Effect of calcium infusion on heart function.

The effects of calcium on heart function were studied in ten critically ill hypocalcemic patients (Ca++ = 1.93 +/- 0.08 mEq/L SD). Total calcium (TC), Ca++, blood pressure (MAP), venous pressure (CVP), pulmonary wedge pressure (PWP), cardiac output (CO), heart work (LVSW), systemic resistance (SPR), and pulmonary resistance (PVR) were measured before, during (15 and 30 minutes), and after (60 minutes) a 30-minute infusion of 1 gm CaCl2 (13.7 mEq). Calcium chloride infusion increased Ca++ significantly at 15 and 30 minutes (2.2 +/- 0.25 mEq/L) and remained elevated at 60 minutes (2.12 +/- 0.24). Cardiac output and LVSW rose at 15 minutes (9.4 leads to 10.6 L/min; 98 leads to 115 gm-m) but fell to below preinfusion levels by 60 minutes (8.9 +/- 2.0 L/min and 92 +/- 30 gm-m, respectively). These data show that calcium infusion for hypocalcemia does not provide meaningful improvement in cardiovascular function and is best avoided unless left heart function is closely monitored.