SummaryThe frequency and duration of postoperative residual neuromuscular block on arrival of 150 patients in the recovery ward following the use of vecuronium (n 50), atracurium (n 50) and rocuronium (n 50) were recorded. Residual block was defined as a train-of-four ratio of ,0.8. An additional group of 10 patients received no neuromuscular blocking drugs during anaesthesia. The incidence of postoperative residual neuromuscular block was 64%, 52% and 39% after the use of vecuronium, atracurium and rocuronium, respectively. Similar numbers of patients were not able to maintain a sustained head or leg lift for 5 s on arrival in the recovery ward. The mean [range] times to attaining a train-of-four ratio of $0.8 after arrival in the recovery ward were 9.2 [1±61], 6.9 [1±24] and 14.7 [1.5±83] min for vecuronium, atracurium and rocuronium, respectively. None of the 10 patients who did not receive neuromuscular blocking drugs had train-of-four ratios ,0.8 on arrival in the recovery ward. It is concluded that a large proportion of patients arrive in the recovery ward with a train-of-four ratio ,0.8, even with the use of intermediate-acting neuromuscular blocking drugs. Although the residual block is relatively short lasting, it may occasionally be prolonged, requiring close observation and monitoring of such patients in the recovery ward.
We have examined the effects on recovery end-points of supplementation of a propofol-based anaesthetic with remifentanil. After induction of anaesthesia with propofol and remifentanil 1.0 microg kg(-1), 15 patients each were randomly allocated to target plasma propofol concentrations of 2, 3, 4 or 5 microg ml(-1) for maintenance of anaesthesia. Remifentanil was administered by infusion for supplementation in doses required for maintenance of adequate anaesthesia. All patients received 50% nitrous oxide in oxygen and ventilation was controlled. The total amount of drugs used and times to different recovery end-points were recorded. Cognitive function was also assessed using a Mini-Mental State questionnaire. The median dose of remifentanil for maintenance of adequate anaesthesia (excluding the initial bolus dose) in the four groups was 0.21, 0.15, 0.11 and 0.13 microg kg(-1) min(-1) respectively (P=0.0026). The median times to eye opening and orientation were shortest in the 2 microg ml(-1) group [6.0 and 6.5 min, 8.5 and 10.8 min, 13.4 and 15.8 min, and 14.2 and 19.5 min respectively in the propofol 2, 3, 4, and 5 microg ml(-1) groups respectively (P<0.001)]. The times to discharge from the recovery ward and the Mini-Mental State scores were not significantly different.
Purpose: To examine the influence of continuing administration of sevoflurane or isoflurane during reversal of rocuronium induced neuromuscular block with neostigmine.Methods: One hundred and twenty patients, divided into three equal groups, were randomly allocated to maintenance of anesthesia with sevoflurane, isoflurane or propofol. Neuromuscular block was induced with rocuronium and monitored using train-of-four (TOF) stimulation of the ulnar nerve and recording the force of contraction of the adductor pollicis muscle. Neostigmine was administered when the first response in TOF had recovered to 25%. At this time the volatile agent administration was stopped or propofol dosage reduced in half the patients in each group (n = 20 in each group). The times to attain TOF ratio of 0.8, and the number of patients attaining this end point within 15 min were recorded.Results: The times (mean ± SD) to recovery of the TOF ratio to 0.8 were 12.0 ± 5.5 and 6.8 ± 2.3 min in the sevoflurane continued and sevoflurane stopped groups, 9.0 ± 8.3 and 5.5 ± 3.0 min in the isoflurane continued and isoflurane stopped groups, and 5.2 ± 2.8 and 4.7 ±1.5 min in the propofol continued and propofol stopped groups (P < 0.5-01). Only 9 and 15 patients in the sevoflurane and isoflurane continued groups respectively had attained a TOF ratio of 0.8 within 15 min (P < 0.001 for sevoflurane).Conclusions: The continued administration of sevoflurane, and to a smaller extent isoflurane, results in delay in attaining adequate antagonism of rocuronium induced neuromuscular block. REVIOUS studies have shown that antagonism of block with relaxants such as vecuronium is impeded in the presence of potent volatile agents such as sevoflurane and isoflurane. [1][2][3] It has also been shown that sevoflurane anesthesia potentiates the effect of rocuronium compared with isoflurane and propofol anesthesia. 4 Although there are reports of antagonism of rocuronium block with neostigmine, these have generally examined the influence of the dosage or the timing of administration of the anticholinesterase. [5][6][7] The aim of the present study was to examine the effect of the sevoflurane on the antagonism of rocuronium by neostigmine, and compare it with the effects of isoflurane, and intravenous anesthesia.
SummaryTarget-controlled infusion systems have been shown to result in the administration of larger doses of propofol, which may result in delayed emergence and recovery from anaesthesia. The aim of this study was to investigate if this was due to a difference in the depth of hypnosis (using the bispectral index monitoring) between the manual and target controlled systems of administration. Fifty unpremedicated patients undergoing elective surgery were randomly allocated to have their anaesthesia maintained with manual or target-controlled propofol infusion schemes. In both groups, the rate of propofol administration was adjusted according to standard clinical criteria while bispectral index scores were recorded by an observer not involved in the delivery of anaesthesia. The total dose of propofol used was higher in the target controlled group (mean 9.9 [standard deviation 1.6] compared with 8.1 [1.0] mg.kg)1 in the manual group [p < 0.0001]). The times to emergence and recovery end-points were comparable between the two groups. The difference in the total dosage of propofol was mainly due to higher rate of propofol administration in the first 30 min in the target controlled infusion group. The bispectral index scores were lower in the target controlled group during this time, being significantly so over the first 15 min of anaesthesia. We conclude that propofol administration by a target controlled infusion system results in the administration of higher doses of propofol and lower bispectral index values mainly in the initial period of anaesthesia.
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