Ionized calcium concentration and cardiovascular function after cardiopulmonary bypass
R. A. Auffant, J. B. Downs and R. Amick
Patients who required cardiopulmonary bypass were studied to determine the
postoperative incidence of hypocalcemia and to quantify the effects of
intravenous (IV) calcium chloride on ionized calcium (Ca++) concentration
in blood and on cardiac function. Patients either received no calcium
chloride postoperatively (control), or received it as an intermittent IV
bolus (5 mg/kg) or as a constant infusion (0.5 mg/kg/min) whenever Ca++
concentration was less than 1.8 mEq/L. Hemodynamic profiles were determined
every 15 minutes during the first two postoperative hours. Regardless of
Ca++ concentration and therapy, cardiac indices, stroke indices, and
vascular resistances of all patients never differed significantly. No
variable changed consistently, other than Ca++ concentration, in those
patients receiving calcium chloride. We conclude that postoperative
hypocalcemia occurs frequently after cardiopulmonary bypass surgery, but
not to the degree that would be expected to cause cardiovascular
depression, and is readily corrected with IV calcium chloride. Myocardial
depression occurred in all patients, but likely resulted from other causes.
