Preoperative clonidine attenuates stress response during emergence from anesthesia.

STUDY OBJECTIVES

To investigate whether a single preoperative IV dose of clonidine blunts the hemodynamic and hyperadrenergic responses not only to intubation, but also to extubation.

DESIGN

Randomized, double-blind, placebo-controlled study.

PATIENTS

29 ASA physical status I and II patients (ages 18-65) who were scheduled for noncardiac, elective surgery. Patients were randomly assigned to either receive clonidine 3 microg/kg IV immediately before anesthesia induction or placebo.

INTERVENTIONS

Insertion of a 14 G cannula in a large cubital vein for the determination of plasma catecholamines using local anesthesia. Insertion of a radial artery catheter for measuring blood pressure (BP) using local anesthesia. Transthoracic echocardiography to determine cardiac output (CO).

MEASUREMENTS

Heart rate (HR), mean arterial pressure (MAP), CO, and plasma catecholamine concentrations. Measurements were performed: before induction (baseline), during intubation, 10 min after intubation, after surgery, during extubation, and 10 min after extubation.

MAIN RESULTS

During intubation MAP, HR, and CO were lower in the clonidine group. Compared with baseline measurements, MAP and CO increased less in the clonidine group during intubation. During extubation, MAP was lower in the clonidine group. CO and MAP increased less as compared with baseline measurements in the clonidine group. Compared with the measurements after surgery CO less in the clonidine group during extubation (p < 0.05 for all results).

CONCLUSIONS

A single preoperative IV dose of clonidine (3 microg/kg) blunts the hemodynamic responses due to extubation in noncardiac surgery of intermediate duration.