Reversal Of Muscle Relaxation Research Articles

Update: Neuromuscular Blockade during General Anesthesia

The correct use of muscle relaxants and neuromuscular monitoring during anesthesia has been subject of controversial discussions for decades. Particularly important in clinical practice are identification and management of residual neuromuscular blockages and avoidance of associated complications. Despite the differences in the molecular mechanisms of action between depolarizing and non-depolarizing muscle relaxants the blockade of the postsynaptic nicotinic acetylcholine receptor remains a common ending pathway. Due to its unfavorable side effect profile, succinylcholine should only be used in justified exceptional cases. The use of muscle relaxants generally reduces the complication rate in airway management. However, even the single use of muscle relaxants increases the likelihood of postoperative pulmonary complications. These complications associated with the use of muscle relaxants, such as residual neuromuscular blockade, must be anticipated. The application of guideline-based approaches, including continuous neuromuscular monitoring and the application of muscle relaxant reversal agents, may significantly reduce the rate of adverse events associated with the use of muscle relaxants.

Reversal of neuromuscular block with neostigmine and sugammadex: a retrospective cohort study in two centers using different types of neuromuscular monitoring.

This bicentric retrospective cohort study evaluates reversal of muscle relaxation in real life achieved either by neostigmine or sugammadex in two hospitals using different types of neuromuscular monitoring (acceleromyography and kinemyography). The research question concerns compliance with recommendations. Patients who underwent an abdominal surgery under general anesthesia in the period from January 2017 through December 2020 with a neuromuscular block with rocuronium were included in the study. Data were extracted from the Centricity anesthesia information management system. In total, 2242 patients were assessed: 459 in center 1 (61 having received neostigmine and 398 sugammadex) and 1783 in center 2 (531 and 1252, respectively). Patients' characteristics differed between centers, with more high-risk patients in center 1. The mean train-of-four (TOF) ratio after supramaximal current determination (supramaximal threshold) was higher in center 1 (p < 0.001). Most patients received neostigmine while the TOF ratio was < 40% (68.6% in center 1 and 62.4% in center 2), while extubation was performed while the TOF ratio was > 90% in 61.0% in center 1 and in 32.1% in center 2 (p < 0.001). Patients received sugammadex irrespective of the number of responses to TOF before reversal, and extubation was performed while the TOF ratio was > 90% in 85.0% in center 1 and in 53.6% in center 2 (p < 0.001). No side effect was encountered. Despite guidelines for the TOF ratio before extubation, recommendations were not adequately respected and more vigilance is mandatory. The TOF test before use gave values that were 100% far apart with an underestimation with acceleromyography and an overestimation using kinemyography.

First non-invasive magnetic phrenic nerve and diaphragm stimulation in anaesthetized patients: a proof-of-concept study

BackgroundMechanical ventilation has side effects such as ventilator-induced diaphragm dysfunction, resulting in prolonged intensive care unit length of stays. Artificially evoked diaphragmatic muscle contraction may potentially maintain diaphragmatic muscle function and thereby ameliorate or counteract ventilator-induced diaphragm dysfunction. We hypothesized that bilateral non-invasive electromagnetic phrenic nerve stimulation (NEPNS) results in adequate diaphragm contractions and consecutively in effective tidal volumes.ResultsThis single-centre proof-of-concept study was performed in five patients who were 30 [IQR 21–33] years old, 60% (n = 3) females and undergoing elective surgery with general anaesthesia. Following anaesthesia and reversal of muscle relaxation, patients received bilateral NEPNS with different magnetic field intensities (10%, 20%, 30%, 40%); the stimulation was performed bilaterally with dual coils (connected to one standard clinical magnetic stimulator), specifically designed for bilateral non-invasive electromagnetic nerve stimulation. The stimulator with a maximal output of 2400 Volt, 160 Joule, pulse length 160 µs at 100% intensity was limited to 50% intensity, i.e. each single coil had a maximal output of 0.55 Tesla and 1200 Volt. There was a linear relationship between dosage (magnetic field intensity) and effect (tidal volume, primary endpoint, p < 0.001). Mean tidal volume was 0.00, 1.81 ± 0.99, 4.55 ± 2.23 and 7.43 ± 3.06 ml/kg ideal body weight applying 10%, 20%, 30% and 40% stimulation intensity, respectively. Mean time to find an initial adequate stimulation point was 89 (range 15–441) seconds.ConclusionsBilateral non-invasive electromagnetic phrenic nerve stimulation generated a tidal volume of 3–6 ml/kg ideal body weight due to diaphragmatic contraction in lung-healthy anaesthetized patients. Further perspectives in critically ill patients should include assessment of clinical outcomes to confirm whether diaphragm contraction through non-invasive electromagnetic phrenic nerve stimulation potentially ameliorates or prevents diaphragm atrophy.

Effectiveness of Sugammadex on muscle relaxant reversal in preterm neonates

ABSTRACT Background & objective Sugammadex is a drug used to reverse the muscle relaxation effect of rocuronium. Its use is still limited in preterm neonates. The aim of this study was to compare the efficacy of Sugammadex with that of neostigmine in reversing rocuronium-induced muscle relaxation in preterm neonates and to evaluate the safety of its use in this age group. Patients and methods This randomized clinical trial was carried out on Sixty preterm neonates, planned for elective inguinal hernia repair under general anaesthesia. The patients were divided into two equal groups. Group N used neostigmine and group S used Sugammadex as the reversal agent for rocuronium. Results In Sugammadex group the mean reversal time (1.15 ± 0.42) min and the mean recovery time (17 ± 6.64) min were significantly shorter than in the neostigmine group (8.9 ± 1.6) min and (27.16 ± 9.26) min respectively, with p value <0.001.The patients in the Sugammadex group showed significantly lower heart rate than those in neostigmine group but showed no significant difference as regard mean blood pressure at 3, 6, 9,12,15 and 18 min after drug injection.There were no significant complications noted in both group Conclusion Sugammadex is well tolerated in the Preterm neonates with shorter recovery and reversal time when compared to neostigmine.

Optimizing Reversal of Muscle Relaxation with Sugammadex to Accelerate Discharge Readiness in Operative Laryngoscopy: A Randomized Clinical Trial.

Operative laryngoscopy is a commonly performed ambulatory procedure in patients with significant co-morbidity. Optimal anesthetics for surgical exposure with rapid return to baseline after the procedure enhances postoperative patient safety. To determine whether sugammadex hastens recovery in patients undergoing operative laryngoscopy under general anesthesia with rocuronium-induced paralysis. Prospective clinical intervention randomized single-blinded, single-center study in an academic tertiary care center. Approved by the institutional review board and registered with ClinicalTrials.gov. Single center tertiary care academic institution. 18years or older, American Society of Anesthesiology physical status I-III with ability to give written informed consent undergoing operative laryngoscopy. Participants were randomized into two groups. Both groups received inhaled anesthetic: sevoflurane, remifentanil, and rocuronium at 0.6-1.2 mg/kg for intubation and anti-nausea prophylaxis. Group 1 received reversal with neostigmine (0.04 mg/kg) and glycopyrrolate (0.01 mg/kg). Group 2 received reversal with sugammadex (4 mg/kg). Vital signs were maintained at 20% of baseline in both groups. Post anesthesia care unit nurses were blinded to the reversal agent and were the evaluators of the discharge criteria and times. Primary end point was time to extubation after the procedures and secondary end points were: Subjective interpretation of surgical conditions by the surgeon, hemodynamic, respiratory parameters, anesthetics, and opioids used, operative time, and duration to achieve discharge readiness. A total of eighty-four participants, who were similar in age, sex, and weight in both groups. The primary end point and secondary end points were similar except time to meet discharge criteria in the two groups. 65% in the sugammadex versus 35% in the neostigmine group met Aldrete criteria of 18 or higher on arrival at the post anesthesia care unit. Optimizing the anesthetic regimen, along with stable intraoperative hemodynamics and reversal with sugammadex improves discharge readiness in patients undergoing operative laryngoscopy.

Comparison between the Effects of Combination of Atropine plus Glycopyrrolate with Atropine alone on Heart Rate for the Reversal of Muscle Relaxant after General Anesthesia

Background: A muscle relaxant is an integral component of general anesthesia. Anticholinesterase drugs employed as their antagonist are associated with certain untoward effects. To counter these undesirable effects, anticholinergic agents, atropine, and glycopyrrolate are often used. Objectives: To compare and quantify the mean change in heart rate in patients receiving atropine (0.5 mg) alone, glycopyrrolate (0.5 mg) alone, and atropine (0.25 mg) plus glycopyrrolate (0.25 mg) after muscle relaxant reversal with neostigmine. Study Design: Randomized controlled trial Place and Duration of Study: Department of Anesthesiology and General Surgery Operation Theatre, Nishtar Medical University Multan from 1st January 2021 to 30th June 2021. Methodology: Ninety patients fulfilling inclusion and exclusion criteria undergoing elective cholecystectomy or ventral hernia repair under general anesthesia were included in this study. Group A (n= 30) received Atropine 0.5mg IV, Group G (n=30) received Glycopyrrolate 0.5mg IV while Group A+G (n=30) received atropine 0.25mg plus glycopyrrolate 0.25mg. Data regarding patients’ age, gender, ASA status, type of procedure and operation time, detailed clinical history, and laboratory investigations were taken for all patients. Heart rate of patients before muscle relaxant reversal and after 3 minutes of reversal was noted and heart rate change was calculated. Results: Mean change in heart rate in group A+G was 9.06±3.55 beats/min, 18.53±9.61 beats/min in group A and 17.26±6.20 beats/min in group G. This difference was statistically significant with a p-value &lt;0.0001. Conclusion: Atropine and glycopyrrolate combination is more effective than atropine or glycopyrrolate alone in preventing the heart rate variability associated with reversal of neuromuscular blockers using neostigmine. Keywords: tropine, Glycopyrrolate, Heart rate.

Transient hypoxemia after endotracheal tube extubation in a patient who received reversal of muscle relaxation using sugammadex after general anesthesia: A case report

Post-operative respiratory depression is common in patients recovering from anesthesia and can result in fatal cardiopulmonary collapse, anoxic brain injury, and mortality. We report a case of a 54-year-old morbidly obese female patient who developed transient hypoxemia after general anesthesia. The patient with obstructive sleep apnea (OSA) underwent breast excision surgery. At the end of the surgery, her muscle function was fully restored using sugammadex. However, the patient developed transient hypoxemia in the post-anesthesia care unit. The clinician should keep in mind that OSA patients are likely to develop hypoxemia due to the residual sedative effects and airway obstruction despite the recovery of muscle function after anesthesia.

175. Opioid sparing anesthesia for adult spinal deformity surgery reduces postoperative pain, length of stay, ICU stay, opioid consumption and opioid-related complications: a propensity matched analysis

<h3>BACKGROUND CONTEXT</h3> The US opioid crisis highlights the dire need to reduce opioid exposure with alternative approaches. Prior studies report that 25% of opioid naive patients are still on opioids two years after spinal fusion surgery. Currently, opioids are a primary component of anesthesia during spinal surgery. We developed an opioid sparing anesthesia (OSA) protocol for adult spinal deformity (ASD) surgery to mitigate opioid exposure. <h3>PURPOSE</h3> The purpose of this study is to compare recovery kinematics and in-hospital opioid consumption of patients undergoing corrective surgery for ASD using OSA compared to traditional anesthesia techniques (Non-OSA). <h3>STUDY DESIGN/SETTING</h3> Retrospective, single-center propensity-matched observational cohort. <h3>PATIENT SAMPLE</h3> Opioid naive patients undergoing > 5 level lumbar fusion at a single multisurgeon tertiary level spine center. <h3>OUTCOME MEASURES</h3> Intraoperative and in-hospital opioid consumption, opioid related complications, emergence time, post-anesthesia care unit (PACU) time, pain score (0 to 10) on transfer in and transfer out of PACU, hospital length of stay (LOS), ICU admission. <h3>METHODS</h3> Opioid naive patients undergoing > 5 level lumbar fusion for were identified. Patients receiving OSA were propensity-matched to non-OSA patients based on sex, smoking status, BMI, ASA grade, surgical invasiveness, number of levels fused, and revision vs primary procedure. OSA has several components from preoperative, intraoperative and emergence. Preoperatively patients received an oral regimen of cyclobenzaprine (10 mg), gabapentin (300-600mg), acetaminophen (650mg-1gm), optional midazolam and antiemetic. Intraoperative induction with bolus doses of lidocaine, diprivan, rocuronium, succinylcholine, ketamine, magnesium, dexmedetomidine and esmolol as needed. Regional block for anterior spine fusion (transversus abdominis) when performed. Maintenance intraoperatively included inhalational and or infusion or boluses of diprivan, dexmedetomidine and esmolol. Emergence entailed reversal of muscle relaxant and antiemetics. The control arm (Non-OSA) included preoperative optional midazolam and antiemetic only. Intraoperatively induction was with bolus doses of lidocaine and fentanyl. Maintenance intraoperatively included inhalational, infusion or bolus doses of diprivan, fentanyl or hydromorphone. Emergence included reversal of muscle relaxant, antiemetics, fentanyl and/or hydromorphone. All patients (OSA and Non-OSA) had a postoperative opioid escalation protocol while in the hospital. <h3>RESULTS</h3> Of 45 OSA patients meeting inclusion criteria, 43 were successfully propensity-matched to 43 non-OSA patients. There were no differences in baseline demographic or surgical parameters. Opioid consumption was reduced intraoperatively (3.6 vs 53.2MME, p=0.000), on POD 1 (67.4 vs 111.6MME, p=0.030), and each POD with decreased total consumption (241.3 vs 453.9MME, p=0.022) in OSA patients compared to NonOSA patients. OSA patients had reduced opioid-related complications (1 vs 9, p=0.015) and less patients required blood transfusion (1 vs 28, p=0.000) despite similar EBL (570 vs 692cc, p=0.294). Emergence time (17.4 vs 14.3min, p=0.374) and PACU time (113.8 vs 142.6min, p=0.077) was similar between cohorts. There was a shorter LOS for OSA patients (4.3 vs 6.2 days, p=0.009) and less ICU admissions (4 vs 14, p=0.015). Pain score on transfer in (4.6 vs 7.6, p=0.000) and out (4.2 vs 6.2, p=0.002) of PACU was lower for OSA patients as well. <h3>CONCLUSIONS</h3> Our results show that OSA in ASD surgery improves immediate postoperative recovery kinetics by reducing the need for ICU, blood transfusion, pain scores, and LOS. Opioid-related complications and total opioid consumption were reduced as well. OSA appears to be an attractive alternative to opioid-dependent anesthesia protocols in ASD surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

The Occurrence of Postoperative Residual Curarization among Post-Coronary Artery Bypass Graft Patients in a Surgical Intensive Care Unit of a Tertiary Hospital

BACKGROUND: Intermediate-acting muscle relaxants have gained favor in fast-track cardiac anesthesia since these are associated with early extubation. However, postoperative residual curarization (PORC) still occur in the post anesthesia care unit. This study aims to determine the occurrence of PORC among post-coronary artery bypass graft (CABG) patients in the surgical intensive care units (SICU) of the Philippine Heart Center. METHODS: A cross-sectional study was undertaken among 60 patients for elective CABG surgery. Within an hour from SICU arrival, Train of Four (TOF) ratio was obtained and a value of &lt;0.7 signified the presence of PORC. RESULTS: 57 out of 60 (95%) were found to have PORC. Patients without PORC were significantly warmer (36.4oC vs 34.8oC, p-value=0.019) upon SICU arrival compared to those with PORC. The duration of ventilatory support was significantly longer in those with PORC (510 min vs 305 mins, p-value=0.021). The rocuronium induction dose and duration of infusion did not differ between those with and without PORC while the use of reversal drug was seen to significantly prevent its occurrence (p-value=0.003). CONCLUSION: This study showed a high incidence of PORC among post-CABG patients in the SICU with the current practice of Rocuronium infusion during surgery. The use of muscle relaxant reversal drug was seen to significantly prevent the development of PORC while higher body temperature upon SICU arrival was observed in patients that did not develop PORC. This study was also able to show that the development of PORC prolonged post-operative mechanical ventilatory support hindering the goals of fast-track cardiac surgery.

Earlier and lower dose administration of sugammadex: A randomised placebo-controlled trial.

Sugammadex allows for rapid reversal of muscle relaxation after the use of rocuronium or vecuronium. The lowest recommended dose is 2 mg kg-1 intravenously when there are two twitches during the train-of-four stimulation. To study the efficacy and risks of a lower dose of sugammadex administered earlier. Monocentric randomised controlled double-blind study. Academic hospital. Eighty patients were enrolled and randomised in 8 groups of 10 patients, 56 were finally evaluated. Patients were distributed in two clusters constituting four groups each. In the first cluster, injections were administered after the return of one twitch with the train-of-four (TOF1). In the second cluster, injections were delivered after the return of two twitches with the TOF (TOF2). We created four groups in each cluster for different dosages: placebo, 0.5, 1 or 2 mg kg-1. Time between the injection of sugammadex and full recovery (TOF ratio > 0.9) that is expressed in minutes. Fifty-six successive patients were assessed between February and August 2018. The difference to TOF greater than 0.9 was not statistically significant between groups with the same dose administered at different times (F value = 0.001, P value = 0.975). There was a significant difference between groups with a different dosage administered at the same time (F ratio = 28.34; P value <0.0001). Concerning the time to TOF greater than 0.9 from the time point of TOF1, the timing of the dosages were statistically significant using log rank test (P < 0.0001). No patient presented a reparalysis. No difference between injecting sugammadex at TOF1 or TOF2 was found regarding time to full recovery. Difference regarding sugammadex quantity was found and compatible with other studies. clinicaltrials.gov: 'BRIDION_ERASME', EudraCT: 2017-005074-19.

Factors Facilitating the Success of Fast Endotracheal Extubation after Cardiac Surgery

Objective: To study factors influencing fast endotracheal extubation after cardiac surgery. Materials and Methods: A one-year retrospective cohort study conducted via hospital medical informatics, included patients aged over 15 years old that underwent elective valvular heart surgery by means of cardiopulmonary bypass under general anesthesia. Results: Fifty-seven patients were enrolled in the present study including nine (15.8%) as fast endotracheal extubation in the operating theatre, 18 (31.6%) within eight hours postoperatively, and 30 (52.6%) non-fast endotracheal extubation eight hours after surgery. The preoperative and intraoperative factors were a younger age (p=0.018), high % left ventricular ejection function (LVEF) (p=0.023), and low creatinine level (p=0.026), as well as post cardiopulmonary bypass dexmedetomidine (p=0.01), reversal of muscle relaxant (p=0.004), and low dose dobutamine (p=0.003), respectively. However, multiple logistic regression analyses showed only two favorable factors, which were preoperative % LVEF of 60 or more (adjusted OR 11.266, 95% CI 1.700 to 74.664, p=0.012), and the intraoperative low dose dobutamine of 3 μg/kg/minute or less (adjusted OR 6.896, 95% CI 1.463 to 32.510, p=0.015). In addition, there were no significant complications. Conclusion: The factors influencing fast endotracheal extubation were preoperative% LVEF of 60 or more and intraoperative low dose dobutamine of 3 μg/kg/minute or less. Keywords: Cardiac surgery, Fast endotracheal extubation, Valvular heart disease

Algorithm-based preventive strategies for avoidance of residual neuromuscular blocks

Postoperative residual neuromuscular block (train of four ratio <0.9) is an outcome-relevant problem in balanced anesthesia, which increases postoperative morbidity and mortality. Implementation of medium and short-acting muscle relaxants, quantitative neuromuscular monitoring and pharmacological reversal of muscle relaxation reduce the incidence of residual neuromuscular block. The question arises whether this is suitable to create apragmatic algorithm integrating these three individual methods to reduce paralysis-associated complications? A selective literature search was carried out in PubMed and guidelines of national specialist societies were searched using special terms. The incidence of residual neuromuscular block varied among the studies but was as high as 93%. Using calibrated acceleromyography it is possible to identify a residual relaxation with anegative predictive value of 97% (95% confidence interval, CI 83-100%). Reversal by administration of the acetylcholinesterase inhibitor neostigmine reduces the incidence of residual neuromuscular block to 15.4%, in combination with calibrated acceleromyography to 3.3%. Reversal with sugammadex can nearly completely eliminate residual neuromuscular block. Quantitative neuromuscular monitoring and pharmacological reversal can be suitably integrated into astage-based, pragmatic treatment algorithm. The algorithm-based concept of quantitative neuromuscular monitoring and pharmacological reversal using neostigmine and sugammadex enables residual neuromuscular block to be treated within 10 min before extubation of the patient. Ongoing educational programs are essential for implementation of modern muscle relaxant management concepts. Quantitative neuromuscular monitoring should be mandatory for all patients receiving neuromuscular blocking drugs. It would be desirable that German-speaking societies for anesthesiology make appropriate recommendations in guidelines.

Respiratory events with sugammadex vs. neostigmine following laparoscopic sleeve gastrectomy: a prospective pilot study assessing neuromuscular reversal strategies.

From September 2012 to February 2013, in a prospective randomized pilot study, two different muscle relaxant reversal agents were administered at the end of surgery in 57 patients undergoing laparoscopic sleeve gastrectomy: sugammadex 2 mg/kg (32 patients) vs. neostigmine 2.5 mg (25 patients). We compared the occurrence of early and late respiratory events/complications by the type of reversal agent. Postoperative respiratory rate, oxyhemoglobin saturation (SpO2), number of patients with SpO2 lower than 95% in PACU, the minimum value of SpO2 in PACU, train-of four counts (TOF) before reversal, unexpected ICU admissions, duration of hospitalization and incidence of reintubation were recorded. SpO2 in the PACU was significantly lower in the neostigmine group - 95.80 (± 0.014)) vs. in sugammadex group - 96.72 (± 0.011) (p < 0.01), despite a lower TOF count measured in the sugammadex group before reversal, meaning a deeper level of residual relaxation in this group before the administration of the reversal agent (2.53 ± 0.98 vs. 3.48 ± 0.58 p < 0.01). Also, the minimal SpO2 was significantly lower in the PACU in the neostigmine group: 93% vs. 94% (p = 0.01). Respiratory rates were not different. After the administration of reversal, both groups had TOF counts of 4 with no fade assessed visually. There were no postoperative respiratory events or complications. The use of sugammadex (as compared to neostigmine) as a reversal agent following laparoscopic sleeve gastrectomy surgery was associated with higher postoperative SpO2 despite the lower TOF count before the administration of reversal agent. Despite the statistical difference in SpO2, its clinical importance seems to be minimal. The lack of difference in the other measured variables may stem from the small number of patients studied (pilot).

Abstract PR446

Background & Objectives: Objective: To compare difference in heart rate and complication after the reversal of non-depolarized muscle relaxant among patients receiving 0.6 mg, 0.9 mg and 1.2 mg of atropine plus 2.5 mg of neostigmine injection. Materials & Methods: Study design: Prospective randomized double-blind controlled trial Method: Consecutive 87 adult patients, ASA I-II who underwent elective surgery during October to November 2015 and received general anesthesia with endotracheal intubation with balanced technique. For reversal of non-depolarizing muscle relaxant, patients will be randomized to receive either 0.6 mg, 0.9 mg or 1.2 mg of atropine 30 second before neostigmine 2.5 mg intravenous injection. After the reversal of muscle relaxant, blood pressure and pulse rate of the patient were recorded every 1 minute for 15 minutes then every 5 minutes until complete 90 minutes of observation. Result: In the first 10 minutes of monitoring the heart rate among 3 groups of the study were difference significantly except for the first and the third minute. We found the maximum increment of heart rate of 34.6%, 22.4% and 21.8% from baseline in 1.2, 0.9 and 0.6 mg of atropine group, respectively. There were two cases of significant delayed bradycardia of 38 and 40 beat per minute, which required additional treatment in 0.6 mg of atropine group. Conclusion: The patient receiving 0.9 mg of atropine group has less tachycardia effect than the 1.2 mg of atropine without any complication. We recommended that the 0.9 mg of atropine injection 30 seconds before neostigmine administration might have a good benefit and can be used safely as an alternative choice in high cardiovascular risk patients.

Next Step in Cost Containment of Public Hospital Economy Could Be Merging of Anesthesia and Surgery Budgets.

Next Step in Cost Containment of Public Hospital Economy Could Be Merging of Anesthesia and Surgery Budgets.

Is the Pressure Control Mode for Pediatric Anesthesia Machines Really Required?

Dear Editor, Choosing an appropriate anesthesia machine for mechanical ventilation of pediatric patients is of paramount importance because small changes in the fractions of the delivered tidal volume can cause a significant difference from the desired tidal volume. The anesthesia machines have classically been divided up into pressure or volume controlled modes, with two main characteristics; the limit (what determines the size of the breath), and the cycle (what actually ends the breath). The traditional anesthesia machines with volume controlled mode are not able to deliver precisely small tidal volumes to the pediatric patients. In the traditional anesthesia machines, fresh gas directly streams to the breathing circuit, so if 6 L/min of fresh gas is added to the previous setting (6 liters/60 seconds) 100 mL/s will be added to the delivered tidal volume, and if the inspiratory time is 2 seconds, 200 mL will be added to the tidal volume. These differences significantly increase the desired tidal volume. Therefore, the conventional anesthesia machines with the volume-controlled ventilation mode are not suitable to deliver a tidal volume less than 200 mL. During ventilation of neonates or children (in which tidal volume is less than 200 cc, respiratory rate is at least 16 - 20/minute and with a 1:2 I/E ratio, inspiratory time is less than 1 second), these differences are not acceptable. Thus, anesthesiologists usually use pressure-controlled ventilation rather than volume-controlled ventilation for pediatric anesthesia. A pressure-limited, time-cycled pulmonary ventilator includes a pressurized gas system that supplies respiratory gas to a patient at a selected inspiratory flow rate; an exhalation valve that opens an expiratory flow path in response to the elapsing of a selected inspiratory time period, and maintains a selected proximal pressure limit during the inspiratory time period. The tidal volume that results from a pressure-targeted machine is attributable to the set inspiratory pressure and patient’s lung-thorax compliance. Circuit compliance, fresh gas flow changes, and even small leaks around an un-cuffed endotracheal tube do not modify the delivered tidal volume (1). Pressure-controlled ventilation offers the advantage of limiting barotrauma in the condition of changing lung compliance, but a decrease in tidal volume will occur in the pressure-controlled ventilation mode, when the compliance of the lung is decreased or a pressure against the abdomen is created (e.g. in laparoscopic surgeries) (2). There are also some pediatric ventilators that deliver the breath by setting the inspiratory and expiratory duration and setting the flow of gas, but management of patients with these ventilators can lead to hypoventilation in the circumstance of increasing of the pulmonary resistance or reversal of muscle relaxants. To deliver a precise tidal volume, some new anesthesia machines have equipped with fresh gas decoupling valves. In these machines, the fresh gas (FGF) is not delivered to the inspiratory limb during inspiration. Practically, it means that FGF does not increase the tidal volume. The function of the fresh gas decoupling valve is to provide a precise delivery of the set tidal volume unaffected by varying fresh gas flow rates. During the inspiratory phase of ventilation, the valve closes, allowing only gas from the ventilator piston chamber to be delivered through the inspiratory branch to the patient. During the expiratory phase, the valve opens, allowing the ventilator piston chamber to fill with a mixture of the exhaled gas that has passed through the absorber and fresh gas (3). A second method for accurate delivery of desired tidal volume is compliance compensation, to replace volume lost to the breathing tubes. A potentially large percentage of the bellows volume is lost into the breathing circuit, secondary to compliance and compression. Leaks and sampled gas flow will further reduce desired tidal volume (4). To ensure that the set tidal volume will be delivered to the patients, new anesthesia machines involve a preuse leak and compliance test during which the end of the circuit must be occluded. The total compliance will be measured and the machine use this data to adjust piston or bellows movement, according to desired pressure airway setting (5). The anesthesiologist can use volume-controlled ventilation by a modern anesthesia machine that equipped with fresh gas decoupling valves and compliance and fresh gas compensation technology with confidence. Minimal tidal volume as low as 30 mL can be delivered precisely (5). The anesthesiologist should not persist in ordering a ventilator with multiple ventilation modes. Rather, choosing a ventilator with a unique mode that delivers a precise tidal volume would be suitable.

Residual Curarization and Postoperative Respiratory Complications Following Laparoscopic Sleeve Gastrectomy. The Effect of Reversal Agents: Sugammadex vs. Neostigmine.

Incomplete muscle relaxant reversal or re-curarization may be associated with postoperative respiratory complications. In this retrospective study we compared the incidence of postoperative residual curarization and respiratory complications in association with the type of muscle relaxant reversal agent, sugammadex or neostigmine, in patients undergoing laparoscopic sleeve gastrectomy. We reviewed the charts of all patients (179) undergoing laparoscopic sleeve gastrectomy from July 2012 to July 2013 at Wolfson Medical Center. Sugammadex 1.5-2 mg/kg (112 patients) or neostigmine 2.5 mg (67 patients) were used as reversal agents. Results were compared by the type of reversal agent employed. Compared parameters included demographic and anaesthetic data, residual curarization, oxyhemoglobin saturation (SpO2) in the recovery room (PACU), episodes of SpO2 lower than 90% in PACU, unexpected intensive care (ICU) admissions, incidence of atelectasis and pneumonia, re-intubation and duration of hospitalization. Obstructive sleep apnea syndrome (OSAS) was more frequent in the sugammadex group (19% vs. 8%; p = 0.026). Total intravenous anesthesia (TIVA) was more frequently associated with sugammadex (33% vs. 16%; p = 0.007). There were no differences in postoperative residual curarization, SpO2 < 90% episodes, reintubation, ICU admissions, pulmonary complications and duration of hospitalization. With the inherent limitations of a retrospective study, the use of sugammadex following laparoscopic sleeve gastrectomy showed no advantage over neostigmine in terms of residual curarization and respiratory complications.

Postoperative Nausea and Vomiting Following General Anaesthesia: A Prospective Study on Surgical Patients in the University of Calabar Teaching Hospital, Calabar, Nigeria

Introduction: Postoperative nausea and vomiting remains a significant problem in our clinical setting. This study at the University of Calabar Teaching Hospital, Calabar in Nigeria aims to investigate the incidence of postoperative nausea and vomiting among gynaecological and nongynaecological patients undergoing surgery under general anaesthesia, compare the incidence as it affects males and females, identify predisposing factors and recommend preventive measures. Methodology: One hundred and sixty six(166) adult patients aged 18 years and above were recruited prospectively excluding cases of full stomach, patients with nasogastric tubes and those who could not be followed up for 24 hours. The past history of motion sickness and postoperative nausea and vomiting was obtained and documented. General anaesthesia was induced with either Original Research Article Kalu et al.; BJMMR, 9(12): 1-12, 2015; Article no.BJMMR.18030 2 sodium thiopentone or ketamine hydrochloride. Maintenance was inhalational with or without a relaxant technique. Intravenous pentazocine and subanaesthetic doses of ketamine were used for intraoperative analgesia. The patients were observed postoperatively and questioned at two hourly intervals for nausea or vomiting and pain was scored using the categorical rating scale. A data sheet was completed at the end of 2 and 24 hours. The data was entered on a microcomputer for analysis with aid of EPI INFO version 6 software. The level of significance was set at 95% confidence interval with P value less than 0.05. Results: The overall incidence of nausea was 11.45% and vomiting 13.35% in the 166 patients studied. There was no significant difference in incidence between the gynaecological and non gynaecological patients. Female patients experienced more postoperative nausea and vomiting than male patients with 11.4% and 18.42% nausea and vomiting. Sodium thiopentone induction, muscle relaxant use and reversal as well as moderate to severe postoperative pain increased the incidence of PONV Conclusion: The use of prophylactic “balanced antiemesis” in high risk patients, avoidance of muscle relaxant reversal and adequate postoperative analgesia are recommended as preventive measures.

手術終了時の筋弛緩薬拮抗：ネオスチグミンで完全回復できるか？

手術終了時の筋弛緩薬拮抗：ネオスチグミンで完全回復できるか？

A comparative study of the effect of caudal dexmedetomidine versus morphine added to bupivacaine in pediatric infra-umbilical surgery.

Background:One of the most commonly used regional anesthetic techniques in pediatric surgeries is the caudal epidural block. Its main disadvantage remains the short duration of action. Hence, different additives have been used. Dexmedetomidine is a potent as well as highly selective α2 adrenergic receptor agonist. The aim of this randomized, double-blinded, study was to compare the duration of postoperative analgesia of caudal dexmedetomidine versus morphine in combination with bupivacaine in pediatric patients undergoing lower abdominal or perineal surgery.Patients and Methods:A total of 50 pediatric patients 1-5 years old The American Society of Anesthesiologists status I, II scheduled for lower abdominal and perineal surgeries were included in the study. The patients were enrolled into 2 equal groups: Group A patients (n = 25) received dexmedetomidine with bupivacaine while Group B patients (n = 25) received morphine with bupivacaine. Patients were placed in a supine position then inhalational general anesthesia was induced, and laryngeal mask airway (LMA) was placed. Patients were then given caudal epidural analgesia. By the end of surgery reversal of muscle relaxation was done and the LMA was removed. Post-operatively, the sedation as well as pain score were observed and recorded.Results:The current study showed that minor complications were recorded in the post-anesthesia care unit; in addition, significantly longer periods of analgesia and sedation were detected in Group A. However, no significant differences in demographic data, as well as in the duration of surgery, and the time of emergence from anesthesia and patient condition during recovery were detected.Conclusion:The present study suggested that use of dexmedetomidine, during single dose injection, as an additive to the local anesthetic bupivacaine in caudal epidural analgesia prolongs the duration of post-operative analgesia following lower abdominal as well as perineal surgery compared with caudal morphine with no side-effects on the vital signs. Postoperative side effects were seen with caudal morphine injection rather than with dexmedetomidine.