Residual Paralysis in the PACU after a Single Intubating Dose of Nondepolarizing Muscle Relaxant with an Intermediate Duration of Action

Background: Residual neuromuscular blockade remains a problem even after short surgical procedures. The train-of-four (TOF) ratio at the adductor pollicis required to avoid residual paralysis is now considered to be at least 0.9. The incidence of residual paralysis using this new threshold is not known, especially after a single intubating dose of intermediate-duration nondepolarizing relaxant. Therefore, the aim of the study was to determine the incidence of residual paralysis in the postanesthesia care unit after a single intubating dose of twice the ED95 of a nondepolarizing muscle relaxant with an intermediate duration of action.

Methods: Five hundred twenty-six patients were enrolled. They received a single dose of vecuronium, rocuronium, or atracurium to facilitate tracheal intubation and received no more relaxant thereafter. Neuromuscular blockade was not reversed at the end of the procedure. On arrival in the postanesthesia care unit, the TOF ratio was measured at the adductor pollicis, using acceleromyography. Head lift, tongue depressor test, and manual assessment of TOF and DBS fade were also performed. The time delay between the injection of muscle relaxant and quantitative measurement of neuromuscular blockade was calculated from computerized anesthetic records.

Results: The TOF ratios less than 0.7 and 0.9 were observed in 16% and 45% of the patients, respectively. Two hundred thirty-nine patients were tested 2 h or more after the administration of the muscle relaxant. Ten percent of these patients had a TOF ratio less than 0.7, and 37% had a TOF ratio less than 0.9. Clinical tests (head lift and tongue depressor) and manual assessment of fade showed a poor sensitivity (11-14%) to detect residual blockade (TOF < 0.9).     

Residual paralysis in the PACU after a single intubating dose of nondepolarizing muscle relaxant with an intermediate duration of action

BACKGROUND: Residual neuromuscular blockade remains a problem even after short surgical procedures. The train-of-four (TOF) ratio at the adductor pollicis required to avoid residual paralysis is now considered to be at least 0.9. The incidence of residual paralysis using this new threshold is not known, especially after a single intubating dose of intermediate-duration nondepolarizing relaxant. Therefore, the aim of the study was to determine the incidence of residual paralysis in the postanesthesia care unit after a single intubating dose of twice the ED(95) of a nondepolarizing muscle relaxant with an intermediate duration of action. METHODS: Five hundred twenty-six patients were enrolled. They received a single dose of vecuronium, rocuronium, or atracurium to facilitate tracheal intubation and received no more relaxant thereafter. Neuromuscular blockade was not reversed at the end of the procedure. On arrival in the postanesthesia care unit, the TOF ratio was measured at the adductor pollicis, using acceleromyography. Head lift, tongue depressor test, and manual assessment of TOF and DBS fade were also performed. The time delay between the injection of muscle relaxant and quantitative measurement of neuromuscular blockade was calculated from computerized anesthetic records. RESULTS: The TOF ratios less than 0.7 and 0.9 were observed in 16% and 45% of the patients, respectively. Two hundred thirty-nine patients were tested 2 h or more after the administration of the muscle relaxant. Ten percent of these patients had a TOF ratio less than 0.7, and 37% had a TOF ratio less than 0.9. Clinical tests (head lift and tongue depressor) and manual assessment of fade showed a poor sensitivity (11-14%) to detect residual blockade (TOF < 0.9). CONCLUSION: After a single dose of intermediate-duration muscle relaxant and no reversal, residual paralysis is common, even more than 2 h after the administration of muscle relaxant. Quantitative measurement of neuromuscular transmission is the only recommended method to diagnose residual block.     

Residual neuromuscular blockade: incidence, assessment, and relevance in the postoperative period

The residual effects of neuromuscular blocking agents may persist into the early postoperative recovery period, even when neuromuscular blockade is carefully monitored and reversed in the operating room. Recent data suggest that mild degrees of residual paresis (train-of-four TOF ratios of 0.7-0.9) may be associated with significant impairment of respiratory and pharyngeal muscle function. Therefore, the new gold standard reflecting acceptable neuromuscular recovery is a TOF ratio > or =0.9. Several investigations have demonstrated that many patients continue to arrive in the postanesthesia care unit with TOF ratios <0.7-0.9. Several techniques may be used to reduce the risk of postoperative residual paresis, which include avoidance of long-acting muscle relaxants, use of neuromuscular monitoring in the operating room, routine reversal of neuromuscular blockade at a TOF count of 2-3, and early administration of reversal agents. Careful management of neuromuscular blockade may limit the occurrence of adverse events associated with residual postoperative paralysis. Large-scale outcome studies are needed to clearly define the impact of residual neuromuscular block on major morbidity and mortality in surgical patients.     

Intraoperative Acceleromyographic Monitoring Reduces the Risk of Residual Neuromuscular Blockade and Adverse Respiratory Events in the Postanesthesia Care Unit

Background: Incomplete recovery from neuromuscular blockade in the postanesthesia care unit (PACU) may contribute to adverse postoperative respiratory events. This study determined the incidence and degree of residual neuromuscular blockade in patients randomized to conventional qualitative train-of-four (TOF) monitoring or quantitative acceleromyographic monitoring. The incidence of adverse respiratory events in the PACU was also evaluated.

Methods: One hundred eighty-five patients were randomized to intraoperative acceleromyographic monitoring (acceleromyography group) or qualitative TOF monitoring (TOF group). Anesthetic management was standardized. TOF patients were extubated when standard criteria were met and no fade was observed during TOF stimulation. Acceleromyography patients had a TOF ratio of greater than 0.80 as an additional extubation criterion. Upon arrival in the PACU, TOF ratios of both groups were measured with acceleromyography. Adverse respiratory events during transport to the PACU and during the first 30 min of PACU admission were also recorded.

Results: A lower frequency of residual neuromuscular blockade in the PACU (TOF ratio <= 0.9) was observed in the acceleromyography group (4.5%) compared with the conventional TOF group (30.0%; P < 0.0001). During transport to the PACU, fewer acceleromyography patients developed arterial oxygen saturation values, measured by pulse oximetry, of less than 90% (0%) or airway obstruction (0%) compared with TOF patients (21.1% and 11.1%, respectively; P < 0.002). The incidence, severity, and duration of hypoxemic events during the first 30 min of PACU admission were less in the acceleromyography group (all P < 0.0001).     

Assessing residual neuromuscular blockade using acceleromyography can be deceptive in postoperative awake patients

Postoperative awake patients may have significant residual neuromuscular block. In awake patients, the results of accelerometry are affected by extra movements to which the thumb may be subject. In this study, we evaluated the repeatability of train-of-four (TOF) ratio using acceleromyography in 253 patients recovering from anesthesia. Immediately after arrival in the postanesthesia care unit, the ulnar nerve was stimulated with TOF stimulation. The evoked response at the thumb was measured by the TOF-Watch apparatus. The current intensity was 30 mA. Two TOF stimulations were applied and recorded at 30-s intervals. A Bland-Altman test was used. The Kappa (kappa) test for clinical agreement between the two measurements was also calculated according to the presence or absence of a residual neuromuscular blockade, defined as a TOF ratio <0.9. According to the presence of a residual neuromuscular blockade, the paired TOF ratios were discordant in 61 patients (24%; 95% confidence interval, 21%-27%). The kappa test indicated a moderate agreement (k = 0.47). We demonstrated that accelerometry as used in this study is not always accurate. Two isolated acceleromyograph TOF ratios are not an accurate representation of the neuromuscular status of the patient recovering from anesthesia. IMPLICATIONS: Clinicians should be aware that acceleromyography as used in this study does not always provide precise train-of-four ratio measurements. Two isolated acceleromyograph train-of-four ratios are not an accurate representation of the neuromuscular status of the patient recovering from anesthesia.     

Residual Block after Mivacurium with or without Edrophonium Reversal in Adults and Children

Background: The rapid recovery from mivacurium-induced neuromuscular block has encouraged omission of its reversal. The purpose of this study was to determine, in children and in adults, whether failure to reverse mivacurium neuromuscular block was associated with residual neuromuscular block on arrival in the postanesthesia care unit.

Methods: In 50 children, aged 2-12 yr, and 50 adults, aged 20-60 yr, anesthesia was induced and maintained with propofol and fentanyl, and neuromuscular block was achieved by an infusion of mivacurium, to maintain one or two visible responses to train-of-four (TOF) stimulation of the ulnar nerve. At the end of surgery, mivacurium infusion was stopped, and 10 min later, reversal was attempted with saline or 0.5 mg *symbol* kg sup -1 edrophonium by random allocation. On arrival in the postanesthesia care unit, a blinded observer assessed patients clinically and by stimulation of the ulnar nerve with a Datex electromyogram in the uncalibrated TOF mode.

Results: Children arrived in the postanesthesia care unit 8.2 +/-3.4 min after reversal of neuromuscular block and showed no sign of weakness, either clinically or by TOF stimulation. Although TOF ratio was greater in children who had received edrophonium (1.00 +/-0.05 vs. 0.93+/-0.01, P < 0.01), TOF was > 0.7 in all children. Adults arrived in the postanesthesia care unit 12.9+/- 5.3 min after reversal of neuromuscular block (P < 0.01 vs. children). Six in the saline group demonstrated weakness (two required immediate reversal of neuromuscular block, and TOF was < 0.7 in four others), compared with TOF < 0.7 in only one of the edrophonium group (P < 0.05).     

Postoperative upper airway obstruction after recovery of the train of four ratio of the adductor pollicis muscle from neuromuscular blockade

Anesthetics, and even minimal residual neuromuscular blockade, may lead to upper airway obstruction (UAO). In this study we assessed by spirometry in patients with a train-of-four (TOF) ratio >0.9 the incidence of UAO (i.e., the ratio of maximal expiratory flow and maximal inspiratory flow at 50% of vital capacity [MEF50/MIF50] >1) and determined if UAO is induced by neuromuscular blockade (defined by a forced vital capacity [FVC] fade, i.e., a decrease in values of FVC from the first to the second consecutive spirometric maneuver of > or =10%). Patients received propofol and opioids for anesthesia. Spirometry was performed by a series of 3 repetitive spirometric maneuvers: the first before induction (under midazolam premedication), the second after tracheal extubation (TOF ratio: 0.9 or more), and the third 30 min later. Immediately after tracheal extubation and 30 min later, 48 and 6 of 130 patients, respectively, were not able to perform spirometry appropriately because of sedation. The incidence of UAO increased significantly (P < 0.01) from 82 of 130 patients (63%) at preinduction baseline to 70 of 82 patients (85%) after extubation, and subsequently decreased within 30 min to values observed at baseline (80 of 124 patients, 65%). The mean maximal expiratory flow and maximal inspiratory flow at 50% of vital capacity ratio after tracheal extubation was significantly increased from baseline (by 20%; 1.39 +/- 1.01 versus 1.73 +/- 1.02; P < 0.01), and subsequently decreased significantly to values observed at baseline (1.49 +/- 0.93). A statistically significant FVC fade was not present, and a FVC fade of > or =10% was observed in only 2 patients after extubation. Thus, recovery of the TOF ratio to 0.9 predicts with high probability an absence of neuromuscular blocking drug-induced UAO, but outliers, i.e., persistent effects of neuromuscular blockade on upper airway integrity despite recovery of the TOF ratio, may still occur.     

Recovery of neuromuscular function after cardiac surgery: pancuronium versus rocuronium

The use of pancuronium in fast-track cardiac surgical patients may be associated with delays in clinical recovery. Our objective in this study was to evaluate the incidence and severity of residual neuromuscular blockade after cardiac surgery in patients randomized to receive either pancuronium (0.08-0.1 mg/kg) or rocuronium (0.6-0.8 mg/kg). Eighty-two patients undergoing cardiopulmonary bypass were randomized to a pancuronium (n = 41) or rocuronium (n = 41) group. Intraoperative and postoperative management was standardized. In the intensive care unit, train-of-four (TOF) ratios were measured each hour until weaning off ventilatory support was initiated. Neuromuscular blockade was not reversed. After tracheal extubation, patients were examined for signs and symptoms of residual paresis. When weaning of ventilatory support was initiated, significant neuromuscular blockade was present in the pancuronium subjects (TOF ratio: median, 0.14; range, 0.00-1.11) compared with the rocuronium subjects (TOF ratio: median, 0.99; range, 0.87-1.21) (P < 0.05). Patients in the rocuronium group were more likely to be free of signs and symptoms of residual paresis than patients in the pancuronium group. Our findings suggest that the use of longer-acting muscle relaxants in cardiac surgical patients is associated not only with impaired neuromuscular recovery, but also with signs and symptoms of residual muscle weakness in the early postoperative period. IMPLICATIONS: The use of long-acting muscle relaxants in fast-track cardiac surgical patients is associated with significant residual neuromuscular block in the intensive care unit, including signs and symptoms of residual paresis.     

Tactile evaluation of the response to double burst stimulation decreases, but does not eliminate, the problem of postoperative residual paralysis

Background: Routine perioperative monitoring with accelero-myography might prevent residual block, whereas routine tactile evaluation of the response to train-of-four (TOF) nerve stimulation does not. The purpose of this prospective, randomised and blinded study was to evaluate the effect of manual evaluation of the response to double burst stimulation (DBS_3.3) upon the incidence of residual block. Methods: Sixty adult patients scheduled for elective abdominal surgery were included in the study. Pancuronium 0.08 to 0.1 mg kg^?1 was given for relaxation and tracheal intubation. For maintenance of neuromuscular block, pancuronium 1–2 mg was administered. The patients were randomly allocated into two groups. In group DBS (double burst stimulation) the degree of block during anaesthesia was assessed by manual evaluation of the response to TOF nerve stimulation. During reversal, when no fade was detectable in the TOF response, the stimulation pattern was changed to DBS_3.3. The trachea was extubated when the anaesthetist judged the neuromuscular function to have recovered adequately and no fade in the DBS_3.3 response could be felt. In group CC (clinical criteria) patients were managed without the use of a nerve stimulator, and the level of neuromuscular block and reversal were evaluated solely on the basis of clinical criteria. In both groups, the TOF ratio was measured by mechanomyography immediately after tracheal extubation. Also, the ability to sustain head lift for 5 s, to protrude the tongue, to open the eyes, and to lift one arm to the opposite shoulder were tested. Results: The TOF ratio, as measured immediately after tracheal extubation, was significantly lower in group CC than in group DBS (means: 0.68 and 0.78, respectively), and the incidence of residual neuromuscular block defined as a TOF ratio <0.7 was significantly higher in group CC than in group DBS (57 and 24%, respectively). The time from the first TOF measurement until the TOF ratio reached 0.8 was significantly longer in group CC than in group DBS (means: 11.5 and 6.2 min, respectively). No significant differences between the two groups of patients were found in duration of anaesthesia, in times from end of surgery to injection of neostigmine, tracheal extubation or TOF ratio 0.8, in dose of pancuronium, or in any other postoperative variable. Conclusion: Routine perioperative manual evaluation of the responses to TOF and DBS_3.3 decreased the incidence and the degree of residual block following the use of pancuronium. It did not, however, exclude clinically significant residual paralysis, nor did it influence the amount of pancuronium used during the operation, the duration of anaesthesia or the time from end of surgery to tracheal extubation or to sufficient recovery of neuromuscular function (TOF=0.8).     

Cisatracurium- and rocuronium-associated residual neuromuscular dysfunction under intraoperative neuromuscular monitoring and postoperative neostigmine reversal: a single-blind randomized trial

BackgroundPostoperative residual neuromuscular blockade (RNMB) is a common complication in the postanesthesia care unit (PACU), but also one of the most controversial issues. Many studies and trials demonstrated that some methods and techniques can reduce the incidence and the extent of the phenomenon.Study ObjectiveTo determine the incidence of RNMB in the PACU at standardized times after extubation with the implementation of a protocol of careful neuromuscular blockade management.DesignRandomized, single-blinded controlled clinical trial.SettingOperating room and PACU.PatientsA total of 120 patients of either sex with American Society of Anesthesiologists grades 1, 2, and 3, aged 18 to 80 years were scheduled to undergo elective abdominal surgical procedures lasting for at least 60 minutes.InterventionsPatients were randomized to receive either cisatracurium (n = 60) or rocuronium (n = 60) at the time of intubation and during surgery. Every patient received quantitative neuromuscular monitoring during general anesthesia. On completion of surgery, patients were given neostigmine 0.05 mg kg⁻¹. Patients were extubated at a train-of-four (TOF) ratio ≥0.9.MeasurementsTOF measurements were performed 15, 30, and 60 minutes after extubation. Tolerability of neuromuscular monitoring was evaluated with a scale from 1 to 10 (with 1 meaning no discomfort at all and 10 meaning maximal discomfort or pain).ResultsSix, 11, and 14 patients (5.0%, 9.2%, and 11.7%) exhibited a TOF ratio <0.9 at 15, 30, and 60 minutes after extubation, respectively. No statistically significant difference in the postoperative RNMB between cisatracurium and rocuronium was found. The median tolerability score for neuromuscular monitoring was 3.ConclusionCareful conduction, monitoring, and subsequent reversal of neuromuscular block may allow for obtaining considerably low incidence of residual neuromuscular block. However, our trial shows that some mid- and long-term cases of TOF ratios <0.9 can still occur, possibly jeopardizing the patients' postoperative recovery.     

Recurarization after sugammadex reversal in an obese patient

Purpose

We report a case that involved immediate postoperative respiratory failure necessitating tracheal intubation, which was possibly related to recurarization after sugammadex reversal.

Clinical findings

A 54-yr-old woman weighing 115-kg was scheduled for laparoscopic repair of abdominal dehiscence under general anesthesia. Muscle relaxation was induced and maintained with rocuronium (170 mg iv total dose). At the end of the 170-min procedure, two twitches were visualized after supramaximal train-of-four (TOF) stimulation at the adductor pollicis muscle, and the patient’s central core temperature was 35.6°C. Sugammadex 200 mg iv (1.74 mg·kg^?1) was administered. With the patient fully awake, a TOF ratio 0.9 was obtained five minutes later. The tracheal tube was then removed, and the patient was transferred to the postanesthesia care unit. Ten minutes later, the patient presented respiratory failure necessitating tracheal intubation and sedation with propofol. One TOF response only was visualized at the adductor pollicis muscle. Another dose of sugammadex 200 mg iv was administered. Forty-five minutes later, the patient was fully awake and her trachea was extubated after repeated measures of the TOF ratio (≥ 0.9) at the adductor pollicis muscle. The patient fully recovered without sequelae, further complication, or prolonged hospital stay.

Conclusion

Shortly after tracheal extubation, an obese patient experienced respiratory failure necessitating tracheal intubation and an additional dose of sugammadex. This occurred despite initial reversal of neuromuscular blockade with an appropriate dose of sugammadex 2 mg·kg^?1 iv given at two responses to TOF stimulation.     

Is the diagnosis of significant residual neuromuscular blockade improved by using double-burst nerve stimulation?

This study evaluated the use of double-burst stimulation (DBS) in the diagnosis of significant post-operative residual neuromuscular blockade. Ninety patients were allocated to three equal groups. In Group A the degree of residual neuromuscular blockade was assessed by clinical criteria (CC) only; in Group B by CC and manual evaluation of the response to train-of-four (TOF) nerve stimulation; and in Group C by CC, manual evaluation of the response to TOF, and DBS stimulation. Immediately after arrival in the recovery room mechanical twitch was recorded using TOF stimulation. The mean (+/- SD) TOF ratios were 0.53 +/- 0.19 in Group A, 0.67 +/- 0.11 in Group B and 0.81 +/- 0.08 in Group C. The incidence of a TOF ratio of less than 0.7 was 83.3% in Group A, 56.7% in Group B and 6.7% in Group C. It is concluded that the use of DBS enabled the anaesthetist to recognize significant residual block and thus reduced the incidence of post-operative residual neuromuscular blockade.     

Residual neuromuscular blockade in the ICU: a prospective observational study and national survey

Residual neuromuscular blockade is associated with significant morbidity. It has been widely studied in anaesthesia; however, the incidence of residual neuromuscular blockade in patients managed in the ICU is unknown. We conducted a prospective observational study in a tertiary ICU to determine the incidence of residual neuromuscular blockade using quantitative accelerographic monitoring. We tested for residual neuromuscular blockade (defined as a train-of-four ratio < 0.9) before cessation of sedation in anticipation of tracheal extubation. We also surveyed 16 other ICUs in New Zealand to determine their use of neuromuscular monitoring. A total of 191 patients were included in the final analysis. The incidence (95%CI) of residual neuromuscular blockade was 43% (36–50%), with a similar incidence observed in non-postoperative and postoperative patients. There was a lower risk of residual neuromuscular blockade with atracurium than rocuronium (risk ratio (95%CI) of 0.39 (0.12–0.78)) and a higher risk with pancuronium than rocuronium (1.59 (1.06–2.49)). Our survey shows that, in New Zealand ICUs, monitoring of neuromuscular function is rarely carried out before tracheal extubation. When neuromuscular monitoring is undertaken, it is based on individual clinician suspicion and performed using qualitative measurements. No ICU reported using a quantitative monitor or a clinical guideline. The results demonstrate a high incidence of residual neuromuscular blockade in our ICU patients and identify the type of neuromuscular blocking drug as a possible risk factor. Monitoring neuromuscular function before tracheal extubation is not currently the standard of care in New Zealand ICUs. These data suggest that residual neuromuscular blockade may be an under-recognised problem in ICU practice.     

舒更葡糖钠对胸腹腔镜食管癌根治术患者术后肌松恢复的影响

目的 探讨舒更葡糖钠对全麻下胸腹腔镜食管癌根治术患者术后肌松恢复的影响.方法 选择全麻下行胸腹腔镜食管癌根治术患者96例,男61例,女35例,年龄18～65岁,ASAⅠ或Ⅱ级.采用随机数字表法将患者分为两组:新斯的明联合阿托品组(C组)和舒更葡糖钠组(S组),每组48例.两组麻醉诱导和术中全麻维持方案相同,使用四个成串...     

Retrospective analysis of spontaneous recovery from neuromuscular blockade produced by empirical use of rocuronium

Purpose  

A train-of-four ratio (TOF ratio) of >0.9 should be the clinical cut-off to avoid residual paralysis. However, it is not rare to extubate patients without measurement of the TOF ratio, although the safe interval from the last administration of rocuronium assuring a TOF ratio of >0.9 has not been established in the daily clinical setting. In this study, to estimate the safe interval to avoid residual paralysis, we retrospectively selected patients in whom the TOF ratio was measured during remifentanil administration before extubation, and we studied the characteristics of recovery from the neuromuscular blockade produced by the empirical use of rocuronium.     

Single acceleromyographic train-of-four, 100-Hertz tetanus or double-burst stimulation: which test performs better to detect residual paralysis?

BACKGROUND: Acceleromyography is regularly used as an isolated test to detect residual paralysis. The performance of acceleromyography, however, has not been investigated for the setting where calibration is impossible. This study first evaluated the reliability of a single acceleromyographic train-of-four (TOF) ratio (T4/T1) to detect residual paralysis and compared it with tactile estimation of fade after double-burst stimulation and 100-Hz, 5-s tetanus. The second part of the study investigated whether uncalibrated acceleromyographic TOF ratio can predict time to complete recovery. METHODS: Anesthesia was induced and maintained with propofol and sufentanil. In the first part of the study (n = 40) neuromuscular blockade was assessed by mechanomyography. After signal stabilization 0.15 mg/kg cisatracurium was given. At the end of surgery a first physician evaluated manual fade after double-burst stimulation, then, in the same patient, a single acceleromyographic TOF ratio was recorded; thereafter a second physician, unaware of the results, assessed fade after a 100-Hz, 5-s tetanus. Sensitivity, specificity, and negative and positive predictive value of the three tests to detect a mechanomyographic TOF > or =0.9 were calculated. In the second part of the study (n = 25) neuromuscular recovery was assessed simultaneously with mechanomyography and uncalibrated acceleromyography (current set manually at 60 mA); the time intervals from acceleromyographic TOF ratios of 0.6, 0.7, 0.8, and 0.9 until complete recovery, i.e., adductor pollicis mechanomyography 0.9 TOF ratios, were determined. RESULTS: The sensitivity of double burst stimulation was 29% (95% confidence interval [CI], 13-45%), its specificity was 100%, the negative predictive value was 29% (95% CI, 13-45%), and the positive predictive value was 100%. For a single acceleromyographic TOF ratio the respective values were 70% (95% CI, 54-86%), 88% (95% CI, 67-100%), 47% (95% CI, 23-71%) and 95% (95% CI, 86-100%). The respective values for 100-Hz, 5-s tetanus were 74% (95% CI, 59-89%), 55% (95% CI, 23-88%), 38% (95% CI, 12-64%), and 85% (95% CI, 72 -99%). At an uncalibrated acceleromyographic TOF ratio was 0.6, complete recovery occurred within 16 min (95% CI, 13.5-17.8 min). At acceleromyographic TOF ratios of 0.7, 0.8, and 0.9 this time interval was 12.5 min (95% CI, 10.2-14.8 min), 8 min (95% CI, 6.1-9.9 min), and 4 min (95% CI, 2.7-5.8 min), respectively. CONCLUSIONS: Acceleromyographic TOF performed better than double-burst stimulation or 100 Hz tetanus, but it did not reliably detect low degrees of residual paralysis when used as an isolated test at the end of surgery. The uncalibrated acceleromyographic TOF ratio, however, did predict the time to complete recovery.     

Antagonism of cisatracurium and rocuronium block at a tactile train-of-four count of 2: should quantitative assessment of neuromuscular function be mandatory?

With a train-of-four (TOF) ratio >0.70 as the standard of acceptable recovery, postoperative residual paralysis is a frequent occurrence in postanesthesia care units (PACUs). However, detailed information regarding prior anesthetic management is rarely provided. We examined the incidence of postoperative weakness after the administration of cisatracurium and rocuronium when using a rigid protocol for muscle relaxant and subsequent neostigmine administration. Under desflurane, N(2)O, and opioid anesthesia, tracheal intubation was accomplished after either cisatracurium 0.15 mg/kg or rocuronium 0.60 mg/kg. The response of the thumb to ulnar nerve stimulation was estimated by palpation. Additional increments of muscle relaxant were given as needed to maintain the TOF count at 1 or 2. At the conclusion of surgery, at a TOF count of 2, neostigmine 0.05 mg/kg plus glycopyrrolate 10 micro g/kg was administered. The mechanical TOF response was then measured with a force transducer starting 5 min postreversal. Patients were observed until a TOF ratio of 0.90 was achieved. There were no significant differences in the recovery profiles of cisatracurium versus rocuronium. TOF ratios at 10 min postreversal were 0.72 +/- 0.10 and 0.76 +/- 0.11, respectively. At 15 min postreversal, only one subject in each group had a TOF ratio of <0.70. No patient in either group arrived in the PACU with a TOF ratio <0.70. Our results suggest that if cisatracurium or rocuronium is administered by using the TOF count as a guide, critical episodes of postoperative weakness in the PACU should be an infrequent occurrence. IMPLICATIONS: After the administration of cisatracurium or rocuronium, train-of-four (TOF) ratios <0.70 should rarely be observed in the postanesthesia care unit if neostigmine-assisted antagonism of residual block is delayed until the tactile TOF count at the thumb is 2 or more.     

Manual evaluation of residual curarization using double burst stimulation: a comparison with train-of-four

Double burst stimulation (DBS) is a new mode of stimulation developed to reveal residual neuromuscular blockade under clinical conditions. The stimulus consists of two short bursts of 50 Hz tetanic stimulation, separated by 750 ms, and the response to the stimulation is two short muscle contractions. Fade in the response results from neuromuscular blockade as with train-of-four stimulation (TOF). The authors compared the sensitivity of DBS and TOF in the detection of residual neuromuscular blockade during clinical anaesthesia. Fifty-two healthy patients undergoing surgery were studied. For both stimulation patterns the frequencies of manually detectable fade in the response to stimulation were determined and compared at various electromechanically measured TOF ratios. A total of 369 fade evaluations for DBS and TOF were performed. Fade frequencies were statistically significantly higher with DBS than with TOF, regardless of the TOF ratio level. Absence of fade with TOF implied a 48% chance of considerable residual relaxation as compared with 9% when fade was absent with DBS. The results demonstrate that DBS is more sensitive than TOF in the manual detection of residual neuromuscular blockade.     

Residual Postoperative Paralysis: Pancuronium Versus Mivacurium, Does It Matter?

Background: Based on a train-of-four (TOF) ratio greater than 0.70 as the standard of acceptable clinical recovery, undetected postoperative residual paralysis occurs frequently in postanesthesia care units. In most published studies, detailed information regarding anesthetic management is not provided. The authors reexamined the incidence of postoperative weakness after the administration of long- and short-acting neuromuscular blockers because few, if any, such comparative studies are available.

Methods: Ninety-one adult patients were studied. In group 1 (mivacurium, n = 35), anesthesia was induced with propofol/fentanyl and maintained with nitrous oxide, desflurane, and opioid supplementation. The response of the adductor pollicis to ulnar nerve stimulation was estimated by palpating the thumb. Mivacurium (0.20 mg/kg) was administered for tracheal intubation, and an infusion was adjusted to maintain the TOF count at 1. When surgery was completed, the infusion was discontinued. When a second twitch could be detected, 7.0 micro gram/kg atropine and then 0.5 mg/kg edrophonium were administered. At 5 and 10 min, the mechanical TOF response was measured. Additional measurements were recorded if possible. Patients were tracheally extubated and discharged from the operating room when they could respond to verbal commands and no TOF fade was palpable. In group 2 (pancuronium-desflurane anesthesia, n = 29), the protocol was identical to that of group 1, except that 0.07 mg/kg pancuronium was administered for tracheal intubation. Additional increments (0.5 to 1 mg) were given as needed. Antagonism was accomplished with 0.05 mg/kg neostigmine and 0.01 mg/kg glycopyrrolate. In group 3 (pancuronium propofol-opioid, n = 27), the protocol was identical to that of group 2, except that anesthesia was maintained with nitrous oxide and a propofol-alfentanil infusion. In all groups, patients were assessed until a TOF ratio of 0.90 or more was achieved

Results: All of the patients in group 1 had TOF ratios greater than 0.80 on arrival in the postanesthesia care unit. Twenty of 35 patients had TOF ratios 0.90 or more while they were still in the operating room. Thirty-three of 35 patients had TOF ratios 0.90 or more within 30 min of reversal, and this value was reached in all patients by 45 min. Recovery parameters in groups 2 and 3 did not differ from each other. Hence data from these groups were pooled. Fifty-four of 56 patients who received pancuronium had TOF values of 0.70 or more, the remaining two patients had values of 0.6 to 0.7. In contrast to the mivacurium group, however, only four patients achieved a TOF ratio of 0.90 or greater while still in the operating room. Finally, eight of these patients did not achieve this degree of recovery within 90 min of reversal.     

Emergency use of sugammadex after failure of standard reversal drugs

Administration of sugammadex, 350 mg IV (4 mg/kg), in the postanesthesia care unit immediately (<60 s) relieved acute respiratory distress due to residual neuromuscular blockade in a 42-yr-old patient with chronic renal failure who had received vecuronium, 10 mg IV, for tracheal intubation, after inadequate reversal of neuromuscular blockade in the operating room with neostigmine, 5 mg IV, and glycopyrrolate, 1 mg IV.