Residual curarization in the recovery room after vecuronium

Inadequate emergence after anesthesia: emergence delirium and hypoactive emergence in the Postanesthesia Care Unit

STUDY OBJECTIVE

To evaluate the frequency, determinants, and outcome of inadequate emergence after elective surgery in the Postanesthesia Care Unit (PACU).

DESIGN

Prospective observational study.

SETTING

12-bed PACU of a tertiary-care hospital in a major metropolitan area.

PATIENTS

266 adult patients admitted to the PACU.

INTERVENTION

To evaluate inadequate emergence, the Richmond Agitation and Sedation Scale (RASS) was administered to patients 10 minutes after their admission to the PACU.

MEASUREMENTS

Demographic data, perioperative variables, and postoperative length of stay (LOS) in the PACU and the hospital were recorded.

MAIN RESULTS

40 (15%) patients showed symptoms of inadequate emergence: 17 patients (6.4%) screened positive for emergence delirium and 23 patients (8.6%) showed hypoactive emergence. Determinants of emergence delirium were longer duration of preoperative fasting (P = 0.001), higher visual analog scale (VAS) scores for pain (P = 0.002), and major surgical risk (P = 0.001); these patients had a higher frequency of postoperative delirium (P = 0.017) and had higher nausea VAS score 6 hours after surgery (P = 0.001). Determinants of hypoactive emergence were duration of surgery (P = 0.003), amount of crystalloids administered during surgery (P = 0.002), residual neuromuscular block (P < 0.001), high-risk surgery (P = 0.002), and lower core temperature on PACU admission (P = 0.028); these patients also had more frequent residual neuromuscular block (P < 0.001) postoperative delirium (P < 0.001), and more frequent adverse respiratory events (P = 0.02). Patients with hypoactive emergence had longer PACU and hospital LOS.

CONCLUSIONS

Preventable determinants for emergence delirium were higher postoperative pain scores and longer fasting times. Hypoactive emergence was associated with longer postoperative PACU and hospital LOSs.

Obese patients: respiratory complications in the post-anesthesia care unit

INTRODUCTION

Obesity has been associated with respiratory complications, and the majority of these complications occur in the Post-Anesthesia Care Unit (PACU). The aim of this study was to evaluate the outcome and incidence of adverse respiratory events (AREs) in obese patients during their stay in the PACU METHODS: We conducted a prospective control study that included 27 obese patients matched with an equal number of patients with body mass index (BMI)<30 (non-obese control group); the 2 groups of patients were similar in respect to gender distribution, age, and type of surgery and had been admitted into the PACU after elective surgery (May 2011). The AREs were identified during PACU stay. Descriptive analysis of variables was performed, and the Mann-Whitney U test, Chi-square test, or Fisher's exact test were used for comparisons. Associations with AREs were studied using univariate and multivariate logistic regression models.

RESULTS

There was a higher frequency of STOP-BANG ≥3 (89% vs. 11%, P<.001) among obese patients and they were less frequently scheduled to undergo high-risk surgery (7% vs. 41%, P=.005) and major surgery (4% vs. 15%, P=.008). Obese patients had more frequent AREs in the PACU (33% vs. 7%, P<.018). Multivariate analysis identified obesity and residual neuromuscular blockade as independent risk factors for the occurrence of AREs. Stay in the PACU was longer for obese patients (120min vs. 84min, P<.01).

CONCLUSIONS

Obesity was considered an independent risk factor for AREs in the PACU. Obese patients stayed longer in the PACU, but they did not stay longer in the hospital.

Effect of sugammadex on rocuronium induced changes in pancreatic mast cells

Mast cells play a vital role in hypersensitivity reactions. Rocuronium is known to cause mast cell mobilization, hypersensitivity, and pancreatitis. The aim of this study was to investigate the effects of sugammadex on pancreatic changes due to rocuronium. A total of 42 Sprague-Dawley male rats were divided into six equal groups to receive either rocuronium 1 mg/kg intravenously (i.v., R group), rocuronium 1 mg/kg + sugammadex 16 mg/kg i.v. (RS16 group), rocuronium 1 mg/kg + sugammadex 96 mg/kg i.v. (RS96 group), sugammadex 16 mg/kg (S16), sugammadex 96 mg/kg i.v. (S96 group), or 0.9% sodium chloride (control group). Sugammadex was administered 5s later following rocuronium. In R group, mast count was higher, and the distribution rate of granules and nuclear changes were different compared with other groups. Distribution rate of granules in groups S16 and S96 were similar to the control group and lower compared with other groups. The amount of mast cells and granule density in groups RS16 and RS96 was lower compared with R group. The amount of mast cells in groups RS16 and RS96 was significantly lower compared with other treatment groups. These results suggest that sugammadex may have an inhibitory effect on mobilization and morphological changes in pancreatic mast cells induced by administration of rocuronium and sugammadex in rats.

Residual neuromuscular block as a risk factor for critical respiratory events in the post anesthesia care unit

OBJECTIVE

Residual neuromuscular block is an important postoperative complication associated to the use of neuromuscular blocking drugs. The purpose of this study was to access the incidence of residual neuromuscular block in a post-anesthesia care unit and to evaluate its association with critical respiratory events.

MATERIAL AND METHODS

Prospective cohort study was conducted in a Post Anesthetic Care Unit (PACU) for a period of 3 weeks. Two hundred two adult patients who submitted to scheduled non-cardiac and non-intracranial surgery were eligible to the study. The primary outcome variable was residual neuromuscular block after arrival to PACU that was defined as train-of-four ratio <0.9 and objectively quantified using acceleromyography. Demographic data, perioperative variables, lengths of hospital and recovery room stay and critical respiratory events were recorded. Inadequate emergence was classified in its different forms according to the Richmond agitation and sedation scale 10 min after admission to the recovery room.

RESULTS

Residual neuromuscular block incidence in the post-anesthesia care unit was 29.7% (95% confidence interval: 23.4, 36.1). Patients with residual neuromuscular block had more frequently overall critical respiratory events (51% versus 16%, P<0.001), airway obstruction (10% versus 2%, P=0.029), mild-moderate hypoxemia (23% versus 4%, P<0.001), severe hypoxemia (7% versus 1%, P=0.033), respiratory failure (8% versus 1%, P=0.031), inability to breathe deeply (38% versus 12%, P<0.001) and muscular weakness (16% versus 1%, P<0.001). Residual neuromuscular block was more common after high-risk surgery (53% versus 33%, P=0.011) and was more often associated with post-operative hypoactive emergence as defined by the Richmond Agitation and Sedation Scale (21% versus 6%, P=0.001).

CONCLUSIONS

This study suggests that residual neuromuscular block is common in the PACU and is associated with more frequent critical respiratory events.

Comparison between the Effects of Rocuronium, Vecuronium, and Cisatracurium Using Train-of-Four and Clinical Tests in Elderly Patients

Background

Postoperative residual blockade, longer duration of action for neuromuscular blockade, and slower recovery were relatively common in elderly patients.

Objectives

We aimed to investigate the safety of train-of-four ratio and clinical tests in the assessment of patient recovery, and to determine the effects of the rocuronium, vecuronium, and cisatracurium on intubation, extubation and recovery times in elderly patients undergoing abdominal surgery.

Patients and Methods

After obtaining institutional approval and informed consent, 60 patients over 60 years old and undergoing elective abdominal operations were included in this double-blind, randomized clinical trial. Following a standard anesthesia induction, 0.6mg kg-1 rocuronium, 0.1mg kg-1 vecuronium, and 0.1mg kg-1 cisatracurium were administered to the patients in Group R, Group V, and Group C, respectively. Train-of-four (TOF) ratios were recorded at 10-minute intervals during and after the operation. Modified Aldrete Score (MAS) and clinical tests were recorded in the recovery room at 10-minute intervals. In addition, intubation and extubation times, duration of recovery room stay, and any complications were recorded.

Results

Intubation time was found to be shorter in Group R than that in Groups V and C (P ˂ 0.001). Times to positive visual disturbances and grip strength tests were shorter in Group C than that in Group V (P = 0.016 and P = 0.011, respectively). In Group R and group C, time to TOF ≥ 0.9 was significantly longer than all positive clinical test times except grip strength (P < 0.05).

Conclusions

We hold the opinion that cisatracurium is safer in elderly patients compared to other drugs. We also concluded that the usage of TOF ratio together with clinical tests is suitable for assessment of neuromuscular recovery in these patients.

Residual Neuromuscular Blockade Affects Postoperative Pulmonary Function

Background

Residual neuromuscular blockade (RNMB) is known to be associated with respiratory complications in the postoperative period after muscle relaxant usage. The authors hypothesized that RNMB causes reductions in pulmonary function test (PFT) parameters in the immediate postoperative period.

Methods

An open-label prospective randomized cohort study was conducted comparing reductions in PFT parameters due to RNMB among different neuromuscular blocking agents. One hundred and fifty patients were randomized to receive vecuronium, atracurium, or rocuronium. After reversal of neuromuscular blockade and extubation, train-of-four ratio was measured every 5 min until the train-of-four ratio of 0.9 or greater was attained. PFTs were performed preoperatively and postoperatively when the patients were willing and fit. The train-of-four ratio, measured at PFT, was used to classify patients into “RNMB absent” and “RNMB present.” RNMB was defined as a train-of-four ratio less than 0.9.

Results

Thirty-nine patients had RNMB at the time of performing PFT. There was no statistically significant difference in the postoperative reductions in PFT parameters in patients with RNMB among different neuromuscular blocking agents. Patients were regrouped as RNMB absent and RNMB present, irrespective of neuromuscular blocking agents. Postoperative PFT values for the RNMB-absent and RNMB-present groups were 62% and 49% of baseline forced vital capacity and 47% and 38% of baseline peak expiratory flow of the baseline, respectively. Postoperative forced vital capacity and peak expiratory flow values of RNMB-present patients were lower by 13% and 9% in absolute terms (P &lt; 0.008) and 21% and 19% in relative terms, respectively, compared with RNMB-absent patients.

Conclusion

RNMB results in reductions in forced vital capacity and peak expiratory flow in the immediate postoperative period indicating impaired respiratory muscle function.

Comparison of the variability of the onset and recovery from neuromuscular blockade with cisatracurium versus rocuronium in elderly patients under total intravenous anesthesia

This study was designed to compare the variability of the onset and offset of the effect of two neuromuscular blocking drugs with different elimination pathways in adult and elderly patients during total intravenous anesthesia (TIVA). After Ethics Committee approval and patients' informed consent, the drugs were compared in 40 adult and 40 elderly patients scheduled for elective surgery under TIVA with tracheal intubation who were randomized to receive a single bolus dose of 0.15 mg/kg cisatracurium or 0.9 mg/kg rocuronium. The time of onset of maximum depression, duration of action, and recovery index time were measured and recorded for each patient and variability is reported as means ± standard deviation. Time of onset was significantly shorter for rocuronium than cisatracurium for the adult and elderly groups (P = 0.000), but the variability of cisatracurium was significantly greater compared with rocuronium for the same age groups (93.25 vs 37.01 s in the adult group and 64.56 vs 33.75 s in the elderly group; P = 0.000). The duration of the effect in the elderly group receiving rocuronium was significantly longer than in the elderly group receiving cisatracurium, and the variability of the duration was significantly greater in the rocuronium group than in the cisatracurium group. Mean time of recovery was significantly longer for the elderly group receiving rocuronium than for the elderly group receiving cisatracurium (P = 0.022), and variability was also greater (P = 0.002). Both drugs favored good intubating conditions. In conclusion, cisatracurium showed less variability in these parameters than rocuronium, especially in the elderly, a fact that may be of particular clinical interest.

Does topical lidocaine before tracheal intubation attenuate airway responses in children? An observational audit

BACKGROUND

The use of topical lidocaine, applied to the airways with various administration techniques, is common practice in pediatric anesthesia in many institutions. However, it remains unclear whether these practices achieve their intended goal of reducing the risk of perioperative respiratory adverse events (PRAE) in children undergoing elective endotracheal intubation without neuromuscular blockade (NMB). The relative frequency of PRAE (laryngospasm, coughing, desaturation <95%) associated with no use of topical airway lidocaine (TAL), with TAL sprayed directly onto the vocal cords, and TAL administered blindly into the pharynx was assessed.

METHODS

This prospective audit involved 1000 patients undergoing general anesthesia with elective endotracheal intubation without NMB. Patients with suspected difficult airways or undergoing airway surgery were excluded. The use of TAL and the mode of administration were recorded. Respiratory adverse events were recorded in the perioperative period.

RESULTS

Two hundred and fifty-four patients had the vocal cords sprayed under direct vision, 236 had lidocaine blindly dripped into the pharynx, and 510 received no TAL. The mean age and known risk factors for PRAE (asthma, recent upper respiratory tract infection (≤2 weeks), passive smoking, hayfever, past or present eczema, nocturnal dry cough) were similar among the groups. The proportion of patients with desaturation (<95%) between induction of anesthesia and discharge from the recovery room was higher in the two groups who received TAL (data combined for all patients receiving lidocaine regardless of administration method, P = 0.01) compared to those who received no TAL. No difference in the rates of laryngospasm (P = 0.13) or cough (P = 0.07) was observed among the groups. There was no difference in the rates of PRAE between the groups given TAL directly onto the vocal cords and in those whom received TAL blindly.

CONCLUSIONS

The incidence of desaturation was higher in patients receiving TAL compared with children who did not. This association should perhaps be considered when contemplating the use of this technique.

Neuromuscular blocking agents for electroconvulsive therapy: a systematic review

Electroconvulsive therapy (ECT) is the transcutaneous application of small electrical stimuli to the brain to induce generalised seizures for the treatment of selected psychiatric disorders. The clinical indications for ECT as an effective therapeutic modality have been considerably expanded since its introduction. Anaesthesia and neuromuscular blocking agents (NMBAs) are required to ensure patients' safety during ECT. The optimal dose of muscle relaxant for ECT reduces muscle contractions without inducing complete paralysis. Slight residual motor convulsive activity is helpful in ascertaining that a seizure has occurred, while total paralysis prolongs the procedure unnecessarily. Suxamethonium is commonly used, but nondepolarising NMBAs are indicated in patients with certain comorbidities. In this review, we summarise current concepts of NMBA management for ECT.

[Clinical evaluation of post-surgical bleeding after a sugammadex injection]

OBJECTIVE

Sugammadex reverses neuromuscular blockade by chemical encapsulation of nondepolarizing neuromuscular blocking drugs (rocuronium and vecuronium). The imprint of this new molecule has recently been supplemented with a section on haemostasis notifying a longer clotting time without documented clinical consequences. This has resulted in recommendations on the use of sugammadex in the presence of coagulation disorders (pharmacologically-induced or not). The objective of this study was to analyze the experience gathered with this molecule on clinically-evaluated bleeding. No study on this subject is currently available.

METHODS

This is a retrospective study over 1 year between August 2009 and August 2010. All patients with laparotomies for cancer surgery requiring suction drains were included. Patients were allocated to groups according to the type of reversal (without sugammadex versus sugammadex 2 or 4 mg/kg). The endpoint was clinically-evaluated postoperative bleeding (reoperation for haemostasis, blood-stained laparotomy dressings in the post-anaesthesia care unit [PACU], cumulative volume collected in suction drains upon arrival in PACU and then after 2 hours and the next morning at 6a.m).

RESULTS

One hundred and ninety-three patients were included in three groups, 78 in the group "without sugammadex", 95 in "sugammadex 2mg/kg" and 20 in "sugammadex 4 mg/kg". There were no reoperations for haemostasis. The comparison among different groups for the endpoint of bleeding showed no significant difference.

CONCLUSION

In this retrospective study performed in patients at high risk of postoperative bleeding, sugammadex at doses of 2 and 4 mg/kg was not associated with increased bleeding. This study, the first in this field, suggests that future prospective investigations should target patients receiving 4 or 16 mg/kg of sugammadex and/or with documented preoperative abnormal coagulations tests.

Anaesthesia for endoscopic sinus surgery

Endoscopic sinus surgery is commonly performed and has a low risk of major complications. Intraoperative bleeding impairs surgical conditions and increases the risk of complications. Remifentanil appears to produce better surgical conditions than other opioid analgesics, and total intravenous anaesthesia with propofol may provide superior conditions to a volatile-based technique. Moderate hypotension with intraoperative beta blockade is associated with better operating conditions than when vasodilating agents are used. Tight control of CO(2) does not affect the surgical view. The use of a laryngeal mask may be associated with improved surgical conditions and a smoother emergence. It provides airway protection equivalent to that provided by an endotracheal tube in well-selected patients, but offers less protection from gastric regurgitation. Post-operatively, multimodal oral analgesia provides good pain relief, while long-acting local anaesthetics have been shown not to improve analgesia.

Neuromuscular block and current treatment strategies for its reversal in children

Even though neuromuscular blocking agents are an essential part of balanced anesthesia and the risks of residual paralysis are well documented, many anesthetists seldomly monitor neuromuscular block. Classical reversal agent neostigmine is unable to antagonise a deep neuromuscular block and is rather slow to antagonise even a moderate block. These caveats may have introduced a practice to use muscle relaxants mainly for an endotracheal intubation. This review presents current views on the effects of muscle relaxants and their reversal agents in pediatric patients. This may help clinicians to reconsider the value of muscle relaxants during anesthesia in children.

Postoperative residual curarization from intermediate-acting neuromuscular blocking agents delays recovery room discharge

BACKGROUND

Postoperative residual curarization (PORC) [train-of-four ratio (T4/T1) <0.9] is associated with increased morbidity and may delay postoperative recovery room (PACU) discharge. We tested the hypothesis that postoperative T4/T1 <0.9 increases PACU length of stay.

METHODS

At admission to the PACU, neuromuscular transmission was assessed by acceleromyography (stimulation current: 30 mA) in 246 consecutive patients. The potential consequences of PORC-induced increases in PACU length of stay on PACU throughput were estimated by application of a validated queuing model taking into account the rate of PACU admissions and mean length of stay in the joint system of the PACU plus patients recovering in operation theatre waiting for PACU beds.

RESULTS

PACU length of stay was significantly longer in patients with T4/T1 <0.9 (323 min), compared with patients with adequate recovery of neuromuscular transmission (243 min). Age (P=0.021) and diagnosis of T4/T1 <0.9 (P=0.027), but not the type of neuromuscular blocking agent, were independently associated with PACU length of stay. The incidence of T4/T1 <0.9 was higher in patients receiving vecuronium. Delayed discharge significantly increases the chances of patients having to wait to enter the PACU. The presence of PORC is estimated to be associated with significant delays in recovery room admission.

CONCLUSIONS

PORC is associated with a delayed PACU discharge. The magnitude of the effect is clinically significant. In our system, PORC increases the chances of patients having to wait to enter the PACU.

Residual neuromuscular block: lessons unlearned. Part I: definitions, incidence, and adverse physiologic effects of residual neuromuscular block

In this review, we summarize the clinical implications of residual neuromuscular block. Data suggest that residual neuromuscular block is a common complication in the postanesthesia care unit, with approximately 40% of patients exhibiting a train-of-four ratio <0.9. Volunteer studies have demonstrated that small degrees of residual paralysis (train-of-four ratios 0.7-0.9) are associated with impaired pharyngeal function and increased risk of aspiration, weakness of upper airway muscles and airway obstruction, attenuation of the hypoxic ventilatory response (approximately 30%), and unpleasant symptoms of muscle weakness. Clinical studies have also identified adverse postoperative events associated with intraoperative neuromuscular management. Large databased investigations have identified intraoperative use of muscle relaxants and residual neuromuscular block as important risk factors in anesthetic-related morbidity and mortality. Furthermore, observational and randomized clinical trials have demonstrated that incomplete neuromuscular recovery during the early postoperative period may result in acute respiratory events (hypoxemia and airway obstruction), unpleasant symptoms of muscle weakness, longer postanesthesia care unit stays, delays in tracheal extubation, and an increased risk of postoperative pulmonary complications. These recent data suggest that residual neuromuscular block is an important patient safety issue and that neuromuscular management affects postoperative outcomes.

Control of perioperative muscle strength during ambulatory surgery

PURPOSE OF REVIEW

This review describes strategies to control perioperative muscle strength in patients undergoing ambulatory surgery.

RECENT FINDINGS

Although it is impossible to improve muscle relaxation (defined as absence of electrical activity) of intact resting muscle by hypnotics, analgesia is required to prevent pain-evoked muscular contractions during surgery. Regional anesthesia, as well as hypnotics and opioids, promotes intraoperative muscle relaxation. Neuromuscular blocking agents (NMBAs) induce dose-dependent muscle relaxation, but their effects vary widely between individuals, and postoperative residual curarization (PORC) exposes patients to additional risk. Low doses of NMBAs should, therefore, be used, effects be monitored quantitatively by acceleromyography, and residual neuromuscular block be reversed. Acetylcholinesterase inhibitor reversal can cause respiratory side effects, so the lowest efficacious dose should be used: as little as 0.015-0.025 mg kg(-1) of neostigmine is required at a train-of-four count of four with minimal fade. Sugammadex encapsulates steroidal NMBAs. Sugammadex reversal is a viable approach to rapidly antagonize deep levels of neuromuscular block.

SUMMARY

Optimal muscle relaxation for ambulatory surgery results from a judicious combination of regional anesthesia, opioids, and low doses of NMBAs. The effects of NMBAs should be monitored quantitatively by acceleromyography and reversed appropriately.

Incidence of Residual Neuromuscular Blockade in a Post-Anaesthetic Care Unit

We conducted a prospective observational study to assess the incidence of residual neuromuscular blockade (RNMB) in a post-anaesthetic care unit (PACU) of a tertiary hospital. The subjects were 102 patients undergoing general anaesthesia with neuromuscular blockade (NMB). The procedural anaesthetists were unaware of their patients’ inclusion in the study, and the choice of muscle relaxant and use of reversal agents were at the anaesthetists’ discretion. On arrival to the PACU, the train-of-four ratio was assessed using electromyography, repeated every five minutes until the train-of-four ratio exceeded 0.9. RNMB was defined as a train-of-four ratio < 0.9. The requirement for airway support, incidence of desaturation while in the PACU and time to eligibility for PACU discharge were recorded. The mean interval between the last dose of relaxant and arrival in the PACU for patients with RNMB was 81 minutes. An intermediate-acting muscle relaxant had been used for most patients. Despite this, RNMB was observed in 31% (95% confidence interval 25 to 47%) of patients. Our findings suggest that RNMB in the PACU is common. As RNMB may predispose to postoperative complications, anaesthetists should utilise quantitative monitoring to assess neuromuscular blockade and optimise reversal use. Anaesthetists should be aware that intervals between the last dose of relaxant of well over one hour do not exclude the possibility of RNMB, even when using intermediate-acting neuromuscular blockade agents.

Reduced-dose rocuronium for day-case tonsillectomy in children where volatile anaesthetics are not used: operating room time saving

OBJECTIVES

Mivacurium, rocuronium, and vecuronium are neuromuscular blocking agents (NMB) commonly used in pediatric day-case anesthesia. Mivacurium is the most appropriate NMB for short surgical procedures where NMB drugs were required but is not available in all countries.

AIM

We evaluated the operating room time minimization after reduced-dose rocuronium (0.45 mg x kg(-1)) during elective day-case tonsillectomy in children.

METHODS/MATERIALS

One hundred and five children (6-9 years, ASA I/II status) scheduled for day-case tonsillectomy were included in prospective, double blind clinical study. Children were randomly divided in three equal groups. All children were premedicated (midazolam 0.25 mg x kg(-1) orally, EMLA). Anesthesia was induced (2.5 mg x kg(-1)) and maintained (0.1 mg x kg(-1) x min(-2)) by propofol and alfentanil (0.0015 mg x kg(-1) x min(-1)) and supplemented by inhalation mixture of 50% of O2/Air. Neuromuscular block was achieved by vecuronium (0.1 mg x kg(-1)) (V) or rocuronium in standard (0.6 mg.kg(-1)) (R) or reduced dose (0.45 mg x kg(-1)) (LD). Neuromuscular transmission was monitored by acceleromyography. Time analysis of NMB drugs action was performed.

RESULTS

Time difference from the end of tonsillectomy to T90 neuromuscular block recovery was significantly shorter in LD Group (7.3 +/- 0.41 min), (V = 15.9 +/- 1.06, R = 16.0 +/- 1.7 min) (P = 0.0011). The onset time of neuromuscular block was prolonged in LD Group (LD=3.1 +/- 0.4, R = 1.3 +/- 0.4, V = 2.2 +/- 0.2 min) (P = 0.0039) without changing the intubating conditions. The maximum operation room time saving per each tonsillectomy was 37% in LD Group (Group V 21%, Group R 17%) (P = 0.0001). Low incidence of postoperative nausea and vomiting (PONV) 3-6% (0.4577) and good visual analog scale (VAS) score (< or =2) (0.5969) were found in all study groups 12 h after surgery.

CONCLUSIONS

Reduced-dose rocuronium in addition with propofol and alfentanil in children where volatile anesthetics are not used effectively saves the operating room time during short elective surgical procedures, avoids delays in patient recovery, allows high level of acceptable intubating conditions, and improves the optimal surgical work. Low incidences of PONV as VAS score may achieved successfully.

A survey of current management of neuromuscular block in the United States and Europe

BACKGROUND

Postoperative residual neuromuscular block is a frequent occurrence. Recent surveys of clinical practice in Europe suggest that neuromuscular blocking drugs are often administered without appropriate monitoring. No comparable survey has been undertaken in the United States (US). From this survey, we compared current clinical neuromuscular practice and attitudes between anesthesia practitioners in the US and Europe.

METHODS

We conducted an Internet-based survey among anesthesia practitioners in the US and Europe. The Anesthesia Patient Safety Foundation and the European Society of Anaesthesiology e-mailed all of their active members, inviting them to anonymously answer a series of questions on a dedicated Internet Protocol address-sensitive website. The survey was available online for 60 days. The chi(2) test and Fisher's exact test were used to compare clinical survey items between the 2 cohorts.

RESULTS

A total of 2636 completed surveys were received. Most respondents from the US (64.1%) and Europe (52.2%) estimated the incidence of clinically significant postoperative residual neuromuscular weakness to be <1% (P < 0.0001). Routine pharmacologic reversal was less common in Europe than in the US (18% vs 34.2%, respectively; P < 0.0001), and quantitative monitors were available to fewer clinicians in the US (22.7%) than in Europe (70.2%) (P < 0.0001). However, 19.3% of Europeans and 9.4% of Americans never use neuromuscular monitors. Most respondents reported that neither conventional nerve stimulators nor quantitative train-of-four monitors should be part of minimum monitoring standards.

CONCLUSIONS

Our results suggest a lack of agreement among anesthesia providers about the best way to monitor neuromuscular function. Efforts to improve awareness by developing formal training programs and/or publishing official guidelines on best practices to reduce the incidence of postoperative neuromuscular weakness and patient morbidity are warranted.

Continuous positive airway pressure improves the immediate post-extubation airway patency

BACKGROUND

Endotracheal tube extubation can cause laryngospasm, aspiration, upper airway obstruction and hypoxia. In addition, the risk of pulmonary complication increases during extubation for the patients with a difficult airway or a cervical spine injury. The aim of this study was to exam the effect of continuous positive airway pressure (CPAP) on the post-extubation airway patency and the recovery from anesthesia at the recovery room.

METHODS

30 adult patients who were scheduled for spine surgery were randomly allocated into 2 groups depending on the using of CPAP before extubation. Neuromuscular monitoring was performed via accelomyography. Tracheal extubation was performed at a TOF ratio of 70%. The incidence of spontaneous recovery of respiration, without airway manipulation and hypoxia, at the recovery room was measured for each group. The time to get a PAR score of 10 at the recovery room and the discharge time from the recovery room were checked too.

RESULTS

The incidence of spontaneous recovery of respiration without airway manipulation was 67% in the CPAP group, which was significantly greater than that of the control group (13%). Yet there was no difference between the CPAP and control groups for the incidence of hypoxia in the recovery room (13% and 20%, respectively). There were also no differences in the time to get a PAR score of 10 at the recovery room and the discharge time from the recovery room.

CONCLUSIONS

CPAP that is applied for tracheal tube extubation improves the immediate post-extubation airway patency, but it does not reduce the recovery room pulmonary complications and the recovery room discharge time.

[Residual curarization and pharyngeal muscles: remain vigilant!]

The different concepts treating of "residual curarization" were presented according to two directions: the analysis of their contents--epidemiologic, clinical, instrumental--and the description of the pharyngeal striated muscles functions in these contexts. It appears that certain, too marked, "residual curarization" levels remain a well-evidenced factor increasing some morbidities in numerous clinical situations. All the methods of instrumental monitoring of the level of curarization--mecanography, electromyography, accelerometry--appeared useful to document the levels of "residual curarization" before patient's extubation or awakening. Today, for our speciality, it became particularly clear that: neither the selected muscle-- adductor pollicis--, neither the test currently privileged--train-of-four 2Hz--, nor the thresholds currently selected--0.90 or 1.00--did not constitute the unavoidable proof of a "residual curarization" complete absence. For the healthy volunteer receiving a curare, a train of four of the adductor pollicis greater than 0.90 can exist in presence of spirometric alterations evidencing the lack of adequate pharyngeal dilatation. In daily routine, the pharyngeal control is already disturbed by numerous molecules including: benzodiazepines, halogenated vapours, propofol, i.e. even under non-hypnotic concentrations. Faced to such evidences, our medical speciality will, undoubtedly, have to acquire new knowledge to develop muscle relaxant management control processes eliminating the surmorbidities related to "residual curarization". These tests must be validated also to exclude morbidity-prone dysfunctions of the pharyngeal striated muscles. Considering this new paradigm would be a major safety evolution for our speciality.

Sugammadex in clinical practice

The availability of sugammadex allows greater flexibility in the use of rocuronium and vecuronium during anaesthesia and surgery. The neuromuscular block induced by both drugs can be reversed from both superficial and deep levels of block by adjusting the dose of sugammadex. The dose of sugammadex for reversal of shallow block produced by these neuromuscular blocking drugs is approximately 2 mg.kg(-1) and for deep block the dose is 4 mg.kg(-1). A larger dose of sugammadex (16 mg.kg(-1)) administered 3 min after the neuromuscular blocking drug allows rapid reversal of a neuromuscular block induced by 1-1.2 mg.kg(-1) of rocuronium, thereby raising the possibility of using rocuronium as a replacement for suxamethonium. The use of sugammadex has not been reported to be associated with recurrence of block provided a dose that is adequate for reversal has been used. Sugammadex appears to have an acceptable safety profile. There are no requirements for dose adjustment for age or the use of potent volatile anaesthetic agents.

Discovery, development, and clinical application of sugammadex sodium, a selective relaxant binding agent

Neuromuscular blockade, induced by neuromuscular blocking agents, has allowed prescribed immobility, improved surgical exposure, optimal airway management conditions, and facilitated mechanical ventilation. However, termination of the effects of neuromuscular blocking agents has, until now, remained limited. A novel cyclodextrin encapsulation process offers improved termination of the paralytic effects of aminosteroidal non-depolarizing neuromuscular blocking agents. Sugammadex sodium is the first in a new class of drug called selective relaxant binding agents. Currently, in clinical trials, sugammadex, a modified gamma cyclodextrin, has shown consistent and rapid termination of neuromuscular blockade with few side effects. The pharmacology of cyclodextrins in general and sugammadex in particular, together with the results of current clinical research are reviewed. The ability of sugammadex to terminate the action of neuromuscular blocking agents by direct encapsulation is compared to the indirect competitive antagonism of their effects by cholinesterase inhibitors. Also discussed are the clinical implications that extend beyond fast, effective reversal, including numerous potential perioperative benefits.

Residual neuromuscular blockade and critical respiratory events in the postanesthesia care unit

BACKGROUND

Incomplete recovery of neuromuscular function may impair pulmonary and upper airway function and contribute to adverse respiratory events in the postanesthesia care unit (PACU). The aim of this investigation was to assess and quantify the severity of neuromuscular blockade in patients with signs or symptoms of critical respiratory events (CREs) in the PACU.

METHODS

We collected data over a 1-yr period. PACU nurses identified patients with evidence of a predefined CRE during the first 15 min of PACU admission. Train-of-four (TOF) ratios were immediately quantified in these patients using acceleromyography (cases). TOF data were also collected in a control group that consisted of patients undergoing a general anesthetic during the same period who were matched with the cases by age, sex, and surgical procedure.

RESULTS

A total of 7459 patients received a general anesthetic during the 1-yr period, of whom 61 developed a CRE. Forty-two of these cases were matched with controls and constituted the study group for statistical analysis. The most common CREs among matched cases were severe hypoxemia (22 of 42 patients; 52.4%) and upper airway obstruction (15 of 42 patients; 35.7%). There were no significant differences between the cases and matched controls in any measured preoperative or intraoperative variables. Mean (+/-sd) TOF ratios were 0.62 (+/-0.20) in the cases, with 73.8% of the cases having TOF ratios <0.70. In contrast, TOF values in the controls were 0.98 (+/-0.07) (a difference of -0.36 with a 95% confidence interval of -0.43 to -0.30, P < 0.0001), and no control patients were observed to have TOF values <0.70 (the 95% confidence interval of the difference was 59%-85%, P < 0.0001).

CONCLUSIONS

A high incidence of severe residual blockade was observed in patients with CREs, which was absent in control patients without CREs. These findings suggest that incomplete neuromuscular recovery is an important contributing factor in the development of adverse respiratory events in the PACU.

Influence of gender on the course of neuromuscular block following a single bolus dose of cisatracurium or rocuronium

BACKGROUND AND OBJECTIVE

There is increasing evidence of gender differences in the pharmacokinetics and pharmacodynamics of aminosteroid neuromuscular blocking agents. Compared to males, females are more susceptible, requiring approximately 30% less rocuronium to achieve the same degree of neuromuscular block. However, little information is available whether this difference is applicable to modern benzylisoquinolines (cisatracurium).

METHODS

In all, 848 patients (423 males, 425 females) undergoing general surgery under total intravenous anaesthesia with muscle relaxation, tracheal intubation and mechanical ventilation were studied. Patients were randomized to receive a single bolus dose of cisatracurium (0.1 mg kg-1, 221 males and 199 females) or rocuronium (0.6 mg kg-1, 202 males and 226 females). The onset time for 95% depression of T1, clinical duration until 25% recovery and recovery index (T1 from 25% to 75%) were determined with an NMT electromyographic module of the Datex-Ohmeda S/5 Anaesthesia Monitor. The data for male and female groups were compared with appropriate statistical tests (unpaired t-test, Mann-Whitney rank sum test and Fisher's exact test).

RESULTS

In both groups (cisatracurium and rocuronium), males were significantly taller (P < 0.001) and heavier (P < 0.001) than females, but the body mass index was comparable. For rocuronium, the onset time was shorter 91.7 +/- 14.3 s vs. 108.0 +/- 14.6 s (P < 0.001) and the clinical duration was increased in females 43.3 +/- 7.8 min vs. 31.3 +/- 5.5 min (P < 0.001). In the cisatracurium group, both onset times (248.9 +/- 60.7 s for males vs. 253.4 +/- 70.9 s for females) and clinical duration (42.6 +/- 6.9 min for males vs. 43.1 +/- 6.9 min for females) were similar. The recovery index was identical for males and females in both groups.

CONCLUSIONS

Females were more sensitive than males to a single bolus dose of rocuronium. Under the study conditions described, the onset time was shorter and the clinical duration was increased in female patients. This suggests that the routine dose of rocuronium should be reduced in females compared to males. On the contrary, we could demonstrate no gender differences in the onset time or clinical duration of cisatracurium.

Prolonged residual paralysis after a single intubating dose of rocuronium

It is often argued that neuromuscular monitoring is unnecessary when only one dose of an intermediate-acting neuromuscular blocking agent is given. This case report documents that it may take more than 3.5 h before it is possible to antagonize a block caused by a normal dose of rocuronium (0.6 mg kg(-1)). Possible causes of the extremely prolonged duration of action are discussed, as is the importance of quantitative neuromuscular monitoring.

Update on neuromuscular pharmacology

Since the introduction of d-tubocurarine into clinical practice, neuromuscular relaxants have been widely used in anaesthesia. Although their clinical use is easy, several points still require further attention and research. There is still a need for a drug with the clinical profile of succinylcholine but fewer unwanted side-effects. A better understanding of the effects of muscle relaxants on different muscles could help in their clinical use during the perioperative period. Much knowledge is needed about residual neuromuscular block and its detection in order to improve the quality of recovery from neuromuscular blockade. If some questions remain to be answered, several recent articles have increased our knowledge and should improve our clinical practice.

Neuromuscular monitoring and postoperative residual curarisation: a meta-analysis

We conducted a meta-analysis to examine the effect of intraoperative monitoring of neuromuscular function on the incidence of postoperative residual curarisation (PORC). PORC has been considered present when a patient has a train-of-four (TOF) ratio of < 0.7 or < 0.9. We analysed data from 24 trials (3375 patients) that were published between 1979 and 2005. We excluded data on mivacurium from this meta-analysis because only three studies had examined the incidence of PORC associated with its use. Long- and intermediate-acting neuromuscular blocking drugs had been given to 662 and 2713 patients, respectively. Neuromuscular function was monitored in 823 patients (24.4%). A simple peripheral nerve stimulator was used in 543 patients, and an objective monitor was used in 280. The incidence of PORC was found to be significantly lower after the use of intermediate neuromuscular blocking drugs. We could not demonstrate that the use of an intraoperative neuromuscular function monitor decreased the incidence of PORC.

Which muscle relaxants should be used in day surgery and when

PURPOSE OF REVIEW

After myorelaxants, myalgia and residual curarization may complicate recovery. Local anaesthesia and minimally invasive airway management make myorelaxants disputable in many outpatient procedures; nevertheless, neuromuscular blockade may be necessary to facilitate intubation or maintain muscle relaxation. Agent selection criteria are discussed.

RECENT FINDINGS

Reduced hospital time is not associated with central neuraxial or peripheral nerve block. To reduce the risk for residual block, neuromuscular monitoring is mandatory. Use of reversal agents should not be restricted, although studies have shown higher incidence of postoperative nausea and vomiting following their use. Higher succinylcholine dosage is followed by lower incidence of myalgia. The relationship between fasciculation and myalgia is unclear. Sodium channel blockers or nonsteroidal antiinflammatory drugs may prevent myalgia. Sugammadex functions as a chelating agent.

SUMMARY

Ear-nose-throat, open eye surgery and laparoscopy may demand myoresolution. Regional and minimally invasive anaesthesia are alternative solutions. Central and peripheral nerve blocks are associated with increased induction time, reduced pain scores, and decreased need for analgesics. Central neuraxial block, however, is associated with prolonged outpatient unit stay. Bad intubating conditions may cause pharyngo-laryngeal complications: the decision to avoid myorelaxants for tracheal intubation appears illogical. Incidence of postoperative residual curarization remains very high. Sugammadex offers new perspectives.