Low and high frequency stimulation tests to characterize the effects of edrophonium on vecuronium-induced neuromuscular block.

We recorded adductor pollicis mechanical activity in response to low (0.1 and 2 Hz) and high (50 and 100 Hz) frequency stimulation 15 min after edrophonium 250, 500 and 1000 micrograms kg-1, given to antagonize vecuronium-induced block at 10, 25 and 50% pre-reversal twitch height. We studied 54 ASA class I and II anaesthetized (methohexitone, fentanyl, nitrous oxide) young adult patients allocated randomly to nine groups of six patients each. The greater sensitivity of train-of four (TOF) ratio and residual force after 100-Hz, 5-s tetanic stimulation (RF100) to residual deficit allowed discrimination more readily between the effects of edrophonium dose and pre-reversal twitch height (P < 0.001, two-way analysis of variance). The highest reversal scores (approximately 0.9 TOF ratio and 0.6 RF100) were obtained when edrophonium 500-1000 mg kg-1 was given at 50% twitch height (P < 0.05, Duncan's test).

[Spontaneous development of paralysis induced by equipotent doses of vecuronium, atracurium, fazadinium, pancuronium, gallamine and d-tubocurarine]. / Evolution spontanée de la paralysie obtenue par des doses équipotentes de vécuronium, atracurium, fazadinium, pancuronium, gallamine et d-tubocurarine.

Thirty-six patients undergoing elective surgery were studied after obtaining their informed consent. They were randomly assigned to six series of six patients each. One hour before anaesthesia, all patients received 0.2 mg.kg-1 diazepam orally. After induction of anaesthesia with 1-1.5 mg.kg-1 methohexitone and 5 micrograms.kg-1 fentanyl, the patients were paralysed and ventilation was controlled manually (semi-open circuit; 50% N2O/50% O2). Each patient received a single dose of either 70 micrograms.kg-1 fazadinium, 70 micrograms.kg-1 pancuronium, 2,500 micrograms.kg-1 gallamine or 450 micrograms.kg-1 d-tubocurarine. Neuromuscular function was monitored by measuring the isometric contraction of the adductor pollicis muscle in response to supramaximal stimulations of the ulnar nerve at the wrist (square wave pulse of 0.2 ms duration at supramaximal intensity delivery at 0.1 Hz). Three parameters were measured: the time between the injection of the relaxant drug and recovery of the twitch height at 50% of its baseline (RT0-50); the time between the injection of the relaxant drug and recovery of the twitch height at 90% of its baseline (RT0-90); the time between the injection of the relaxant drug and recovery of the twitch height from 25 to 75% of its baseline (RT25-75). The values of the observed parameters were expressed in minutes (means +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of age on the establishment of muscle paralysis induced in anaesthetized adult subjects by ORG NC 45.

The establishment of muscle paralysis produced by a single dose of 70 micrograms . kg-1 of ORG NC 45 was studied in 30 healthy anaesthetized patients, aged 15-85 years, by recording adductor pollicis isometric mechanical activity-twitch height (TH). Significant correlations were observed between age and the latency of ORG NC 45 action, defined as the reduction of TH to 95% of its initial value (r:0.315, P less than 0.05) and between age and the onset time, defined as the time elapsing between ORG NC 45 administration and maximum TH depression observed (r:0.454, P less than 0.005). Correlation between age and maximum TH depression was not significant. These results show that if the maximum TH depression observed after a standard dose of ORG NC 45 is not altered by the age of the patient, the establishment of the paralysis is delayed by ageing.