Rocuronium Induced Nuromuscular Blockade During Different Concentrations Of Sevoflurane Anesthesia

BACKGROUNDNeuromuscular blocking agents (NMBAs) is an important part in general anesthesia for maintaining Neuromuscular relaxant, eliminating patients' action,providing preferable operation conditions, which can prevent deep anaesthesia.Many difficulty and fine operations have made mighty advances as the medical treatments have developed at high speed during the past few years, surgeons require that patients shoud be maintained neuromuscular relaxant during operation and outbated as early as possible after operation, anaesthetists ought to make the least use of NMBAs in the operation to satisfy the neuromuscular relaxant requirement.The time course of rocuronium can be affected by many medicines used in the operation,such as inhalational anesthetics, vasopressors, antibiotics, local anesthetics and et al;It can also be affected by patients' pathology , physiology and surgical operations.Understanding these factors conduce to the NMBAs' efficient use .But patients pathology, physiology and surgical operations cannot be altered,what anaesthetists cando is adjusting the NMBAs' dose when it is associated with these medicines. Previous studies have shown that potent inhalation anaesthetics augment the effect of NMBAs,but the studies were always combined with midazo-lam and fentanyl.Propofol and remifentanil have short duration of effect.Sevoflurane is a new volatile agents ,has properties of a low blood/gas partition coefficient and tissue/gas solubility, pleasant smell and a non-irritant effect on the airways,allow rapid and smooth induction.Its rapid elimination makes it a particularly useful agent for general anaesthia.Rocuronium bromide is a new steroidal non-depolarizing neuromuscular blocking drug ,has characters of rapid onset and intermediate duration of neuromuscular block. The neuromuscular block will not surplus or inadequate if the neuromuscular transmission is measured during the whole operation,but many national hospitals cannot attain such conditions.Understanding the effect of sevoflurane on the rocuronium can somewhat prevent the NMBAs' surplus.The aim of the present study was to quantify the relationship between the dose-response and time course of action of rocuronium with the different end-tidal concentrations of sevoflurane,or during IV anesthesia in adult patients.OBJECTIVETo examine the influence of continuing administration of different end-tidal concentrations of sevoflurane(1.5MAC and 1.0MAC) or IV anesthesia on the onset , maintain of rocuronium and reversal of rocuronium induced neuromuscular block with neostigmine.METHODSSixty male American Society of Anesthesiologists physical status I and II patients scheduled for laparoscopy cholestcyst,age<60 year,with normal cardiac, lung, hepatic, renal function.Exclusion criteria were: patients with massive bleeding , hypothermia and other accident requiring urgent management in operation,those with a body mass index >30kg.m"2,those with neuromuscular and respiratory disease.Patients were randomly allocated into three groups:Group P received propofol for induction,after BIS value acheieved 60 ,remifentanil 1.5ug/kg was given over 30s,laryngoscopy and tracheal intubtion were performed lmin later. Intubation conditions were evaluated according to a standard score.Anaesthesia maintained with propofol by plasma concentration controlled infusion according to BIS value which was maintained around 50;Group Si.5 and S1.0: anesthesia was induced with sevoflurane 8% using a vital capacity breath technique, after BIS value acheieved 60 ,remifentanil 1.5ug/kg was given over 30s,laryngoscopy and tracheal intubtion were performed lmin later. Anaesthesia was maintained with different end-tidal concentrations 1.5MAC and 1.0MAC.After anaesthesia was maintained for 30 min, patients received a bolus dose of 0.6mg/kg rocuronium in three groups.When the first response in TOF had recovered to 20%,rocuronium 0.3mg.kg"' was injected if the operation was continuing. During induction of anaesthesia,arterial pressure , heart rate,BIS values were recorded at 1-min intervals from before induction of anaesthesia until 10 min after intubation. Neostigmine 0.04mg/kg was administered when the first response in TOF had recovered to 25% after operation,The ulnar nerve was stimulated transcutaneously at the wrist,with supramaximal stimuli of 0.2 msec duration in a train-of-four(TOF) mode at 2 HZ every 12s for the onset and duration of action part of the study.RESULTS1. Anesthesia inductionBaseline heart rate and arterial pressure was similar in all groups,but decreased after induction and remained significantly lower after intubation compared to basline.Heart rate and arterial pressure increased slightly after intubation in each group but there no significantl differences in mean heart rate between groups at any time. Mean times to loss of eyelash reflex . obtain a BIS<60 and intubation performed were significantly more rapid with propofol, comparable intubation scores were seen during three groups.2. The onset time of rocuroniumThe mean±SD times to onset of maximal block after rocuronium 0.6mg.kg-l were 86± 15, 57±9and 51+6 sec in the group P,group Si.o and group Si.5 respectively.(P<0.05 for propofol versus sevoflurane),the onset between 1.5MAC sevoflurane and 1.0MAC sevoflurane was not significantly different. 3.The clinical duration of rocuroniumThe clinical duration (time between administration of rocuronium and recovery to 20% twitch height )of the first dose was found to be longer in the group SI.5,SI.O than in the group P(57±9vs37±7min;48 ±4vs37±7min;P<0.05);and also in the group SI.5 was longer than in the group S1.0(57 + 9vs48±4min;P<0.05). 4.The recovery of rocuroniumThe recovery index(time from 25% to 75% twitch height recovery) was significantly longer in the groups Si.5,Si.o than in the group P(5.0± 1.7vs2.2±1.0min;3.4±1.2vs2.2 + 1.0min;P<0.05);also in the group Si.5 was longer than in the group Si.0(5.0± 1.7vs3.4± 1.2min;P<0.05). From neostigmine administration to attaine a TOF ratio of 0.8 was significantly longer in the groups Si.5,Si.o than in the group P(11.8±5.7vs4.3±0.9min;7.3±1.5vs4.3±0.9min;P<0.05);in the group Si.5 was longer than in the group Si.0(H.8±5.7vs7.3±1.5min, P<0.05).CONCLUSION1. Propofol or sevoflurane combined with remifentanil can attain excellent intubation conditions without NMBAs.2. After 30min inhalation of 1.5MAC and 1.0MAC end-tidal concentrations of sevoflurane ,the onset of rocuronium is shortened,but there is no significantly different between the groups S1.5 and S1 o-3. Maintenance sevoflurane at 1.5MAC and 1.0MAC end-tidal concentrations can prolong the single dose of rocuronium' clinical duration,maintenance sevoflurane at 1.5MAC is more significantly.4. Reversal of rocuronium induced neuromuscular block with neostigmine is retardaced by sevoflurane, the recovery index is higher in the sevoflurane groups.