The Effects of Labetalol or Fentanyl on Hemodynamic Responses to Endotracheal Intubation in Normotensive Patients

Song, He Sun; No, Shi Uhn; Kim, Seong Su; Kim, Dong Sun; Kim, Dong Chan

Abstract

Induction of general anesthesia with tracheal intubation may eause hypertension and tachycardia with concomitant increase in plasam catecholamine concentration. These transient stress responses are undesirable, especially in patients with cardiovascular or intracrainal diseases. Many drugs(topical or i.v. lidocaine, inhalation anestheties, opioids, adrenergic blockers, etc) are used in an attempt to blunt these potentially adverse hemodynamic responses. This study was made to examine blunting effect of labetalol and fentanyl for hemodynamic changes after tracheal intubation. Eighty patients, ASA physical status I or II, scheduled for elective surgery were selected randomly. They were divided into four groups. Group l: Control(saline)(n=20) Group 2: Labetalol 0.125 mg/kg(n=20) Group 3: Labetalol 0.25 mg/kg(n=20) Group 4: Fentanyl 3 ug/kg(n=20) Study drugs were injected 3 minutes before induction with thiopental sodium. Patients were induced with thiopental sodium 5 mg/kg and succinylcholine chloride l mg/kg i.v.in all groups. 5 minutes after injection of study drug, laryngoscopy was initiated and performed tracheal in- tubation. After the completion of intubation, 50% nitrous oxide in oxygen and 1.5vol.% halothane was administed. The blood pressure and heart rate were measured using automated noninvasive blood pressure device and E.C.G. monitoring for 10 minutes per 1 minute. Data were analyzed with Stu- dent's t-test within the group and unpaired t-test between the groups. P<0.05 was considered significant. Labetalol or fentanyl pretreatment significantly blunted the increase in heart rate and rate pressure product caused by laryngoscopy and endotracheal intubation. But the increase of arterial blood pressure was blunted significantly in fentanyl 3 ug/kg group. Labetalol and fentanyl may offer an important role in patients in whom an increase in blood pressure, heart rate and/or rate pressure product should be avoided during the endotracheal intubation.