Capillary leakage in cardiac surgery with cardiopulmonary bypass.

Cardiopulmonary bypass causes a systemic inflammatory response, which can lead to capillary leak syndrome. In 15 adults undergoing elective cardiac surgery with cardiopulmonary bypass, we determined the volume and peak time of capillary leakage from the measurements of extracellular fluid volume and circulating blood volume taken preoperatively, at various intervals up to 24 hours after surgery, and on the 7th postoperative day. Extracellular fluid volume rose from 15.5 +/- 2.7 L preoperatively to a peak 4 hours after surgery of 18.3 +/- 3.2 L and remained elevated at 24 hours. Circulating blood volume fell from 4.10 +/- 0.68 L preoperatively to 3.20 +/- 0.58 L at the end of surgery. Fluid administered intraoperatively did not raise the circulating blood volume. Intraoperative fluid balance was positive at 2.62 +/- 0.72 L but negative at all time points postoperatively. There was significant postoperative capillary leakage, increasing from 4.7% +/- 2.3% of body weight at the end of surgery to a peak 4 hours later of 5.4% +/- 2.0% and falling to 2.8% +/- 3.3% at 24 hours. This knowledge of the pattern of change in capillary leakage after cardiac surgery with cardiopulmonary bypass might serve as a valuable guide for postoperative management.