Cardiovascular responses to calcium administered intravenously to man during halothane anesthesia.

Calcium chloride (7 mg/kg) was administered intravenously to six healthy volunteers anesthetized with halothane. Cardiovascular changes were measured during constant ventilation and anesthetic depth under three conditions: 1) respiratory alkalosis, 2) normocarbia, and 3) respiratory acidosis. At each Paco2, calcium infusion significantly increased cardiac index, left ventricular minute work index, and stroke index. Heart rate, total peripheral resistance, and cardiac pre-ejection period decreased. No significant change in mean arterial blood pressure or central venous pressure followed calcium administration, and no arrhythmias occurred. It is concluded that calcium administration increases myocardial performance, presumably by increasing the availability of intracellular calcium ion for actomyosin interaction.