Intravenous heparin for cardiopulmonary bypass is an acute vasodilator.
OBJECTIVE
To investigate the changes in hemodynamic profile during cardiopulmonary bypass, and determine the effect of intravenous (IV) heparin on serum chemistry and acid-base status.


METHODS
Prospective study.


METHODS
Three Canadian hospitals.


METHODS
43 consecutive patients undergoing elective aortocoronary bypass.


METHODS
Anesthetic technique was standarized. Hemodynamic profile, blood gases, and serum electrolytes were measured immediately before IV heparin for cardiopulmonary bypass, and 5 minutes after.


RESULTS
Mean arterial pressure (MAP) decreased by a mean of 11.2 mmHg (12.5%, p = 0.0001) in all patients, of whom 28% were treated with vasoactive drugs to restore MAP. Mean systemic vascular resistance decreased by 418 dyne sec/cm(5) (25%, p = 0.0001), and mean serum potassium increased by 0.14 meq/L (p = 0.0002). The reduction in MAP correlated strongly with the reduction in SVR (p = 0.004), but not with changes in potassium or other variables.


CONCLUSIONS
Mean arterial pressure is significantly affected by IV heparin for cardiopulmonary bypass. The hemodynamic mechanism is systemic vasodilation, implying that treatment with a short-acting vasoconstrictor is appropriate, if necessary. Unlike earlier studies, the increase in serum potassium observed, although reproducible, was trivial.
Jacka
Michael J
MJ
Department of Anesthesia and Critical Care, University of Alberta, Edmonton, Alberta, Canada.
Clark
Andrew G
AG
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000925:Anticoagulants / Q000008:administration & dosage* / Q000494:pharmacology*; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D002315:Cardiopulmonary Bypass; D004573:Electrolytes / Q000097:blood; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects*; D006493:Heparin / Q000008:administration & dosage* / Q000494:pharmacology*; D006801:Humans; D007275:Injections, Intravenous; D011446:Prospective Studies; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000008:administration & dosage* / Q000494:pharmacology*
D000925:Anticoagulants; D004573:Electrolytes; D014665:Vasodilator Agents; D006493:Heparin