Attenuation of Haemodynamic Responses to Laryngoscopy & Intubation following Nitroglycerin and Esmolol infusion

摘要

Background: Adrenergic stress response induced by laryngoscopy and tracheal intubation appears to be attenuated by esmolol and nitroglycerine but their potential clinical benefits have not been fully weighed against possible adverse effects.Objective: The objective of the present study was to compare the efficacy of intravenous infusions of nitroglycerin and esmolol in attenuating hemodynamic responses to laryngoscopy and endotracheal intubation.Methods: Sixty ASA 1 and 2 patients scheduled for elective surgical procedures were randomly divided into three groups of 20 patients each. The patients of groups C, E and N received intravenous infusions of normal saline, esmolol hydrochloride (100 mgm/kg/min) and nitroglycerin (0.5 mgm/kg/min) respectively. Infusions were started 5 minutes before induction and continued till 5 minutes after intubation. Anesthesia was induced with thiopentone sodium and succinylcholine and maintained with nitrous oxide-oxygen and vecuronium bromide.Results: It was observed that nitroglycerin prevented a rise in diastolic blood pressure and attenuated the rise in systolic blood pressure, but failed to attenuate increase in the heart rate, while esmolol effectively controlled the increase in systolic BP, diastolic BP and heart rate following intubation.Conclusion: It was concluded that esmolol infusion is more effective in attenuating hemodynamic responses to intubation as compared to nitroglycerin infusion. Introduction In 1940, Reid and Brace1 first described hemodynamic response to laryngoscopy and intubation. Laryngoscopy and tracheal intubation are known to cause sympathoadrenal stimulation. This manifests as hypertension and tachycardia. Usually these transient changes have no deleterious consequences in healthy individual, but in some patients they can provoke left ventricular failure, myocardial ischemia and cerebral hemorrhage2,3. These complications are more likely to occur in the presence of coronary or cerebral atheroma or pre-existing hypertension4. The present study was conducted to study the efficacy of intravenous infusions of nitroglycerin and esmolol in attenuating these responses. Materials and methods The study was approved by the ethical committee of the hospital and was conducted in 60 ASA grade I and II patients of both sex, posted for surgery under general anaesthesia. Patients suffering from hypertension or other cardiovascular diseases were not included in the study. After obtaining informed consent they were randomly allocated to one of the following three groups of 20 patients each, depending on the infusion of the hypotensive agent through a syringe pump.Group C-Normal saline infusion (control group)Group E-Esmolol hydrochloride infusion 100 ?g/kg/minGroup N-Nitroglycerin infusion 0.5 ?g/kg/minAll patients were premedicated with alprazolam 0.5 mg two hours before operation. On arrival in the operation theatre patients’ baseline heart rate, systolic, diastolic and mean blood pressures were recorded and 0.2 mg glycopyrrolate and 0.5 mg/kg of pentazocine were administered intravenously. The infusion of normal saline/ study drug was started. The induction was done with thiopentone sodium 1-2 mg/kg and neuromuscular blockade was achieved by succinylcholine 1.5 mg/kg. Direct laryngoscopy was done and tracheal intubation was completed within 30 sec in all the patients. Serial measurement of heart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were done with a bioview monitor. The infusion (study drug/ saline) was stopped 5 minutes after intubation. Anaesthesia was maintained with 66% nitrous oxide in oxygen and vecuronium bromide. Data was analyzed by Chi square test and Students‘t’ test as applicable. Results The three groups were comparable with respect to age, weight and gender (Table 1).