摘要：Patients who undergo thoracic aortic surgery with deep hypothermia frequently have postoperative respiratory failure as a complication. Severe lung injury in these patients results in a fatal outcome. A specific neutrophil elastase inhibitor, sivelestat sodium hydrate, is an innovative therapeutic drug for acute lung injury. We evaluated the protective effects of sivelestat sodium hydrate on severe lung injury after thoracic aortic surgery with deep hypothermia. From January 2002 to July 2007, 71 consecutive patients underwent thoracic aortic surgery with deep hypothermia. Of these patients, 22 had postoperative respiratory failure with PaO₂/FiO₂ ratios of less than 150. They were randomly assigned to one of two groups. The first group (Group S, n = 10) was administered sivelestat sodium hydrate continuously at 0.2 mg/kg/h until weaning from mechanical ventilation; the second group (Group C, n = 12) was not administered sivelestat sodium hydrate. The groups were comparable with respect to clinical data. There were no significant differences between the two groups in age, operation duration, total cardiopulmonary bypass time, circulatory ischemia time, cardiac arrest time, intraoperative blood loss, and total transfusion volume. The improvement of pulmonary function was observed in the both groups, but more marked in Group S by statistical analysis using analysis of variance for repeated measurements. Especially, in the early phase, pulmonary function improvement was more marked in Group S. The duration of mechanical ventilation, the length of stay in the intensive care unit, and the length of hospital stay were shorter in Group S, but not significantly. Sivelestat sodium hydrate is a specific neutrophil elastase inhibitor that improves pulmonary function in patients with severe postoperative respiratory failure following thoracic aortic surgery with deep hypothermia. The drug may shorten the duration of postoperative ventilation, intensive care unit stay, and hospital stay.