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Ionized calcium concentration and cardiovascular function after cardiopulmonary bypass
Insights
Postoperative hypocalcemia is common after cardiopulmonary bypass surgery. Intravenous calcium chloride effectively corrects low ionized calcium (Ca++) levels without significantly impacting cardiac function.
Area of Science:
- Cardiovascular Surgery
- Anesthesiology
- Critical Care Medicine
Background:
- Cardiopulmonary bypass surgery frequently leads to hypocalcemia.
- The impact of hypocalcemia on cardiac function post-surgery requires clarification.
Purpose of the Study:
- To determine the incidence of postoperative hypocalcemia.
- To evaluate the effects of intravenous calcium chloride on ionized calcium levels and cardiac function.
Main Methods:
- Studied patients undergoing cardiopulmonary bypass.
- Administered intravenous calcium chloride (bolus or infusion) to correct low ionized calcium (Ca++) levels (<1.8 mEq/L).
- Monitored hemodynamic profiles, including cardiac index, stroke index, and vascular resistance, for two postoperative hours.
Main Results:
- Postoperative hypocalcemia was frequently observed.
- No significant differences in cardiac indices, stroke indices, or vascular resistances were found across groups, regardless of calcium therapy.
- Intravenous calcium chloride effectively corrected ionized calcium (Ca++) concentrations.
Conclusions:
- Postoperative hypocalcemia after cardiopulmonary bypass is common but typically not severe enough to cause significant cardiovascular depression.
- Intravenous calcium chloride is an effective treatment for correcting hypocalcemia in this patient population.
- Myocardial depression observed in patients likely stemmed from causes other than hypocalcemia.
Abstract:
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.