Which of the following does not typically occur during the first few minutes of cardiopulmonary bypass?

A. Interstitial fluid increases.

DISCUSSION: Several events occur during the first few minutes of bypass. The tubing and oxygenator surfaces are coated by serum proteins that in turn activate platelets. This reduces the platelet count. The roller pump produces nonpulsatile flow, which is different from the usual pulsatile cardiac flow. Serum complement is activated by exposure of blood to the nonphysiologic surfaces of the pump-oxygenator, and systemic vascular resistance falls. Interstitial fluid accumulates during bypass; however, this occurs later during bypass.