Sugammadex, a selective reversal medication for preventing postoperative residual neuromuscular blockade

BACKGROUND

Sugammadex is the first selective relaxant binding agent that has been studied for reversal of neuromuscular blockade induced by rocuronium and other steroidal non-depolarizing neuromuscular blocking agents (NMBAs).

OBJECTIVES

To assess the efficacy and safety of sugammadex in reversing neuromuscular blockade induced by steroidal non-depolarizing NMBAs and in preventing postoperative residual neuromuscular blockade.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 3), MEDLINE (1950 to August 2008), and EMBASE (1980 to August 2008). In addition, we handsearched reference lists of relevant articles and meeting abstracts. Furthermore, we contacted the medication's manufacturer for more information.

SELECTION CRITERIA

All randomized controlled trials (RCTs) on adult patients (>/= 18 years old) in which sugammadex was compared with placebo or other medications, or in which different doses of sugammadex were compared with each other. We excluded non-randomized trials and studies on healthy volunteers.

DATA COLLECTION AND ANALYSIS

We independently performed determination of trial inclusion, quality assessment, and data extraction. We applied standard meta-analytic techniques.

MAIN RESULTS

We included18 RCTs (n = 1321 patients). Seven trials were published as full-text papers, and 11 trials only as meeting abstracts. All the included trials had adequate methods of randomization and allocation concealment. The results suggest that, compared with placebo or neostigmine, sugammadex can more rapidly reverse rocuronium-induced neuromuscular blockade regardless of the depth of the block. We identified 2, 4, and 16 mg/kg of sugammadex for reversal of rocuronium-induced neuromuscular blockade at T(2) reappearance , 1 to 2 post-tetanic counts, and 3 to 5 minutes after rocuronium, respectively. The number of trials are very limited regarding vecuronium and pancuronium. Serious adverse events occurred in < 1% of all patients who received the medication. There was no significant difference between sugammadex and placebo in terms of the prevalence of drug-related adverse events (RR 1.20, 95% CI 0.61 to 2.37; P = 0.59, I(2) = 0%, 5 RCTs). Also, no significant difference was found between sugammadex and neostigmine for adverse events (RR 0.98, 95% CI 0.48 to1.98; P = 0.95, I(2) = 43%, 3 RCTs).

AUTHORS' CONCLUSIONS

Sugammadex was shown to be effective in reversing rocuronium-induced neuromuscular blockade. This review has found no evidence of a difference in the instance of unwanted effects between sugammadex, placebo or neostigmine. These results need to be confirmed by future trials on larger patient populations and with more focus on patient-related outcomes.

An update on sugammadex sodium

Sugammadex sodium is the generic drug name for the novel modified gamma cyclodextrin that terminates neuromuscular blockade induced by aminosteroidal neuromuscular blocking agents. Published phase II and phase III clinical data support preclinical and clinical phase I study findings of fast, safe, and efficacious reversal of all levels of neuromuscular blockade induced by rocuronium and vecuronium. Low levels of neuromuscular blockade induced by pancuronium have also been successfully reversed by sugammadex. This agent does not reverse the bis-isoquinoline neuromuscular blocking agents. Special patient populations, including pediatric, elderly, cardiac, and renal-compromised subjects, have been studied in phase III. This update focuses on the most recent findings of phase II and III clinical studies.

[Reversal of neuromuscular blockade and complications of remaining blocking effect]

We Japanese anesthesiologists can now use rocuronium as well as vecuronium. Although the onset of rocuronium is more rapid, the non-depolarizing neuromuscular blocking (NMB) agent has similar characteristics of duration and recovery compared to vecuronium. Reversal of NMB is therefore essential to recover patients safely. Conventional standard of reversal of NMB [train of four (TOF) >0.7] is not enough to have sufficient vital capacity and inspiratory force, resulting in pulmonary regurgitation or atelectasis. Even though the reversal of NMB cannot sufficiently be completed by anti-cholinesterase (ChE) agents such as neostigmine, it is needed to reverse the NMB because of their late spontaneous recovery. We also have to take care of patients with neuromusclar diseases such as Duchenne-type muscle dystrophy, when we use anti-ChE agents. Sugammadex is a novel and unique compound designed as an antagonist of rocuronium and possibly other steroid NMB agents. Sugammadex exerts its effect by forming very tight water-soluble complexes at a 1 : 1 ratio with steroid NMB agents (rocuronium>vecuronium>>pancuronium). PhaseIII trials in Japan as well as Europe and the US have just been finished, and it is expected to be used clinically in the near future.

Is recovery of neuromuscular transmission complete after the use of neostigmine to antagonize block produced by rocuronium, vecuronium, atracurium and pancuronium?

To test if recovery of neuromuscular transmission is complete after the use of neostigmine under standardized conditions, we have measured adductor pollicis mechanical activity in response to 0.1 Hz (twitch height), train-of-four (TOF) and 100 Hz (RF 100 Hz) ulnar nerve stimulations. We studied 56 adult anaesthetized (thiopentone, fentanyl, nitrous oxide in oxygen) patients, allocated randomly to one of four groups (n = 14) to receive rocuronium (group Roc), vecuronium (group Vec), atracurium (group Atr) or pancuronium (group Pan). Recovery of neuromuscular transmission was studied for 15 min after neostigmine 40 micrograms kg-1 was given at 25% recovery of twitch height. Fifteen minutes after antagonism, the TOF ratio was 0.91 (SEM 0.01), 0.88 (0.02) and 0.92 (0.01) (ns), and RF 100 Hz was 0.78 (0.01), 0.79 (0.02) and 0.78 (0.01) (ns) respectively, in patients in groups Roc, Vec and Atr, respectively. In patients in group Pan, TOF ratio and RF 100 Hz were only 0.76 (0.01) and 0.33 (0.04) respectively (P < 0.01, one-way analysis of variance, Duncan's multiple classification range tests). In contrast with pancuronium, antagonism of rocuronium-, vecuronium- and atracurium-induced neuromuscular blocks produced a similar high degree of recovery of neuromuscular transmission.

Perioperative train-of-four monitoring and residual curarization

It has been suggested that perioperative train-of-four (TOF) monitoring does not reduce the incidence of postoperative residual curarization (PORC). The purpose of this study was to examine whether the use of tactile assessment of the response of the adductor pollicis to supramaximal TOF stimulation of the ulnar nerve at the wrist during anaesthesia affected the incidence of PORC. Thirty-nine ASA I or II surgical patients were studied during thiopentone/fentanyl N2O/enflurane anaesthesia. Pancuronium (70-100 micrograms.kg-1) was used to facilitate tracheal intubation and additional pancuronium increments used to maintain surgical relaxation. The requirement for incremental doses of pancuronium and adequacy of recovery following reversal were assessed according to random allocation, either with (Group A; n = 20) or without (Group B; n = 19) access to TOF monitoring. Patients in the two groups received neostigmine in similar doses (Group A: 53 micrograms.kg-1 (5.9); Group B: 55 micrograms.kg-1 (5.4)). On arrival of the patient to the recovery area, neuromuscular function was assessed electromyographically (using the Datex NMT 221 to measure TOF ratio) and clinically. The incidence of PORC (TOF ratio < 70%) was greater in Group B (47%) than in Group A (15%) (P = 0.029). We conclude that the use of perioperative TOF monitoring decreases the incidence of pancuronium-induced PORC.

Antagonism of pancuronium- and pipecuronium-induced neuromuscular block

We have compared the antagonism of neuromuscular block produced by pipecuronium with pancuronium in 80 anaesthetized surgical patients using mechanomyography and electromyography. Pancuronium 0.1 mg kg-1 or pipecuronium 0.07 mg kg-1 was given after induction of anaesthesia and neuromuscular block was adjusted to 75% twitch depression at the time of antagonism. The following regimens were used: edrophonium 0.5 and 1.0 mg kg-1, neostigmine 0.04 mg kg-1, pyridostigmine 0.3 mg kg-1 and edrophonium 0.25 mg kg-1 with pyridostigmine 0.15 mg kg-1. Antagonism was evaluated also by the head lift test. There was no difference between the reversibility of neuromuscular block produced by pancuronium or pipecuronium. Edrophonium produced a significantly faster antagonism than neostigmine or pyridostigmine but onset of action was not significantly faster than that of edrophonium with pyridostigmine. All regimens produced 100% (or near 100%) antagonism of twitch response within 15 min. However, TOF fade antagonism was more complete with pyridostigmine, neostigmine and edrophonium 1.0 mg kg-1 than with edrophonium 0.5 mg kg-1. The head lift test indicated somewhat less antagonism with edrophonium 0.5 and 1.0 mg kg-1. Using five monitoring methods, the rank order of reversal potency was: pyridostigmine approximately neostigmine > edrophonium 1.0 mg kg-1 > edrophonium+pyridostigmine > edrophonium 0.5 mg kg-1.

Train-of-four recovery after pharmacologic antagonism of pancuronium-, pipecuronium-, and doxacurium-induced neuromuscular block in anaesthetized humans

Previous studies have suggested that the increased duration of action of long-acting neuromuscular relaxants may make their pharmacologic antagonism more difficult and, thus, increase the likelihood of residual block. This hypothesis was tested in healthy, adult humans who received a background of isoflurane/N2O/fentanyl anaesthesia. Study subjects were paralyzed with either pancuronium (N = 8), pipecuronium (N = 8), or the longer-acting relaxant, doxacurium (N = 8). Neuromuscular function was monitored, and, using a blinded, randomized study design, the relaxants were titrated to identify the ED95 dose in each patient. Thereafter, spontaneous recovery was observed until there was 25% of baseline response to the first supramaximal twitch (T1) in a train-of-four (TOF). At this time, the block was antagonized with neostigmine 0.07 mg/kg and glycopyrrolate 0.014 mg/kg i.v., and recovery of TOF was recorded. Spontaneous recovery to 25% of the baseline T1 response occurred at 52 +/- 14 min (mean +/- SD) following administration of either pancuronium and pipecuronium, and 85 +/- 33 min following doxacurium (P < 0.05 for doxacurium versus pancuronium and pipecuronium). In doxacurium-treated patients, reversal of block with neostigmine was less predictable and less complete than with the other two relaxants. For example, the ratio of the fourth to first twitch (T4/T1) of the TOF at 10 and 15 min after reversal was significantly less with doxacurium (59 +/- 14% and 61 +/- 16%, respectively) than with either pancuronium (75 +/- 6% and 75 +/- 10%) or pipecuronium (76 +/- 9% for both).(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of doxacurium and pancuronium neuromuscular blockade with neostigmine in children

Recovery after doxacurium and pancuronium neuromuscular blockade and their acceleration by neostigmine have not been compared in children. Therefore, 60 paediatric surgical patients aged 2-10 yr (ASA 1-2) were studied. They were randomized to receive doxacurium 30 micrograms.kg-1 or pancuronium 70 micrograms.kg-1 iv during propofol, fentanyl, isoflurane and nitrous oxide anaesthesia. Electromyographic (EMG) responses of the adductor pollicis to train-of-four (TOF) stimulation of the ulnar nerve were recorded every ten seconds using a Datex NMT monitor. Six patients in each relaxant group received neostigmine (0, 5, 10, 20 or 40 micrograms.kg-1) with atropine by random allocation when first twitch height (T1) had recovered to 25% of control. Spontaneous recovery after ten minutes was similar following doxacurium (mean +/- SEM values of 45.0 +/- 3.9 vs 49.5 +/- 10.0% for T1 and 25.2 +/- 3.8 vs 14.8 +/- 3.6% for TOF ratios). Dose-responses to neostigmine were calculated from the log dose vs logit of T1 or TOF ratio after ten minutes. Neostigmine-assisted recovery was not different in the two groups, with ED70 and ED90 doses for T1 of 14.3 +/- 1.8 and 25.7 +/- 2.7 micrograms.kg-1 for doxacurium and 12.5 +/- 1.7 and 25.3 +/- 2.3 micrograms.kg-1 for pancuronium. Time to recovery of TOF ratio to 70% after neostigmine 40 micrograms.kg-1 was 2.3 +/- 1.0 and 4.2 +/- 1.7 min (P = NS) following pancuronium and doxacurium, respectively. Adjusted recovery due to neostigmine alone (spontaneous recovery subtracted from the total) required two to three times higher doses of neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

[Antagonism to neuromuscular effect of subcutaneous administration of pancuronium by neostigmine]

It has been reported that subcutaneous administration of pancuronium produces prolonged neuromuscular blockade. The purpose of this study was to evaluate the antagonistic effect of neostigmine on neuromuscular blockade following subcutaneous injection of pancuronium in anesthetized patients. Fourteen male patients aged 32-67 yr, weighing 50-58 kg, and scheduled for surgical operation lasting more than 6 hr were included in the study. None of the patients had paresis. Anesthesia was induced with thiamylal and SCC. Patients under N2O-oxygen-enflurane (1.0-1.5%) anesthesia, were divided into two groups (n = 7 in each group). Group A was given an intravenous bolus of pancuronium 6 mg. Group B received pancuronium 6 mg subcutaneously in the ankle. Train-of-four responses were evaluated every 12s by measuring the force of thumb adduction produced in response to supramaximal stimulation of the ulnar nerve at the wrist. When the train-of-four ratios recovered to approximately 0.2 in groups A and B, a mixture of neostigmine 1.0 mg and atropine 0.5 mg was administered. The onset of fade in train-of-four responses was significantly more rapid in group A (intravenous administration) than in group B (subcutaneous administration). Time intervals to maximum train-of-four depression from pancuronium administration in groups A and B averaged 2.6 and 125.4 min, respectively. No significant differences in the recovery times of the train-of-four ratios from 0.2 to 0.7 following neostigmine administration in groups A and B were demonstrated. None of the patients who received pancuronium subcutaneously showed recurarization following neostigmine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Recovery of neuromuscular function after atracurium and pancuronium maintenance of pancuronium block

The study was undertaken to determine whether a neuromuscular blockade induced with pancuronium but maintained with atracurium was associated with a shorter time to complete recovery after administration of neostigmine than if the blockade was maintained with pancuronium alone. Anaesthesia consisted of thiopentone, N2O/O2/enflurane and fentanyl, and the neuromuscular blockade, induced by pancuronium 0.1 mg.kg-1 was monitored by the force of contraction of adductor pollicis during major abdominal surgery lasting 2-5 hr. In 24 patients--Group 1--atracurium 0.07 mg.kg-1 was repeated when the first twitch of the train-of-four (TOF) returned to 25% of control (T1/TC 25). In 28 patients--Group 2--pancuronium 0.015 mg.kg-1 was given at similar recovery of T1/TC. At the end of surgery, neostigmine 0.07 mg.kg-1 and glycopyrolate 0.015 mg.kg-1 were given to reverse the residual neuromuscular blockade which was indicated by a T1/TC of less than 25% in all patients. The time from injection of the reversal drugs to a TOF ratio of 70% was similar in both groups (Group 1, 11.6 +/- 7.6 min; Group 2, 10.1 +/- 6 min; P = NS), but the recovery index was smaller in Group 2 (Group 1, 4 +/- 2.6 min; Group 2, 2.61 +/- 1.2 min; P < 0.05). Furthermore, there was no difference between groups in the duration of action of each redose. The study showed that when compared with pancuronium, equipotent doses of atracurium were not associated with (a) a shorter time to complete recovery from a neuromuscular blockade induced with pancuronium or (b) a shorter duration of action.

Prolonged paralysis after long-term, high-dose infusion of pancuronium in anaesthetized cats

We have studied the neuromuscular effects of a 48-h infusion of high-dose pancuronium (400 micrograms kg-1 h-1) in four cats anaesthetized with pentobarbitone, using contraction of tibialis anterior muscles after direct and indirect stimulation. After cessation of the pancuronium infusion, prolonged paralysis existed. The first twitch in the train-of-four stimuli (TOF) reappeared 8-12 h after termination of the pancuronium infusion. Twenty-four hours after termination of the infusion, TOF ratios were less than 0.08 and twitch contraction averaged 39 (SE 8)% of initial values. Twitch contraction after direct stimulation did not differ from initial values. Antagonism of paralysis was accomplished with neostigmine 60 micrograms kg-1 in two animals and neostigmine 90 micrograms kg-1 and 4-aminopyridine 500 micrograms kg-1 in the others. Steady-state plasma concentration of pancuronium (2000 ng ml-1) decreased rapidly after termination of the infusion, but then stabilized at about 130 ng ml-1. These results indicate that prolonged paralysis after long-term administration of high-dose pancuronium is caused primarily by failure of neuromuscular transmission, most likely caused by the persistent plasma concentrations of the drug in the pharmacologically active range.

Atracurium after an anticholinesterase. Does prior reversal with edrophonium or neostigmine influence the response to atracurium?

This study documents the response to atracurium (75 micrograms.kg-1) administered 30 min after a pancuronium- or tubocurarine-induced neuromuscular block has been reversed with either neostigmine (50 micrograms.kg-1) or edrophonium (0.5 mg.kg-1). Twenty-one ASA 1 or 2 patients were studied, of whom 11 received neostigmine and 10 edrophonium. The degree of neuromuscular block was measured electromyographically from the first dorsal interosseous muscle of the hand using train-of-four stimulation of the ulnar nerve. When atracrium was administered, the single twitch response compared with control was 100% in all patients and the mean train-of-four ratios were 91% and 65% in the neostigmine and edrophonium groups respectively. After atracurium (75 micrograms.kg-1), minimum values for the single twitch response compared with control were 52% and 66% in the neostigmine and edrophonium groups respectively. Prior administration of atracurium appears to potentiate the neuromuscular blocking effects of atracurium administered 30 min later.

Reversal by suramin of neuromuscular block produced by pancuronium in the anaesthetized rat

1. Rats were anaesthetized with sodium pentobarbitone and maximal twitches of a tibialis anterior muscle were evoked by stimulation of the motor nerve. 2. Suramin, injected intravenously in a series of cumulative bolus doses, each 15 mg kg-1, completely reversed a 90% depression of twitches maintained by a continuous intravenous infusion of pancuronium. The cumulated dose necessary to restore twitches to 50% of their control amplitude was 35 mg kg-1. Suramin did not modify a similar degree of block produced by suxamethonium, nor did it affect the amplitude of control maximal twitches, even in cumulative doses up to 150 mg kg-1. 3. The effects of bolus doses of suramin (85 mg kg-1), neostigmine (0.03 mg kg-1) and 4-aminopyridine (1.2 mg kg-1), calculated to restore pancuronium-blocked twitches to 95% of control amplitude, were compared. Suramin produced the most rapid reversal (1.1 +/- 0.5 min), but its duration of action was the shortest (9.4 +/- 1.6 min). Suramin was without effect on heart rate or blood pressure in the doses used. 4. The results showed that suramin reversed neuromuscular block produced by nondepolarizing blocking drug, pancuronium, but was without effect on a block produced by the depolarizing blocking drug, suxamethonium. Its short duration of action suggests that suramin would probably not be of value clinically as a reversal agent. However, it is possible that it might serve as a starter compound for the synthesis and development of a new class of reversal agents for use in anaesthetic practice.

Neostigmine and edrophonium antagonism of moderate neuromuscular block induced by pancuronium or tubocurarine

Edrophonium and neostigmine are anticholinesterase drugs used commonly to antagonize competitive neuromuscular block. Although it has a faster onset of action than neostigmine, edrophonium is unreliable when used to antagonize deep neuromuscular block. We have compared the antagonist characteristics of these two drugs when used to antagonize a moderate degree of pancuronium- or tubocurarine-induced neuromuscular block. Forty ASA I or II patients undergoing surgical procedures were allocated randomly to receive either pancuronium 70 micrograms kg-1 or tubocurarine 0.5 mg kg-1, and to receive either edrophonium 0.5 mg kg-1 or neostigmine 0.05 mg kg-1. Antagonism was attempted when the first response to train-of-four (TOF) stimulation recovered spontaneously to 25% of the control height. Neuromuscular function was monitored using the evoked integrated electromyogram of the first dorsal interosseous muscle of the hand. Adequate recovery was defined as the achievement of a TOF ratio of 0.70 or greater. Only seven of 20 patients who received edrophonium demonstrated adequate recovery 30 min after antagonism. Under the conditions described in this study, edrophonium 0.5 mg kg-1 was less effective as an antagonist than neostigmine 0.05 mg kg-1.

Continuous infusions of atracurium and vecuronium, compared with intermittent boluses of pancuronium: dose requirements and reversal

This study was designed to determine the effect of prolonged infusion on the ease of reversal of atracurium and vecuronium, and whether factors which potentiate the block delayed reversal. In phase one, 40 patients were randomized (double blind) to determine the steady state conditions for atracurium and vecuronium. Fourteen atracurium patients and 17 vecuronium patients were evaluable. The unblinded second phase involved the steady state conditions using halothane or isoflurane and atracurium infusions. The infusion required for 95% twitch depression (TD95) for atracurium was 7.6 +/- 1.1 micrograms.kg-1 x min-1. The requirement for vecuronium changes with time: TD95 at 30 min was 1.01 +/- 0.16, at 60 min 0.89 +/- 0.12 and after 90 min 0.85 +/- 0.17 micrograms.kg-1 x min-1 (P < 0.05). The mean TD95 was 0.94 +/- 0.23 micrograms.kg-1 x min-1. Multivariate regression analysis of the infusion data revealed a vecuronium model predicting TD95 by the duration of infusion (P < 0.05) and weight (P = 0.05). Atracurium TD95 was predicted by age (P = 0.05). The addition of an inhalation agent to atracurium reduced the infusion rate by 2.01 +/- 0.28 micrograms.kg-1 x min-1 (P = 0.0001) for each increase in MAC. The mean reversal times for atracurium with three different anaesthetics and for vecuronium were not different. Reversal of pancuronium blockade, from less profound twitch depression (86.4 vs 95%) took twice as long as for atracurium and vecuronium for which the following predictors were identified: age, weight, duration of infusion, level of blockade, and type of anaesthetic, using a stepwise regression model.(ABSTRACT TRUNCATED AT 250 WORDS)

Method of intraoperative monitoring of neuromuscular function and residual blockade in the recovery room

We evaluated the method used intraoperatively to assess the degree of neuromuscular blockade prior to pharmacologic reversal to determine its role in preventing residual blockade in the postanesthesia care unit (PACU). We studied 38 patients who received a nondepolarizing muscle relaxant during general anesthesia for carotid endarterectomy or thoracotomy. The anesthesiologist assessed the degree of neuromuscular blockade intraoperatively prior to pharmacologic reversal either by the standard method of visually counting the number of evoked thumb twitches elicited by supramaximal train-of-four stimulation of the ulnar nerve (i.e., thumb train-of-four count), or by an alternative method such as 1) visually counting the number of evoked orbicularis oculi muscle twitches elicited by supramaximal train-of-four stimulation of the facial nerve, or 2) observing the patient for clinical evidence of partial recovery (e.g., swallowing or attempts to breathe). Residual blockade in the PACU was defined as 1) a train-of-four ratio less than 0.70 (measured by a mechanomyograph), or 2) the inability of the patient to perform clinical tests of neuromuscular function (e.g., a sustained head lift for 5 seconds) and evidence of neuromuscular weakness that was resolved following administration of edrophonium. Five of the 22 patients (23%) in whom one of the alternative methods was used had residual blockade in the PACU; none of the 16 patients with a thumb train-of-four count of 3 or 4 before pharmacologic reversal of NMB had residual blockade in the PACU (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of neostigmine and edrophonium on human erythrocyte acetylcholinesterase activity

Erythrocyte acetylcholinesterase (AChE) activities in vivo were measured over 60 min using a spectrophotometric method after administration of neostigmine or edrophonium for antagonism of pancuronium-induced neuromuscular block in 31 patients. Erythrocyte AChE activities decreased to 11.3 (SD 1.2)% and 11.4 (0.8)% of baseline values (P less than 0.001) within 2 min, then recovered slowly and were 43.2 (6.2)% and 27.9 (2.9)% (P less than 0.001) 60 min after administration of neostigmine 0.036 mg kg-1 and 0.071 mg kg-1, respectively. However, the enzyme activity after edrophonium 1.43 mg kg-1 did not change significantly over 60 min. The results suggest that mechanisms other than AChE inhibition may be responsible for the anti-curare effect of edrophonium.

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.

[Conversion to 2nd degree from 1st degree atrioventricular (AV) block by the reversal of neuromuscular blockade]

A case of intraoperative conversion to 2nd degree from 1st degree AV block by the reversal of neuromuscular blockade was reported. A 78 year old male, who originally suffered from 1st degree AV block, underwent choledocholithotomy and T-tube drainage for choledocholithiasis. He was administered 4 mg of pancuronium at the time of intubation. The operation lasted for 160 minutes under epidural anesthesia, NLA and nitrous oxide-oxygen. The patient started spontaneous breathing and the recovery was confirmed after the operation which finished without any problem. Neuromuscular blockade was reversed with atropine 0.5 mg and neostigmine 1.0 mg that were administered simultaneously taking 3 minutes. Then he was extubated without any troublesome stimulation. Suddenly, however, he suffered from the worse condition of bradycardia with the 2nd degree AV block. It took about 45 minutes until he recovered to the original 1st degree AV block despite atropine treatment. We believe that this accident was induced by a vasovagal reflex which was triggered by extubation under the effect of neostigmine which acts longer than that of atropine. We should be careful in reversing the effect of the non-depolarizing neuromuscular blockade. A short acting neuromuscular blockade, i.e. vecuronium, is preferable so as to avoid neostigmine reversal, and extubation should be performed when the effect of neuromuscular blockade is confirmed to be exhausted.

Reversal of profound paralysis: use of large doses of edrophonium to antagonize vecuronium and pancuronium induced neuromuscular blockade

The ability to evoke reversal of dense vecuronium- and pancuronium-induced paralysis (T1 10% of control) with edrophonium 1.0 mg.kg-1 was studied using train-of-four nerve stimulation and electromyographic monitoring. Two different end-points, train-of-four ratios of 0.5 and 0.7, were used to define "adequate reversal", and the results for both relaxants were compared. Reversal was reliable and rapid for vecuronium if either ratio was used with times of 2.8 (1.5) and 9 (3) min required to achieve ratios of 0.5 and 0.7, respectively. However, if the block was due to pancuronium, reversal was unreliable with 2 of 9 and 4 of 9 patients not achieving ratios of 0.5 and 0.7, respectively. Reversal was also markedly prolonged in this group with a mean time of 37 (23) min to achieve a ratio of 0.7, and in almost half these patients a supplementary dose of edrophonium was required.

Atropine-neostigmine mixture: a dose-response study

The dose-response relationship and the doses of atropine required to prevent neostigmine from lowering heart rates below baseline in 50 per cent (ED50) and 95 percent (ED95) of patients after antagonism of pancuronium-induced neuromuscular blockade were determined in 70 patients with neostigmine-atropine mixtures. Neostigmine 0.04 mg.kg-1 (group A, n = 35) or 0.06 mg.kg-1 (group B, n = 35) was randomly mixed with one of seven doses of atropine (ranging from 0.014 to 0.04 mg.kg-1) in group A and from 0.02 to 0.04 mg.kg-1 in group B), with dose-response curves for atropine being constructed for both groups 5 and 10 min after injection of the mixture. These dose-response curves were found to be parallel in both groups. The calculated ED50 and ED95 values of atropine were similar in both groups. The estimated ED50 doses of atropine in groups A and B at 5 min were 0.031 and 0.033 mg.kg-1 respectively, and at 10 min the ED50 doses were 0.037 and 0.037 mg.kg-1 respectively. The calculated ED95 doses of atropine in groups A and B at 5 min were 0.05 and 0.046 mg.kg-1, and at 10 min the ED95 doses were also similar, being 0.06 and 0.055 mg.kg-1 respectively. Under the conditions employed in this study it would seem that in order to prevent late reductions in heart rates, the appropriate doses of atropine when used with neostigmine should be greater than that commonly used.

Phenytoin-induced resistance to pancuronium. Use of atracurium infusion in management of a neurosurgical patient

A case report is presented of a patient receiving chronic phenytoin therapy who demonstrated resistance to pancuronium by increased hourly requirements. Stable neuromuscular blockade was achieved by atracurium infusion at normal rates. Possible explanations for the differences in response to the two non-depolarizing muscle relaxants are discussed.

Neostigmine and edrophonium as antagonists of atracurium and pancuronium

Edrophonium 0.5 mg/kg or neostigmine 0.04 mg/kg were administered to two groups of 30 patients each for antagonism of atracurium- or pancuronium-induced neuromuscular block at 25% single twitch recovery. Neuromuscular block was studied using both single twitch and train-of-four (TOF) nerve stimulation. The times to 100% single twitch recovery were significantly more rapid for patients receiving edrophonium (P less than 0.01) in both groups (atracurium and pancuronium); the TOF ratios were similar for atracurium, but for pancuronium they were greater after neostigmine than after edrophonium, and only at 25 min were these ratios similar. It is concluded that edrophonium in a dose of 0.5 mg/kg antagonizes neuromuscular blockade induced by atracurium, as does neostigmine in a dose of 0.04 mg/kg, but the former does not consistently antagonize neuromuscular blockade induced by pancuronium even at 25% of single twitch recovery.

Atropine-edrophonium mixture: a dose-response study

The dose-response and the doses required to prevent bradycardia in 50% (ED50) and 95% (ED95) of patients were determined for atropine after antagonism of pancuronium-induced neuromuscular blockade in 72 patients with edrophonium-atropine mixtures. Edrophonium 0.67 mg/kg (group A, n = 37) or 1.0 mg/kg (group B, n = 35) was randomly mixed with one of seven doses of atropine (ranging from 0.0125 to 0.0215 mg/kg in group A and from 0.02 to 0.04 mg/kg in group B); with dose-response curves for atropine being constructed for both groups 5 and 10 minutes after the injection of the mixture. These dose-response curves were found to be parallel in both groups. The calculated ED50 values of atropine were 1.6-2 times greater in group B, compared with those in group A. The estimated ED50 doses of atropine in groups A and B at 5 minutes were 0.018 and 0.029 mg/kg, respectively, and at 10 minutes, the ED50 doses were similar, being 0.016 and 0.032 mg/kg, respectively. The calculated ED95 doses of atropine in groups A and B at 5 minutes were 0.024 and 0.055 mg/kg, and at 10 minutes, the ED95 doses were also similar, being 0.027 and 0.05 mg/kg, respectively.

Reversal of pancuronium. Neuromuscular and cardiovascular effects of a mixture of neostigmine and glycopyrronium

Moderate to deep (67-99% single twitch depression) pancuronium-induced neuromuscular blockade was antagonised with neostigmine (30 micrograms/kg, 60 micrograms/kg, or 80 micrograms/kg) in combination with glycopyrronium. Twenty-seven patients were reversed from 91%-99% twitch depression. Recovery of the first twitch of a train-of-four to 95% of control twitch took at least 20 minutes with neostigmine 30 micrograms/kg. The higher doses were significantly faster (60 micrograms/kg p less than 0.05, 80 micrograms/kg p less than 0.01) and took 15.8 and 14.8 minutes respectively. Reversal to a train of four ratio of 0.75 was not consistently achieved in under 30 minutes with any dose of neostigmine. Nineteen patients were antagonised from a 67%-80% depression of first twitch and in all but two recovery to 95% of control took under 10 minutes. To achieve a train of four ratio of 0.75 took less than 12.5 minutes except in three patients, two of whom, both given neostigmine 30 micrograms/kg, took longer than 20 minutes. Neostigmine 60 micrograms/kg produced as rapid a degree of antagonism as 80 micrograms/kg. Heart rates after reversal decreased gradually in all groups, although the decrease was initially greater in the low dose neostigmine (30 micrograms/kg) group. A fixed 5:1 ratio of neostigmine and glycopyrronium will usually antagonise a moderate (70%-80%) pancuronium block to a train of four of greater than 75% within 12.5 minutes if at least 60 micrograms/kg of neostigmine is administered. More than 30 minutes may be required for reversal whatever the dose of neostigmine, for antagonism from greater than 90% twitch depression.

Postanaesthetic arousal time in elderly patients. A double-blind study of glycopyrrolate and atropine

Postanaesthetic arousal time was studied in elderly patients given either glycopyrrolate 0.01 mg kg-1 or atropine 0.02 mg kg-1 before antagonism of neuromuscular blockade. Forty patients (age greater than or equal to 65 yr) undergoing elective hip replacement were included in a double-blind study. Arousal was scored for 2 h after recovery using a modified scoring system. No difference in arousal time was found between the two groups.

Halogenated vapor anesthetics adversely influence edrophonium reversal

Reversal of the pancuronium induced neuromuscular block by edrophonium was studied in different groups of male surgical patients. All groups received similar premedication and identical induction of anesthesia. Neuromuscular function was monitored by the transduced response of the thumb adductor muscle to different [e.g. 0.2, 2 and 50 counts per second (cps)] supramaximal electrical stimuli applied to the ulnar nerve. When the regimen of anesthesia maintenance included halogenated vapor anesthetics the reversal of neuromuscular block was of lesser degree than in the case of N2O/O2 + fentanyl anesthesia. The reversal of the "fade-type" (e.g. tetanic and "train of four") responses was particularly incomplete with halothane and isoflurane. Compared with edrophonium, pyridostigmine was found to be more effective under halothane anesthesia. Based on these results, edrophonium may not be the first choice in the clinical reversal of deep levels of nondepolarizing neuromuscular block in the presence of vapor anesthetics.

Prolonged bradycardia and hypotension after neostigmine administration in a patient receiving atenolol

A 78-year-old woman admitted for an elective hip operation was maintained on atenolol for control of her hypertension. She received neostigmine and atropine for reversal of muscle relaxation at the end of general anaesthesia. She then developed prolonged bradycardia and hypotension which necessitated the use of adrenaline and isoprenaline. Such an adverse reaction with atenolol has not been described previously.

Neostigmine, pyridostigmine and edrophonium as antagonists of deep pancuronium blockade

To compare the ability of equipotent doses of neostigmine, pyridostigmine and edrophonium to antagonize intense pancuronium neuromuscular blockade, one hundred and twenty ASA physical status I or II patients scheduled for elective surgery received 0.06 mg.kg-1 pancuronium during a thiopentone nitrous oxide-enflurane anaesthetic. Train-of-four stimulation was applied every 12 s and the force of contraction of the adductor pollicis muscle was recorded. In the first 60 patients, spontaneous recovery was allowed until ten per cent of initial first twitch height. Then neostigmine (0.005, 0.01, 0.02 or 0.05 mg.kg-1), pyridostigmine (0.02, 0.04, 0.1 or 0.2 mg.kg-1), or edrophonium (0.1, 0.2, 0.4 or 1 mg.kg-1) was injected by random allocation. Dose-response relationships were established from the measurement of first twitch height (T1) ten minutes later. From these, neostigmine, 0.04 and 0.08 mg.kg-1 was found to be equipotent to pyridostigmine, 0.2 and 0.38 mg.kg-1, and edrophonium, 0.54 and 1.15 mg.kg-1, respectively. These doses were given by random allocation to the next 60 patients, but at one per cent spontaneous recovery. Neostigmine, 0.04 mg.kg-1, produced a T1 of 73 +/- 4 per cent (mean +/- SEM), and a train-of-four ratio (TOF) of 39 +/- 3 per cent. This was significantly greater than with pyridostigmine, 0.2 mg.kg-1 (T1 = 50 +/- 6 per cent; TOF = 25 +/- 3 per cent), and edrophonium, 0.54 mg.kg-1 (T1 = 54 +/- 3 per cent; TOF = 17 +/- 2 per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Antagonism of pancuronium and tubocurarine blocks by edrophonium or neostigmine: a comparative study

Edrophonium 0.5 and neostigmine 0.05 mg kg-1 were compared as antagonists of pancuronium and tubocurarine-induced neuromuscular blocks, at varying degrees of recovery, in groups of 20 patients each. Adequate antagonism was defined as attaining a sustained train-of-four (TOF) ratio of 0.7 or more. Administration of edrophonium was associated with a more rapid onset of action (17 s with both relaxants with edrophonium, and 31 s and 29 s with neostigmine with pancuronium and tubocurarine, respectively), and a shorter time to attain a TOF ratio of 0.7 (74 s and 48 s with edrophonium and 230 s and 293 s with neostigmine for pancuronium and tubocurarine blocks, respectively). However, whereas neostigmine administration provided adequate antagonism in all 20 patients given pancuronium and in 19 out of 20 patients given tubocurarine, edrophonium failed to achieve adequate antagonism in six patients after pancuronium and eight patients after tubocurarine. The majority of these patients had shown three or less responses to a TOF stimulation prior to antagonism. Two separate groups of 10 patients each with relatively deeper pancuronium or tubocurarine blocks (three or less responses to TOF stimulation) were given edrophonium in a dose of 1.0 mg kg-1. However, adequate antagonism even with this dose of edrophonium was attained in only two out of 10 patients given pancuronium and in five out of 10 patients given tubocurarine. It is concluded that edrophonium is unreliable for antagonism of relatively deep blocks by pancuronium or tubocurarine and that neostigmine is the preferred and more reliable antagonist.

Incomplete reversal of pancuronium neuromuscular blockade by neostigmine, pyridostigmine, and edrophonium

Three clinically used anticholinesterases--neostigmine, pyridostigmine, and edrophonium--were tested for their ability to reverse two levels (60% and 95%) of neuromuscular blockade produced by pancuronium. A controlled in vitro environment of the rat diaphragm-phrenic nerve system was used for the studies. Concentrations of anticholinesterases spanned the clinical range and were extended beyond to establish dose-response curves. Neostigmine was the most potent reversal drug (ED50 for 95% block 5.5 +/- 4 nM), followed by pyridostigmine (0.27 +/- 0.06 microM) and edrophonium (2.1 +/- 0.05 microM). The three drugs were equally effective at reversal of block and fade as measured by train-of-four stimulation. The dose-response curves for all three drugs showed a ceiling effect for reversal of tension and fade. Supraclinical concentrations of drug did not effect complete reversal, especially at 95% block. High concentrations of anticholinesterase led to randomly appearing hyperactivity manifested by spontaneous twitching and repetitive firing with severe fade on stimulation.

Dose-response curves for edrophonium, neostigmine, and pyridostigmine after pancuronium and d-tubocurarine

To determine the potencies of neostigmine, pyridostigmine, and edrophonium in reversing pancuronium and d-tubocurarine blockade, dose-response curves were established for first twitch height recovery and train-of-four ratio. One hundred and twenty ASA physical status I or II patients scheduled for elective surgery received either 0.06 mg/kg pancuronium or 0.36 mg/kg d-tubocurarine during a thiopental-nitrous oxide-enflurane anesthetic. Train-of-four stimulation was applied every 12 s, and the force of contraction of the adductor pollicis muscle was recorded. When first twitch height had recovered spontaneously to 10% of its initial value, neostigmine (0.005, 0.01, 0.02 or 0.05 mg/kg), pyridostigmine (0.02, 0.04, 0.1, or 0.2 mg/kg), or edrophonium (0.1, 0.2, 0.4 or 1 mg/kg) was injected by random allocation. Recovery was measured 10 min after the injection of the antagonist. First twitch ED50's were 0.013, 0.085, and 0.17 mg/kg after pancuronium, and 0.017, 0.11, and 0.27 mg/kg after d-tubocurarine, for neostigmine, pyridostigmine, and edrophonium, respectively. The ED50 for pyridostigmine and edrophonium obtained after d-tubocurarine was significantly larger (P less than 0.05) than that after pancuronium. The train-of-four dose-response curves were significantly flatter for edrophonium than for the other two agents, indicating a greater ability of edrophonium to antagonize fade at low doses. It is concluded that the potency of reversal agents may be different for different relaxants, and that potency ratios might depend upon the end-point chosen as full neuromuscular recovery.

Recovery times following edrophonium and neostigmine reversal of pancuronium, atracurium, and vecuronium steady-state infusions

The ability of edrophonium and neostigmine to antagonize nondepolarizing neuromuscular blockade produced by steady-state infusions of atracurium, pancuronium, and vecuronium was studied in 71 adult patients anesthetized with nitrous oxide and halothane. Infusion rates of blocking drugs were adjusted so that single twitch depression as measured by the evoked integrated EMG of the hypothenar muscles was kept at 10% of control. Two minutes after the termination of the infusion either edrophonium (0.75 mg/kg) or neostigmine (0.05 mg/kg) was administered. Single twitch depression and train-of-four (T4/T1) fade was recorded during the recovery period. T4/T1 fade ratios observed at 20 min postreversal were 0.80 (atracurium-edrophonium); 0.76 (vecuronium-edrophonium); 0.44 (pancuronium-edrophonium); 0.95 (atracurium-neostigmine); 0.89 (vecuronium-neostigmine); and 0.68 (pancuronium-neostigmine). Under conditions of this study neostigmine produced more rapid and complete recovery than did edrophonium. Although edrophonium produced adequate antagonism of atracurium if 20-30 min were allowed to elapse, edrophonium reversal of pancuronium was rarely acceptable even at 30 min. Increasing the dose of edrophonium to 1.0 mg/kg produced single twitch values of 0.90 at 5 min postreversal but did not increase the rate of recovery of the train-of-four fade ratio. Neostigmine reversal of pancuronium, on the other hand, generally produced T4/T1 ratios of greater than 0.70 in 20-30 min. Although the pattern of recovery seen after reversal of vecuronium was in general quite similar to that seen after atracurium, two patients in the vecuronium-edrophonium group showed delayed recovery and also failed to respond significantly to subsequent doses of neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

Edrophonium antagonizes combined lidocaine-pancuronium and verapamil-pancuronium neuromuscular blockade in cats

The effects of lidocaine or verapamil on pancuronium neuromuscular blockade and the ability of anticholinesterase agents to antagonize these combined blockades were studied in 14 cats using a standard peroneal nerve-anterior tibialis muscle preparation. Pancuronium was infused at a constant rate to produce a stable 50% depression of single twitch tension. In nine cats, intravenous lidocaine boluses followed by a constant infusion produced serum lidocaine levels of 5.09 +/- 1.9 micrograms/ml (mean +/- SD) and resulted in an additional 20.0 +/- 5.5% depression of twitch tension. In the other five cats, intravenous injection of 0.15 mg/kg of verapamil produced an additional 12.8 +/- 8.0% twitch depression of pancuronium-induced neuromuscular blockade. For individual animals, edrophonium antagonism of the combined lidocaine-pancuronium-induced neuromuscular blockade or combined verapamil-pancuronium-induced neuromuscular blockade was not significantly different from antagonism of an equivalent twitch depression produced by pancuronium alone. It is concluded that lidocaine and verapamil augment neuromuscular blockade caused by pancuronium and that anticholinesterase antagonism of this augmented blockade can be expected to occur in a normal fashion.

Interaction of verapamil with gallamine and pancuronium and reversal of combined neuromuscular blockade with neostigmine and edrophonium

In this in vitro study, the effects and interactions of verapamil with gallamine and pancuronium and reversal by edrophonium and neostigmine of combined neuromuscular blockade, produced by the muscle relaxants and verapamil, were studied in an avian skeletal muscle. The results show that verapamil reduced the amplitude of indirectly-elicited twitch tension and potentiated the neuromuscular blockade produce by the two muscle relaxants. Edrophonium and neostigmine reversed the neuromuscular blockade produce by the muscle relaxants alone, and in combination with verapamil. Edrophonium was more potent than neostigmine in reversing the combined neuromuscular blockade produced by the muscle relaxants with and without verapamil.

Neostigmine and edrophonium antagonism of varying intensity neuromuscular blockade induced by atracurium, pancuronium, or vecuronium

To compare the time course of neostigmine and edrophonium antagonism of varying intensity neuromuscular blockade induced by atracurium, pancuronium, or vecuronium, the authors studied 98 patients anesthetized with nitrous oxide (60%) and halothane or enflurane. Neuromuscular blockade, as monitored by single stimulus-induced twitch tension (TT), was antagonized at varying degrees of spontaneous recovery (2-80% of control TT). Time to antagonism (time from injection of neostigmine or edrophonium to 90% recovery of control TT) was not different between edrophonium, 0.5 mg/kg, and neostigmine, 0.04 mg/kg, when spontaneous recovery had been allowed to occur to at least 11% of control TT prior to antagonist administration (P greater than 0.05). For profound neuromuscular blockade (TT less than or equal to 10% of control) induced by pancuronium or vecuronium, time (mean +/- SD) to antagonism with neostigmine, 0.04 mg/kg, was 7.0 +/- 2.2 min and 5.6 +/- 1.7 min, respectively, while the same for edrophonium, 0.5 mg/kg, was 20.0 +/- 8.0 min and 15.0 +/- 12.5 min, respectively (P less than 0.05). Time to antagonism of profound atracurium-induced neuromuscular blockade was 8.5 +/- 3.3 min for neostigmine, 0.04 mg/kg, and 9.8 +/- 7.0 min for edrophonium, 0.5 mg/kg, (P less than 0.05). For profound vecuronium-and pancuronium-induced neuromuscular blockade, time to antagonism by edrophonium, 1.0 mg/kg, was 4.6 +/- 3.0 min and 3.9 +/- 1.6 min respectively. The authors conclude that neostigmine, 0.04 mg/kg, antagonizes neuromuscular blockade within 12 min when TT is greater than 2% of control at time of reversal. When TT is greater than 10% of control, edrophonium, 0.5 mg/kg, produces similar time to antagonism.(ABSTRACT TRUNCATED AT 250 WORDS)

Antagonism of non-depolarising neuromuscular blockade by aminopyridines in cats

The antagonism of pipecuronium- and vecuronium-induced neuromuscular blockade by 4-aminopyridine (4AP), 3,4-diaminopyridine (3,4AP) and 3-[(dimethylamino)-carbonyl] amino-4-aminopyridine (LF14) were studied in anaesthetized cats during constant infusion of the relaxants. Aminopyridines were administered cumulatively at steady state 90% block level. The ED50 values of 4AP, 3,4AP and LF14 were 243, 106 and 254 micrograms kg-1 in pipecuronium, and 232, 195 and 235 micrograms kg-1 in vecuronium blockade. It has been assumed that in cats the anticurare effect of aminopyridines is mainly a result of K+ channel blockade on motor nerve terminals which enhances the evoked release of acetylcholine.

The potencies of edrophonium and neostigmine as antagonists of pancuronium

Dose response curves were constructed for edrophonium and neostigmine when used to antagonise pancuronium, 0.07 mg/kg during thiopentone-nitrous oxide-halothane anaesthesia. The antagonist was given when 10% twitch height had been restored and the effect was measured 10 minutes later. Recoveries to 50% and 90% twitch height were achieved with 167 and 828 micrograms/kg of edrophonium, and 10.5 and 51 micrograms/kg of neostigmine. The dose response curves were parallel and neostigmine was 16 times more potent than edrophonium. Combinations of equipotent doses of edrophonium and neostigmine were also administered and produced additive but not synergistic effects. It is concluded that either edrophonium or neostigmine may be used for the reversal of pancuronium neuromuscular blockade, but the combination of the two offers no advantage.

Vecuronium in the myasthenic patient

The use of vecuronium in six patients with myasthenia gravis undergoing thymectomy is described the train-of-four twitch technique was used to monitor neuromuscular function. The first two patients received an initial dose of 0.02 mg/kg and incremental doses of 4 micrograms/kg, which is in the order of one fifth of that normally used. Satisfactory depression of the first twitch of the train-of-four, however was not obtained and, therefore, in the remaining four patients the doses were doubled. At this dose satisfactory depression of the first twitch was achieved. Neostigmine 5.0 mg produced adequate reversal of residual neuromuscular blockade and the train-of-four twitch response recovered to normal levels. With reduced dosage and with careful neuromuscular monitoring, vecuronium can be used safely in the myasthenic patient.

Vecuronium bromide in anaesthesia for laparoscopic sterilization

Vecuronium bromide 70 micrograms kg-1 was used to facilitate tracheal intubation and provide neuromuscular blockade in 52 patients undergoing laparoscopic sterilization. Anaesthesia was maintained with 67% nitrous oxide in oxygen. Patients were monitored clinically and by tactile assessment of the evoked response of the adductor pollicis to a supramaximal train-of-four stimulation. Intubating conditions were assessed at 90 s in the first 33 patients, and were poor. They improved significantly in the subsequent 19 patients when intubation was delayed until 150 s (P less than 0.05). Operating conditions were good in all except two patients. Residual neuromuscular blockade was antagonized rapidly at completion of surgery by neostigmine 2.5 mg i.v., which was administered provided there was at least one twitch response. The mean duration of the procedure was 14.3 min (SD 2.5 min). The mean time from injection of neostigmine to satisfactory spontaneous breathing and neuromuscular recovery was 1.6 min (SD 0.7 min).

Edrophonium and neostigmine for reversal of the neuromuscular blocking effect of vecuronium

The effect of edrophonium for reversal of the non-depolarizing neuromuscular blockade produced by a continuous infusion of vecuronium was compared to that of neostigmine in 20 adult patients during neurolept anaesthesia. When antagonism was attempted at 10% twitch height recovery, reversal time to a train-of-four ratio of 0.7 was significantly shorter following neostigmine 0.04 mg/kg than after edrophonium 0.75 mg/kg (9.8 min and 18.7 min, respectively) but the same after edrophonium 1.5 mg/kg (10.3 min). There was no statistically significant difference in reversal time between neostigmine 0.04 mg/kg given at 10% twitch height and edrophonium 0.75 mg/kg given at 25% twitch height recovery (6.0 min). Additional doses of atropine were necessary following edrophonium 1.5 mg/kg.

Pattern of CNS recovery following reversal of neuromuscular blockade. Comparison of atropine and glycopyrrolate

Recovery from anaesthesia was compared, in a group of patients (n = 25) receiving a mixture of glycopyrrolate and neostigmine (to reverse non-depolarizing neuromuscular blockade), with recovery in a group of patients (n = 25) receiving an atropine-neostigmine mixture. Recovery following anaesthesia was more rapid in the patients receiving the glycopyrrolate-neostigmine mixture.

Comparison between glycopyrrolate and atropine in a mixture with neostigmine for reversal of neuromuscular blockade. Studies in patients following open heart surgery

Atropine and glycopyrrolate were compared in a mixture with neostigmine for reversal of neuromuscular blockade in patients undergoing open heart surgery. In patients not receiving beta-blocking drugs, glycopyrrolate was shown to possess advantages over atropine in terms of a lower initial increase in heart rate, better protection against the muscarinic effects of neostigmine, and smaller increases in rate-pressure product. The concomitant administration of beta-adrenergic blocking therapy significantly attenuated the effect of reversal on heart rate and the differences between atropine and glycopyrrolate were not significant. There was no difference in the incidence of arrhythmias between patients who received beta-blocking drugs and those who did not.