The Effects Of Sevoflurance On Neuromuscular Block Of Vecuronium

Objective To observe the effects of sevoflurane on neuromuscular block of vecuronium. Methods Sixty patients undergoing breast cancer under general anesthesia ASA I or II aged 40-55 yr weighing 45-80 kg were randomly divided into 2 groups (n=30 each):sevoflurane group (group S) and propofol group (group P).Patients with hepatic,renal or neuromuscular disease and those on medications known to affect neuromuscular blocking drugs were excluded. All patients were fasted at least 8 hours before surgery.Patients were not drug allergy and difficulty airway.The operation time was about 2 hours. Anesthesia was induced by 8% sevoflurane with vital capacity and oxygen flow 6L/min in group S or intravenous injection of propofol 2mg/kg in group P. When the patients'eyelash reflex disappeared in two groups, vecuronium O.lmg/kg and fentanyl 4μg/kg were gived before tracheal intubation.When the count of TOF was 2, vecuronium was given one third of induction dose. Anesthesia was maintained with inhalation of 2%-3% sevoflurane in group S or continuous intravenous injection of 4-8 mg/kg/h propofol in group P respectively. Fentanyl was injected intermittently and muscle relaxation was monitored by TOF-WatchSX during operation. Sevoflurane was not inhaled and propofol was not pumped injection immediately at the end of the operation. At the same time, oxygen flow was 10L/min in group S and sevoflurane was discharged. When the count of TOF was 2 in two group, neostigmine 0.05mg/kg and atropine0.02mg/kg were given to antagonize vecuronium.The time of the patients' eyelash reflex lost and conscious recovery were recorded.The time of onset, duration of action, average consumption dose of vecuronium, and adverse events of induction and extubation were recorded.The variation of heart rate and mean arterial pressure were also recorded.Results The time of eyelash reflex lost in group P was shorter than that in group S[(40.50±5.76)s vs.(49.80±7.39)s] (P<0.01).The onset time of vecuronium was shorter in group S than that in group P [(185.00±14.02)s vs.(206.50±17.20)s] (P< 0.01).The action time of vecuronium in group S was longer than that in group P [(38.90±5.06)min vs.(29.00±5.03)] (P <0.01).The consumption dose of vecuronium in group S was less than that in group P [(1.75±0.10)ug/kg/min vs.(2.03±0.14)μg/kg/min](P<0.01).The time of opening eyes in response to voice is shorter in group S than that in group P [(7.59±1.27)min vs. (11.00±2.30)min] (P<0.01).The heart rate in group S was significantly lower (P<0.05) and the mean arterial pressure in group P was also significantly lower (P<0.05)before tracheal intubation,there was no significant difference in variation of the heart rate and mean arterial pressure in two groups during and at the end of operation.There were no irritating cough,breath holding, laryngospasm and respiratory inhibition during induction.There were no restlessness, nausea and vomiting during extubation. All patients in two groups could correctly answer questions and had no discomfort. Conclusion Sevoflurane can not only maintain hemodynamic stability but also enhance the effect of neuromuscular block of vecuronium and decrease the requirement of vecuronium and the patients' breathing recovered faster.