The impact of diaphragm management on prolonged ventilator support after thoracoabdominal aortic repair

Purpose: The relationship of the division of the diaphragm during thoracoab dominal aortic repair to prolonged ventilator support has not been studied. The purpose of this study was (1) to determine whether preservation of dia phragm integrity has a significant effect on postoperative ventilator durat ion and (2) to elucidate other pulmonary risk factors related to thoracoabd ominal aortic surgery and to study the relationship of these factors to the intact diaphragm technique. Methods: Between February 1991 and January 1997, me repaired 397 descending and thoracoabdominal aortic aneurysms. Descending thoracic aneurysms mere not included in the study because their repair does not include the diaphra gm. A total of 256 patients participated in this study. The diaphragm was d ivided in 150 patients and left intact in 106 patients. Examined as potenti al risk factors were patient demographics, history and physical findings, a neurysm extent, urgency of the procedure, acute dissection, crossclamp time , homologous and autologous blood product consumption, and adjunctive opera tive techniques. FEV1 also was considered in the 197 patients far whom preo perative spirometry was available. Prolonged mechanical ventilation was def ined as ventilator support for >72 hours. Data were analyzed by univariate contingency table and multiple logistic regression methods. Results: Increasing age (odds ratio [OR], 1.02/y; P <.02, current smoking ( OR, 2.6; P<.0008), total cross-clamp time (OR, 1.0/min; P<.008), units pack ed red blood cells transfused (OR, 1.06/unit; P <.008), and division of the diaphragm (OR, 2.03; P <.02) were significant, independent predictors of p rolonged ventilation. Sixty-seven percent of patients (71 of 106) whose dia phragms were preserved were extubated in <72 hours compared with 52% of pat ients (78 of 150) who underwent diaphragm division (OR, 0.53; P<.02). Conclusion: Independently of well known pulmonary risk factors, an intact d iaphragm during thoracoabdominal aortic repair results in a higher probabil ity of early ventilator weaning.