Correction of hypocalcaemia in the critically ill: what is the haemodynamic benefit?

OBJECTIVE

The prevalence of hypocalcaemia is known to be elevated in critically ill patients, but the expected benefit from calcium repletion in hypocalcaemic patients has not been well defined. The objective of the present study was therefore prospective determination of the cardiovascular response to calcium administration in critically ill patients with hypocalcaemia.

PATIENTS

A total of 17 patients found to have ionized hypocalcaemia (Ca2+ < 1.05 mmol/l) from a group of 32 patients who were invasively monitored as part of their ICU management.

INTERVENTION

Slow intravenous injection of 1 g of calcium chloride.

MEASUREMENTS AND RESULTS

Calcium administration was followed by an increase in mean arterial pressure from 77 +/- 8 to 90 +/- 12 mmHg (P < 0.01). There was no significant change in cardiac filling pressures or heart rate. Cardiac index and systemic vascular resistance increased slightly but not significantly (from 2.67 +/- 0.92 to 2.81 +/- 1.25 1/min.m2 and from 2133 +/- 647 to 2378 +/- 817 dynes.s.cm-5 m-2, respectively). Left ventricular stroke work index increased from 23 +/- 8 to 32 +/- 13 g.m/m2 (P < 0.01). These changes were maintained for 60 min.

CONCLUSIONS

The correction of hypocalcaemia can result in a significant increase in arterial pressure that can persist for at least 1 h. Despite an associated improvement in left ventricular function, cardiac index and oxygen delivery do not increase significantly.