Monitoring of beta-receptor sensitivity in cardiac surgery.
OBJECTIVE
To determine the repeatability of the hemodynamic response to repeated isoproterenol challenge doses to validate the standardized isoproterenol sensitivity test as an index of cardiovascular beta-receptor function.


METHODS
Prospective, single-blind, nonrandomized clinical trial.


METHODS
University department of cardiothoracic anesthesia.


METHODS
Twenty middle-aged men scheduled for primary elective coronary artery bypass surgery, 10 of whom had been treated with cardioselective beta1-antagonists for more than 3 months.


METHODS
After induction of anesthesia and baseline hemodynamic evaluation, cardiac beta-receptor sensitivity was estimated from the chronotropic/inotropic responses to four intravenous 4-microg isoproterenol bolus doses.


RESULTS
Baseline cardiovascular function and pharmacodynamic response to the four isoproterenol challenge doses were monitored with catheters in the radial and pulmonary arteries (thermodilution). Heart rate was continuously recorded and calculated from the electrocardiogram. Baseline hemodynamic status and response to the first 4 microg of isoproterenol were similar in the 10 patients treated with beta1-antagonists and the rest of the patients. In all 20 patients, heart rate response to the three subsequent isoproterenol challenge doses decreased progressively by 28%.


CONCLUSIONS
The standardized isoproterenol sensitivity test is unreliable for clinical monitoring of cardiac beta-adrenoceptor function.
Yndgaard
S
S
Department of Anaesthesiology, Gentofte Hospital, University of Copenhagen, Denmark.
Lippert
F K
FK
Bigler
D
D
Berthelsen
P G
PG
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D001026:Coronary Artery Bypass; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007545:Isoproterenol; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D011446:Prospective Studies; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013268:Stimulation, Chemical
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D007545:Isoproterenol