Time Window For Tracheal Intubation Of Rocuronium In Two Induction Modes For General Anesthesia

Succinylcholine is the only available neuromuscular blocker with a rapid onset of effect and an ultra short duration of action.Administration of 1mg/kg succinylcholine results in complete suppression of response to neuromuscular stimulation in approximately 60 seconds.Rocuronium 0.9 mg/kg has the same onset of effect with succinylcholine,which has been suggested as an alternative to succinylcholine for intubation.But nondepolarizing neuromuscular blocker has great individual difference.Rocuronium 0.9 mg/kg may not allow for adequate intubating conditions 60 seconds after administration in part of the patients,which associated with postoperative hoarseness,vocal cord sequelae and difficult intubation.Gu miaoning promoted the theory of time window for tracheal intubation,and performed relevant studies on timing of intubation of Rocuronium.In purpose of finding the optimal time for intubation,the author investigated the intubation conditions,glottic exposure and hemodynamic at 1,1.5,2,3,4 and 5min after the administration of rocuronium(0.9 mg/kg),during induction given by bolus of propofol,fentanil and target-controlled infusions(TCI) of propofol and remifentanil.Patients and MethodsFollowing approval by the Hospital Ethics Committee and written informed consent,one hundred and eighty ASAâ… orâ…¡patients aged 18～60 yr undergoing elective surgery under general anesthesia were randomized into two groups:group BOLUS was induced by bolus of propofol,fentanil and group TCI was induced by TCI of propofol and remifentanil.And then the patients in each group were randomized into six groups according to the intubation time of 1min,1.5min,2min, 3min,4min and 5min after the administration of neuromuscular blocking drugs. Patients with increased risk of pulmonary aspiration of gastric content,a potentially difficult airway,and patients who deviated by more than 30%from their ideal weight were excluded.None of the patients was taking drugs known to interact with neuromuscular blocking agents,or had evidence of renal,hepatic,metabolic,or neuromuscular disease.General anesthesia was induced by bolus of propofol,fentanil(group BOLUS) and target-controlled infusions of propofol(target concentration 3-4μg/ml) and remifentanil(target concentration 4ng/ml)(group TCI.).A senior anesthesiologist 'blinded' for randomization,performed the intubations 1min,1.5min,2min,3min,4min,5min after a bolus dose of 0.9 mg/kg rocuronium. Intubation conditions were evaluated according to Cooper's score.And we chose the Cormack-Lehane(C/L) score method for the grade of the glottic exposure.The electrocardiography(ECG),heart rate(HR),noninvasive arterial blood pressure(NIBP),pulse oxygen saturation(SpO₂) were monitored throughout the study period.The volumes of HR and systolic blood pressure(SBP) were recorded at the time before induction(T₁),one minutes after induction(T₂) and the time before intubation(T₃),one minute after intubation(T₄),three minute after intubation(T₅). Neuromuscular monitoring was started after successful automatic calibration of an acceleromyographic monitor(TOF-watch SX;Organon,Dublin,Ireland),attached to the adductor pollicis muscle and using ulnar nerve stimulation with a train-of-four for every 10s.The skin of the arm and wrist was cleaned with alcohol and application of a conductive jelly to the surface electrodes to facilitate optimal monitoring.The number reach maximum T₁ block at the time of intubation was recorded.Patients who admitted hospital by sequence were randomly divided into groups according to the table of random numbers.SPSS 13.0 were used to analyze the data. All data are reported as the mean±standard deviation((?)±s).Test of homogeneity of variances was analyzed firstly,and then analysis of one-way-ANOVA was used to evaluate the basic status data such as age,height and body weight.Two-factor study with repeated measures analysis of variance data was used to analyze HR and SBP.2 and several independent samples for non-parametric tests were used to analyze sex ratio,intubation conditions,the grade of the glottic exposure and the number reach maximum T₁ block.P values of＜0.05 were accepted as significant.Results1.The baseline dataThere is no statistic significance between sex ratio,body weight,age and height (P＞0.05).2.The intubation conditionsThere were no significant difference(P＞0.05) in acceptable intubating conditions between group BOLUS and group TCI.But the acceptable intubating conditions in group BOLUS_1min differed significantly from other groups in group BOLUS(P＜0.05) and the acceptable intubating conditions in group TCI_1min differed significantly from other groups in group TCI(P＜0.05)3.The glottic exposureThere were no statistically significant differences with the glottic exposure between group BOLUS and group TCI.But the glottic exposure in group BOLUS_1min differed significantly from other groups in group BOLUS(P＜0.05) and the glottic exposure in group TCI_1min differed significantly from other groups in group TCI(P＜0.05).4.The ratio of maximum T₁ blockThere were no statistically significant differences with the the ratio of maximum T₁ block between group BOLUS and group TCI.But the ratio of maximum T₁ block in group BOLUS_1min differed significantly from other groups in group BOLUS (P＜0.05) and the ratio of maximum T₁ block in group TCI_1min differed significantly from other groups in group TCI(P＜0.05).5.Haemodynaic variablesThere were no significant differences in haemodynaic variables among the groups prior to induction.Systolic blood pressure(SBP) decreased in all groups after induction of anesthesia.HR and SBP in group BOLUS and group TCI increased significantly after tracheal intubation(P＜0.05),the increase in SBP in group BOLUS_1min and TCI_1minwas significantly larger than that in other groups in group BOLUS and group TCI respectively(P＜0.05),the increase in SBP in group BOLUS was significantly larger than that in group B(P＜0.05)Conclusions1.1.5～5min after administration of rocuronium(0.9 mg/kg)was the ideal time for intubation during induction given by bolus of propofol,fentanil and target-controlled infusions of propofol and remifentanil.2.TCI enables more smoothly and longer intubation conditions than bolus.