Effects of intravenous and oral clonidine on hemodynamic and plasma-catecholamine response due to endotracheal intubation.
OBJECTIVE
To investigate the effects of intravenous (IV) versus oral clonidine on alterations of heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and plasma-catecholamines due to endotracheal intubation.


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


METHODS
University hospital surgery operating room.


METHODS
33 ASA physical status I patients were randomly assigned to either receive clonidine 3 micrograms/kg IV immediately prior to anesthesia induction, clonidine 4 micrograms/kg orally 90 minutes prior to anesthesia induction, or placebo.


METHODS
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 determined CO.


RESULTS
Heart rate, MAP, CO, and plasma-catecholamine concentrations were measured. Measurements were performed prior to induction, during intubation, and 10 minutes after intubation. During endotracheal intubation, MAP was significantly lower in the IV clonidine group compared with the placebo and the oral clonidine groups. Cardiac output was significantly lower in the IV clonidine group only. In contrast to the placebo group, norepinephrine plasma concentrations did not increase in either clonidine group. Significant alterations of epinephrine plasma concentrations due to intubation were not observed in either group. Hemodynamics after intubation were not impaired by clonidine treatment.


CONCLUSIONS
In conclusion, IV clonidine reduced stress response to endotracheal intubation compared with placebo. Oral clonidine at the dose used was less effective in blunting hemodynamic stress response than IV clonidine.
Zalunardo
M P
MP
Institute of Anesthesiology, University Hospital Zurich, Switzerland.
Zollinger
A
A
Spahn
D R
DR
Seifert
B
B
Radjaipour
M
M
Gautschi
K
K
Pasch
T
T
D000284:Administration, Oral; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002395:Catecholamines / Q000097:blood*; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007275:Injections, Intravenous; D007442:Intubation, Intratracheal / Q000009:adverse effects*; D008297:Male
D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D003000:Clonidine