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Background Mechanomyography is the traditional gold standard research technique for quantitative assessment of neuromuscular blockade. Mechanomyography directly measures the isometric force generated by the thumb in response to ulnar nerve stimulation. Researchers must construct their own mechanomyographs since commercial instruments are no longer available. A mechanomyograph was constructed, and its performance was compared against an archival mechanomyography system from the 1970s that utilized an FT-10 Grass force transducer, hypothesizing that train-of-four ratios recorded on each device would be equivalent. Methods A mechanomyograph was constructed using 3D-printed components and modern electronics. An archival mechanomyography system was assembled from original components, including an FT-10 Grass force transducer. Signal digitization for computerized data collection was utilized instead of the original paper strip chart recorder. Both devices were calibrated with standard weights to demonstrate linear voltage response curves. The mechanomyographs were affixed to opposite arms of patients undergoing surgery, and the train-of-four ratio was measured during the onset and recovery from rocuronium neuromuscular blockade. Results Calibration measurements exhibited a positive linear association between voltage output and calibration weights with a linear correlation coefficient of 1.00 for both mechanomyography devices. The new mechanomyograph had better precision and measurement sensitivity than the archival system: 5.3 mV versus 15.5 mV and 1.6 mV versus 5.7 mV, respectively (P < 0.001 for both). A total of 767 pairs of train-of-four ratio measurements obtained from 8 patients had positive linear association (R 2 = 0.94; P < 0.001). Bland–Altman analysis resulted in bias of 3.8% and limits of agreement of −13% and 21%. Conclusions The new mechanomyograph resulted in similar train-of-four ratio measurements compared to an archival mechanomyography system utilizing an FT-10 Grass force transducer. These results demonstrated continuity of gold standard measurement of neuromuscular blockade spanning nearly 50 yr, despite significant changes in the instrumentation technology. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Background The dose of sugammadex recommended by the manufacturer for reversal of rocuronium is 2 mg/kg when the train-of-four count is 2 or more and 4 mg/kg when it is less than 2 but there is a post-tetanic count of at least 1. The purpose of this dose-finding study was to titrate sugammadex to produce a train-of-four ratio ≥0.9 at the conclusion of cardiac surgery, and to continue monitoring neuromuscular blockade in the ICU to identify recurrent paralysis. The hypothesis was that many patients would require less than the recommended dose of sugammadex, but that some would require more, and that recurrent paralysis would not occur. Methods Neuromuscular blockade was monitored using electromyography during cardiac surgery. Administration of rocuronium was at the discretion of the anesthesia care team. During sternal closure, sugammadex was titrated in 50 mg increments every 5 minutes until a train-of-four ratio ≥0.9 was obtained. Neuromuscular blockade was monitored with electromyography in the ICU until sedation was discontinued prior to extubation or for a maximum of 7 hours. Results Ninety-seven patients were evaluated. The dose of sugammadex required to achieve a train-of-four ratio of ≥0.9 varied from 0.43 to 5.6 mg/kg. There was a statistically significant relationship between the depth of neuromuscular blockade and the sugammadex dose required for reversal, but there was a large variation in dose required at any depth of neuromuscular blockade. Eighty-four of 97 patients (87%) required less than the recommended dose, and 13 (13%) required more. Two patients required additional sugammadex administration for recurrent paralysis. Conclusions When sugammadex was titrated to effect, the dose was usually less than the recommended dose, but it was more in some patients. Therefore, quantitative twitch monitoring is essential for ascertaining that adequate reversal has taken place following sugammadex administration. Recurrent paralysis was observed in 2 patients.

Respiratory viruses are transmitted via respiratory particles that are emitted when people breath, speak, cough, or sneeze. These particles span the size spectrum from visible droplets to airborne particles of hundreds of nanometers. Barrier face coverings (“cloth masks”) and surgical masks are loose-fitting and provide limited protection from airborne particles since air passes around the edges of the mask as well as through the filtering material. Respirators, which fit tightly to the face, provide more effective respiratory protection. Although healthcare workers have relied primarily on disposable filtering facepiece respirators (such as N95) during the COVID-19 pandemic, reusable elastomeric respirators have significant potential advantages for the COVID-19 and future respiratory virus pandemics. However, currently available elastomeric respirators were not designed primarily for healthcare or pandemic use and require further development to improve their suitability for this application. The authors believe that the development, implementation, and stockpiling of improved elastomeric respirators should be an international public health priority.

An error in the administration of an anaesthetic medication related to an automated dispensing cabinet resulted in a patient fatality and a highly publicised criminal prosecution of a healthcare worker, which concluded in 2022. Urgent action is required to re-engineer systems and workflows to prevent such errors. Exhortation, blame, and criminal prosecution are unlikely to advance the cause of patient safety.

The purpose of this study was to compare train-of-four count and ratio measurements with the GE electromyograph to the TwitchView electromyograph, that was previously validated against mechanomography, and to palpation of train-of-four count. Electrodes for both monitors were applied to the same arm of patients undergoing an unrestricted general anesthetic. Train-of-four measurements were performed with both monitors approximately every 5 min. In a subset of patients, thumb twitch was palpated by one of the investigators. Eleven patients contributed 807 pairs of train-of-four counts or ratios. A subset of 5 patients also contributed palpated train-of-four counts. Bland–Altman analysis of the train-of-four ratio found a bias of 0.24 in the direction of a larger ratio with the GE monitor. For 72% of data pairs, the GE monitor train-of-four ratios were larger. For 59% of data pairs, the GE monitor train-of-four counts were larger (p

Many health care systems around the world continue to struggle with large numbers of SARS-CoV-2-infected patients, while others have diminishing numbers of cases following an initial surge. There will most likely be significant oscillations in numbers of cases for the foreseeable future, based on the regional epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Less affected hospitals and facilities will attempt to progressively resume elective procedures and surgery. Ramping up elective care in hospitals that deliberately curtailed elective care to focus on SARS-CoV-2-infected patients will present unique and serious challenges. Among the challenges will be protecting patients and providers from recurrent outbreaks of disease while increasing procedure throughput. Anesthesia providers will inevitably be exposed to SARS-CoV-2 by patients who have not been diagnosed with infection. This is particularly concerning in consideration that aerosols produced during airway management may be infective. In this article, we recommend an approach to routine anesthesia care in the setting of persistent but variable prevalence of SARS-CoV-2 infection. We make specific recommendations for personal protective equipment and for the conduct of anesthesia procedures and workflow based on evidence and expert opinion. We propose practical, relatively inexpensive precautions that can be applied to all patients undergoing anesthesia. Because the SARS-CoV-2 virus is spread primarily by respiratory droplets and aerosols, effective masking of anesthesia providers is of paramount importance. Hospitals should follow the recommendations of the Centers for Disease Control and Prevention for universal masking of all providers and patients within their facilities. Anesthesia providers should perform anesthetic care in respirator masks (such as N-95 and FFP-2) whenever possible, even when the SARS-CoV-2 test status of patients is negative. Attempting to screen patients for infection with SARS-CoV-2, while valuable, is not a substitute for respiratory protection of providers, as false-negative tests are possible and infected persons can be asymptomatic or presymptomatic. Provision of adequate supplies of respirator masks and other respiratory protection equipment such as powered air purifying respirators (PAPRs) should be a high priority for health care facilities and for government agencies. Eye protection is also necessary because of the possibility of infection from virus coming into contact with the conjunctiva. Because SARS-CoV-2 persists on surfaces and may cause infection by contact with fomites, hand hygiene and surface cleaning are also of paramount importance.

Critical patient care information is often omitted or misunderstood during handoffs, which can lead to inefficiencies, delays, and sometimes patient harm. We implemented an aviation-style post-anesthesia care unit (PACU) handoff checklist displayed on a tablet computer to improve PACU handoff communication. We developed an aviation-style computerized checklist system for use in procedural rooms and adapted it for tablet computers to facilitate the performance of PACU handoffs. We then compared the proportion of PACU handoff items communicated before and after the implementation of the PACU handoff checklist on a tablet computer. A trained observer recorded the proportion of PACU handoff information items communicated, any resistance during the performance of the checklist, the type of provider participating in the handoff, and the time required to perform the handoff. We also obtained these patient outcomes: PACU length of stay, respiratory events, post-operative nausea and vomiting, and pain. A total of 209 PACU handoffs were observed before and 210 after the implementation of the tablet-based PACU handoff checklist. The average proportion of PACU handoff items communicated increased from 49.3% (95% CI 47.7–51.0%) before checklist implementation to 72.0% (95% CI 69.2–74.9%) after checklist implementation (p

Summary The extent of neuromuscular blockade during anaesthesia is frequently measured using a train‐of‐four stimulus. Various monitors have been used to quantify the train‐of‐four, including mechanomyography, acceleromyography and electromyography. Mechanomyography is often considered to be the laboratory gold standard of measurement, but is not commercially available and has rarely been used in clinical practice. Acceleromyography is currently the most commonly used monitor in the clinical setting, whereas electromyography is not widely available. We compared a prototype electromyograph with a newly constructed mechanomyograph and a commercially available acceleromyograph monitor in 43 anesthetised patients. The mean difference (bias; 95% limits of agreement) in train‐of‐four ratios was 4.7 (−25.2 to 34.6) for mechanomyography vs. electromyography; 14.9 (−13.0 to 42.8) for acceleromyography vs. electromyography; and 9.8 (−31.8 to 51.3) for acceleromyography vs. mechanomyography. The mean difference (95% limits of agreement) in train‐of‐four ratios between opposite arms when using electromyography was −0.7 (−20.7 to 19.3). There were significantly more acceleromyography train‐of‐four values > 1.0 (23%) compared with electromyography or mechanomography (2–4%; p 1.0, complicating the interpretation of acceleromyography results in the clinical setting.

BACKGROUND We implemented a previously described barcode-based drug safety system in all of our anesthetizing locations. Providers were instructed to scan the barcode on syringes using our Anesthesia Information Management System before drug administration, but the rate of provider adherence was low. We studied an implementation intervention intended to increase the rate of scanning. METHODS Using our Anesthesia Information Management System and Smart Anesthesia Manager software, we quantified syringe drug administrations by anesthesia providers with and without barcode scanning. We use an anesthesia team model in which an attending anesthesiologist is paired with a certified registered nurse anesthetist (CRNA) or a resident. Our system identified the pair of providers associated with a particular drug administration, but did not distinguish which providers actually administered the drug. Therefore, the rate of barcode scanning for a particular case was assigned to both providers equally. A baseline rate of scanning was established over a period of 17 months. An audit and feedback intervention was then performed that consisted of monthly performance reports sent by email to individual providers along with coffee gift card awards for top performers. The coffee gift cards were awarded in only the first 2 months of the intervention, while the email performance reports continued on a monthly basis. The coffee card awards were made public. The monthly emails reported the individual provider's rank order of performance relative to other providers, but was otherwise anonymous. The baseline rate of scanning was compared to the rate of scanning after the intervention for a period of 7 months. RESULTS From November 2014 to March 2017, we accumulated 60,197 cases performed by 88 attending anesthesiologists, 65 CRNAs, and 148 residents. The total number of syringe drug administrations was 653,355. Average scanning performance improved from 8.7% of syringe barcodes scanned during the baseline period from November 2014 to February 2016 to 64.4% scanned during the period September 2016 to March 2017 (P < .001). Variation in performance among individuals was marked, ranging from 0% to 100% of syringes scanned. The performance of some individuals showed marked oscillation over time. There was greater variation in performance attributable to residents than in performance attributable to CRNAs. CONCLUSIONS Feedback of individual provider performance data from the anesthesia information system to providers can be used in conjunction with other measures to improve performance. Despite improved average performance, there was marked variation in performance between individuals, and some individuals had marked oscillation of their performance over time.

Commercially available bite blocks used for invasive imaging procedures have design limitations, including bulky profile, being made of hard plastic that may damage surrounding tissue, and tendency to dislodge. We designed a novel bite block to address these limitations and evaluated this bite block in 50 patients undergoing diagnostic or intraprocedural transesophageal echocardiography examinations. Nine of 11 (82%) imagers who used the redesigned bite block preferred it over the standard bite block used at our institution. The novel bite block is an alternative device to standard bite blocks that was redesigned to protect both the patient and probe.

BackgroundQuantitative twitch monitoring is recommended for avoiding residual neuromuscular blockade. Electromyograph twitch monitors are a form of quantitative twitch monitoring. The TwitchView electromyograph has been previously validated against “gold standard” mechanomyography, and may serve as a comparator for other monitors. We have previously shown that the GE electromyograph monitor overcounted twitches, frequently misinterpreting noise as a twitch. This is a pilot study to evaluate the performance of the TetraGraph electromyograph in comparison to the TwitchView electromyograph.MethodsTwitchView and TetraGraph electrodes were applied to opposite arms of patients prior to induction of anesthesia. Post-tetanic count, train-of-four count and train-of-four ratio were then measured approximately every 5 minutes during an unrestricted general anesthetic. Measurements were not made for 10 minutes following neuromuscular blocking drugs or reversal agents.ResultsEight patients were enrolled. The mean baseline train-of-four ratio was 1.02 (SD=0.04) for the TwitchView and 0.99 (SD=0.03) for the TetraGraph (p=0.22). Bland Altman analysis of all of the train-of-four ratio data found that average TwitchView train-of-four values were larger with a bias of 0.10. Train-of-four counts and train-of-four ratios were generally less when measured with TetraGraph than when measured with TwitchView.In 83% (209/253) of data pairs, the result from TetraGraph was less than the result from TwitchView and in 6% (16/253) of data pairs, the result from TetraGraph was greater than the result from TwitchView (pConclusionsUsers of the TetraGraph electromyograph should be aware that significant underestimation of post-tetanic-count, train-of-four count and train-of-four ratio may occur. This could result in administration of unnecessary reversal agents, excessive doses of reversal agents, or delay in extubation. We are undertaking a comparison of the TetraGraph monitor to mechanomyography to confirm the results of this pilot study.

Background Train-of-four twitch monitoring can be performed using palpation of thumb movement, or by the use of a more objective quantitative monitor, such as mechanomyography, acceleromyography, or electromyography. The relative performance of palpation and quantitative monitoring for determination of the train-of-four ratio has been studied extensively, but the relative performance of palpation and quantitative monitors for counting train-of-four twitch responses has not been completely described. Methods We compared train-of-four counts by palpation to mechanomyography, acceleromyography (Stimpod™), and electromyography (TwitchView Monitor™) in anaesthetised patients using 1691 pairs of measurements obtained from 46 subjects. Results There was substantial agreement between palpation and electromyography (kappa = 0.80), mechanomyography (kappa = 0.67), or acceleromyography (kappa = 0.63). Electromyography with TwitchView and mechanomyography most closely resembled palpation, whereas acceleromyography with StimPod often underestimated train-of-four count. With palpation as the comparator, acceleromyography was more likely to measure a lower train-of-four count, with 36% of counts less than palpation, and 3% more than palpation. For mechanomyography, 31% of train-of-four counts were greater than palpation, and 9% were less. For electromyography, 15% of train-of-four counts were greater than palpation, and 12% were less. The agreement between acceleromyography and electromyography was fair (kappa = 0.38). For acceleromyography, 39% of train-of-four counts were less than electromyography, and 5% were more. Conclusions Acceleromyography with the StimPod frequently underestimated train-of-four count in comparison with electromyography with TwitchView.

Lipemic blood was noted in the surgical field by a neurosurgeon after 12.5 hours of anesthesia consisting of infusions of propofol (total dose, 14,956 mcg) and remifentanil (total dose, 25,091 mcg). For most of that time, the rate of propofol was 120-160 mcg·kg-1·min-1 and never exceeded 160 mcg·kg-1·min-1. Lipemia was confirmed by allowing a sample of the patient's blood to settle in a syringe. The triglyceride concentration was 15.8 mmol/L. There was no metabolic acidosis or other indications of propofol infusion syndrome. Postoperatively, liver enzymes were elevated (peak aspartate aminotransferase, 420 units/L) but returned to nearly normal within 5 days. The patient recovered from surgery uneventfully. Reports of intraoperative lipemia during propofol anesthesia are very rare but raise concerns about the safety of prolonged propofol infusion.

Background: A number of mechanical complications can occur during the insertion of a central venous catheter (CVC), including breakage or loss of the wire and unrecognized failure to remove the wire. Complications related to retention of a guidewire can be serious or fatal. Methods: Incident reports on retained CVC guidewires entered into the University HealthSystem Consortium (UHC) Safety Intelligence Patient Safety Organization (PSO) database (Chicago, IL) over a 5-year period were reviewed to improve our understanding of their circumstances, causes, and related patient outcomes. Findings: A total of 42 events that involved retention of a whole guidewire or a fragment of a wire were found in the UHC Safety Intelligence PSO database from 2008 through 2012. Although one-third of these events were discovered during or at the end of the CVC insertion procedure, retained CVC guidewires were commonly discovered days to years after the procedure and on imaging tests performed for unrelated reasons or during other subsequent care. Managers who reviewed the events commonly recommended education and training to prevent retained CVC guidewires, but factors contributing to these events such as distractions and emergency situations also suggest the need for a device design that prevents the occurrence. Conclusions: Efforts to prevent the loss of CVC guidewires should include clinician education and the development of a device design that prevents inadvertent guidewire loss and alerts clinicians when the end of the guidewire is near.

INIMALLY INVASIVE cardiac surgery is becoming increasingly and has advantages, but it involves decreased surgical exposure. The authors report a case in which a minimally invasive approach to the aortic valve precluded manual palpation of the left ventricle during administration of antegrade cardioplegia. Transesophageal echocardiography (TEE) showed maldistribution of cardioplegia, with the solution entering the left ventricle and, subsequently, left atrium, through incompetent aortic and mitral valves. This led to a change in the surgical plan, successful myocardial protection, and good outcome. CASE REPORT

Inadvertent arterial placement of a large-bore catheter during attempted placement of a central venous catheter (CVC) occurs at a rate of 0.1% to 1.0% and may result in hemorrhage, pseudoaneurysm, stroke, or death. Ultrasound guidance or observation of color and pulsatility of blood are not reliable methods for avoiding this serious complication. Measurement of pressure in the needle or short plastic catheter before insertion of the guidewire has been shown to be highly reliable; however, traditional pressure measurement methodology is cumbersome. Recently a compact, sterile, single-use pressure transducer with an integrated digital display has become available. In this study, we evaluated the performance of this new device (Compass® Vascular Access).In this prospective, observational study at 4 academic medical centers 298 CVCs were placed. Pressure was measured using the Compass transducer before and after guidewire insertion. Other details of the procedure were at the discretion of the clinician. Data describing the CVC placement and any complications were collected.Trainees placed 279 of 298 CVCs. Ultrasound guidance was used for 286 of 298 CVCs. Seven of the CVC placements occurred in the intensive care unit, with the balance occurring in the operating room. Ten of the CVCs were placed in a subclavian vein, with the balance being internal jugular vein. Two hundred seventy-four of 298 CVCs were placed on the right side. Venous pressure measured before and after guidewire insertion was 7.2 ± 4.3 (SD) and 6.5 ± 4.3 (SD) mm Hg respectively (P = 0.03). The satisfaction score recorded by the physician performing the procedure was 8.0 ± 2.1 (SD; visual analog scale 1-10, 10 being most satisfying). There were 5 inadvertent arterial punctures (1.7%). Ultrasound guidance was used in all 5 cases of arterial puncture. All of the arterial punctures were recognized before guidewire insertion by measurement of arterial pressure with the Compass transducer. No guidewires or CVC catheters were placed in arteries.The Compass pressure transducer for CVC placement performed as intended in 298 cases from 4 academic medical centers. There were 5 inadvertent arterial punctures despite the use of ultrasound guidance, all of which were correctly identified by pressure measurement using the Compass. The device was easily used by trainees, and users expressed a positive level of satisfaction.

Background Imaging the guidewire with ultrasonography in the internal jugular vein during central venous catheterization often is used to verify proper guidewire placement and to aid in prevention of inadvertent arterial catheterization. It is known, however, that inadvertent arterial catheterization can occur despite imaging the guidewire in the internal jugular vein because the guidewire may continue through the far wall of the internal jugular vein and into an adjacent artery. We propose confirmation of the guidewire in the brachiocephalic vein with ultrasonography as a more reliable method of confirming proper guidewire placement. Methods A prospective feasibility study of 200 adult cardiothoracic surgery patients undergoing internal jugular vein catheterization was performed to determine whether the guidewire could be imaged with ultrasonography in the brachiocephalic vein. The guidewire was imaged in the internal jugular vein in a short-axis view, and the transducer was then angled caudally under the clavicle, following the guidewire into the brachiocephalic vein. Results The right internal jugular vein was catheterized in 193 patients and the left internal jugular in 7 patients. The brachiocephalic vein was successfully imaged in all but 2 patients. In 3 patients, the guidewire could not be clearly identified in the brachiocephalic vein because of interference from the leads of a heart rhythm device (pacemaker or defibrillator) or preexisting catheter. In 2 patients, the guidewire was not seen initially in the brachiocephalic vein because of coiling in the internal jugular vein, and in 1 patient because of the guidewire passing into the right subclavian vein, but all 3 were subsequently imaged in the brachiocephalic vein after repositioning. Conclusions During internal jugular vein catheterization, the brachiocephalic vein was imaged with ultrasonography in 99% of patients (the lower 1-sided 99% confidence limit is 96%). The guidewire was imaged in the brachiocephalic vein in all cases except when leads from a heart rhythm device caused interference, although in some patients with leads, the guidewire could be imaged without difficulty. The absence of the guidewire from the brachiocephalic vein was indicative of a malpositioned guidewire.

Background CT scan measures of emphysema and airway disease have been correlated with lung function in cohorts of subjects with a range of COPD severity. The contribution of CT scan-assessed airway disease to objective measures of lung function and respiratory symptoms such as dyspnea in severe emphysema is less clear. Methods Using data from 338 subjects in the National Emphysema Treatment Trial (NETT) Genetics Ancillary Study, densitometric measures of emphysema using a threshold of −950 Hounsfield units (%LAA-950) and airway wall phenotypes of the wall thickness (WT) and the square root of wall area (SRWA) of a 10-mm luminal perimeter airway were calculated for each subject. Linear regression analysis was performed for outcome variables FEV 1 and percent predicted value of FEV 1 with CT scan measures of emphysema and airway disease. Results In univariate analysis, there were significant negative correlations between %LAA-950 and both the WT ( r = −0.28, p = 0.0001) and SRWA ( r = −0.19, p = 0.0008). Airway wall thickness was weakly but significantly correlated with postbronchodilator FEV 1 % predicted (R = −0.12, p = 0.02). Multivariate analysis showed significant associations between either WT or SRWA (β = −5.2, p = 0.009; β = −2.6, p = 0.008, respectively) and %LAA-950 (β = −10.6, p = 0.03) with the postbronchodilator FEV 1 % predicted. Male subjects exhibited significantly thicker airway wall phenotypes (p = 0.007 for WT and p = 0.0006 for SRWA). Conclusions Airway disease and emphysema detected by CT scanning are inversely related in patients with severe COPD. Airway wall phenotypes were influenced by gender and associated with lung function in subjects with severe emphysema.

Objectives The authors hypothesized that intravenous acetaminophen as an adjunct analgesic would significantly decrease 24-hour postoperative opioid consumption. Design Double-blind, randomized, placebo-controlled trial. Setting A single academic medical center. Participants The study was comprised of 68 adult patients undergoing cardiac surgery. Interventions Patients were assigned randomly to receive either 1,000 mg of intravenous acetaminophen or placebo immediately after anesthesia induction, at the end of surgery, and then every 6 hours for the first 24 hours in the intensive care unit, for a total of 6-1,000 mg doses. Measurements and Main Results The primary outcome was 24-hour postoperative opioid consumption. The secondary outcomes included 48-hour postoperative opioid consumption, incisional pain scores, opioid-related adverse effects, length of mechanical ventilation, length of intensive care unit stay, and the extent of wound hyperalgesia assessed at 24 and 48 hours postoperatively. The mean±standard deviation postoperative 24-hour opioid consumption expressed in morphine equivalents was significantly less in the acetaminophen group (45.6±29.5 mg) than in the placebo group (62.3±29.5 mg), representing a 27% reduction in opioid consumption (95% CI, 2.3-31.1 mg; p = 0.024). There were no differences in pain scores and opioid-related adverse effects between the 2 groups. A significantly greater number of patients in the acetaminophen group responded “very much” and “extremely well” when asked how their overall pain experience met their expectation (p = 0.038). Conclusions The administration of intravenous acetaminophen during cardiac surgery and for the first 24 hours postoperatively reduced opioid consumption and improved patient satisfaction with their overall pain experience but did not reduce opioid side effects.

Depth-of-anesthesia monitoring with EEG or EEG combined with mLAER is becoming widely used in anesthesia practice. Evidence shows that this monitoring improves outcome by reducing the incidence of intra-operative awareness while reducing the average amount of anesthesia that is administered, resulting in faster wake-up and recovery, and perhaps reduced nausea and vomiting. As with any monitoring device, there are limitations in the use of the monitors and the anesthesiologist must be able to interpret the data accordingly. The limitations include the following. The currently available monitoring algorithms do not account for all anesthetic drugs, including ketamine, nitrous oxide and halothane. EMG and other high-frequency electrical artifacts are common and interfere with EEG interpretation. Data processing time produces a lag in the computation of the depth-of-anesthesia monitoring index. Frequently the EEG effects of anesthetic drugs are not good predictors of movement in response to a surgical stimulus because the main site of action for anesthetic drugs to prevent movement is the spinal cord. The use of depth-of-anesthesia monitoring in children is not as well understood as in adults. Several monitoring devices are commercially available. The BIS monitor is the most thoroughly studied and most widely used, but the amount of information about other monitors is growing. In the future, depth-of-anesthesia monitoring will probably help in further refining and better understanding the process of administering anesthesia.

Background The purpose of this study was to determine whether monitoring Bispectral Index (BIS) would affect recovery parameters in patients undergoing inpatient surgery. Methods Anesthesia providers (n = 69) were randomly assigned to one of two groups, a BIS or non-BIS control group. A randomized crossover design was used, with reassignment at monthly intervals for 7 months. Duration of time in the postanesthesia care unit, time from the end of surgery to leaving the operating room, and incidence of delayed recovery (> 50 min in recovery) were compared in patients treated intraoperatively with or without BIS monitoring. Data were analyzed by analysis of variance, unpaired t test, or chi-square test as appropriate. Results One thousand five hundred eighty patients in an academic medical center were studied. The mean BIS in the monitored group was 47. No differences were found in recovery parameters between the BIS-monitored group and the control group when comparisons were made using all subjects or when data were analyzed within anesthetic subgroups stratified by anesthetic agent or duration of anesthesia. There were some small reductions in the intraoperative concentration of sevoflurane (but not isoflurane). Conclusions The use of BIS monitoring for inpatients undergoing a wide variety of surgical procedures in an academic medical center had some minor effects on intraoperative anesthetic use but had no impact on recovery parameters.

Awareness with recall after general anesthesia is an infrequent, but well described, phenomenon that may result in posttraumatic stress disorder. There are no recent data on the incidence of this complication in the United States. We, therefore, undertook a prospective study to determine the incidence of awareness with recall during general anesthesia in the United States. This is a prospective, nonrandomized descriptive cohort study that was conducted at seven academic medical centers in the United States. Patients scheduled for surgery under general anesthesia were interviewed in the postoperative recovery room and at least a week after anesthesia and surgery by using a structured interview. Data from 19,575 patients are presented. A total of 25 awareness cases were identified (0.13% incidence). These occurred at a rate of 1-2 cases per 1000 patients at each site. Awareness was associated with increased ASA physical status (odds ratio, 2.41; 95% confidence interval, 1.04-5.60 for ASA status III-V compared with ASA status I-II). Age and sex did not influence the incidence of awareness. There were 46 additional cases (0.24%) of possible awareness and 1183 cases (6.04%) of possible intraoperative dreaming. The incidence of awareness during general anesthesia with recall in the United States is comparable to that described in other countries. Assuming that approximately 20 million anesthetics are administered in the United States annually, we can expect approximately 26,000 cases to occur each year.

Some patients experience disordered breathing during sleep and arterial oxygen desaturation after major inpatient surgery. We performed this study to determine whether similar events occur after ambulatory surgery. Forty-five ambulatory surgery patients received an unrestricted anesthetic. Continuous unattended nocturnal recordings of breathing pattern and oxygen saturation were made in the patients' homes before surgery and during the first and second postoperative nights. Nine patients had a respiratory disturbance index >10 and/or >1% of recording time with oxygen saturation

Despite the widespread use of methadone for the treatment of acute and chronic pain, the hemodynamic effects of methadone administered by IV bolus have not been studied. We compared the hemodynamic effects of an IV bolus of methadone 20 mg with those of fentanyl 10 microg/kg for the induction of anesthesia in combination with etomidate 0.3 mg/kg. Forty-three patients undergoing major surgery were randomized to one of the two treatments in a double-blinded fashion. Plasma concentrations of histamine were measured before and 2 min after opioid administration. Heart rate and arterial blood pressure were measured via an arterial line just before opioid administration, etomidate administration, and tracheal intubation; during intubation; and 1 min after intubation. There were no significant differences in mean heart rate between the methadone and fentanyl groups at any time point. Systolic and diastolic blood pressures were significantly lower (P0.05) in the fentanyl group just before intubation, during intubation, and 1 min after intubation. Mean plasma concentrations of histamine before and after the administration of methadone or fentanyl were 1.54 ng/mL (SD, 0.65 ng/mL) and 1.57 ng/mL (SD, 1.37 ng/mL) or 1.00 ng/mL (SD, 0.58 ng/mL) and 1.04 ng/mL (SD, 0.47 ng/mL), respectively. Despite the lack of a significant change in mean plasma concentrations of histamine, substantial increases in plasma histamine occurred in 2 of 23 patients who received methadone. There were no obvious hemodynamic effects associated with histamine concentrations up to 6.2 ng/mL. Methadone appears to have the potential for producing histamine release. Although methadone administration did not produce hemodynamic instability in this study, the possible hemodynamic side effects of histamine release should be considered when IV boluses of methadone are given.The same dose of IV methadone (20 mg) that is effective for postoperative pain is also suitable for the induction of anesthesia in combination with etomidate. The plasma histamine concentration was notably increased in two patients, without obvious hemodynamic sequelae. Therefore, methadone appears to have the potential for producing histamine release.

Background To assess changing patterns of injury and liability associated with central venous or pulmonary artery catheters, the authors analyzed closed malpractice claims for central catheter injuries in the American Society of Anesthesiologists Closed Claims database. Methods All claims for which a central catheter (i.e., central venous or pulmonary artery catheter) was the primary damaging event for the injury were compared with the rest of the claims in the database. Central catheter complications were defined as being related to vascular access or catheter use or maintenance. Statistical analysis was performed using the chi-square test, Fisher exact test, or Z test (proportions) and the Kolmogorov-Smirnov test (payments). Results The database included 110 claims for injuries related to central catheters (1.7% of 6,449 claims). Claims for central catheter injuries had a higher severity of injury, with an increased proportion of death (47%) compared with other claims in the database (29%, P < 0.01). The most common complications were wire/catheter embolus (n = 20), cardiac tamponade (n = 16), carotid artery puncture/cannulation (n =16), hemothorax (n =15), and pneumothorax (n =14). Cardiac tamponade, hemothorax, and pulmonary artery rupture had a higher proportion of death (P < 0.05) compared with the rest of the central catheter injures. The proportion of claims for vascular access injury increased (47% to 84%) and use/maintenance injury decreased (53% to 16%) in 1994-1999 compared with 1978-1983 (P < 0.05). Conclusions Claims related to central catheters had a high severity of patient injury. The most common complications causing injury were wire/catheter embolus, cardiac tamponade, carotid artery puncture/cannulation, hemothorax, and pneumothorax.

Summary Diprivan has earned a prominent place in the armamentarium of anesthesiologists, owing to its favorable pharmacokinetic profile, the clearheaded and slightly euphoric emergence associated with Diprivan, and useful secondary properties such as reduction of postoperative nausea and vomiting. Diprivan also has many shortcomings, including several directly related to the Intralipid vehicle: the ability to support bacterial growth, pain on injection, hypertriglyceridemia with prolonged infusions, and the potential for Intralipid to compromise the immune response. Many companies have attempted to improve on the original propofol formulation. AstraZeneca added EDTA to reduce the risk of infection, and serendipitously may have found a formulation that actually improves survival in critically ill patients. Gensia Sicor added metabisulfite to the formulation. Despite an initial furor over the lack of clinical safety data the product appears to be safe, effective, and therapeutically equivalent within the scope of its narrowed labeling. Braun developed propofol in a medium-chain/long-chain triglyceride formulation. This formulation appears to provide identical pharmacokinetics and pharmacodynamics while reducing pain on injection. More complex formulation changes include nanoparticulate and cyclodextrin technologies, or administering propofol as a water-soluble prodrug. These latter approaches will not be commercially available for several years. The interest in altered formulations is a testament to the quality of propofol as an anesthetic. These diverse development programs also demonstrate encouraging interest in pharmaceutical companies in improving the anesthetic experience and clinical outcome for our surgical patients.

Invasive monitoring in anesthesiology is relatively safe. Arterial catheterization in particular has an extremely low rate of serious complications. Radial, brachial, and femoral artery catheterization sites appear to have similar and low complication rates. CVP and PA catheters are more dangerous and entail potentially fatal complications. The most troublesome complication with CVP catheters is perforation of the heart or cava, which should be avoidable under most circumstances if care is taken to position the catheter properly, outside the heart. Chest radiography should be used to specifically ascertain that the catheter is not in a dangerous location. The most troublesome complication with PA catheters is perforation of the pulmonary artery. This is probably a sporadic problem, and it is not necessarily avoidable by adherence to particular techniques. It should be assumed that hemoptysis in a patient with a PA catheter is caused by perforation of the pulmonary artery until proven otherwise, and it should be treated aggressively.

We compared (a) the perioperative complications; (b) times to eligibility for, and actual time of the following: extubation, less intense monitoring, intensive care unit (ICU), and hospital discharge; and (c) resource utilization of nursing ratio for patients receiving either a typical fentanyl/isof