Lung dysfunction following cardiopulmonary bypass

It is well known by now that during open heart surgery many detrimental factors are involved in lung injury. The influence mainly of cardiopulmonary bypass (CPB), anesthesia, hypothermia, operation itself, as well as medication and transfusion, can cause a diffuse injury in the lungs, which most often leads to a postoperative pulmonary edema and abnormal gas exchange.

We performed an unrestricted search of Pubmed Medline and EMBASE from 1966 through 2008. Clinical, experimental, basic science, and review papers were included.

The hypothesis that a systemic inflammatory reaction takes place after the use of CPB, could explain most of these effects influences in the lung. On the other hand, the release of various pro-inflammatory cytokines like TNF-á, IL-1, IL-2, IL-6, IL-8, and endotoxin during CPB can lead to the entrapment of neutrophils in the pulmonary capillaries. Consequently, the following chain of reactions is likely to occur: an endothelial cell swelling, plasma and protein extravasation into the interstitial tissue, release of proteolytic enzymes, congestion of the alveoli with plasma, erythrocytes and inflammatory debris.

In this review we highlight the possible pathophysiological mechanisms implicated in the observed postoperative lung dysfunction.