Attenuation Of CVS Response To Direct Larngoscopy And Intubation: A Omparative Study Of Fentanyl VS Lignocaine VS Lacebo During General Anaesthesia

OBJECTIVE: Direct laryngoscopy and endotracheal intubation is one of the most intensive stimuli in anesthesia and frequently induces a cardiovascular stress response due to reflex sympathetic stimulation. This response may be hazardous in patients with Hypertension, Coronary artery disease, Myocardial disease, cerebrovascular disease. Numerous agents have therefore been utilized to blunt this response. The present randomized, prospective and placebo controlled study was undertaken in view of above mentioned facts, to compare efficacy of intravenous fentanyl and lignocaine in attenuation of the cardiovascular stress response to direct laryngoscopy and intubation during general anaesthesia.METHOD: Seventy five patients with ASA physical status I and II adult patients aged 16-60 years undergoing elective surgical procedures, requiring general anesthesia and orotracheal intubation were allocated to any of the three groups (25 each)-Group I (fentanyl 2μ/kg), Group II (lignocaine 1.5 mg/kg , Group III ( 0.9% saline as placebo) . In all groups respective drug was given 5 min prior to intubation. All the patients were subjected to the same standard anesthetic technique which includes pre-oxygenation, anesthetic medications , laryngoscopy technique lasting less than 15 seconds and not more than two attempts at intubation was used.Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure(DBP) were recorded prior to induction(baseline value), at time of intubation and 1, 3, and 5 min after intubation. The three groups were then compared and analysed for statistical significance by using ANOVA with SPSS 19. The p value of < 0.05 is considered as statistically significant. Heart rate changes > 20% and BP changes > 15% above or below the basal values were considered as clinically significant. Heart rate, Mean arterial pressure and the rate pressure product at different stages of the study were calculated.RESULTS: HR and BP were comparable before induction and intubation. There was increase in HR and BP in all the three groups after laryngoscopy.The maximum percentage change from baseline mean heart rate was less in the group I (22%), than in the groups II & III (31.4% and 33.33% respectively). There was a significant difference between group I and groups II & III in the change in heart rate response to laryngoscopy and intubation. There was no significant difference between group III (control) and group II (lignocaine) in change in heart rate response to laryngoscopy and intubation.The maximum percent change from base line mean systolic blood pressure was less in the group I (8.6%) than the group II & III (21.2% and 26.7% respectively). There is statistically significant difference in mean systolic blood pressures between all groups after laryngoscopy and intubation. In fentanyl and lignocaine groups there was increase in SAP and DAP during the 1st min after intubation, but the increase is significantly less when compared to control group(p<0.05). Later in 3rd and 5th minutes this increased BP returned back to baseline values and this didnot happen with the control group. SAP and DAP was significantly lower in the fentanyl group vs control group at 1,3 and 5 min after intubation(p<0.05). SAP was significantly lower in the fentanyl group vs lignocaine group at 1,3 and 5 min after intubation(p<0.05). There is no statistically significant difference in DBP between fentanyl and lignocaine groups after intubation. SAP and DAP was significantly lower in the lignocaine group vs control group at 3 and 5 min after intubation(p<0.05).The maximum percent change from baseline mean arterial blood pressure was less in the fentanyl (group I) (11.2%) than in the group II and III (25.6% and 30.8% respectively). There is statistically significant difference in mean arterial blood pressures between all groups after laryngoscopy and intubation.The maximum change in rate pressure product from baseline was less in the fentanyl (group I) (34%) than in the group II and III (83% and 69.8% respectively). There is statistically significant difference in mean arterial blood pressures between all groups after laryngoscopy and intubation There was statistically significant difference in mean rate pressure product among all the three groups. at the end of 1st , 3rd and 5th minute after intubation except for the groups III & II at the end of 1st minute.. CONCLUSIONS: In lower doses, fentanyl(2μg/kg) is a better agent than lignocaine (1.5 mg/kg) in attenuating the sympathomimetic response to laryngoscopy and intubation. Fentanyl effectively decreases heart rate , systolic and diastolic blood pressure responses to direct laryngoscopy and intubation. Even though lignocaine blunts the systolic and diastolic blood pressure response to direct laryngoscopy and intubation but not as effectively as that of fentanyl.