The Journal of Thoracic and Cardiovascular Surgery, Vol 104, 327-332, Copyright © 1992 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The effect of calcium on pulmonary vascular resistance and right ventricular function
MK Urban and R Hines
Department of Anesthesiology, Yale University School of Medicine, New Haven, Conn. 06510.
Calcium chloride is frequently administered to patients immediately after
separation from cardiopulmonary bypass to improve the contractile state of
the myocardium. Animal studies suggest that calcium chloride may produce
increases in pulmonary vascular resistance, which can precipitate right
ventricular failure. In an attempt to determine the effect of calcium
chloride administration after cardiopulmonary bypass on right ventricular
function, this study was designed to evaluate patients with normal and
elevated pulmonary vascular resistance. Fifty patients scheduled for
elective cardiac surgery were prospectively studied for changes in ionized
calcium levels before and after bypass. The impact of calcium
administration on right ventricular function was assessed by a pulmonary
artery catheter modified for the measurement of right ventricular ejection
fraction. In all patients the level of ionized calcium decreased during
bypass from a mean of 4.91 to 4.29 mg.dl-1. However, the infusion of
calcium chloride (10 mg.kg-1) after bypass resulted in increasing the
ionized calcium levels to prebypass levels. Administration of calcium
chloride after bypass to patients with normal right ventricular function
resulted in a transient increase in both cardiac output and right
ventricular ejection fraction without any change in pulmonary vascular
resistance. Eight patients with both elevated pulmonary vascular resistance
and depressed right ventricular function were evaluated to determine the
effect of calcium chloride after bypass on pulmonary vascular resistance
and right ventricular ejection fraction. Administration of calcium chloride
(10 mg.dl-1) to these patients did not result in any significant increase
in pulmonary vascular resistance or depression of right ventricular
performance. More important, in these patients, right ventricular ejection
fraction and cardiac output were significantly increased after calcium
chloride administration. In summary, the results of this study fail to
demonstrate any increase in pulmonary vascular resistance or deterioration
of right ventricular function with the administration of calcium chloride
(10 mg.kg-1) after bypass in patients with elevated pulmonary vascular
resistance.
