Comparison of the Effects of High Dose and Low (Common) Dose of Alfentanyl on Hemodynamic Changes Induced by Laryngoscopy and Tracheal Intubation

Sympathetic stimulation and pressor responses including tachycardia, hypertension and tachyarrhytmias caused by laryngoscopy and tracheal intubation may result in severe complications in susceptible patients. Opioid anesthetics are one of the several drugs used to attenuate this response but prolonged postoperative respiratory depression is the major complication distracting from their high dose administration which is nceded for complete amelioration of pressor response. In this study Alfentanyl, as a rapid acting and short duration opioid (without prolonged respiratory depression), was used in two different dosages for controlling of pressor response.

In a single blind, controlled clinical trial, 236 patients in the range of 18 to 70 years old), whom needing laryngoscopy and tracheal intubation were selected and randomly divided into two equal groups. First group received low (current) dose (15u gr/kg) Alfentanyl, and the other received high dose (450gr/kg), prior to laryngoscopy and tracheal intubation. Type and dosage of induction drugs were the same and matched in both groups. Blood pressure and heart rate were measured before intravenous induction and after intubation of the tracheal in all patients. Mercurial sphygmomanometer and pulse oximeter were used for these measurements. Incidence of such complications as hypotention, muscle stiffness and neurologic hyper reactivity, were also measured. Data were analysed by Z distribution and Chi square tests.

Alfentanyl was cffective in controlling pressor response in both groups. In the case of heart rate, the mean difference between two groups was not significant. There was a significant difference mean arterial pressure between two groups (p<0.05). In high dose group, incidence of complications was higher for severe hypotension (p<0.05), stiff chest syndrome (p<0.05), and neurologic hyperreactivity (p<0.05).

High dose of Alfentanyl is more efficient in controlling of pressor response than low dose of the drug. High dose administration also may results in some complications. In this study current dose of Alfentanyl is recommended for controlling of pressor response, but high dose may be used with some modification in the dose of induction agents.