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Background: Intravenous (IV) infusions of volatile anesthetics in lipid emulsion may increase blood lipid concentration, potentially altering the anesthetic agent's blood solubility and blood-gas partition coefficient (BGPC). We examined the influence of a low-lipid concentration 20% sevoflurane emulsion on BGPC, and the anesthetic potency of this emulsion using dogs., Methods: We compared BGPC and anesthetic characteristics in 6 dogs between the IV anesthesia of emulsion and the sevoflurane inhalation anesthesia in a randomized crossover substudy. Minimum alveolar concentrations (MACs) were determined by tail-clamp stimulation by using the up-and-down method. Blood sevoflurane concentration and partial pressure were measured by gas chromatography; end-tidal sevoflurane concentration was measured using a gas monitor. The primary outcome was BGPC at the end of IV anesthesia and inhalation anesthesia. Secondary outcomes were time to loss/recovery of palpebral reflex, finish intubation and awakening, MAC, blood concentration/partial pressure at MAC and awakening, correlation between blood partial pressure and gas monitor, and the safety of emulsions., Results: BGPC showed no difference between IV and inhaled anesthesia (0.859 [0.850-0.887] vs 0.813 [0.791-0.901]; P = .313). Induction and emergence from anesthesia were more rapid in IV anesthesia of emulsion than inhalation anesthesia. MAC of emulsion (1.33% [1.11-1.45]) was lower than that of inhalation (2.40% [2.33-2.48]; P = .031), although there was no significant difference in blood concentration. End-tidal sevoflurane concentration could be estimated using gas monitor during IV anesthesia of emulsion. No major complications were observed., Conclusions: IV anesthesia with emulsion did not increase the BGCP significantly compared to inhalation anesthesia. It was suggested that the anesthetic potency of this emulsion may be equal to or more than that of inhalation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 International Anesthesia Research Society.)

Objective: To develop an ergonomically designed computerized recordkeeping tool for anesthesiologists that allows the clinician to maintain visual contact with the patient while performing recordkeeping.Methods: To simplify the human interface software, we developed two general use software components. All purpose menu type 1 (APM1) was used for entering events using a tree structured menu. APM1 was designed to adapt to the limits of human memory, by using Miller's rule of 7 to guide the input process. APM1 can be considered to be a three-dimensional table list consisting of 7 vertical and 7 horizontal choices, which has further 5 tree-structured divergences. APM1 is also completely configurable by the user. All purpose menu 2 (APM2) was used to implement the system-initiated human interface where the system will prompt the user by voice for each entry. When users touch a key on APM1 and APM2, the system was designed to respond with a voice prompt. A touch-screen was also utilized and designed to fit the anesthesia machine. The screen is equipped with a small speaker for voice response and a microphone for voice recognition. The positions of the screen are adjustable supported by a long flexible limb (85 cm).Results: After improving the design, systems were assembled for 10 operating rooms. Of the multiple features of the VOCAAR user interface, the following were well accepted by users and employed daily: touch-screen input, and voice response. The noncompulsory use rate was 87% during the initial 2 weeks, increased to 94% after 2 weeks and 100% after two months. The mean sound emission by voice response (n = 10, mean +/- SD) was 8.2 +/- 2.3 dB at the main anesthetist site (35 cm from the speaker mounted on the touch-screen), 2.2 +/- 1.3 dB at the staff site (1.5 m from the touch-screen), which was only audible for anesthesiologist but for surgeon.Discussion: An EARK system was designed to allow the user to maintain visual contact with the patient while performing recordkeeping tasks. The combination of a mobile touch screen and voice response/recognition facilitated the design goals of the system. Although the system has enjoyed universal clinical acceptance, the voice functions remain too limited to satisfy the needs of a completely handsfree user interface. Enhancements to voice recognition technology will offer the potential for improved functionality. Additional research is also needed to better define the relationship between vigilance and visual contact with the patient. [ABSTRACT FROM AUTHOR]

Disseminated carcinomatosis of the bone marrow (DCBM) is characterized by diffuse metastasis to bone marrow and sudden mortality. To the best of our knowledge, no studies to date have reported progression of oral squamous cell carcinoma to DCBM. Herein, we report a case of squamous cell carcinoma in the maxillary gingiva suspected of progressing to DCBM. A 64-year-old woman presented with white lesions on the left maxillary gingiva. The lesions were diagnosed as squamous cell carcinoma (T2, N0, M0), and partial maxillectomy performed. Two years and 5 months after surgery, metastasis was noted in the left cervical lymph node and left radical neck dissection carried out. The subsequent diagnosis was right cervical lymph node metastasis and multiple bone metastases. The patient also presented with thrombocytopenia, anemia, and elevated levels of alkaline phosphatase, probably due to metastatic bone disease. Although various antitumor therapies were administered, the patient died 6 months after diagnosis of multiple bone metastases.

Objective. In order to predict the partial pressure of volatile anesthetics in brain tissue, we developed a pharmacokinetic simulation model suitable for real time application. The accuracy of this model was examined by comparing the predicted values against measured values for blood sampled from the internal jugular vein, which was used as a measure of the partial pressure in the brain. Methods. Our model consists of six compartments: alveoli, arterial blood, a group of vessel-rich organs (VRG), muscle, fat, and venous blood. A volatile anesthetic, sevoflurane partial pressure in each compartment were calculated using the parameters of volume, blood flow, and solubility for each tissue as reported in previous studies. Simulated sevoflurane partial pressures in VRG were considered to reflect those in the brain. We studied 11 patients undergoing elective abdominal surgery or mastectomy. Sevoflurane was maintained at a concentration of 3% (by vaporizer setting) for 25 min. Sampling points were at 0 min (before sevoflurane administration) and 1, 2, 4, 9, 16, and 25 min after the start of inhalation. We measured the sevoflurane partial pressure in inspiratory gas (PIS), in end-expiratory gas (PETS), in arterial blood (PaS), and in internal jugular vein blood (PjS). These values were compared against those for the simulated brain (PBSsim). Results. The sevoflurane partial pressures increased, in order from least rapid to most rapid, as follows: PjS, PBSsim, PaS, PETS, and PIS. The differences between PjS and PBSsim were significantly smaller than those between PjS and PETS at all sampling points. PBSsim did not differ significantly from PjS at any sampling points after 4 min of inhalation, while PETS differed significantly from PjS at all sampling points. Conclusion.We conclude that our model is clinically useful for predicting sevoflurane partial pressure in the brain, assuming that PjS reflects the sevoflurane partial pressure in the brain. [ABSTRACT FROM AUTHOR]

Tension pneumoperitoneum may force gas into a small injured vessel if the opening is kept patent by surrounding tissues. However, the amount of carbon dioxide (CO2) that penetrates through injured or noninjured peritoneum has not been systematically determined. In 25 patients undergoing elective laparoscopic ultrasonography and cholecystectomy, CO2 output (VCO2) and O2 uptake (VO2) were measured at baseline and during anesthesia, pneumoperitoneum, laparoscopic surgical procedure (Surgery), and after hemostasis of the surgical field (Postsurgery). Before anesthesia, VCO2/BSA and VO2/BSA were 97.7 +/- 11.3 and 116.0 +/- 10.0 ml x min(-1) x m(-2), respectively. During anesthesia, they fell to 72.3 +/- 6.0 and 89.8 +/- 7.6 ml x min(-1) x m(-2), respectively (p < 0.05). VCO2/BSA increased to 96.0 +/- 11.1 at pneumoperitoneum (p < 0.05) and increased further to 126.1 +/- 11.0 ml x min(-1) x m(-2) at Surgery. It fell to 111.7 +/- 10.9 ml x min(-1) x m(-2) Postsurgery. VO2/BSA remained unchanged during pneumoperitoneum. Minute volume increased from 2.24 +/- 0.20 in anesthesia to 2.89 +/- 0.25, 4.01 +/- 0.32, and 3.46 +/- 0.28 L x min(-1) x m(-2) during pneumoperitoneum, Surgery, and Postsurgery, respectively, to maintain PaCO2. We conclude that the amount of CO2 absorbed following pneumoperitoneum prior to surgery is lower than that during Surgery or Postsurgery. The amount of CO2 absorbed through the surgical field was 2.3 times higher than that through the nonsurgical field while that from the peritoneum after hemostasis of surgical field was 1.6 times higher. [ABSTRACT FROM AUTHOR]

TiO2/sapphire beam splitter (BS) for high-order harmonics was studied and fabricated through taking advantage of the self-limiting nature of atomic layer epitaxy (ALE). Theoretical calculation indicated that the highest reflectivity of the TiO2/sapphire BS was 44.8 % at 21.24 nm, which corresponds to the 37th-order harmonics of the 800-nm pump pulse and then the optimal thickness of the TiO2 layer was 67.4 nm. Incident angle was set at 70.5° for TiO2, which corresponds to the Brewster's angle of the 800-nm pump pulse. Moreover, experimental results indicated that refractive indices (λ = 632.8nm) of the TiO2 films were almost constant at a value of 2.59 and growth rate of TiO2 films was 0.077nm/cycle, which corresponds to 885 cycles in order to deposit the TiO2 layer with the optimal film thickness as an anti-reflection layer. [ABSTRACT FROM AUTHOR]

Summary The concentrations of nitrous oxide, sevoflurane and oxygen in the circle system of a closed-circuit anaesthesia machine, the PhysioFlex™, were measured in seven patients. During anaesthesia, the settings for each gas were changed and their concentrations recorded. At the induction of anaesthesia, it took 80–510 s (median 190 s) for the end-tidal sevoflurane concentration to reach 2.0%, and 920–2640 s (median 1500 s) for the oxygen in the breathing circuit to reach 30%. At this time, the nitrous oxide concentration was 60 ± 3% (mean ± SD). During anaesthesia, it took 90–480 s (median 140 s) for the end-tidal sevoflurane concentration setting to decrease from 3.0 to 1.0%, and 90–400 s (median 110 s) to return from 1.0 to 3.0%. When the inspired oxygen was increased from 30 to 50%, circuit concentrations reached equilibrium in 40–60 s (median 40 s), and when decreased from 50% back to 30%, equilibrium took 310–470 s (median 450 s). During recovery from anaesthesia, inspiratory sevoflurane concentration took 40–70 s (median 50 s) to decrease to 0.2%. The PhysioFlexTM provided adequate control of sevoflurane and oxygen concentrations, but not of increasing nitrous oxide concentrations. [ABSTRACT FROM AUTHOR]

In the present study, we evaluated activated areas of the cerebral cortex with regard to the mirror neuron system during swallowing. To identify the activated areas, we used magnetoencephalography. Subjects were ten consenting volunteers. Swallowing-related stimuli comprised an animated image of the left profile of a person swallowing water with laryngeal elevation as a visual swallowing trigger stimulus and a swallowing sound as an auditory swallowing trigger stimulus. As control stimuli, a still frame image of the left profile without an additional trigger was shown, and an artificial sound as a false auditory trigger was provided. Triggers were presented at 3,000 ms after the start of image presentation. The stimuli were combined and presented and the areas activated were identified for each stimulus. With animation and still-frame stimuli, the visual association area (Brodmann area (BA) 18) was activated at the start of image presentation, while with the swallowing sound and artificial sound stimuli, the auditory areas BA 41 and BA 42 were activated at the time of trigger presentation. However, with animation stimuli (animation stimulus, animation + swallowing sound stimuli, and animation + artificial sound stimuli), activation in BA 6 and BA 40, corresponding to mirror neurons, was observed between 620 and 720 ms before the trigger. Besides, there were also significant differences in latency time and peak intensity between animation stimulus and animation + swallowing sound stimuli. Our results suggest that mirror neurons are activated by swallowing-related visual and auditory stimuli.

We analyze a duopolistic health care market in which a rural public hospital competes against an urban public hospital on medical quality, by using a Hotelling-type spatial competition model extended into a two-region model. We show that the rural public hospital provides excess quality for each unit of medical service as compared to the first-best quality, and the profits of the rural public hospital are lower than those of the urban public hospital because the provision of excess quality requires larger expenditure. In addition, we investigate the impact of the partial (or full) privatization of local public hospitals.

Background: Advancing a tracheal tube into the bronchus produces unilateral breath sounds. We created a Visual Stethoscope that allows real-time fast Fourier transformation of the sound signal and 3-dimensional (frequency-amplitude-time) color rendering of the results on a personal computer with simultaneous processing of 2 individual sound signals. The aim of this study was to evaluate whether the Visual Stethoscope can detect bronchial intubation in comparison with auscultation., Methods: After induction of general anesthesia, the trachea was intubated with a tracheal tube. The distance from the incisors to the carina was measured using a fiberoptic bronchoscope. While the anesthesiologist advanced the tracheal tube from the trachea to the bronchus, another anesthesiologist auscultated breath sounds to detect changes of the breath sounds and/or disappearance of bilateral breath sounds for every 1 cm that the tracheal tube was advanced. Two precordial stethoscopes placed at the left and right sides of the chest were used to record breath sounds simultaneously. Subsequently, at a later date, we randomly entered the recorded breath sounds into the Visual Stethoscope. The same anesthesiologist observed the visualized breath sounds on the personal computer screen processed by the Visual Stethoscope to examine changes of breath sounds and/or disappearance of bilateral breath sound. We compared the decision made based on auscultation with that made based on the results of the visualized breath sounds using the Visual Stethoscope., Results: Thirty patients were enrolled in the study. When irregular breath sounds were auscultated, the tip of the tracheal tube was located at 0.6 +/- 1.2 cm on the bronchial side of the carina. Using the Visual Stethoscope, when there were any changes of the shape of the visualized breath sound, the tube was located at 0.4 +/- 0.8 cm on the tracheal side of the carina (P < 0.01). When unilateral breath sounds were auscultated, the tube was located at 2.6 +/- 1.2 cm on the bronchial side of the carina. The tube was also located at 2.3 +/- 1.0 cm on the bronchial side of the carina when a unilateral shape of visualized breath sounds was obtained using the Visual Stethoscope (not significant)., Conclusions: During advancement of the tracheal tube, alterations of the shape of the visualized breath sounds using the Visual Stethoscope appeared before the changes of the breath sounds were detected by auscultation. Bilateral breath sounds disappeared when the tip of the tracheal tube was advanced beyond the carina in both groups.

Objective: The purpose of this study was to investigate the reliability of cardiac output (CO) measured by a new ultrasound dilution method (COud) in comparison with CO by pulmonary artery thermodilution (COtd) in adult patients undergoing surgery., Design: A prospective study., Setting: A university hospital, single institutional., Participants: Twenty-nine adult patients undergoing abdominal surgery., Measurements and Main Results: After approval of the institutional ethics review board, 29 adult patients were evaluated. After induction, radial and pulmonary artery catheters were inserted. A disposable extracorporeal AV loop was connected between existing arterial and central venous catheters. Reusable ultrasound sensors that measure changes in blood ultrasound velocity after dilution by isotonic saline were clamped onto the arterial and venous limbs of the loop. Ultrasound dilution (UD) measurements (COstatus; Transonic Systems, Inc, Ithaca, NY) were obtained by injecting 30 mL of body-temperature isotonic saline into the venous limb of the AV loop. An average of 3 COud and 5 COtd was obtained for comparison. Bland-Altman plot and correlation analysis were used for statistical comparison. A total of 142 comparison measurements were obtained. The correlation coefficient between the 2 techniques was r = 0.91. Bland-Altman analysis did not produce any significant bias (bias = 0.02, standard deviation = 0.56). The percentage error of these data was 23.53%., Conclusions: COud measurements agreed well with COtd. The results of this study indicated that COud might be interchangeable with conventional COtd in perioperative adult patients.

We investigate a health care market with uncertainty in a mixed duopoly, where a partially privatized public hospital competes against a private hospital in terms of quality choice. We use a simple Hotelling-type spatial competition model by incorporating mean-variance analysis and the framework of partial privatization. We show how the variance in the quality perceived by patients affects the true quality of medical care provided by hospitals. In addition, we show that a case exists in which the quality of the partially privatized hospital becomes higher than that of the private hospital when the patient's preference for quality is relatively high.

Background: Although hemorrhagic shock decreases the minimum alveolar concentration (MAC) of inhaled anesthetics, it minimally alters the electroencephalographic (EEG) effect. Hemorrhagic shock also induces the release of endorphins, which are naturally occurring opioids. We tested whether the release of such opioids might explain the decrease in MAC., Methods: Using the dew claw-clamp technique in 11 swine, we determined the isoflurane MAC before hemorrhage, after removal of 30% of the estimated blood volume (21 mL/kg of blood over 30 min), after fluid resuscitation using a volume of hydroxyethylstarch equivalent to the blood withdrawn, and after IV administration of 0.1 mg/kg of the mu-opioid antagonist naloxone., Results: Hemorrhagic shock decreased the isoflurane MAC from 2.05% +/- 0.28% to 1.50% +/- 0.51% (P = 0.0007). Fluid resuscitation did not reverse MAC (1.59% +/- 0.53%), but additional administration of naloxone restored it to control levels (1.96% +/- 0.26%). The MAC values decreased depending on the severity of the shock, but the alterations in hemodynamic variables and metabolic changes accompanying fluid resuscitation or naloxone administration did not explain the changes in MAC., Conclusions: Consistent with previous reports, we found that hemorrhagic shock decreases MAC. In addition, we found that naloxone administration reversed the effect on MAC, and we propose that activation of the endogenous opioid system accounts for the decrease in MAC during hemorrhagic shock. Such an activation would not be expected to materially alter the EEG, an expectation consistent with our previous finding that hemorrhagic shock minimally alters the EEG.

Introduction: The Skin-to-Epidural Space Distance (SESD) is likely to be different at two different parts of the spine in the same individual and also in the same part of the spine in two different individuals. The knowledge of the expected depth of the epidural space can be very useful in placing the epidural needle appropriately and avoiding unwanted dural puncture. Although many studies have been conducted to study the relation of lumbar SESD with various physical and anthropometric parameters, the literature on thoracic SESD is scant. Aim: To determine the correlation between SESD and Abdominal Girth (AG) in the mid-thoracic, lower thoracic, and lumbar regions of the spine in adult patients scheduled for elective surgical procedures. Materials and Methods: After obtaining Ethics Committee clearance (EC/NIMS/2671/2020, 51st ESGS No: 1082/2020), this prospective observational study was carried out at Nizam's Institute of Medical Sciences, Hyderabad, India, from October 2021 to February 2022. The study recruited 202 patients, and data from 194 patients was analysed. During the preoperative visit, all physical parameters, including AG, were noted. Using an 18G Tuohy needle, the epidural space was identified, and SESD was measured. Its correlation with AG, age, height, weight, and body mass index was studied. The data was analysed using the Statistical Pacakge for Social Sciences Software (SPSS) (2011, IBM, Armonk, NY, United States of America) version 20.0. Results: The mean SESD was 4.7±1.09 cm in the mid-thoracic region, 4.71±0.98 cm in the lower thoracic region, and 4.8±0.82 cm in the lumbar region. The correlation coefficient of SESD with AG was 0.42, 0.44, and 0.78 in the mid-thoracic, lower thoracic, and lumbar regions, respectively, and the significance level was <0.001 in all three regions. Body weight had a good correlation (r-values of 0.56, 0.66, 0.53 in mid-thoracic, lower thoracic, and lumbar areas, respectively, and p-value of <0.001 in all three anatomical regions of the spine) with SESD. All other physical parameters were correlated weakly with SESD. Conclusion: AG has a strong correlation with SESD in the lumbar area but a moderate correlation in the thoracic spine. SESD in the lumbar, mid, and lower thoracic regions have a good correlation with weight. [ABSTRACT FROM AUTHOR]

Background: The propofol awakening concentration can vary. However, the effect site awakening propofol concentration will be a fixed value. The purpose of this study was to determine the awakening propofol concentrations obtained from infusion Schede using abrupt discontinuation of propofol (half-maximal effective concentration [EC50]) or a descending decrease in concentration to allow blood-effect site equilibration (EC50eq)., Methods: Patients undergoing short-term (group 1) and long-term (group 2) elective surgery were anesthetized with computer-assisted continuous infusion of propofol and fentanyl, with both groups receiving the same propofol (3 microg/ml) and fentanyl (1 ng/ml) concentrations 20-30 min before the end of surgery until the end. Then both groups were further divided into two subgroups: subgroup A abrupt discontinuation, and subgroup B descending concentrations of propofol (15-min duration per concentration). In the A subgroups, the response to verbal command was evaluated every 30 s. In the B subgroups, the blood propofol concentrations just permitting and just preventing response to command were averaged individually. The EC50 and EC50eq values were determined by probit analysis., Results: The EC50 of group 1A was 1 microg/ml, which was significantly less than the 1.6 microg/ml of group 2A (P < 0.05). The awakening time of group 1A was 5.2 +/- 1.8 min, which was significantly shorter than the 9.3 +/- 3.5 min of group 2A (means +/- SD). The EC50eq of both groups 1B and 2B was 2.2 microg/ml., Conclusions: The EC50eq was independent of propofol infusion length, compared with the EC50. Thus the potential for hysteresis during emergence from propofol anesthesia was confirmed.

Long-time oral intake of magnesium-silicate-containing drugs is thought to be a causative factor inducing silicate urolithiasis. Besides, magnesium seems to play an anti-urolithogenic part in the formation of calcium oxalate stones. We report a recurrent calcium oxalate former who had been treated with magnesium aluminometasilicate antacid for gastric ulcer for approximately 17 years. One of the fragments found during extracorporeal shock wave lithotripsy was identified as 100% silicate. Deposition of silica was also found on other fragments. A large dose of magnesium (given in a part of the drug) might have little influence on the formation of calcium oxalate.

Introduction: Hemodialysis treatment using standard dialysate bicarbonate concentrations cause transient metabolic alkalosis possibly associated with hemodynamic instability. The aim of this study was to perform a detailed comparison of high and low dialysate bicarbonate in terms of blood pressure, intradialytic hemodynamic parameters, orthostatic blood pressure, and electrolytes. Methods: Fifteen hemodialysis patients were examined in a single‐blind, randomized, controlled, crossover study. Participants underwent a 4‐h hemodialysis session with dialysate bicarbonate concentration of 30 or 38 mmol/L with 1 week between interventions. Blood pressure was monitored throughout hemodialysis, while cardiac output, total peripheral resistance, stroke volume, and central blood volume were assessed with ultrasound dilution technique (Transonic). Orthostatic blood pressure was measured pre‐ and post‐hemodialysis. Findings: With similar ultrafiltration (UF) volume (2.6 L), systolic blood pressure (SBP) tended to decrease more during high dialysate bicarbonate compared to low dialysate bicarbonate; the mean (95% confidence interval) between treatment differences in SBP were: 8 (−4; 20) mmHg (end of hemodialysis) and 7 (0; 15) mmHg (post‐hemodialysis). Stroke volume decreased whereas total peripheral resistance increased significantly more during high dialysate bicarbonate compared to low dialysate bicarbonate with mean between treatment differences: Stroke volume: 12 (1; 23) mL; Total peripheral resistance: −2.9 (−5.3; −0.5) mmHg/(L/min). Cardiac output tended to decrease more with high dialysate bicarbonate compared to low dialysate bicarbonate with mean between treatment difference 0.7 (0.0; 1.4) L/min. High dialysate bicarbonate caused alkalosis, hypocalcemia, and lower plasma potassium, whereas patients remained normocalcemic with normal pH during low dialysate bicarbonate. Orthostatic blood pressure response after dialysis did not differ significantly. Discussion: The use of high dialysate bicarbonate compared to low dialysate bicarbonate was associated with hypocalcemia, alkalosis, and a more pronounced hypokalemia. During hemodialysis with UF, a better preservation of blood pressure, stroke volume, and cardiac output may be achieved with low dialysate bicarbonate compared to high dialysate bicarbonate. [ABSTRACT FROM AUTHOR]

Background: Propofol is the preferred drug for the induction of anesthesia in many centers. However, its ubiquitous use is hampered by adverse effects. The rationale behind our study is to prove that whether the administration of an opioid drug before propofol induction, lowers the amount of propofol requirement for balanced anesthesia, and enhances hemodynamic stability. Aim: The present study intends to know the consequence of the differing time intervals between the administration of fentanyl and propofol on the dosage of propofol required to achieve induction of general anesthesia. Methods: In this observational study, 84 patients were included in the study. Patients who received propofol immediately after fentanyl injection were included in Group 1, whereas patients who received propofol at 3 min and 6 min after fentanyl injection, respectively, were grouped as Group 2 and Group 3. The total propofol required, the hemodynamic variations and the entropy values were recorded. SSPS version 25.09 (IBM) was used for statistical analysis. Results: In this study, it was observed that there was a significant reduction in propofol requirement in Group 2 and Group 3 compared with Group 1. The incidence of hypotension was seen in about 42.9% of Group 1 when compared to Group 2 and 3, which was 28.6% and 17.8%, respectively. Furthermore, the entropy values in Group 3 were initially higher and later were comparable in all the groups. Conclusion: Our study concluded that as the duration between the administration of propofol and fentanyl increases, the hemodynamic stability also increases and there is no variation in the depth of anesthesia attained in the distinct study population. [ABSTRACT FROM AUTHOR]

Critically ill or anesthetized patients commonly receive pump-driven intravenous infusions of potent, fast-acting, short half-life medications for managing hemodynamics. Stepwise dosing, e.g. over 3-5 min, adjusts physiologic responses. Flow rates range from < 0.1 to > 30 ml/h, depending on pump type (large volume, syringe) and drug concentration. Most drugs are formulated in aqueous solutions. Hydrophobic drugs are formulated as lipid emulsions. Do the physical and chemical properties of emulsions impact delivery compared to aqueous solutions? Does stepwise dose titration by the pump correlate with predicted plasma concentrations? Precise, gravimetric, flow rate measurement compared delivery of a 20% lipid emulsion (LE) and 0.9% saline (NS) using different pump types and flow rates. We measured stepwise delivery and then computed predicted plasma concentrations following stepwise dose titration. We measured the pharmacokinetic coefficient of short-term variation, (PK-CV), to assess pump performance. LE and NS had similar mean flow rates in stepwise rate increments and decrements between 0.5 and 32 ml/h and continuous flows 0.5 and 5 ml/h. Pharmacokinetic computation predictions suggest delayed achievement of intended plasma levels following dose titrations. Syringe pumps exhibited smaller variations in PK-CV than large volume pumps. Pump-driven deliveries of lipid emulsion and aqueous solution behave similarly. At low flow rates we observed large flow rate variability differences between pump types showing they may not be interchangeable. PK-CV analysis provides a quantitative tool to assess infusion pump performance. Drug plasma concentrations may lag behind intent of pump dose titration., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

We developed a miniature mixing chamber, the bymixer, that aids in the measurement of respiratory gas metabolism and inhalation anesthetic uptake. A small fraction of total respiratory gas flow is bypassed from the inspiratory or expiratory limb of the breathing circuit to the bymixer. We tested the relationship between total flow and bypass flow. To analyze the error and response time of the system, we compared the mixed expired carbon dioxide from the bymixer (capacity, 0.3 L, ratio of bypass flow to total flow, 1/4.5) with that from a conventional 2.0-L mixing chamber in 15 volunteers and 12 anesthetized patients during spontaneous or controlled ventilation. Bypass flow correlated well with total flow (r2 = 0.999 to 1.000) when total flow ranged from 0 to 70 L/min and the ratio of bypass flow to total flow ranged from 1/3 to 1/20. The difference between the values of mixed expired carbon dioxide from the two mixing chambers was small, ranging from -0.03 to 0.01 vol% in both of the ventilatory modes. The relative error was within 2.3% of the carbon dioxide values obtained from the conventional chamber. We observed the error at the lowest minute volume (4 L/min). The 90% response time of the bymixer (24.8 seconds) was similar to that of the conventional chamber (19.1 seconds) at a minute volume of 7.5 L/min. For clinical use, we combined a conventional breathing circuit with two bymixers, one for mixing inspired gas and the other for mixing expired gas. We found this device accurate and easy to use.

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Purpose: Different organs have different autoregulatory capacities for blood pressure changes and/or circulatory volume changes. This study assessed the autoregulation of the stomach, liver, kidney and skeletal muscle, under baseline, hypovolemic, and post-fluid-resuscitation conditions using near-infrared spectroscopy (NIRS). Methods: Ten pigs (bodyweight 24.5 ± 0.5 kg) were anesthetized with 2.5% isoflurane and administered 0.5, 1, 2 and 5 µg kg− 1 min− 1 of phenylephrine at 10-min intervals, followed by similar stepwise infusion of sodium nitroprusside (SNP) to induce a wide range of mean arterial pressures (MAPs). A 600-ml bleed was induced to create the hypovolemic condition, and only phenylephrine was re-administered. Hydroxyethyl starch (600 ml) was infused to create the post-fluid-resuscitation condition, and phenylephrine and SNP were re-administered. Average relationships between mean arterial pressure (MAP) and each tissue oxygenation index (TOI) were assessed, and the individual relationships were evaluated based on the correlation coefficients between MAP and TOI during each vasoactive drug infusion. Results: Based on the evaluation using each TOI as a substitute of blood flow, the kidney autoregulation was robust, similar to muscle, but had a prominent lower limit. The stomach had weaker autoregulation than the kidney and muscle. The liver had no autoregulation. The kidney TOI showed 2-fold greater changes in response to volume condition changes than the stomach and liver TOIs. Conclusion: In our NIRS-based assessment of autoregulatory capacity, the liver oxygenation is highly blood pressure dependent, and the kidney is highly susceptible and the skeletal muscle is highly tolerable to low blood pressure and volume loss. [ABSTRACT FROM AUTHOR]

Stethoscopes were originally designed for the auscultation of a patient's chest for the purpose of listening to lung and heart sounds. These aid medical professionals in their evaluation of the cardiovascular and respiratory systems, as well as in other applications, such as listening to bowel sounds in the gastrointestinal system or assessing for vascular bruits. Listening to internal sounds during chest auscultation aids healthcare professionals in their diagnosis of a patient's illness. We performed an extensive literature review on the currently available stethoscopes specifically for use in chest auscultation. By understanding the specificities of the different stethoscopes available, healthcare professionals can capitalize on their beneficial features, to serve both clinical and educational purposes. Additionally, the ongoing COVID-19 pandemic has also highlighted the unique application of digital stethoscopes for telemedicine. Thus, the advantages and limitations of digital stethoscopes are reviewed. Lastly, to determine the best available stethoscopes in the healthcare industry, this literature review explored various benchmarking methods that can be used to identify areas of improvement for existing stethoscopes, as well as to serve as a standard for the general comparison of stethoscope quality. The potential use of digital stethoscopes for telemedicine amidst ongoing technological advancements in wearable sensors and modern communication facilities such as 5G are also discussed. Based on the ongoing trend in advancements in wearable technology, telemedicine, and smart hospitals, understanding the benefits and limitations of the digital stethoscope is an essential consideration for potential equipment deployment, especially during the height of the current COVID-19 pandemic and, more importantly, for future healthcare crises when human and resource mobility is restricted. [ABSTRACT FROM AUTHOR]