Pulmonary risk factors of elective abdominal aortic surgery

The purpose of this study was to retrospectively identify risk factors for postoperative pulmonary complications in patients undergoing elective abdominal aortic surgery via a midline incision.

We reviewed 181 consecutive patients who underwent operation between July 1986 to December 1992. Preoperative factors analyzed included age, sex, diabetes mellitus, history of smoking, chronic obstructive pulmonary disease, obesity, indication for surgery (aneurysm [126] or aortoiliac occlusive disease [AIOD] [55]), history of coronary artery disease, length of preoperative hospital stay, American Society of Anaesthesiologists class, and pulmonary function tests. Intraoperative factors analyzed included endotracheal tube diameter, percent of inspired oxygen, blood loss, blood and crystalloid replacement, total operative time, epidural analgesia, and stress ulcer prophylaxis.

Although the operative mortality rate was only 1.7% (3 of 181), major pulmonary complications occurred in 29 (16%) patients, including two lung-related deaths. Pneumonia occurred in 17 (9%) patients, prolonged intubation greater than 24 hours occurred in nine (5%), and reintubation caused by pulmonary insufficiency occurred in three (2%). On univariate analysis, the following were associated with major pulmonary complications (p < 00.05): American Society of Anaesthesiologists class IV, age greater than 70 years, ideal body weight greater than 150%, forced vital capacity of 80% or less predicted, forced expiratory flow rate (25 to 75) of 60% or less predicted, crystalloid replacement greater than 6 L, and total operative time greater than 5 hours.

The presence of these pulmonary risk factors, notably increased age and weight, decreased forced vital capacity and forced expiratory flow rate (25 to 75), and expected prolonged operative time, influences our decision not to proceed with surgery for small aortic aneurysms or for AIOD causing claudication. Patients at high pulmonary risk with AIOD who require revascularization for limb salvage would be more likely to undergo extraanatomic bypass. Pulmonary risk factors may play as important a role as cardiac factors in elective aortic surgery.