Comparison between mivacurium and atracurium in neuromuscular block and cardiovascular effects in patients receiving nitrous oxide - oxygen - halothane or nitrous oxide - oxygen - narcotic anaesthesia

ABSTRACT

This study was done on 60 patients of both sexes ASA I and II undergoing routine surgical operation in Al-Zahraa Hospital from March 1996 to March 1997, the study was undertaken to determine the neuromuscular block and cardiovascular effects of mivacurium in comparison with atracurium in 60 patients in two groups, each group 30 patients was subdivided into [a, b, c]. In group I, Halothane group [HAL] it was found that the mean onset for the low dose of mivacurium and that of atracurium were similar while the onset of high dose was much shorter, there was a highly significant difference between atracurium and both doses of mivacurium for the train of four [TOF] and the recovery index [RI]. In group II, [BAL] the balanced group there was no difference in the onset between both doses of mivacurium and that of atracurium, in comparison there was a highly significant difference between atracurium and the high dose of mivacurium in RI and TOF. Comparing group I and II halothane was found to potentiate the effect of mivacurium at neuromuscular junction with a high significant difference both at the low dose and at the high dose when compared with the balanced group. It was concluded that the spontaneous recovery from mivacurium induced neuromuscular block is very rapid and there is less need for neostigmine- atropine induced antagonism. The haemodynamic effects of mivacurium was also assessed, that the cardiovascular safety of mivacurium is proved by absence of clinically significant alteration from base line mean arterial pressure [MAP] and heart rate [HR] during bolus administration at doses up to 0.15 mg/kg. The cardiovascular effects of mivacurium may become evident after injection of larger doses. The present study revealed that mivacurium may be a useful nondepolarizing alternative to suxamethonium in elective procedures and in situation where rapid onset of action is not necessary. Due to its short duration of action and rapid recovery it is used as an adjunct to general anaesthesia, to facilitate tracheal intubation and provide skeletal muscle relaxation during surgery or mechanical ventilation for short procedures, and in situation where antagonism of residual neuromuscular block is considered undesirable