Oral clonidine blunts the hemodynamic responses to brief but not prolonged laryngoscopy.
OBJECTIVE
To determine whether a 300 micrograms dose of oral clonidine given 90 minutes prior to laryngoscopy and intubation provides hemodynamic protection from the stress of a brief (15-second) and/or a prolonged (45-second) laryngoscopy.


METHODS
Randomized, double-blind, placebo-controlled study.


METHODS
Inpatients and outpatients scheduled for general anesthesia with intubation at a university-affiliated medical center.


METHODS
Forty patients who gave informed, written consent to receive either an oral placebo or clonidine 5 micrograms/kg (up to a maximum dose of 300 micrograms) 90 minutes prior to induction of anesthesia and to undergo either brief or prolonged laryngoscopy prior to intubation.


METHODS
The patients underwent a standardized induction sequence that included d-tubocurarine 3 mg, thiopental sodium 5 mg/kg, and succinylcholine 1.5 mg/kg. The four treatment groups (each n = 10) included (1) placebo with 15-second laryngoscopy, (2) placebo with 45-second laryngoscopy, (3) clonidine with 15-second laryngoscopy, and (4) clonidine with 45-second laryngoscopy. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were mechanically obtained and recorded at 1-minute intervals for 12 minutes.


RESULTS
There were no differences between groups in the premedication hemodynamic measurements. Within each group, maximal hemodynamic variables increased significantly over the corresponding baseline values for that group. In the 15-second, but not the 45-second, laryngoscopy, clonidine successfully blunted the maximum SBP and DBP obtained when compared with the corresponding control group. In both the 15- and 45-second clonidine groups, maximum HR was significantly lower than in the corresponding placebo groups.


CONCLUSIONS
Oral clonidine, when used as a preoperative medication, affords hemodynamic protection to patients undergoing a 15-second laryngoscopy. However, the stress of a 45-second laryngoscopy may be too great or the 300 micrograms dose of clonidine too low to provide hemodynamic protection for patients in this group.
Laurito
C E
CE
Department of Anesthesiology, University of Illinois College of Medicine, Chicago.
Baughman
V L
VL
Becker
G L
GL
Cunningham
F
F
Pygon
B H
BH
Citron
G M
GM
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects*; D003000:Clonidine / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007442:Intubation, Intratracheal; D007828:Laryngoscopy; D008875:Middle Aged; D010919:Placebos; D013997:Time Factors
D010919:Placebos; D003000:Clonidine