胸骨縦切開による大動脈弁置換術中に発生した片側性肺水腫

Unilateral Pulmonary Edema during Aortic Valve Replacement through Median Sternotomy

片側性肺水腫は，典型的には大量の胸水貯留や気胸による虚脱肺をドレナージにより急速に再膨張させる際に発生する1）．近年，右開胸による低侵襲心臓手術（MICS）の際においても片側性肺水腫が発生する場合があるとされ，その発生機序は明らかではないが，合併症や死亡率の増加に関係すると報告されている2～4）．胸骨縦切開による心臓手術における片側性肺水腫の発生に関してはこれまで注目されておらず5），発生頻度や予後は不明である．われわれは，胸骨縦切開による大動脈弁置換術において片側性肺水腫を経験したので，発生機序や予後について若干の文献的考察を加え報告する．

Unilateral pulmonary edema （UPE） has been reported as a re-expansion pulmonary edema that occurs following rapid re-expansion of a collapsed lung in a patient with pneumothorax or large volume of pleural fluid. Recently, UPE after minimally invasive cardiac surgery through right-sided thoracotomy has received considerable attention because of its increasing morbidity and mortality. However, development of UPE in patients undergoing cardiac surgery through median sternotomy has not generally been recognized. Herein, we present our experience of UPE of the right lung after aortic valve replacement through median sternotomy. UPE may reflect ventilation-induced lung injury in concomitant systemic inflammation by cardiopulmonary bypass. Heterogeneity of lung collapse and wide pleural opening, which induced lung overdistension during recruitement, were considered to be associated with the occurrence of UPE in this case. Preventive measures should be considered for patients with multiple risk factors, and a meticulous recruitment maneuver is required for lung re-expansion during cardiac surgery.