari, Anthony G. Doufas, Sara Kazerounian, Katja Schlemitz, Luke F. Reynolds, Akikio Taguchi, Yusuke Kasuya, Luca Stocchi, Edith Fleischmann, Mujeeb Arain, Christian C. Apfel, Suman Rajogopalan, Rainer Lenhardt, Susan Galandiuk, D. I. Sessler, Papiya Sengupta, D.J. Buggy, Anupama Wadhwa, Erol Erdik, Mukadder Orhan-Sungur, Sonja Sindhuber, Jackie Ragheb, Pia Mikocki, Eva Obewegeser, Ryu Komatsu, Monika Niedermayer, Hassan Nagem, Samuel T. Chen, Edward J. Mascha, Romana Rozum, Daniel I. Sessler, Andre Kugener, and Klaus Eredics
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Male ,Nausea ,medicine.medical_treatment ,Placebo ,Dexamethasone ,law.invention ,Postoperative Complications ,Randomized controlled trial ,law ,Oxygen therapy ,Medicine ,Humans ,Surgical Wound Infection ,business.industry ,Incidence ,Perioperative ,Middle Aged ,Oxygen ,Anesthesiology and Pain Medicine ,Anesthesia ,Vomiting ,Antiemetics ,Female ,medicine.symptom ,business ,Colorectal Surgery ,Postoperative nausea and vomiting ,medicine.drug - Abstract
Background Tissue oxygenation is a strong predictor of surgical site infection. Improving tissue oxygenation should thus reduce wound infection risk. Supplemental inspired oxygen can improve tissue oxygenation, but whether it reduces infection risk remains controversial. Low-dose dexamethasone is often given to reduce the risk of postoperative nausea and vomiting, but steroid-induced immunosuppression can increase infection risk. We therefore tested the hypotheses that supplemental perioperative oxygen reduces infection risk and that dexamethasone increases it. Methods Using a factorial design, patients having colorectal resections expected to last ≥2 h were randomly assigned to 30% (n=270) or 80% (n=285) inspired oxygen during and for 1 h after surgery, and to 4 mg intraoperative dexamethasone (n=283) or placebo (n=272). Physicians blinded to group assignments evaluated wounds postoperatively, using US Centers for Disease Control criteria. Results Subject and surgical characteristics were similar among study groups. Surgical site infection incidence was similar among groups: 30% oxygen 15.6%, 80% oxygen 15.8% (P=1.00); dexamethasone 15.9%, placebo 15.4%, (P=0.91). Conclusions Supplemental oxygen did not reduce surgical site infection risk. The preponderance of clinical evidence suggests that administration of 80% supplemental inspired oxygen does not reduce infection risk. We did not observe an increased risk of surgical site infection with the use of a single low dose of dexamethasone, indicating that it can be used for nausea and vomiting prophylaxis without promoting wound infections. Clinical trial registration ClinicalTrials.gov number: NCT00273377.
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- 2014
15. Opioids Inhibit Febrile Responses in Humans, Whereas Epidural Analgesia Does Not
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Rainer Lenhardt, Hiva Bastanmehr, Katharine Ettinger, Andrew R. Bjorksten, Makoto Ozaki, Daniel I. Sessler, and Chiharu Negishi
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Hyperthermia ,medicine.medical_specialty ,Ropivacaine ,Local anesthetic ,medicine.drug_class ,business.industry ,medicine.disease ,Fentanyl ,Surgery ,Route of administration ,Anesthesiology and Pain Medicine ,Opioid ,Anesthesia ,Anesthetic ,medicine ,Antipyretic ,business ,medicine.drug - Abstract
Background Epidural analgesia is frequently associated with hyperthermia during labor and in the postoperative period. The conventional assumption is that hyperthermia is caused by the technique, although no convincing mechanism has been proposed. However, pain in the "control" patients is inevitably treated with opioids, which themselves attenuate fever. Fever associated with infection or tissue injury may then be suppressed by opioids in the "control" patients while being expressed normally in patients given epidural analgesia. The authors therefore tested the hypothesis that fever in humans is manifested normally during epidural analgesia, but is suppressed by low-dose intravenous opioid. Methods The authors studied eight volunteers, each on four study days. Fever was induced each day by 150 IU/g intravenous interleukin 2. Volunteers were randomly assigned to: (1) a control day when no opioid or epidural analgesia was given; (2) epidural analgesia using ropivacaine alone; (3) epidural analgesia using ropivacaine in combination with 2 microg/ml fentanyl; or (4) intravenous fentanyl at a target plasma concentration of 2.5 ng/ml. Results Fentanyl halved the febrile response to pyrogen, decreasing integrated core temperature from 7.0 +/- 3.2 degrees C. h on the control day, to 3.8 +/- 3.0 degrees C. h on the intravenous fentanyl day. In contrast, epidural ropivacaine and epidural ropivacaine-fentanyl did not inhibit fever. The fraction of core-temperature measurements that exceeded 38 degrees C was halved by intravenous fentanyl, and the fraction exceeding 38.5 degrees C was reduced more than fivefold. Conclusions These data support the authors' proposed mechanism for hyperthermia during epidural analgesia. Fever during epidural analgesia should thus not be considered a complication of the anesthetic technique per se.
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- 2001
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16. Alfentanil reduces the febrile response to interleukin-2 in humans
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Makoto Ozaki, Chiharu Negishi, Rainer Lenhardt, Kathleen Vuong, Andrew R. Bjorksten, Jin Soo Kim, Daniel I. Sessler, and Hiva Bastanmehr
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Adult ,Male ,Hyperthermia ,Agonist ,Fever ,medicine.drug_class ,Sedation ,Critical Care and Intensive Care Medicine ,medicine ,Humans ,Alfentanil ,Volunteer ,Dose-Response Relationship, Drug ,business.industry ,Interleukin ,medicine.disease ,Crossover study ,Analgesics, Opioid ,Opioid ,Anesthesia ,Interleukin-2 ,medicine.symptom ,business ,Body Temperature Regulation ,medicine.drug - Abstract
OBJECTIVE Manifestation of intraoperative fever is impaired by volatile anesthetics and muscle relaxants. Opioids are common anesthetic adjuvants and remain the dominant treatment for postoperative surgical pain and sedation of critically ill patients. The effect of opioids on normal thermoregulatory control is well established. However, the extent to which these drugs might inhibit fever remains unknown. Accordingly, we tested the hypothesis that relatively low plasma concentrations of the mu-receptor agonist alfentanil reduce fever magnitude. DESIGN Prospective, randomized, crossover study. SETTING Outcomes Research Laboratory, at the Department of Anesthesia and Perioperative Care, University of California, San Francisco. PATIENTS Eight healthy male volunteers, aged 25-31 yrs, each studied on three separate days. INTERVENTION Each volunteer was given an intravenous injection of 30 IU/g interleukin (IL)-2, followed 2 hrs later by 70 IU/g. One hour after the second dose, the volunteers were randomly assigned to three doses of alfentanil: a) none (control); b) a target plasma concentration of 100 ng/mL; and c) a target concentration of 200 ng/mL. Opioid administration continued for 5 hrs. METHODS AND MAIN RESULTS Alfentanil significantly reduced the febrile response to pyrogen, decreasing integrated tympanic membrane temperatures from 7.5+/-2.2 degrees C x hr on the control day, to 4.9+/-1.5 degrees C x hr with 100 ng/mL alfentanil, and to 5.1+/-1.7 degrees C x hr with 200 ng/mL alfentanil (p = .011). Peak temperatures were also significantly reduced from 38.5+/-0.4 degrees C on the control day, to 38.0+/-0.4 degrees C on the 100 ng/mL-alfentanil day and 38.0+/-0.6 degrees C on the 200-ng/mL day (p = .019). Plasma cytokine concentrations increased after IL-2 administration, roughly in proportion to the elevation in core temperature. However, cytokine concentrations did not differ significantly among the treatment groups. CONCLUSION Alfentanil significantly reduced the febrile response to IL-2 administration. However, the reduction was comparable at plasma concentrations near 100 and 200 ng/mL. These data indicate that concentrations of opioids commonly observed in critical care patients significantly inhibit the manifestation of fever.
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- 2000
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17. Relative Contribution of Skin and Core Temperatures to Vasoconstriction and Shivering Thresholds during Isoflurane Anesthesia
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Rainer Lenhardt, Sonja Laciny, Angela Rajek, Robert Greif, Hiva Bastanmehr, and Daniel I. Sessler
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Adult ,Male ,Core (anatomy) ,Isoflurane ,business.industry ,Shivering ,Skin temperature ,Thermoregulation ,Frisson ,Body Temperature ,Anesthesiology and Pain Medicine ,Vasoconstriction ,Anesthesia ,Anesthetics, Inhalation ,medicine ,Humans ,medicine.symptom ,Anesthesia, Inhalation ,Skin Temperature ,business ,medicine.drug - Abstract
Background Thermoregulatory control is based on both skin and core temperatures. Skin temperature contributes approximately 20% to control of vasoconstriction and shivering in unanesthetized humans. However, this value has been used to arithmetically compensate for the cutaneous contribution to thermoregulatory control during anesthesia--although there was little basis for assuming that the relation was unchanged by anesthesia. It even remains unknown whether the relation between skin and core temperatures remains linear during anesthesia. We therefore tested the hypothesis that mean skin temperature contributes approximately 20% to control of vasoconstriction and shivering, and that the contribution is linear during general anesthesia. Methods Eight healthy male volunteers each participated on 3 separate days. On each day, they were anesthetized with 0.6 minimum alveolar concentrations of isoflurane. They then were assigned in random order to a mean skin temperature of 29, 31.5, or 34 degrees C. Their cores were subsequently cooled by central-venous administration of fluid at approximately 3 degrees C until vasoconstriction and shivering were detected. The relation between skin and core temperatures at the threshold for each response in each volunteer was determined by linear regression. The proportionality constant was then determined from the slope of this regression. These values were compared with those reported previously in similar but unanesthetized subjects. Results There was a linear relation between mean skin and core temperatures at the vasoconstriction and shivering thresholds in each volunteer: r2 = 0.98+/-0.02 for vasoconstriction, and 0.96+/-0.04 for shivering. The cutaneous contribution to thermoregulatory control, however, differed among the volunteers and was not necessarily the same for vasoconstriction and shivering in individual subjects. Overall, skin temperature contributed 21+/-8% to vasoconstriction, and 18+/-10% to shivering. These values did not differ significantly from those identified previously in unanesthetized volunteers: 20+/-6% and 19+/-8%, respectively. Conclusions The results in anesthetized volunteers were virtually identical to those reported previously in unanesthetized subjects. In both cases, the cutaneous contribution to control of vasoconstriction and shivering was linear and near 20%. These data indicate that a proportionality constant of approximately 20% can be used to compensate for experimentally induced skin-temperature manipulations in anesthetized as well as unanesthetized subjects.
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- 1999
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18. Tissue Heat Content and Distribution During and After Cardiopulmonary Bypass at 17[degree sign]C
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Ursula Jantsch, Rainer Lenhardt, Daniel I. Sessler, P. Mares, Martin Grabenwöger, Angela Rajek, Johannes Kastner, and Eva M. Gruber
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Adult ,Male ,Afterdrop ,Time Factors ,Core temperature ,Body Temperature ,law.invention ,Intraoperative Period ,Nuclear magnetic resonance ,Hypothermia, Induced ,law ,Cardiopulmonary bypass ,Humans ,Medicine ,Anesthesia ,Postoperative Period ,Rewarming ,Muscle, Skeletal ,Aged ,Aged, 80 and over ,Tissue temperature ,Leg ,Cardiopulmonary Bypass ,business.industry ,Hemodynamics ,Heat losses ,Skin temperature ,Middle Aged ,Thermoregulation ,Anesthesiology and Pain Medicine ,Circulacion extracorporea ,Arm ,Thermodynamics ,Female ,Skin Temperature ,business - Abstract
UNLABELLED We measured afterdrop and peripheral tissue temperature distribution in eight patients cooled to approximately 17 degrees C during cardiopulmonary bypass and subsequently rewarmed to 36.5 degrees C. A nasopharyngeal probe evaluated trunk and head temperature and heat content. Peripheral tissue temperature (arm and leg temperature) and heat content were estimated using fourth-order regressions and integration over volume from 30 tissue and skin temperatures. Peripheral tissue temperature decreased to 19.7+/-0.9 degrees C during bypass and subsequently increased to 34.3+/-0.7 degrees C during 104+/-18 min of rewarming. The core-to-peripheral tissue temperature gradient was -5.9+/-0.9 degrees C at the end of cooling and 4.7+/-1.5 degrees C at the end of rewarming. The core-temperature afterdrop was 2.2+/-0.4 degrees C and lasted 89+/-15 min. It was associated with 1.1+/-0.7 degrees C peripheral warming. At the end of cooling, temperatures at the center of the upper and lower thigh were (respectively) 8.0+/-5.2 degrees C and 7.3+/-4.2 degrees C cooler than skin temperature. On completion of rewarming, tissue at the center of the upper and lower thigh were (respectively) 7.0+/-2.2 degrees C and 6.4+/-2.3 degrees C warmer than the skin. When estimated systemic heat loss was included in the calculation, redistribution accounted for 73% of the afterdrop, which is similar to the contribution observed previously in nonsurgical volunteers. IMPLICATIONS Temperature afterdrop after bypass at 17 degrees C was 2.2+/-0.4 degrees C, with approximately 73% of the decrease in core temperature resulting from core-to-peripheral redistribution of body heat. Cooling and rewarming were associated with large radial tissue temperature gradients in the thigh.
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- 1999
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19. The effect of Pyrogen Administration on Sweating and Vasoconstriction Thresholds during Desflurane Anesthesia
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Hiva Bastanmehr, Katharine Ettinger, Errol Lobo, Makoto Ozaki, Rainer Lenhardt, Chiharu Negishi, and Daniel I. Sessler
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Adult ,Male ,Hyperthermia ,Sympathetic nervous system ,Minimum alveolar concentration ,Fever ,General anesthetics ,Sweating ,Desflurane ,medicine ,Recombinant interleukin-2 ,Humans ,Isoflurane ,business.industry ,Thermoregulation ,medicine.disease ,Anesthesiology and Pain Medicine ,medicine.anatomical_structure ,Vasoconstriction ,Anesthesia ,Anesthetics, Inhalation ,Interleukin-2 ,medicine.symptom ,Anesthesia, Inhalation ,business ,Body Temperature Regulation ,medicine.drug - Abstract
Background General anesthetics increase the sweating-to-vasoconstriction interthreshold range (temperatures not triggering thermoregulatory defenses), whereas fever is believed to only increase the setpoint (target core temperature). However, no data characterize thresholds (temperatures triggering thermoregulatory defenses) during combined anesthesia and fever. Most likely, the combination produces an expanded interthreshold range around an elevated setpoint. The authors therefore tested the hypothesis that thermoregulatory response thresholds during the combination of fever and anesthesia are simply the linear combination of the thresholds resulting from each intervention alone. Methods The authors studied eight healthy male volunteers. Fever was induced on the appropriate days by intravenous injection of 30 IU/g human recombinant interleukin 2 (IL-2), followed 2 h later by an additional 70 IU/g. General anesthesia consisted of desflurane 0.6 minimum alveolar concentration (MAC). The volunteers were randomly assigned to the following groups: (1) control (no desflurane, no IL-2); (2) IL-2 alone; (3) desflurane alone; and (4) desflurane plus IL-2. During the fever plateau, volunteers were warmed until sweating was observed and then cooled to vasoconstriction. Sweating was evaluated from a ventilated capsule and vasoconstriction was quantified by volume plethysmography. The tympanic membrane temperatures triggering significant sweating and vasoconstriction identified the respective response thresholds. Data are presented as the mean +/- SD; P < 0.05 was considered significant. Results The interthreshold range was near 0.40 degrees C on both the control day and during IL-2 administration alone. On the IL-2 alone day, however, the interthreshold range was shifted to higher temperatures. The interthreshold range increased significantly during desflurane anesthesia to 1.9+/-0.6 degrees C. The interthreshold range during the combination of desflurane and IL-2 was 1.2+/-0.6 degrees C, which was significantly greater than on the control and IL-2 alone days. However, it was also significantly less than during desflurane alone. Conclusion The combination of desflurane and IL-2 caused less thermoregulatory inhibition than would be expected based on the effects of either treatment alone. Fever-induced activation of the sympathetic nervous system may contribute by compensating for a fraction of the anesthetic-induced thermoregulatory impairment.
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- 1999
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20. The effects of physical treatment on induced fever in humans
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Rainer Lenhardt, Andrew R. Bjorksten, Chiharu Negishi, Kathleen Vuong, Daniel I. Sessler, Jin Soo Kim, and Hiva Bastanmehr
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Adult ,Male ,Core (anatomy) ,Mean arterial pressure ,Fever ,business.industry ,General Medicine ,Thermoregulation ,Body Temperature ,Human Experimentation ,Epinephrine ,Anesthesia ,Active cooling ,Shivering ,medicine ,Humans ,Antipyretic ,medicine.symptom ,Skin Temperature ,business ,Volunteer ,Body Temperature Regulation ,medicine.drug - Abstract
Initial treatments for fever include the amelioration of underlying causes and administration of antipyretic medications. However, patients who fail these treatments are often actively cooled, which may be counterproductive because decreasing skin temperature increases the thermoregulatory core target temperature. Cooling may also provoke metabolic and autonomic stress and thermal discomfort.We studied 9 subjects, each on 3 days. Fever was induced each day with 100,000 IU/kg of interleukin-2 administered intravenously (elapsed time zero). Randomly assigned treatments were 1) control (a cotton blanket), 2) cooling (forced air at 15 degrees C), or 3) self-adjust (forced-air warming adjusted to comfort). Treatments were maintained for 3 to 8 elapsed hours.Peak core temperatures (mean +/- SD) were 38.4 +/- 0.5 degrees C on the control day, 38.1 +/- 0.5 degrees C on the cooling day, and 38.5 +/- 0.4 degrees C on the self-adjust day. Integrated core temperatures were 6.0 +/- 1.6 degrees C x h on the control day, 5.7 +/- 2.2 degrees C x h on the cooling day, and 6.4 +/- 1.2 degrees C x h on the self-adjust day. Neither peak nor integrated core temperatures differed significantly on the 3 days. Shivering was common on the cooling day but otherwise rare. Oxygen consumption was normal on the control and self-adjust days but increased 35% to 40% during cooling (P = 0.0001). Mean arterial pressure and plasma norepinephrine and epinephrine concentrations were significantly greater during cooling (P0.05). On a self-reported thermal comfort scale, the subjects were miserable during cooling and significantly more comfortable on the self-adjust than control day (P0.05).We conclude that active cooling should be avoided in unsedated patients with moderate fever, because it does not reduce core temperature but does increase metabolic rate, activate the autonomic nervous system, and provoke thermal discomfort.
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- 1999
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21. Bispectral EEG Index during Nitrous Oxide Administration
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Chiharu Negishi, Rainer Lenhardt, Ira J. Rampil, Daniel I. Sessler, and Jin Soo Kim
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Adult ,Male ,medicine.diagnostic_test ,Electrodiagnosis ,business.industry ,medicine.drug_class ,Sedation ,Nitrous Oxide ,Electroencephalography ,Nitrous oxide ,equipment and supplies ,chemistry.chemical_compound ,Anesthesiology and Pain Medicine ,Nitrogen Protoxide ,chemistry ,Bispectral index ,Sedative ,Anesthesia ,medicine ,Humans ,Hypnotics and Sedatives ,Female ,medicine.symptom ,business - Abstract
Background Nitrous oxide (N2O) is a commonly used sedative for painful diagnostic procedures and dental work. The authors sought to characterize the effects of N2O on quantitative electroencephalographic (EEG) variables including the bispectral index (BIS), a quantitative parameter developed to correlate with the level of sedation induced by a variety of agents. Methods Healthy young adult volunteers (n = 13) were given a randomized sequence of N2O/O2 combinations via face mask. Five concentrations of N2O (10, 20, 30, 40, and 50% atm) were administered for 15 min (20 min for the first step). EEG was recorded from bilateral frontal poles continuously. At the end of each exposure, level of sedation was assessed using primarily the Observer Assessment of Alertness/Sedation (OAA/S) scale. Results One subject withdrew from the study because of emesis at 50% N2O. N2O (50%) increased theta, beta, 40-50 Hz, and 70-110 Hz band powers. BIS and spectral edge frequency during 50% N2O/O2 did not differ significantly from baseline values. Abrupt decreases from higher to lower concentrations frequently evoked a profound, transient slowing of activity. No significant change in OAA/S was detected during the study. Conclusions Although the spectral content of the EEG changed during N2O administration, reflecting some pharmacologic effect, the subjects remained cooperative and responsive throughout, and therefore N2O can only be considered a weak sedative at the tested concentrations. Despite changes in the lower and higher frequency ranges of EEG activity, the BIS did not change, which is consistent with its design objective as a specific measure of hypnosis.
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- 1998
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22. Paralysis Only Slightly Reduces the Febrile Response to Interleukin-2 during Isoflurane Anesthesia
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Rainer Lenhardt, Daniel I. Sessler, Makoto Ozaki, Farzin Tayefeh, Chiharu Negishi, and Andrea Kurz
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Hyperthermia ,Fever ,medicine.drug_class ,Frisson ,Aldesleukin ,Paralysis ,medicine ,Humans ,Anesthesia ,Vecuronium Bromide ,Isoflurane ,business.industry ,Shivering ,Muscle relaxant ,medicine.disease ,Anesthesiology and Pain Medicine ,Vasoconstriction ,Anesthetics, Inhalation ,Interleukin-2 ,medicine.symptom ,Vecuronium bromide ,business ,Body Temperature Regulation ,Neuromuscular Nondepolarizing Agents ,medicine.drug - Abstract
Background Fever sometimes occurs during anesthesia. However, it is rare considering how often pyrogenic causes are likely to be present and how common fever is after surgery. This low incidence results in part from dose-dependent inhibition of fever by volatile anesthetics. Paralysis, however, may contribute by preventing shivering and the associated increase in metabolic heat production. Therefore the authors tested the hypothesis that paralysis during anesthesia decreases the febrile response to pyrogen administration. Methods Seven volunteers each participated on two study days. They were given 30 IU/g intravenous interleukin-2, followed 90 min later by an additional 70 IU/g dose. Anesthesia was induced 30 min after the second dose and maintained for 6 h with 0.6 minimum alveolar concentration isoflurane. The volunteers were randomly assigned to (1) paralysis with vecuronium or (2) no muscle relaxants. Body heat content and distribution were determined from measured tissue and skin temperatures. Data are presented as mean +/- SD; P < 0.05 was considered significant. Results There was no clinically important difference in peak core (tympanic membrane) temperatures on the unparalyzed (37.6+/-0.9 degrees C) and paralyzed (37.2+/-0.6 degrees C) days. Core heat content increased 1.2+/-0.7 kcal/kg over the last 5 h of anesthesia on the unparalyzed day, but only by 0.9+/-0.4 kcal/kg when the volunteers were paralyzed. Peripheral tissue heat content increased 0.1+/-1.1 kcal/kg on the unparalyzed day but decreased 1.1+/-0.7 kcal/kg when the volunteers were paralyzed. Consequently, body heat content increased 1.3+/-1.3 kcal/kg on the unparalyzed day but decreased significantly by 0.2+/-0.8 kcal/kg when the volunteers were paralyzed. Conclusions Paralysis prevented shivering from increasing the metabolic rate. Consequently, body heat content decreased during paralysis, whereas otherwise it increased. Thermoregulatory vasoconstriction was nonetheless able to maintain similar peak and integrated core temperatures on each study day. Administration of muscle relaxants thus is not the primary explanation for the relative paucity of intraoperative fever.
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- 1998
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23. Tissue Heat Content and Distribution during and after Cardiopulmonary Bypass at 31 [degree sign]C and 27 [degree sign]C
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Andrea Kurz, Angela Rajek, Richard Christensen, Günther Laufer, Michael Hiesmayr, Daniel I. Sessler, Takashi Matsukawa, and Rainer Lenhardt
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Adult ,Male ,Afterdrop ,Body Temperature ,law.invention ,Nuclear magnetic resonance ,Hypothermia, Induced ,law ,Cardiopulmonary bypass ,Humans ,Medicine ,Cardiac Surgical Procedures ,Aged ,Tissue temperature ,Cardiopulmonary Bypass ,business.industry ,Total body ,Peripheral compartment ,Middle Aged ,Thermoregulation ,Hypothermia ,Peripheral ,Anesthesiology and Pain Medicine ,Anesthesia ,Female ,medicine.symptom ,business - Abstract
Background Afterdrop following cardiopulmonary bypass results from redistribution of body heat to inadequately warmed peripheral tissues. However, the distribution of heat between the thermal compartments and the extent to which core-to-peripheral redistribution contributes to post-bypass hypothermia remains unknown. Methods Patients were cooled during cardiopulmonary bypass to nasopharyngeal temperatures near 31 degrees C (n=8) or 27 degrees C (n=8) and subsequently rewarmed by the bypass heat exchanger to approximately 37.5 degrees C. A nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. Results In the 31 degrees C group, the average peripheral tissue temperature decreased to 31.9+/-1.4 degrees C (means+/-SD) and subsequently increased to 34+/-1.4 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 3.5+/-1.8 degrees C at the end of rewarming, and the afterdrop was 1.5+/-0.4 degrees C. Total body heat content decreased 231+/-93 kcal. During pump rewarming, the peripheral heat content increased to 7+/-27 kcal below precooling values, whereas the core heat content increased to 94+/-33 kcal above precooling values. Body heat content at the end of rewarming was thus 87+/-42 kcal more than at the onset of cooling. In the 27 degrees C group, the average peripheral tissue temperature decreased to a minimum of 29.8 +/-1.7 degrees C and subsequently increased to 32.8+/-2.1 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 4.6+/-1.9 degrees C at the end of rewarming, and the afterdrop was 2.3+/-0.9 degrees C. Total body heat content decreased 419+/-49 kcal. During pump rewarming, core heat content increased to 66+/-23 kcal above precooling values, whereas peripheral heat content remained 70+/-42 kcal below precooling values. Body heat content at the end of rewarming was thus 4+/-52 kcal less than at the onset of cooling. Conclusions Peripheral tissues failed to fully rewarm by the end of bypass in the patients in the 27 degrees C group, and the afterdrop was 2.3+/-0.9 degrees C. Peripheral tissues rewarmed better in the patients in the 31 degrees C group, and the afterdrop was only 1.5+/-0.4 degrees C.
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- 1998
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24. Anesthetic considerations
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Stuart Bertsch, Rainer Lenhardt, and Ozan Akca
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business.industry ,Anesthesia ,Anesthetic ,Medicine ,business ,medicine.drug - Published
- 2014
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25. Assessment of perioperative hypothermia
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Rainer Lenhardt
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Anesthesiology and Pain Medicine ,business.industry ,Anesthesia ,Medicine ,Perioperative ,Hypothermia ,medicine.symptom ,business - Published
- 1997
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26. Undetected hypoglycemia in a patient receiving TPN
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Saeed A. Jortani, Lynn Nelson, Rainer Lenhardt, Daniel A. Rosenblatt, and Thomas Kampfrath
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Blood Glucose ,medicine.medical_specialty ,Supine position ,Time Factors ,medicine.medical_treatment ,Point-of-Care Systems ,Clinical Biochemistry ,Hypoglycemia ,Biochemistry ,Glucose testing ,Crohn Disease ,medicine ,Humans ,Hypoglycemic Agents ,Insulin ,Diagnostic Errors ,Intensive care medicine ,Point of care ,Crohn's disease ,Abstract case ,Blood Specimen Collection ,business.industry ,Biochemistry (medical) ,Malnutrition ,General Medicine ,Middle Aged ,medicine.disease ,Parenteral nutrition ,Anesthesia ,Female ,Parenteral Nutrition, Total ,business - Abstract
Case report A 58-year-old female was admitted to the hospital in a severely malnourished state. She was treated for Crohn's disease with total parental nutrition (TPN). The patient's blood glucose was monitored by point of care (POC) testing every 4 h, and a specimen is also drawn daily for metabolic assessment. The POC blood glucose values were consistently much higher than the lab values. Humalog insulin (5 U) was given to the patient to decrease high blood glucose levels that developed following administration of TPN. The patient then became hypoglycemic as a result of this insulin treatment. POC glucose testing, performed every 4 h, did not detect the iatrogenic hypoglycemia, while lab glucose results were not given close attention. The lab sample was always drawn 1–2 h after insulin was given to the patient and resulted in a lower blood glucose value. In addition, the symptoms of hypoglycemia such as shaking and dizziness were masked by the patient's poor health status, supine position, and the continuously given TPN. Conclusions These findings highlighted the importance of the correct sampling time following insulin administration and the consideration of the lab results in addition to POC. The patient's insulin regimen was modified to prevent further hypoglycemic events.
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- 2013
27. Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization
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Andrea Kurz, Daniel I. Sessler, and Rainer Lenhardt
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medicine.medical_specialty ,business.industry ,Surgical wound ,General Medicine ,Perioperative ,Hypothermia ,Fluid warmer ,Colorectal surgery ,Oxygen tension ,Surgery ,Anesthesia ,Anesthetic ,medicine ,Cefamandole ,medicine.symptom ,business ,medicine.drug - Abstract
Background Mild perioperative hypothermia, which is common during major surgery, may promote surgical-wound infection by triggering thermoregulatory vasoconstriction, which decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissue impair oxidative killing by neutrophils and decrease the strength of the healing wound by reducing the deposition of collagen. Hypothermia also directly impairs immune function. We tested the hypothesis that hypothermia both increases susceptibility to surgical-wound infection and lengthens hospitalization. Methods Two hundred patients undergoing colorectal surgery were randomly assigned to routine intraoperative thermal care (the hypothermia group) or additional warming (the normothermia group). The patients' anesthetic care was standardized, and they were all given cefamandole and metronidazole. In a double-blind protocol, their wounds were evaluated daily until discharge from the hospital and in the clinic after two weeks; wounds containing culture-positive pu...
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- 1996
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28. PERIOPERATIVE HYPOTHERMIA DOES NOT INCREASE THE RISK OF CANCER DISSEMINATION
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Yueksel Yücel, Daniel I. Sessler, Rainer Lenhardt, and Murat Barlan
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Anesthesiology and Pain Medicine ,business.industry ,Anesthesia ,Medicine ,Cancer ,Perioperative ,Hypothermia ,medicine.symptom ,business ,medicine.disease - Published
- 2003
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29. The effect of anesthesia on body temperature control
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Rainer Lenhardt
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Fever ,Sweating ,Hypothermia ,Anesthesia, General ,Autonomic Nervous System ,General Biochemistry, Genetics and Molecular Biology ,Postoperative fever ,Postoperative Complications ,Anesthesia, Conduction ,medicine ,Coagulopathy ,Humans ,Anesthesia ,Adverse effect ,Intraoperative Complications ,Anesthetics ,General Immunology and Microbiology ,business.industry ,Shivering ,Perioperative ,Thermoregulation ,medicine.disease ,Vasodilation ,Vasoconstriction ,medicine.symptom ,business ,Body Temperature Regulation - Abstract
The human thermoregulatory system usually maintains core body temperature near 37 degrees C. This homeostasis is accomplished by thermoregulatory defense mechanisms such as vasoconstriction and shivering or sweating and vasodilatation. Thermoregulation is impaired during general anesthesia. Suppression of thermoregulatory defense mechanisms during general anesthesia is dose dependant and mostly results in perioperative hypothermia. Several adverse effects of hypothermia have been identified, including an increase in postoperative wound infection, perioperative coagulopathy and an increase of postoperative morbid cardiac events. Perioperative hypothermia can be avoided by warming patients actively during general anesthesia. Fever is a controlled increase of core body temperature. Various causes of perioperative fever are given. Fever is usually attenuated by general anesthesia. Typically, patients develop a fever of greater magnitude in the postoperative phase. Postoperative fever is fairly common. The incidence of fever varies with type and duration of surgery, patient's age, surgical site and preoperative inflammation.
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- 2010
30. Hyperthermia during anaesthesia and intensive care unit stay
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Martin Grady, Andrea Kurz, and Rainer Lenhardt
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Hyperthermia ,Fever ,business.industry ,Incidence (epidemiology) ,Critical Illness ,Malignant hyperthermia ,Regional anaesthesia ,Thermoregulation ,Length of Stay ,medicine.disease ,Intensive care unit ,law.invention ,Intensive Care Units ,Anesthesiology and Pain Medicine ,law ,Anesthesia ,medicine ,Humans ,In patient ,Nervous System Diseases ,Practice Patterns, Physicians' ,business ,Severe sepsis - Abstract
Nosocomial hyperthermia (fever) occurs in about 30% of all medical patients at some time during their hospital stay. In patients admitted to the intensive care unit with severe sepsis the incidence of hyperthermia is greater than 90%, while in a specialized neurological critical care unit the incidence is reported as 47%. In contrast, hyperthermia during anaesthesia is rare owing to the impairment of thermoregulation by anaesthetic agents. This article is designed to give an overview on the various causes of hyperthermia with special emphasis on fever during general and regional anaesthesia in general and neurological critical care patients.
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- 2009
31. New circulating-water devices warm more quickly than forced-air in volunteers
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Pamela Barnes, Mukadder Orhan-Sungur, Ryu Komatsu, Janghyeok In, Rainer Lenhardt, Anupama Wadhwa, and Daniel I. Sessler
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Adult ,Male ,Adolescent ,business.industry ,Energy transfer ,Air ,Water ,Core temperature ,Rate of increase ,Body Temperature ,Anesthesiology and Pain Medicine ,Lower body ,Anesthesia ,Healthy volunteers ,Medicine ,Humans ,Chest surgery ,Forced-air ,Rewarming ,business ,Warming rate ,Hydrotherapy - Abstract
BACKGROUND Newer circulating-water systems supply more heat than forced-air, mainly because the heat capacity of water is much greater than for that of dry warm air and, in part, because they provide posterior as well as anterior heating. Several heating systems are available, but three major ones have yet to be compared directly. We therefore compared two circulating-water systems with a forced-air system during simulation of upper abdominal or chest surgery in volunteers. METHODS Seven healthy volunteers participated on three separate study days. Each day, they were anesthetized and cooled to a core temperature near 34 degrees C, which was maintained for 45-60 min. They were then rewarmed with one of three warming systems until distal esophageal core temperature reached 36 degrees C or anesthesia had lasted 8 h. The warming systems were 1) energy transfer pads (two split torso pads and two universal pads; Kimberly Clark, Roswell, GA); 2) circulating-water garment (Allon MTRE 3365 for cardiac surgery, Akiva, Israel); and 3) lower body forced-air warming (Bair Hugger #525, #750 blower, Eden Prairie, MN). Data are presented as mean +/- sd; P < 0.05 was statistically significant. RESULTS The rate of increase of core temperature from 34 degrees C to 36 degrees C was 1.2 degrees C +/- 0.2 degrees C/h with the Kimberly Clark system, 0.9 degrees C +/- 0.2 degrees C/h with the Allon system, and 0.6 degrees C +/- 0.1 degrees C/h with the Bair Hugger (P = 0.002). CONCLUSIONS The warming rate with the Kimberly Clark system was 25% faster than with the Allon system and twice as fast as with the Bair Hugger. Both circulating-water systems thus warmed hypothermic volunteers in significantly less time than the forced-air system.
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- 2007
32. Temporal artery versus bladder thermometry during perioperative and intensive care unit monitoring
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Rainer Lenhardt, Oliver Kimberger, Delphine Cohen, and Udo M. Illievich
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Adult ,Male ,Adolescent ,Remote patient monitoring ,Thermometers ,Urinary Bladder ,Core temperature ,Sensitivity and Specificity ,Neurosurgical Procedures ,law.invention ,Body Temperature ,law ,Predictive Value of Tests ,Monitoring, Intraoperative ,medicine ,Humans ,Aged ,Monitoring, Physiologic ,Aged, 80 and over ,Urinary bladder ,business.industry ,Perioperative ,Middle Aged ,Intensive care unit ,Temporal Arteries ,Intensive Care Units ,Anesthesiology and Pain Medicine ,medicine.anatomical_structure ,Anesthesia ,Temporal artery ,Female ,business - Abstract
Core temperature measurements are an important component of perioperative patient monitoring. It is fairly easy to obtain core temperature measurements invasively in anesthetized patients. However, such measurements are more difficult to obtain noninvasively in awake patients. Recently, a new version of a temporal artery thermometer for noninvasive core temperature measurements (TemporalScanner TAT-5000) was introduced with accuracy and precision advertised as being comparable to invasive core temperature measurements. In this study, we sought to determine if this new thermometer is an acceptable substitute for invasive bladder temperature measurement.In 35 patients undergoing neurosurgical interventions and 35 patients in the neurosurgical intensive care unit, measurements from the temporal artery thermometer were compared with those from a bladder thermometer. Four measurements were obtained from each patient.Overall 280 measurement pairs were obtained. The mean bias between the methods was 0.07 degrees C +/- 0.79 degrees C; the limits of agreement were approximately 3 times greater than the a priori defined limit of +/-0.5 degrees C (-1.48 to 1.62). The sensitivity for detecting fever (core temperature37.8 degrees C) using the temporal artery thermometer was 0.72, and the specificity was 0.97. The positive predictive value for fever was 0.89; the negative predictive value was 0.94. The sensitivity for detecting hypothermia (core temperature35.5 degrees C) was 0.29, and the specificity was 0.95. The positive predictive value for hypothermia was 0.31, and the negative predictive value was 0.95.The results of this study do not support the use of temporal artery thermometry for perioperative core temperature monitoring; the temporal artery thermometer does not provide information that is an adequate substitute for core temperature measurement by a bladder thermometer.
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- 2007
33. Hyperthermia and Fever
- Author
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Rainer Lenhardt
- Subjects
Hyperthermia ,business.industry ,Anesthesia ,medicine ,medicine.disease ,business - Published
- 2004
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34. Pharmacokinetics of an implanted osmotic pump delivering sufentanil for the treatment of chronic pain
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Norma Kellett, Dennis M. Fisher, and Rainer Lenhardt
- Subjects
Adult ,Male ,Osmosis ,Sufentanil ,Population ,Pain ,Absorption (skin) ,Pharmacology ,Drug Delivery Systems ,Pharmacokinetics ,In vivo ,medicine ,Humans ,Local anesthesia ,education ,education.field_of_study ,business.industry ,Infusion Pumps, Implantable ,Bioavailability ,Anesthesiology and Pain Medicine ,Anesthesia ,Chronic Disease ,Female ,business ,Perfusion ,medicine.drug - Abstract
Background A matchstick-sized implanted osmotic pump (Chronogesic) that delivers sufentanil subcutaneously for more than 90 days is being developed to treat chronic pain. This study evaluates pharmacokinetic characteristics related to the absorption of sufentanil using a prototype 60-day system. Methods Twelve opioid-naive volunteers were given naltrexone to prevent opioid effects. Sufentanil, 60 microg, was infused intravenously over 6 h, then 48 h later, the pump was implanted subcutaneously in the upper arm under local anesthesia. Pumps were removed 9 days later. In six volunteers, fever (1.6-3.3 degrees C) was induced with interleukin-2. Plasma was sampled and population pharmacokinetic modeling was performed to estimate in vivo release rate and absorption half-life. Bioavailability was calculated by comparing in vivo to in vitro release rates. The impact of perturbations in release rate on sufentanil plasma concentration (Cp) was simulated. Results Fever had no systematic effect on Cp. Release rate estimated in vivo was similar to that measured in vitro; bioavailability did not differ from 100%. Absorption half-life was 16.2 h. Simulation demonstrated that supplemental release of sufentanil from the implant (as might occur with local heating) increases Cp an average of 2.5-2.8% per hours supplemental dose. Conclusions An implantable osmotic pump delivered sufentanil in vivo at the rate predicted from in vitro experiments. The rate at which sufentanil was absorbed from the subcutaneous space (half-life > 16 h) was markedly slower than reported with subcutaneous or intramuscular administration of large volumes of dilute opioids; this slow absorption dampens potential changes in Cp if release rate is perturbed.
- Published
- 2003
35. Can Transnasal Flexible Fiberoptic Laryngoscopy Contribute to Airway Management Decisions?
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Michael F. Heine, Ozan Akca, and Rainer Lenhardt
- Subjects
Anesthesiology and Pain Medicine ,business.industry ,medicine.medical_treatment ,Anesthesia ,Flexible fiberoptic laryngoscopy ,Medicine ,Airway management ,business - Published
- 2011
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36. Desflurane anesthesia inhibits fever in humans
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Rainer Lenhardt, Daniel I. Sessler, and Chiharu Negishi
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Male ,medicine.medical_specialty ,Time Factors ,Fever ,Isoflurane ,business.industry ,General Neuroscience ,Hemodynamics ,General Biochemistry, Genetics and Molecular Biology ,Surgery ,Body Temperature ,Desflurane ,History and Philosophy of Science ,Anesthesia ,Anesthetics, Inhalation ,Injections, Intravenous ,medicine ,Humans ,Interleukin-2 ,business ,Anesthesia, Inhalation ,medicine.drug - Published
- 1999
37. Desflurane reduces the febrile response to administration of interleukin-2
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Chiharu Negishi, Jan L. De Witte, Rainer Lenhardt, Daniel I. Sessler, Takehiko Ikeda, Errol Lobo, and Andrea Kurz
- Subjects
Hyperthermia ,Adult ,Male ,Minimum alveolar concentration ,Fever ,Anesthesia, General ,Body Temperature ,Desflurane ,medicine ,Humans ,Intraoperative Complications ,Dose-Response Relationship, Drug ,Isoflurane ,business.industry ,Area under the curve ,Hemodynamics ,Thermoregulation ,medicine.disease ,Recombinant Proteins ,Anesthesiology and Pain Medicine ,Anesthesia ,Anesthetics, Inhalation ,Shivering ,Interleukin-2 ,medicine.symptom ,business ,Vasoconstriction ,medicine.drug - Abstract
Background Intraoperative fever is relatively rare considering how often pyrogenic causes are likely to be present and how common fever is postoperatively. This low incidence suggests that general anesthesia per se inhibits the normal response to pyrogenic stimulation. The authors therefore tested the hypothesis that desflurane-induced anesthesia produces a dose-dependent inhibition of the febrile response. Methods Eight volunteers were studied, each on 3 study days. Each was given an intravenous injection of 50,000 IU/ kg of interleukin-2 (elapsed time, 0 h), followed 2 h later by 100,000 IU/kg. One hour after the second dose, the volunteers were assigned randomly to three doses of desflurane to induce anesthesia: (1) 0.0 minimum alveolar concentration (MAC; control), (2) 0.6 MAC, and (3) 1.0 MAC. Anesthesia continued for 5 h. Core temperatures were recorded from the tympanic membrane. Thermoregulatory vasoconstriction was evaluated using forearm-minus-fingertip skin temperature gradients; shivering was evaluated with electromyography. Integrated and peak temperatures during anesthesia were compared with repeated-measures analysis of variance and Scheffé's F tests. Results Values are presented as mean +/- SD. Desflurane reduced the integrated (area under the curve) febrile response to pyrogen, from 7.7 +/- 2.0 degrees C x h on the control day to 2.1 +/- 2.3 degrees C x h during 0.6 MAC and to -1.4 +/- 3.1 degrees C x h during 1.0 MAC desflurane-induced anesthesia. Peak core temperature (elapsed time, 5-8 h) decreased in a dose-dependent fashion: 38.6 +/- 0.5 degrees C on the control day, 37.7 +/- 0.7 degrees C during 0.6 MAC and 37.2 +/- 1.0 degrees C during 1.0 MAC desflurane anesthesia. Rising core temperature was always associated with fingertip vasoconstriction and often with shivering. Conclusions Desflurane-induced anesthesia produced a dose-dependent decrease in integrated and peak core temperatures after administration of pyrogen, with 1.0 MAC essentially obliterating fever. Anesthetic-induced inhibition of the pyrogenic response is therefore one reason that fever is an inconsistent clinical response to inflammation during surgery.
- Published
- 1998
38. Mild intraoperative hypothermia prolongs postanesthetic recovery
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E. Narzt, Elvine Marker, Heinz D. Tschernich, F. Lackner, Andrea Kurz, V. Goll, Rainer Lenhardt, and Daniel I. Sessler
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Adult ,Male ,medicine.medical_specialty ,Time Factors ,Hemodynamics ,Hypothermia ,Body Temperature ,Abdomen ,medicine ,Humans ,Prospective Studies ,Rewarming ,Intraoperative Complications ,Pain, Postoperative ,business.industry ,Analgesia, Patient-Controlled ,Thermoregulation ,Middle Aged ,Intraoperative hypothermia ,Surgery ,Anesthesiology and Pain Medicine ,Anesthesia ,Anesthetic ,Anesthesia Recovery Period ,Female ,medicine.symptom ,Complication ,business ,Hemodynamic instability ,medicine.drug - Abstract
Background Intraoperative hypothermia is common and persists for several hours after surgery. Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing hemodynamic instability, or depressing cognitive function. Accordingly, the authors tested the hypothesis that intraoperative hypothermia prolongs postoperative recovery. Methods Patients undergoing elective major abdominal surgery (n = 150) were anesthetized with isoflurane, nitrous oxide, and fentanyl. They were randomly assigned to routine thermal management (hypothermia) or extra warming (normothermia). Postoperative surgical pain was treated with patient-controlled analgesia. Fitness for discharge from the postanesthesia care unit was evaluated at 20-min intervals by investigators blinded to group assignment and postoperative core temperatures. Scoring was based on a modification of a previously published system that included activity, ventilation, consciousness, and hemodynamic responses. Patients were considered fit for discharge when they sustained a score of 80% (13 points) for at least two consecutive measurement periods. Results Morphometric characteristics and anesthetic management were similar in each group. Final intraoperative core temperatures differed by approximately 2 degrees C: 34.8 +/- 0.6 versus 36.7 +/- 0.6 degrees C (mean +/- SD, P < 0.001). Postoperative pain scores and postoperative use of patient-controlled opioid were similar. Hypothermic patients required approximately 40 min longer (94 +/- 65 vs. 53 +/- 36 min) to reach fitness for discharge, even when return to normothermia was not a criterion (P < 0.001). Duration of recovery in the two groups differed by approximately 90 min when a core temperature >36 degrees C was also required (P < 0.001). Conclusion Maintaining core normothermia decreases the duration of postanesthetic recovery and may, therefore, reduce costs of care.
- Published
- 1998
39. Morphometric influences on intraoperative core temperature changes
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E. Narzt, Franz Lackner, Andrea Kurz, Daniel I. Sessler, and Rainer Lenhardt
- Subjects
Adult ,Male ,Body Surface Area ,Analytical chemistry ,Core temperature ,Body Temperature ,Intraoperative Period ,Colon surgery ,Phase (matter) ,medicine ,Humans ,Anesthesia ,Aged ,Core (anatomy) ,business.industry ,Body Weight ,Thermoregulation ,Hypothermia ,Middle Aged ,Cooling rate ,Anesthesiology and Pain Medicine ,Vasoconstriction ,Surgical Procedures, Operative ,Body Constitution ,Female ,medicine.symptom ,business - Abstract
Intraoperative core hypothermia develops in three characteristic phases:1) core-to-peripheral redistribution of body heat that is most prominent during the first hour after induction of anesthesia; 2) subsequent slow linear decrease in core temperature resulting largely from heat loss exceeding metabolic heat production; and 3) core temperature plateau resulting when thermoregulatory vasoconstriction decreases cutaneous heat loss and constrains metabolic heat to the core thermal compartment. Accordingly, we tested the hypotheses that: 1) core cooling does not depend on body fat (BF) or the ratio of weight-to-surface area (Wt/SA) during the initial redistribution phase; 2) the core cooling rate is a function of the Wt/SA ratio during the second phase; and 3) the rate of core cooling during the plateau phase (after vasoconstriction) will be determined by the percentage of BF. In 40 patients undergoing elective colon surgery, the amount of redistribution hypothermia was inversely proportional to the percentage of BF (Delta TC = 0.034 centered dot BF - 2.2, r2 = 0.63) and the Wt/SA ratio (Delta TC = 0.052 centered dot Wt/SA - 3.35, r2 = 0.66). The core cooled linearly during the second phase, and the cooling rate was inversely proportional to the Wt/SA ratio (rate = 0.035 centered dot (Wt/SA) - 2.2, r2 = 0.29). Thermoregulatory vasoconstriction was effective in virtually all patients independent of their morphology, and produced a fourfold reduction in the core cooling rate. These results indicate that patient morphometric characteristics substantially influence intraoperative core temperature changes, and that the effect depends on the hypothermia phase. (Anesth Analg 1995;80:562-7)
- Published
- 1995
40. MAGNESIUM DOES NOT REDUCE THE THRESHOLD OR GAIN OF SHIVERING
- Author
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Anupama Wadhwa, Daniel I. Sessler, Ozan Akca, Anthony G. Doufas, Keith Hanni, Rainer Lenhardt, and Jaleel Durrani
- Subjects
Anesthesiology and Pain Medicine ,chemistry ,Magnesium ,business.industry ,Anesthesia ,Shivering ,medicine ,chemistry.chemical_element ,medicine.symptom ,business - Published
- 2003
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41. Thermoregulatory thresholds during epidural and spinal anesthesia
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Andrea Kurz, Makoto Ozaki, Azita Moayeri, Rainer Lenhardt, Katherine M. Noyes, Daniel I. Sessler, Edda Rotheneder, and Marc Schroeder
- Subjects
Adult ,Anesthesia, Epidural ,Male ,business.industry ,Shivering ,Spinal anesthesia ,Sweating ,Thermoregulation ,Anesthesia, Spinal ,Anesthesiology and Pain Medicine ,Regional anesthesia ,Reference Values ,Vasoconstriction ,Anesthesia ,Reference values ,medicine ,Humans ,In patient ,medicine.symptom ,Anesthetics, Local ,business ,Procaine ,Body Temperature Regulation ,Monitoring, Physiologic - Abstract
There are significant physiologic differences between spinal and epidural anesthesia. Consequently, these two types of regional anesthesia may influence thermoregulatory processing differently. Accordingly, in volunteers and in patients, we tested the null hypothesis that the core-temperature thresholds triggering thermoregulatory sweating, vasoconstriction, and shivering are similar during epidural and spinal anesthesia.Six male volunteers participated on three consecutive study days: epidural or spinal anesthesia were randomly assigned on the 1st and 3rd days (approximately T10 level); no anesthesia was given on the 2nd day. On each day, the volunteers were initially warmed until they started to sweat, and subsequently cooled by central venous infusion of cold fluid until they shivered. Mean skin temperature was kept constant near 36 degrees C throughout each study. The tympanic membrane temperatures triggering a sweating rate of 40 g.m-2.h-1, a finger flow less than 0.1 ml/min, and a marked and sustained increase in oxygen consumption (approximately 30%) were considered the thermoregulatory thresholds for sweating, vasoconstriction, and shivering, respectively. Twenty-one patients were randomly assigned to receive epidural (n = 10) or spinal (n = 11) anesthesia for knee and calf surgery (approximately T10 level). As in the volunteers, the shivering threshold was defined as the tympanic membrane temperature triggering a sustained increase in oxygen consumption.The thresholds and ranges were similar during epidural and spinal anesthesia in the volunteers. However, the sweating-to-vasoconstriction (inter-threshold) range, the vasoconstriction-to-shivering range, and the sweating-to-shivering range all were significantly increased by regional anesthesia. The shivering thresholds in patients assigned to epidural and spinal anesthesia were virtually identical.Comparable sweating, vasoconstriction, and shivering thresholds during epidural and spinal anesthesia suggest that thermoregulatory processing is similar during each type of regional anesthesia. However, thermoregulatory control was impaired during regional anesthesia, as indicated by the significantly enlarged inter-threshold and sweating-to-shivering ranges.
- Published
- 1994
42. Epidural and Spinal Anesthesia Alter Thermoregulatory Response Thresholds
- Author
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Katherine M. Noyes, E. Rotheneder, Azita Moayeri, Martin Kurz, Marc Schroeder, Andrea Kurz, Rainer Lenhardt, Daniel I. Sessler, and Makoto Ozaki
- Subjects
animal structures ,Regional anesthesia ,business.industry ,Anesthesia ,Shivering ,medicine ,Skin temperature ,Spinal anesthesia ,Vasodilation ,Core temperature ,medicine.symptom ,business ,Vasoconstriction - Abstract
The core temperature triggering thermoregulatory action defines the threshold for that response. Elevated core temperatures trigger sweating and active pre-capillary vasodilation whereas progressively lower temperatures trigger arterio-venous shunt vasoconstriction and shivering. Temperatures between the sweating and vasoconstriction thresholds, which do not trigger thermoregulatory responses, identify the interthreshold range (1).
- Published
- 1994
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43. Does Intraoperative Core Hypothermia Increase the Incidence of Surgical Wound Infections and Prolong Hospitalization?
- Author
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G. Huemer, Andrea Kurz, Daniel I. Sessler, F. Lackner, Rainer Lenhardt, and E. Narzt
- Subjects
medicine.medical_specialty ,Core (anatomy) ,Mild hypothermia ,integumentary system ,business.industry ,Incidence (epidemiology) ,Surgical wound infections ,Hypothermia ,Surgery ,Increasing risk ,Anesthesia ,medicine ,In patient ,medicine.symptom ,business ,Abdominal surgery - Abstract
Wound infections are among the most common serious complications of anesthesia and surgery. The reported incidence of wound infections in patients having two or more factors increasing risk of infection (e.g., abdominal surgery, surgery lasting more than 2 hours, “contaminated” or “dirty-infected” wounds, or three or more underlying diagnoses), ranges from 8 to 27% (1).
- Published
- 1994
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44. Buspirone and dexmedetomidine synergistically reduce the shivering threshold in humans
- Author
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Rainer Lenhardt, Mukadder Orhan-Sungur, and Ryu Komatsu
- Subjects
animal structures ,business.industry ,Sedation ,Antagonist ,Hypothermia ,Critical Care and Intensive Care Medicine ,medicine.disease ,Buspirone ,Anesthesia ,Poster Presentation ,Shivering ,Medicine ,Serotonin ,Dexmedetomidine ,medicine.symptom ,business ,Stroke ,medicine.drug - Abstract
Hypothermia may be therapeutically beneficial in stroke victims; however, it provokes vigorous shivering. Buspirone, a partial serotonin 1A antagonist, and dexmedetomidine, an α2 agonist, linearly reduce the shivering threshold (triggering core temperature) with minimal sedation and respiratory depression. We tested the hypothesis that buspirone and dexmedetomidine synergistically reduce the shivering threshold without producing substantial sedation or respiratory depression.
- Published
- 2007
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45. Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization
- Author
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Andrea Kurz, Rainer Lenhardt, and Daniel I. Sessler
- Subjects
medicine.medical_specialty ,business.industry ,Obstetrics and Gynecology ,Surgical wound ,General Medicine ,Perioperative ,Hypothermia ,Colorectal surgery ,Oxygen tension ,Metronidazole ,Anesthesia ,Anesthetic ,medicine ,Cefamandole ,medicine.symptom ,business ,medicine.drug - Abstract
Background Mild perioperative hypothermia, which is common during major surgery, may promote surgical-wound infection by triggering thermoregulatory vasoconstriction, which decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissue impair oxidative killing by neutrophils and decrease the strength of the healing wound by reducing the deposition of collagen. Hypothermia also directly impairs immune function. We tested the hypothesis that hypothermia both increases susceptibility to surgical-wound infection and lengthens hospitalization. Methods Two hundred patients undergoing colorectal surgery were randomly assigned to routine intraoperative thermal care (the hypothermia group) or additional warming (the normothermia group). The patients' anesthetic care was standardized, and they were all given cefamandole and metronidazole. In a double-blind protocol, their wounds were evaluated daily until discharge from the hospital and in the clinic after two weeks; wounds containing culture-positive pu...
- Published
- 1996
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46. Erratum to ‘Fever during anaesthesia’ [Best Practice and Research Clinical Anaesthesiology 17 (2003) 499–517]
- Author
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Rainer Lenhardt and Chiharu Negishi
- Subjects
medicine.medical_specialty ,Anesthesiology and Pain Medicine ,business.industry ,Anesthesia ,Best practice ,medicine ,Intensive care medicine ,business - Published
- 2004
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47. Influence of Nitrous Oxide on Bowel Distension
- Author
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Rainer Lenhardt, Edith Fleischmann, Ozan Akca, and Dan I. Sessler
- Subjects
chemistry.chemical_compound ,Anesthesiology and Pain Medicine ,chemistry ,business.industry ,Anesthesia ,Bowel distension ,Medicine ,Nitrous oxide ,business - Published
- 2002
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48. Local warming and insertion of peripheral venous cannulas: single blinded prospective randomised controlled trial and single blinded randomised crossover trial
- Author
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Brigitte Stoiser, Rainer Lenhardt, Tanja Seybold, Oliver Kimberger, and Daniel I. Sessler
- Subjects
Male ,medicine.medical_specialty ,Hot Temperature ,Randomization ,Neurosurgical Procedures ,law.invention ,Patient satisfaction ,Randomized controlled trial ,Insertion time ,law ,Catheterization, Peripheral ,medicine ,Humans ,Single-Blind Method ,Prospective Studies ,Infusions, Intravenous ,Prospective cohort study ,General Environmental Science ,Cross-Over Studies ,Leukemia ,business.industry ,General Engineering ,General Medicine ,Middle Aged ,Hand ,Cannula ,Crossover study ,Surgery ,Clinical trial ,Anesthesia ,Papers ,Arm ,General Earth and Planetary Sciences ,Female ,business - Abstract
Objective: To determine whether local warming of the lower arm and hand facilitates peripheral venous cannulation. Design: Single blinded prospective randomised controlled trial and single blinded randomised crossover trial. Setting: Neurosurgical unit and haematology ward of university hospital. Participants: 100 neurosurgical patients and 40 patients with leukaemia who required chemotherapy. Interventions: Neurosurgical patients9 hands and forearms were covered for 15 minutes with a carbon fibre heating mitt. Patients were assigned randomly to active warming at 52°C or passive insulation (heater not activated). The same warming system was used for 10 minutes in patients with leukaemia. They were assigned randomly to active warming or passive insulation on day 1 and given alternative treatment during the subsequent visit. Main outcome measures: Primary: success rate for insertion of 18 gauge cannula into vein on back of hand. Secondary: time required for successful cannulation. Results: In neurosurgical patients, it took 36 seconds (95% confidence interval 31 to 40 seconds) to insert a cannula in the active warming group and 62 (50 to 74) seconds in the passive insulation group (P=0.002). Three (6%) first attempts failed in the active warming group compared with 14 (28%) in the passive insulation group (P=0.008). The crossover study in patients with leukaemia showed that insertion time was reduced by 20 seconds (8 to 32, P=0.013) with active warming and that failure rates at first attempt were 6% with warming and 30% with passive insulation (P Conclusions: Local warming facilitates the insertion of peripheral venous cannulas, reducing both time and number of attempts required. This may decrease the time staff spend inserting cannulas, reduce supply costs, and improve patient satisfaction.
- Published
- 2002
- Full Text
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49. Room B, 10/17/2000 2: 00 PM - 4: 00 PM (PS) Effect of Hypothermia on the Expression of Platelet GP IIb-IIIa and P-Selectin
- Author
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Sibylle A. Kozek, M. Felfernig, Edith Fleischmann, Josef Stark, and Rainer Lenhardt
- Subjects
Anesthesiology and Pain Medicine ,P-selectin ,business.industry ,Anesthesia ,Medicine ,Platelet ,Pharmacology ,Hypothermia ,medicine.symptom ,business - Published
- 2000
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50. Efficacy of Two Methods for Reducing Postbypass Afterdrop
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Gabriele Brunner, Angela Rajek, Günther Laufer, Daniel I. Sessler, Johannes Kastner, Markus Haisjackl, and Rainer Lenhardt
- Subjects
Adult ,Male ,Nitroprusside ,Mean arterial pressure ,Vasodilator Agents ,Vasodilation ,Hypothermia ,Convection ,law.invention ,Postoperative Complications ,law ,medicine ,Cardiopulmonary bypass ,Humans ,Prospective Studies ,Rewarming ,Forced-air ,Aged ,Aged, 80 and over ,Cardiopulmonary Bypass ,business.industry ,Middle Aged ,Thermoregulation ,Peripheral ,Anesthesiology and Pain Medicine ,Regional Blood Flow ,Anesthesia ,Female ,Sodium nitroprusside ,medicine.symptom ,business ,Algorithms ,medicine.drug - Abstract
Background Afterdrop, defined as the precipitous reduction in core temperature after cardiopulmonary bypass, results from redistribution of body heat to inadequately warmed peripheral tissues. The authors tested two methods of ameliorating afterdrop: (1) forced-air warming of peripheral tissues and (2) nitroprusside-induced vasodilation. Methods Patients were cooled during cardiopulmonary bypass to approximately 32 degrees C and subsequently rewarmed to a nasopharyngeal temperature near 37 degrees C and a rectal temperature near 36 degrees C. Patients in the forced-air protocol (n = 20) were assigned randomly to forced-air warming or passive insulation on the legs. Active heating started with rewarming while undergoing bypass and was continued for the remainder of surgery. Patients in the nitroprusside protocol (n = 30) were assigned randomly to either a control group or sodium nitroprusside administration. Pump flow during rewarming was maintained at 2.5 l x m(-2) x min(-1) in the control patients and at 3.0 l x m(-2) x min(-1) in those assigned to sodium nitroprusside. Sodium nitroprusside was titrated to maintain a mean arterial pressure near 60 mm Hg. In all cases, a nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 18 intramuscular needle thermocouples, nine skin temperatures, and "deep" hand and foot temperature. Results In patients warmed with forced air, peripheral tissue temperature was higher at the end of warming and remained higher until the end of surgery. The core temperature afterdrop was reduced from 1.2+/-0.2 degrees C to 0.5+/-0.2 degrees C by forced-air warming. The duration of afterdrop also was reduced, from 50+/-11 to 27+/-14 min. In the nitroprusside group, a rectal temperature of 36 degrees C was reached after 30+/-7 min of rewarming. This was only slightly faster than the 40+/-13 min necessary in the control group. The afterdrop was 0.8+/-0.3 degrees C with nitroprusside and lasted 34+/-10 min which was similar to the 1.1+/-0.3 degrees C afterdrop that lasted 44+/-13 min in the control group. Conclusions Cutaneous warming reduced the core temperature afterdrop by 60%. However, heat-balance data indicate that this reduction resulted primarily because forced-air heating prevented the typical decrease in body heat content after discontinuation of bypass, rather than by reducing redistribution. Nitroprusside administration slightly increased peripheral tissue temperature and heat content at the end of rewarming. However, the core-to-peripheral temperature gradient was low in both groups. Consequently, there was little redistribution in either case.
- Published
- 2000
- Full Text
- View/download PDF
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