Train-of-four Ratio Research Articles

Rocuronium: automatic infusion versus manual administration with TOF monitorisation.

TOF (train-of-four) monitoring provides objective data in application of neuromuscular blocking agent. Thus, applicator-based differences are eliminated and optimum muscle relaxation is maintained during operation. In the present study, we aimed to compare the effects of target-controlled infusion system and standard TOF monitoring, on use of rocuronium. ASA I-II patients, who were aged between 18 and 75years and scheduled for elective abdominal surgery at Haydarpaşa Numune Training and Research Hospital, were enrolled in the study. In order to evaluate neuromuscular blockade, the patients in Group 1 were connected to the acceleromyography device of the target-controlled infusion pump (Veryark-CLMRIS-I-China) while the ones in Group 2 were connected to the routinely used acceleromyography device (TOF Watch SX). There was no significant difference between groups regarding patient characteristics, the durations of anaesthesia and surgery, quality of intubation, time to extubation and time to recovery (TOF ratio of 0.9). Intubation time was significantly longer in Group 1 (Automated group) as compared to Group 2 (Control group) (p<0.05). The total rocuronium amount used in Group 1 was found to be significantly higher than the amount used in Group 2 (p<0.05). There was no clinical evidence of residual neuromuscular blockage or reoccurrence of neuromuscular blockage in any patient in either group. Both methods can be used for administration of neuromuscular blocker agent during moderate time anesthesia. No advantage was noted when rocuronium was administered via automatical infusion pump during anaesthesia.

The RECITE Study: A Canadian Prospective, Multicenter Study of the Incidence and Severity of Residual Neuromuscular Blockade.

Postoperative residual neuromuscular blockade (NMB), defined as a train-of-four (TOF) ratio of <0.9, is an established risk factor for critical postoperative respiratory events and increased morbidity. At present, little is known about the occurrence of residual NMB in Canada. The RECITE (Residual Curarization and its Incidence at Tracheal Extubation) study was a prospective observational study at 8 hospitals in Canada investigating the incidence and severity of residual NMB. Adult patients undergoing open or laparoscopic abdominal surgery expected to last <4 hours, ASA physical status I-III, and scheduled for general anesthesia with at least 1 dose of a nondepolarizing neuromuscular blocking agent for endotracheal intubation or maintenance of neuromuscular relaxation were enrolled in the study. Neuromuscular function was assessed using acceleromyography with the TOF-Watch SX. All reported TOF ratios were normalized to the baseline values. The attending anesthesiologist and all other observers were blinded to the TOF ratio (T4/T1) results. The primary and secondary objectives were to determine the incidence and severity of residual NMB (TOF ratio <0.9) just before tracheal extubation and at arrival at the postanesthesia care unit (PACU). Three hundred and two participants were enrolled. Data were available for 241 patients at tracheal extubation and for 207 patients at PACU arrival. Rocuronium was the NMB agent used in 99% of cases. Neostigmine was used for reversal of NMB in 73.9% and 72.0% of patients with TE and PACU data, respectively. The incidence of residual NMB was 63.5% (95% confidence interval, 57.4%-69.6%) at tracheal extubation and 56.5% (95% confidence interval, 49.8%-63.3%) at arrival at the PACU. In an exploratory analysis, no statistically significant differences were observed in the incidence of residual NMB according to gender, age, body mass index, ASA physical status, type of surgery, or comorbidities (all P > 0.13). Residual paralysis is common at tracheal extubation and PACU arrival, despite qualitative neuromuscular monitoring and the use of neostigmine. More effective detection and management of NMB is needed to reduce the risks associated with residual NMB.

Reversal of Pipecuronium-Induced Moderate Neuromuscular Block with Sugammadex in the Presence of a Sevoflurane Anesthetic: A Randomized Trial.

Pipecuronium is a steroidal neuromuscular blocking agent. Sugammadex, a relaxant binding γ-cyclodextrin derivative, reverses the effect of rocuronium, vecuronium, and pancuronium. We investigated whether sugammadex reverses moderate pipecuronium-induced neuromuscular blockade (NMB) and the doses required to achieve reversal. This single-center, randomized, double-blind, 5-group parallel-arm study comprised 50 patients undergoing general anesthesia with propofol, sevoflurane, fentanyl, and pipecuronium. Neuromuscular monitoring was performed with acceleromyography (TOF-Watch SX) according to international standards. When the NMB recovered spontaneously to train-of-four count 2, patients randomly received 1.0, 2.0, 3.0, or 4.0 mg/kg of sugammadex or placebo. Recovery time from sugammadex injection to normalized train-of-four (TOF) ratio 0.9 was the primary outcome variable. The recovery time from the sugammadex injection to final T1 was the secondary end point. Postoperative neuromuscular functions were also assessed. Each patient who received sugammadex recovered to a normalized TOF ratio of 0.9 within 5.0 minutes (95% lower confidence interval for the lowest dose 70.1%; for all doses 90.8%) and 79% of these patients reached a normalized TOF ratio 0.9 within 2.0 minutes (95% lower confidence interval for the lowest dose 26.7%; for all doses 63.7%). T1 recovered several minutes after the TOF ratio. No residual postoperative NMB was observed. Sugammadex adequately and rapidly reverses pipecuronium-induced moderate NMB during sevoflurane anesthesia. Once the train-of-four count has spontaneously returned to 2 responses following pipecuronium administration, a dose of 2.0 mg/kg of sugammadex is sufficient to reverse the NMB.

Comparison of train-of-four ratios measured with Datex-Ohmeda’s M-NMT MechanoSensor™ and M-NMT ElectroSensor™

Neuromuscular blockade is usually monitored using train-of-four (TOF) stimulation pattern. A TOF ratio of higher than 90% is recommended to reduce the risk of adverse effects after anaesthesia. TOF ratio 90% is used in clinical practice with all different neuromuscular monitors. Kinemyography (KMG) is one commercialized method to obtain numerical TOF values. We compared the KMG data obtained with Datex M-NMT MechanoSensor™ module, to the EMG data collected with Datex ElectroSensor™, during clinical anaesthesia. Ipsilateral comparisons of the sensors were performed in 20 female patients during clinical procedures in propofol-remifentanil anaesthesia. After initial bolus dose of rocuronium (0.6mg/kg), the spontaneous recovery of TOF ratio and T1% were monitored. KMG gave higher TOF values than EMG. The difference was significant at KMG TOF values of 40% or higher. After anaesthetic induction, but before administration of rocuronium, both TOF sensor values drifted from the TOF value of 1.0, showing either significant spontaneous fade (T1>T4) or tendency of reverse fade (T1<T4). KMG overestimates the recovery from neuromuscular blockade when compared with EMG. KMG and EMG cannot be used interchangeably, and TOF ratio 90% cannot be considered as adequate level of recovery with all monitoring devices.

Nov način odmerjanja sugamadeksa za odpravo z vekuronijem povzročene nevromišične blokade

Background and Goal of Study: Sugammadex is a selective binding agent that bindsaminosteroid muscle relaxants. Each molecule of sugammadex binds one molecule of musclerelaxant. To produce the same depth of the neuromuscular block (NMB) much less molecules ofvecuronium are needed than molecules of rocuronium. In theory less sugammadex would beneeded to neutralise the neuromuscular block if vecuronium was used to produce the neuromuscular block. Our aim was to compare reversal of vecuronium induced muscle relaxation between a new way of dosing sugammadex, which takes into account TOF value at the end of the surgery and the amount of vecuronium given during the surgery with neostigmine atropine combination. We also wanted to know how much this dosage regime can save compared to standard per kg dosage.Materials and Methods: 20 adult patients requiring a general anesthesia for surgery were analysed. The first group of 11 patients (SUG) received sugammadex at the end of the surgery according to the table one for NMB reversal. The second group of 9 patients (NEO) received neostigmine and atropine. Train of four (TOF) value was recorded at the end of the surgery and then continuously until the TOF value reached more than 0.9 and the patient was extubated. The time required for the TOF value reaching 0.9 was compared between the groups. For economical evaluation we compared the amount of sugammadex used in the SUG group to standard sugammadex per kg dosage.Results and Discussion: Mean time to recovery to a TOF ratio of 0.9 with sugammadex was 5.12min versus 12.6 min with neostigmine atropine (P &lt; 0.05). No sign of postoperative residual curarisation was observed in the SUG group. For patients in our study 530 mg of sugammadex were used to neutralise the NMB. If standard per kg sugammadex dosing had been used we would have used 2420 mg for the NMB reversal.Conclusion(s): New dosing for sugammadex was successful in neutralising the NMB regardlessof the TOF value at the end of the surgery. The economic impact of the proposed dosing is significant as an average cost for the vecuronium NMB reversal is reduced from around 80 € to 20 € per patient.

Uso de sugamadex no paciente queimado: estudo descritivo

ObjectivesThe burn patient is a challenge for the anesthesiologist, undergoing several surgeries during admission, and requiring general anesthesia and muscle relaxation most of the times. They have respiratory system impairment and a response to muscle relaxants that differs from the healthy patient, thus proper monitoring and reversal is crucial. We analyzed sugammadex effectiveness and safety in this population. Material and methodsProspectively descriptive study including four patients, all of them considered major burn patients, who underwent escharotomy with general anesthesia and neuromuscular relaxation. The main variable was the time for recovery of a TOF higher than 0.9 after the administration of sugammadex before extubation. ResultsMean time of recovery from a TOF ratio higher than 0.9 following the administration of Sugammadex was of 4.95minutes 95% CI (3.25‐6.64, p=.53); ConclusionsThe reversion of neuromuscular relaxation with sugammadex appears to be effective and safe in the burn patient. More analytical, comparative studies, of larger populations would be necessary to confirm this data.

Use of sugammadex on burn patients: descriptive study

ObjectivesA burn patient is a challenge for any anesthesiologist, undergoing several surgeries during admission, and requiring general anesthesia and muscle relaxation most of the times. The victim may have respiratory system impairment and a response to muscle relaxants that differs from the healthy patient, thus proper monitoring and reversal is crucial. We analyzed sugammadex effectiveness and safety in this population. Materials and methodsIt was a prospectively descriptive study, including 4 patients, and all of them were considered major burn patients, who underwent escharotomy with general anesthesia and neuromuscular relaxation. The main variable was the time for recovery of a TOF higher than 0.9 after the administration of sugammadex before extubation. ResultsMean time of recovery from a TOF ratio higher than 0.9 following the administration of Sugammadex was of 4.95min 95% CI (3.25–6.64, p=.53). ConclusionsThe reversion of neuromuscular relaxation with sugammadex appears to be effective and safe in the burn patient. More analytical, comparative studies of larger populations would be necessary to confirm these data.

Utilización del sugammadex en el paciente quemado: estudio descriptivo

ObjectivesThe burn patient is a challenge for the anesthesiologist, undergoing several surgeries during admission, and requiring general anesthesia and muscle relaxation most of the times. They have respiratory system impairment and a response to muscle relaxants that differs from the healthy patient, thus proper monitoring and reversal is crucial. We analyzed sugammadex effectiveness and safety in this population. Material and methodsProspectively descriptive study including 4 patients, all of them considered major burn patients, who underwent escharotomy with general anesthesia and neuromuscular relaxation. The main variable was the time for recovery of a TOF higher than 0.9 after the administration of sugammadex before extubation. ResultsMean time of recovery from a TOF ratio higher than 0.9 following the administration of Sugammadex was of 4.95min 95% CI (3.25-6.64, P=.53); Conclusionsthe reversion of neuromuscular relaxation with sugammadex appears to be effective and safe in the burn patient. More analytical, comparative studies, of larger populations would be necessary to confirm this data.

Postoperative impairment of motor function at train-of-four ratio ≥0.9 cannot be improved by sugammadex (1 mg kg−1)

A train-of-four ratio (TOFR) ≥0.9 measured by quantitative neuromuscular monitoring is accepted as an indication of sufficient neuromuscular recovery for extubation, even though many postsynaptic acetylcholine receptors may still be inhibited. We investigated whether antagonism with sugammadex after spontaneous recovery to TOFR≥0.9 further improves muscle function or subjective well-being. Following recovery to TOFR≥0.9 and emergence from anaesthesia, 300 patients randomly received either sugammadex 1.0 mg kg(-1) or placebo. Fine motor function (Purdue Pegboard Test) and maximal voluntary grip strength were measured before and after surgery (before and after test drug administration). At discharge from the postanaesthesia care unit, well-being was assessed with numerical analogue scales and the Quality-of-Recovery Score 40 (QoR-40). Patients' fine motor function [6 (sd 4) vs 15 (3)pegs(30 s)(-1), P<0.05] and maximal voluntary grip strength (284 (126) vs 386 (125) N, P<0.05) were significantly lower after anaesthesia compared with the pre-anaesthesia baseline. After sugammadex or placebo, motor function was significantly improved in both groups but did not reach the preoperative level. There was no difference between groups at any time. Global well-being was unaffected (QoR-40: placebo, 174 vs 185; sugammadex, 175 vs 186, P>0.05). Antagonizing rocuronium at TOF≥0.9 with sugammadex 1.0 mg kg(-) (1) did not improve patients' motor function or well-being when compared with placebo. Our data support the view that TOFR≥0.9 measured by electromyography signifies sufficient recovery of neuromuscular function. The trial is registered at ClinicalTrials.gov (NCT01101139).

Differences between acceleromyography and electromyography during neuromuscular function monitoring in anesthetized Beagle dogs

ObjectiveQuantitative neuromuscular monitoring is essential for studies of potency and duration of neuromuscular blocking agents, and for detecting residual paralysis in anesthetized patients. This investigation evaluates whether there are systematic differences between acceleromyography (AMG) and electromyography (EMG); two quantitative methods for monitoring neuromuscular block. Study designProspective. AnimalsTen healthy Beagle dogs. MethodsDogs were anesthetized with isoflurane and dexmedetomidine. Both ulnar nerves were stimulated with a train-of-four (TOF) pattern every 15 seconds. The magnitude of the first twitch (T1) and the TOF ratio (magnitude of T4/T1; TOFR) were quantified simultaneously with AMG and EMG, applied randomly to each extremity. The extent of maximal block (T1 depression) and onset time were measured by AMG and EMG during TOF monitoring after the administration of cisatracurium (0.05 mg kg−1). In addition, recovery of T1 to 25% and 75%, the recovery index (time between T1 of 25% and 75%), and recovery of the TOFR to 0.9 were used to characterize recovery from cisatracurium and were compared between monitors. Regression and Bland-Altman plots for T1 and TOFR were also created. ResultsMaximal block and onset time were not different between monitors. Time to recovery of T1 to 25% and 75%, and time to TOF ratio 0.9 was significantly shorter with AMG. The recovery index was not different between monitors. When the TOFR returned to 0.9 with AMG, EMG still measured considerable residual block (TOFR 0.47). Conclusions and clinical relevanceElectromyography consistently detected residual NMB when recovery from NMB was complete as assessed by AMG.

Neuromuscular blocking effects of vecuronium in dogs with autosomal-recessive centronuclear myopathy.

To evaluate the potency of vecuronium and duration of vecuronium-induced neuromuscular blockade in dogs with centronuclear myopathy (CNM). 6 Labrador Retrievers with autosomal-recessive CNM and 5 age- and weight-matched control dogs. Dogs were anesthetized on 2 occasions (1-week interval) with propofol, dexmedetomidine, and isoflurane. Neuromuscular function was monitored with acceleromyography and train-of-four (TOF) stimulation. In an initial experiment, potency of vecuronium was evaluated by a cumulative-dose method, where 2 submaximal doses of vecuronium (10 μg/kg each) were administered IV sequentially. For the TOF's first twitch (T1), baseline twitch amplitude and maximal posttreatment depression of twitch amplitude were measured. In the second experiment, dogs received vecuronium (50 μg/kg, IV) and the time of spontaneous recovery to a TOF ratio (ie, amplitude of TOF's fourth twitch divided by amplitude of T1) ≥ 0.9 and recovery index (interval between return of T1 amplitude to 25% and 75% of baseline) were measured. Depression of T1 after each submaximal dose of vecuronium was not different between groups. Median time to a TOF ratio ≥ 0.9 was 76.7 minutes (interquartile range [IQR; 25th to 75th percentile], 66.7 to 99.4 minutes) for dogs with CNM and 75.0 minutes (IQR, 47.8 to 96.5 minutes) for controls. Median recovery index was 18.0 minutes (IQR, 9.7 to 23.5 minutes) for dogs with CNM and 20.2 minutes (IQR, 8 to 25.1 minutes) for controls. For the study dogs, neither potency nor duration of vecuronium-induced neuromuscular blockade was altered by CNM. Vecuronium can be used to induce neuromuscular blockade in dogs with autosomal-recessive CNM.

Effectiveness and safety of low-dose vecuronium on globe position of pediatric patients in ocular surgery

To test the effectiveness and safety of low-dose vecuronium (0.01 mg/kg) for correcting eccentric eye position during ocular surgery. A total of 80 ASA I-II children undergoing cataract or squint surgery were randomized into 2 groups (n = 40 each). Fentanyl and propofol were used for induction and then laryngeal mask (LMA) was inserted. 0.01 mg/kg vecuronium was administered to the low-dose group (L group) and 0.08 mg/kg vecuronium for high-dose group (H group). The ToF-Watch was fixed to monitor the train of four ratio (TOFR) of adductor pollicis. Eyeball eccentricity ratio before and after dosing, TOFR, duration of eyeball in central position, duration of surgery, the time from the end of surgery to removal of LMA and oculist satisfaction were recorded. The incidence of eccentric eyeball position was nearly 100% in both groups. The eyeball eccentricity ratio was 0.30 ± 0.11 in L group and 0.29 ± 0.12 in H group (P = 0.852) after/before vecuronium injection. The eyeballs were fixed well in the central position in both groups after vecuronium injection. The duration was shorter in L group than that in H group (23.43 ± 2.45 vs 37.63 ± 7.75 min, P < 0.001) . The time from the end of surgery to removal of LMA was (8.57 ± 3.49) min in L group and (12.28 ± 4.26) min in H group (P = 0.014). TOFR had merely mild reduction in L group and returned to normal in 10 minutes. At the end of surgery, TOFR was 102.43% ± 4.70% in L group and 80.47 ± 5.53 in H group (P < 0.001). Oculists were satisfied with eyeball position in both groups (P = 0.958). Low-dose vecuronium can correct eccentric eyeball position effectively and safely during ocular surgery while it has little effect on respiratory muscles.

Comparison of neostigmine induced reversal of vecuronium in normal weight, overweight and obese female patients.

Background and Aims:Obese patients are more vulnerable to residual neuromuscular block (NMB) and its associated complications in the post-operative period. This study was carried out to compare neostigmine induced reversal of vecuronium in normal weight, overweight and obese female patients, objectively using neuromuscular (NM) monitoring.Methods:Twenty female patients each belonging to normal weight, overweight and obese, based on body mass index, requiring general anaesthesia were recruited for this prospective cross sectional study. NMB was induced with vecuronium (0.1 mg/kg) dose based on patient's real body weight (RBW) and monitored using acceleromyographic train of four (TOF). All patients received neostigmine 40 μg/kg and glycopyrrolate 10 μg/kg at 25% of spontaneous recovery of first twitch height (T1) of TOF (DUR 25%) and were allowed to recover to TOF ratio of 0.9. Statistical analysis was done using analysis of variance test.Results:Recovery of TOF ratio to 0.5 was comparable in all three groups. Recovery of TOF ratio to 0.7 was delayed in obese (9.82 ± 3.21 min) compared with normal weight group (7.50 ± 2.52 min). Recovery of TOF to 0.9 was significantly delayed in both overweight (12.18 ± 4.29 min) and obese patients (13.78 ± 4.30 min). DUR 25% was significantly longer in overweight (mean, standard deviation [range]; 30.10 [19–40 min]) and obese (28.8 [12–45 min]) compared with normal weight patients (22.75 [16–30 min]).Conclusion:In overweight and obese patients, when vecuronium induction dose is based on RBW, neostigmine induced recovery of NMB is delayed in late phases (TOF 0.7-0.9), which may result in vulnerability for associated complications of incomplete recovery. Ensuring safe recovery thus requires objective NM monitoring.

Postoperative Residual Neuromuscular Paralysis at an Australian Tertiary Children’s Hospital

Purpose. Residual neuromuscular blockade (RNMB) is known to be a significant but frequently overlooked complication after the use of neuromuscular blocking agents (NMBA). Aim of this prospective audit was to investigate the incidence and severity of RNMB at our Australian tertiary pediatric center. Methods. All children receiving NMBA during anesthesia were included over a 5-week period at the end of 2011 (Mondays to Fridays; 8 a.m.–6 p.m.). At the end of surgery, directly prior to tracheal extubation, the train-of-four (TOF) ratio was assessed quantitatively. Data related to patient postoperative outcome was collected in the postoperative acute care unit. Results. Data of 64 patients were analyzed. Neostigmine was given in 34 cases and sugammadex in 1 patient. The incidence of RNMB was 28.1% overall (without reversal: 19.4%; after neostigmine: 37.5%; n.s.). Severe RNMB (TOF ratio < 0.7) was found in 6.5% after both no reversal and neostigmine, respectively. Complications in the postoperative acute care unit were infrequent, with no differences between reversal and no reversal groups. Conclusions. In this audit, RNMB was frequently observed, particularly in cases where patients were reversed with neostigmine. These findings underline the well-known problems associated with the use of NMBA that are not fully reversed.

Comparative study between sugammadex and neostigmine in neurosurgical anesthesia in pediatric patients

Background:Postoperative recurarization remains a risk following the use of the conventional neuromuscular blocking agents. In addition, none of the commonly used reversal agents, such as neostigmine or edrophonium are capable of reliably reversing profound blockade. The present comparative and randomized study investigated the use of sugammadex for reversing profound neuromuscular blockade (NMB) in pediatric neurosurgical patients undergone posterior fossa tumor excision.Patients and Methods:Forty pediatric patients undergoing elective craniotomy for posterior fossa tumor excision were randomly divided into either of neostigmine or sugammadex group in which muscle relaxant was reversed at the end of anesthesia either with neostigmine 0.04 mg/kg added to atropine 0.02 mg/kg or sugammadex 4 mg/kg alone, respectively. The primary endpoint was the time from the administration of sugammadex or neostigmine to recovery of the train of four (TOF) ratio to 90% after rocuronium-induced neuromuscular block. Unpaired t-test was used to compare continuous variables between groups. Meanwhile, repeated ANOVA was used to detect intragroup differences.Results:Patients in sugammadex group attained a TOF ratio 90% in statistically shorter time (1.4 ± 1.2 min) than those in neostigmine group (25.16 ± 6.49 min) for reversal of the rocuronium. Mean arterial pressure and heart rate were significantly higher in neostigmine group at 2, 5 and 10 min after administration of the reversal agents and returned nonsignificantly different after that. With no recurarization in any patient throughout the study period.Conclusion:Sugammadex rapidly and effectively reverses rocuronium-induced NMB in pediatric patients undergoing neurosurgery when administered at reappearance of T2 of TOF at dose 4 mg/kg.

The combination of sugammadex and neostigmine can reduce the dosage of sugammadex during recovery from the moderate neuromuscular blockade.

BackgroundSugammadex is a novel neuromuscular reversal agent, but its associated hypersensitivity reaction and high cost have been obstacles to its widespread use. In the interest of reducing the necessary dosage of sugammadex, the reversal time of the combined use of sugammadex and neostigmine from moderate neuromuscular blockade were investigated.MethodsThe patients enrolled ranged in age from 18 to 65 years old with American Society of Anesthesiologists class 1 or 2. The subjects were randomly assigned into one of the four groups (Group S2, S1, SN, and N; n = 30 per group). The reversal agents of each groups were as follows: S2 - sugammadex 2 mg/kg, S1 - sugammadex 1 mg/kg, SN - sugammadex 1 mg/kg + neostigmine 50 µg/kg + glycopyrrolate 10 µg/kg, N - neostigmine 50 µg/kg + glycopyrrolate 10 µg/kg. The time to recovery of the train-of-four (TOF) ratio was checked in each group.ResultsThe time to 90% recovery of TOF ratio was 182.6 ± 88.9, 371.1 ± 210.4, 204.3 ± 103.2, 953.2 ± 379.7 sec in group S2, S1, SN and N, respectively. Group SN showed a significantly shorter recovery time than did group S1 and N (P < 0.001). However, statistically significant differences between the S2 and SN groups were not be observed (P = 0.291). No hypersensitivity reactions occurred in all groups.ConclusionsFor the reversal from rocuronium-induced moderate neuromuscular blockade, the combined use of sugammadex and neostigmine may be helpful to decrease the recovery time and can also reduce the required dosage of sugammadex. However, the increased incidence of systemic muscarinic side effects must be considered.

Prevalence and Risk Factors of Postoperative Residual Curarization in Patients Arriving at Postanesthesia Care Unit after General Anesthesia: A Prospective Cohort Study

Background: Postoperative residual curarization (PORC) following the use of neuromuscular blocking drugs (NMBDs) remains a significant problem. The purpose of this study was to determine the prevalence and risk factors of PORC in patients who were admitted to postanesthesia care unit (PACU) after general anesthesia during our routine clinical practice.Methods: This was a prospective, observational cohort study. Patients who were admitted to PACU after general anesthesia were enrolled. Neuromuscular function was monitored using acceleromyography and train-of-four (TOF) stimulation. A TOF ratio of less than 0.9 was defined as having PORC. Multivariate Logistic regression analysis was performed to identify risk factors of PORC.Results: A total of 542 patients completed the study. PORC occurred in 30.6% (166/542) of patients. Increasing age (odds ratio [OR] 1.211, 95% confidence interval [CI] 1.068-1.374, P=0.003), combined use of two different non-depolarizing NMBDs during surgery (OR 1.693, 95% CI 1.138-2.520, P=0.009) and hypothermia at PACU arrival (OR 1.778, 95% CI 1.043-3.032, P=0.035) were associated with increased risk of PORC, whereas administration of neostigmine at the end of surgery (OR 0.341, 95% CI 0.164-0.709, P=0.004) and prolonged time interval from last dose of NMBDs to PACU arrival (OR 0.326, 95% CI 0.215-0.496, P<0.001) were associated with decreased risk of PORC. Patients with PORC at PACU arrival had prolonged PACU stay, increased occurrence of adverse events during PACU stay and increased rate of PORC at PACU discharge.Conclusions: PORC was common in patients who were admitted to PACU after general anesthesia. Increasing age, combined use of two different non-depolarizing NMBDs during surgery and hypothermia at PACU arrival were associated with increased risk of PORC. Citation: Min Xie, Dong-Xin Wang, Zhi-Yu Geng. Prevalence and risk factors of postoperative residual curarization in patients arriving at postanesthesia care unit after general anesthesia: a prospective cohort study. J Anesth Perioper Med 2014; 1: 72-8. doi: 10.24015/JAPM.2014.0012This is an open-access article, published by Evidence Based Communications (EBC). This work is licensed under the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium or format for any lawful purpose. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Usefulness of sugammadex in a patient with Becker muscular dystrophy and dilated cardiomyopathy

A 54-year-old patient with Becker muscular dystrophy and dilated cardiomyopathy underwent laparoscopic cholecystectomy under total intravenous anesthesia. Muscle relaxation was induced by rocuronium (0.4 mg/kg body weight) under train-of-four (TOF) ratio monitoring. The TOF ratio was 0 at intubation, and 0.2 at the end of surgery. Residual muscle relaxant activity was successfully reversed by sugammadex (2 mg/kg body weight) without any hemodynamic adverse effects (TOF ratio 1.0 at extubation). The clinical and hemodynamic findings suggest that sugammadex can be safely used in patients with Becker muscular dystrophy and dilated cardiomyopathy.

Safe use of rocuronium for a post-polio syndrome patient

To the Editor: Patients with ‘‘post-polio syndrome’’ can experience recurrent muscle weakness years after acute poliovirus infection [1]. We report a case of a 64-year-old woman who was scheduled for mastectomy. We report the effect of rocuronium, as evaluated by train-of-four (TOF) monitoring of this patient. She had undergone two caesarean sections, under spinal anesthesia with prolongation of hypesthesia and under general anesthesia with delayed awakening, which was speculated to be caused by residual neuromuscular blockade (NMB). She presented with muscle weakness in the lower extremities and the right upper extremity (manual muscle testing 3/5), but spirometry values were normal. After induction of general anesthesia, neuromuscular monitoring was started by use of TOF monitoring of the right adductor pollicis muscle. The TOF ratio was 100 %. Rocuronium (0.6 mg/kg) was used for NMB. Anesthesia was maintained with sevoflurane and remifentanil. The change of TOF ratio is shown in the figure. Because TOF monitoring showed the ratio was 100 % at the end of surgery, NMB was not reversed. She did not report any respiratory complaints. Patients with post-polio syndrome are known to be potentially hypersensitive to NMBs, anesthetic agents, and opioids [1]. Because they have fewer motor neurons than normal [1], shorter acting non-depolarizing NMBs are desirable and neuromuscular monitoring is necessary. In our case, it seems likely she did not experience prolongation of the rocuronium effect. Moreover, we did not observe any signs of hypersensitivity to sevoflurane or remifentanil. Prolongation of the effects of these drugs is likely to depend on the extent of paralysis. Recurarization after spontaneous complete recovery does not occur with non-depolarizing NMBs. Although we did not reverse the rocuronium, it might be better to administer sugammadex. Conflict of interest None.

Performance of acceleromyography with a short and light TOF-tube compared with mechanomyography

Disturbances in the thumb's movement interfere with the functioning of acceleromyography in many clinical settings. The short and light (SL) train-of-four (TOF)-Tube is a new version of a rigid tubular device that was designed to protect the thumb from external disturbances during surgery, even when the hand is not accessible by the anaesthesiologist. To compare the precision and performance of acceleromyography performed with the aid of the SL TOF-Tube (AMGTT) with standard isometric mechanomyography (MMG). Simultaneous arm-to-arm comparison of both methods in the same anaesthetised patient. A monocentric study, performed from September 2007 to June 2008. Nineteen ASA I to II patients scheduled to undergo lower limb orthopaedic surgery under general anaesthesia. Neuromuscular transmission monitoring during baseline, onset and spontaneous recovery of rocuronium-induced neuromuscular block. Initial baseline and repeatability coefficients were assessed during 10 consecutive measurements of the first twitch height (T1) and TOF T4/T1 ratio and compared using a z test. The spontaneous recoveries of defined blockade levels (onset, T1 25% of initial calibration and TOF ratio 0.9) were compared in terms of duration and intensity. Agreement between both techniques was assessed by the Bland-Altman method. The mean ± SD control TOF ratios were 98 ± 1% (MMG) and 103 ± 2% (AMGTT). The repeatability coefficients were higher (P < 0.001) and the onset was longer (mean 0.44 min) (P < 0.001) when they were measured by AMGTT. The recoveries of T1 25% and TOF ratio 0.9 were not significantly different between the two methods, and the limits of agreement were in the usual range of contralateral comparisons (-19 and +24% for TOF ratio 0.9). Compared with mechanomyography, acceleromyography performed with the aid of an SL TOF-Tube offered acceptable precision and equivalent performance during neuromuscular block recovery.