COMPARISON OF 3%, 5% AND 8% CONCENTRATIONS OF SEVOFLURANE FOR INDUCTION AND INTUBATION IN ADULTS WITHOUT USING NEUROMUSCULAR BLOCKING AGENTS

Introduction: Tracheal intubation is commonly facilitated by the use of muscle relaxants. Sevoflurane fulfills the criteria for successful rapid & smooth inhalational induction when muscle relaxants are contra-indicated. Aim: To compare the success rate of intubation characteristics, hemodynamic changes, the effectiveness of the trapezius squeezing test for an adequate condition for intubation. Method: A total of 150 patients of ASA grade I and II undergoing elective surgical procedures of aged 20-60 years were included in our study. Patients on MAO-inhibitors, antidepressants, and B-blockers were excluded. 50 patients in each group; were randomized to groups A, B. and C with sevoflurane dial concentration of 3%, 5%, and 8% respectively. Before induction, priming of the circuit with allotted group done with 3 times bag full and empty cycles. Once the trapezius squeeze test is negative, IPPV (intermittent positive pressure ventilation) was continued for another one minute. Mean arterial pressure (MAP) and heart rate (HR), jaw relaxation, body movements vocal cord position; complications were recorded for all patients. Results: The incidence of successful intubation in the first attempt was 72%, 94%, 100% in groups A, B, and group C respectively (P <= 0.0001). 14/50 patients in group A and 3/50 patients in group B required a second attempt for intubation due to the stiff jaw or moderate to severe body movement. In all groups, induction time is maximum in group A p-value <0.0001. Significant increase in mean blood pressure and pulse was present from laryngoscopy to 4 min after intubation in groups A, and group B. Cardiovascular stability is seen in group C. Conclusion: Higher concentration 8% sevoflurane (group C) has a faster and more successful induction with cardiovascular stability and lesser incidence of body movements, cough compare to 5% sevoflurane (group B). TST is used as an indicator of anesthesia depth which also seems adequate and simple to perform.