Clinical Trials

The subjective experience of residual neuromuscular blockade after emergence from anesthesia has not been examined systematically during postanesthesia care unit (PACU) stays. The authors hypothesized that acceleromyography monitoring would diminish unpleasant symptoms of residual paresis during recovery from anesthesia by reducing the percentage of patients with train-of-four ratios less than 0.9. Read More on PubMed

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. Read More on PubMed

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. Read More on PubMed

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. Read More on PubMed

This systematic review describes the evidence on the use of acceleromyography for perioperative neuromuscular monitoring in clinical practice and research. The review documents that although acceleromyography is widely used in research, it cannot be used interchangeably with mechanomyography and electromyography for construction of dose-response curves or for recording different pharmacodynamic variables after injection of a neuromuscular blocking agent. Some studies indicate that it may be beneficial to use a preload to increase the precision of acceleromyography, and to "normalize" the train-of-four ratio to decrease the bias in relation to mechanomyography and electromyography. However, currently the evidence is insufficient to support the routine clinical use of preload and "normalization." In contrast, there is good evidence that acceleromyography improves detection of postoperative residual paralysis. A train-of-four ratio of 1.0 predicts with a high predictive value recovery of pulmonary and upper airway function from neuromuscular blockade. Read More on PubMed

At present in the UK there is no consensus regarding the parameters anaesthetists use to indicate adequacy of reversal from neuromuscular blockade. In an attempt to determine current practice, we carried out a survey covering 12 anaesthetic departments throughout the UK. Individuals were asked to give details regarding their usage of available monitors or, alternatively, to list those clinical parameters which they felt offered the best guidance as to the adequacy of recovery from neuromuscular blockade. There was no consensus among anaesthetists as to the most reliable clinical signs of recovery from neuromuscular blockade. There was an apparent lack of understanding of the limitations of some clinical signs used to determine recovery, as well as inappropriate application of others. In all departments where monitors (quantitative or qualitative) were available, there was limited knowledge regarding the current minimum recommended train-of-four ratio which should be observed prior to extubation. There is an apparent overall confusion among clinicians as to the best method to confirm recovery from neuromuscular blockade. This is probably due to the lack of a single reliable clinical test which can be applied in the immediate postoperative period. Insufficient reliance is placed upon the use of quantitative monitors. There is a lack of clarity in national anaesthetic guidelines with respect to monitoring of neuromuscular function. Current standards need to be re-assessed in the light of recent improvements in nerve stimulators. Read More on PubMed

The set of guidelines for good clinical research practice (GCRP) in pharmacodynamic studies of neuromuscular blocking agents, which was developed following an international consensus conference in Copenhagen, has been revised and updated following the second consensus conference in Stockholm in 2005. It is hoped that these guidelines will continue to help researchers in the field and assist the pharmaceutical industry and equipment manufacturers in enhancing the standards of the studies they sponsor. Read More on PubMed

To review established techniques and to provide an update on new methods for clinical monitoring of neuromuscular function relevant to anesthesia. Read More on PubMed

Postoperative residual paralysis is an important complication of the use of neuromuscular blocking drugs. In this prospective study, the incidence of residual paralysis detected as a train-of-four response <90% was less frequent in surgical outpatients (38%) than inpatients (47%) (P = 0.001). This might have been the result of the more frequent use of mivacurium for outpatients. Before undertaking tracheal extubation, the anesthesiologists had applied clinical criteria (outpatients, 49%; inpatients, 45%), pharmacological reversal (26%, 25%), neuromuscular transmission monitoring (12%, 11%), or a combination of these. None of these measures seemed to reduce the incidence of residual paralysis except for quantitative train-of-four monitoring. Postoperatively, eight individual clinical tests or a sum of these tests were also unable to predict residual paralysis by train-of-four. Although the incidence of residual paralysis was less frequent in surgical outpatients, predictive criteria were not evident. Read More on PubMed

We investigated postoperative residual curarization after administration of either vecuronium or rocuronium with reversal by pyridostigmine in 602 consecutive patients without perioperative neuromuscular monitoring. On arrival in the recovery room, neuromuscular function was assessed both by acceleromyography in a train-of-four (TOF) pattern and also clinically by the ability to sustain a head-lift for >5 s and the tongue-depressor test. Postoperative residual curarization was defined as a TOF ratio <0.7. One fifth of 602 patients (vecuronium, 24.7%; rocuronium, 14.7%) had a TOF <0.7 in the recovery room. There were no significant differences in the TOF ratios between 10 mg and 20 mg of pyridostigmine. The patients with residual block had several associated factors: the absence of perioperative neuromuscular monitoring, the use of pyridostigmine, which is less potent than neostigmine, a larger dose of vecuronium, shorter time from the last neuromuscular blocker to TOF monitoring, or peripheral cooling. We conclude that significant residual neuromuscular block after vecuronium or rocuronium was not eliminated even with reversal by a large dose of pyridostigmine. Read More on PubMed

Residual muscle paralysis after anesthesia is common after pancuronium, but less common following the intermediate-acting drugs vecuronium and atracurium. Therefore, many anesthetists do not monitor neuromuscular function when using an intermediate-acting agent. The purpose of this prospective, randomised and double-blind study was to establish the incidence and degree of postoperative residual block following the use of rocuronium in patients not monitored with a nerve stimulator, and to compare it with results obtained in patients monitored using acceleromyography (AMG). Read More on PubMed

After anaesthesia involving pancuronium a high incidence of both residual neuromuscular block and postoperative pulmonary complications (POPC) has been reported. The aim of this study was to compare the incidence of POPC following the use of pancuronium, atracurium, and vecuronium, and to examine the effect of residual neuromuscular block on the incidence of POPC. Read More on PubMed

The accuracy of visual and tactile assessment of the neuromuscular fade in response to train-of-four (TOF) and double-burst stimulation (DBS) were compared to assess their relative utility in the clinical setting. For each of 74 data sets with a mechanographic TOF ratio less than 0.70, an observer (blinded to the presence or degree of fade) performed visual and tactile assessments of fade in response to TOF, DBS3,3, and DBS3,2 stimuli at low current (20 and 30 mA) and high current (50 and 60 mA). For the range of mechanographic TOF ratios between 0.41 and 0.70, visual assessment failed to identify TOF, DBS3,3, and DBS3,2 fade in 46%, 18%, and 14% of cases at high current and in 23%, 5%, and 0% of cases at low current, respectively. Tactile assessments failed to identify fade in 55%, 23%, and 14% of cases at high current and in 23%, 14%, and 14% of cases at low current. Overall, the ability to detect fade was comparable for visual and tactile assessments regardless of the method of neurostimulation (P = NS with paired t-test). However, the degree of overestimation of the fade ratio (i.e., quantitative assessment) tended to be less when using tactile means; the difference achieved significance for TOF at low current and DBS3,3 at both low and high currents. We conclude that the differences between the visual and tactile means of assessment are relatively small compared to the differences among the TOF and DBS patterns of neurostimulation. Both subjective techniques are often inadequate in settings in which assurance of full recovery of neuromuscular function is critical. Read More on PubMed

The present study was undertaken to determine whether the discomfort associated with the sequential bursts of stimuli comprising the two recommended forms of double burst stimulation (DBS) is comparable to that associated with the repetitive stimuli of train-of-four (TOF). Twenty-one unmedicated volunteers rated on a visual analog scale the discomfort associated with randomly applied DBS and TOF stimulations at 20, 30 and 50 mA. All participants were blinded to the mode of stimulation, as well as to the current intensity. At each amperage tested, TOF produced significantly less discomfort than either form of DBS (P less than 0.01). Stimulation at 50 mA produced median visual analog scale scores of 7.5, 7.0, and 5.0 for DBS3,2, DBS3,3, and TOF, respectively. At 30 mA the corresponding median visual analog scale scores were 4.5, 5.5, and 3.0, whereas at 20 mA the scores were 4.0, 4.5, and 2.0, respectively. Thus, DBS is more uncomfortable than TOF at each current tested; however, in light of reports of its higher sensitivity, DBS may be the preferred means of assessing neuromuscular function in the awake as well as the anesthetized patient when a force transducer and recorder are not readily available. Read More on PubMed