Evaluation of Neuromuscular Blockade with Vecuronium during General Anesthesia with Oxygen, Nitrous Oxide, Isoflurane versus Oxygen, Air, Isoflurane: A Randomized Controlled Study

BACKGROUND: The use of air oxygen mixture with isoflurane has become more common in the place of nitrous oxide, especially in laparoscopic and abdominal surgeries. With a varied mixture of gases and isoflurane used in general anesthesia, the exact dosing requirement and time duration of action have not been precisely studied with vecuronium when given as a bolus, as is given routinely. PURPOSE: This study was undertaken to evaluate and compare the neuromuscular effect of vecuronium during anesthesia with oxygen, nitrous oxide and isoflurane versus oxygen, air and isoflurane. METHODOLOGY: The study was a prospective, randomized controlled trial on 70 patients allocated into two groups as follows: Group N (nitrous oxide group) and Group A (medical air group). The primary objective was to measure and compare the posttetanic count (PTC(1)) – train of four (TOF(1)) interval, to evaluate the time taken for recovery from the intense blockade in both groups. The secondary objectives were to compare time duration for twitch height depression to be 30% of baseline after administering vecuronium, time duration from vecuronium administration to appearance of the first PTC(1), PTC (n) at the reappearance of the 1(st) twitch, time interval between TOF(1) and TOF(3) and time from vecuronium administration to appearance of TOF(3) in both the groups. RESULTS: There is no significant difference between both the groups with reference to the block onset time using 30% depression of single twitch and recovery time from neuromuscular blockade using PTC, PTC(1)-TOF(1) and TOF(1)-TOF(3) time intervals. CONCLUSION: Measuring and comparing neuromuscular transmission monitoring parameters such as the onset time(ST depression to 30%), and recovery using PTC, PTC(1)-TOF(1) and TOF(1)-TOF(3) time intervals, it is concluded that the character of neuromuscular block with vecuronium is unaffected and not prolonged with or without nitrous oxide when used with isoflurane.