The pathogenesis of lung injury following pulmonary resection

Postpneumonectomy pulmonary oedema (PPO) develops in similar to 5% of patie nts undergoing pneumonectomy or lobectomy, and has a high associated mortal ity (>50%). In its extreme form, PPO follows a clinical and histopathotogic al course indistinguishable from acute respiratory distress syndrome. Perioperative fluid overload, impaired lymphatic drainage following node di ssection and trauma caused by surgical manipulation have been implicated in the pathogenesis of PPO, However, PPO more probably represents the pulmona ry manifestation of a panendothelial injury consequent upon inflammatory pr ocesses induced by the surgical procedure, which involves collapse and re-e xpansion of the operative lung to permit hilar dissection and pulmonary res ection. High inspired oxygen concentrations are required to overcome the effects of shunt. Animal studies have shown that pulmonary ischaemia/reperfusion can result in oedema formation, possibly due to the generation of pro-oxidant f orces. Moreover, plasma taken from patients undergoing lobectomy or pneumon ectomy (but not lesser resections) shows evidence of oxidative damage. Such evidence suggests either that the high inspired oxygen concentrations associated with one-lung ventilation, or ischaemia/reperfusion injury; may modulate postpneumonectomy pulmonary oedema. Mechanisms by which redox imba lance may result in tissue damage and postpneumonectomy pulmonary oedema ar e discussed.