Lung Injury after Cardiopulmonary Bypass

Pulmonary injury during cardiopulmonary bypass is common as patient factors (smoking, pain, pneumonia) and the effects of cardiopulmonary bypass combine to compromise lung function after cardiac surgery. Lung injury follows the propagation of an inflammatory response involving cytokines, complement, neutrophils, monocytes, activated endothelial cells and platelets. Neutrophils sequester in the lung in response to chemo-tactic agents and release injurious oxygen free radicals and specific enzymes resulting in widespread pulmonary injury. To alleviate this lung injury a number of possible interventions exist. Off pump surgery may reduce the degree of systemic inflammation but respiratory impairment still occurs and the clinical advantage is uncertain. The use of leukocyte filtration can attenuate the acute inflammatory response with encouraging though variable results. Aprotinin, Pentoxyfilline, Nitric oxide, Aspirin and other agents have shown benefits in lung function after cardiopulmonary bypass induced lung injury. Given the magnitude and diversity of the inflammatory response to cardiopulmonary bypass many possible interventions exist to attenuate lung injury resulting from extracorporeal circulation. Immediate clinical benefits are likely to result from successful amelioration of the processes involved.