Identifying risk factors for postoperative ileus following open abdominal aortic aneurysm repair

Abstract

Background: Postoperative ileus (POI) is a common complication following major abdominal surgery. The majority of the data available regarding POI after abdominal surgery is from the gastrointestinal and urological literature. These data have been extrapolated to vascular surgery, especially with regard to enhanced recovery programs for open abdominal aortic aneurysm (AAA) surgery. However, vascular patients are a unique patient population and extrapolation of gastrointestinal and urological data may not necessarily be appropriate. Therefore, the purpose of this study was to delineate the prevalence and risk factors of POI in patients undergoing open AAA surgery.

Methods: This was a retrospective, single-institution study of patients who underwent open AAA surgery from January 2016 to July 2023. Patients were excluded if they had undergone nonelective repairs or had expired within 72 hours of their index operation. The primary outcome was rates of POI, which was defined as the presence of two or more of the following after the third postoperative day: nausea and/or vomiting, inability to tolerate oral food intake, absence of flatus, abdominal distension, or radiological evidence of ileus.

Results: A total of 123 patients met study criteria with an overall POI rate of 8.9% (n = 11). Patients who developed a POI had a significantly lower body mass index (24.3 kg/m² vs 27.1 kg/m²; P = .003), were more likely to undergo a transperitoneal approach (81.8% vs 42.0%; P = .022), midline laparotomy (81.8% vs 37.5%; P = .008), longer total clamp times (151.6 minutes vs 97.7 minutes; P = .018), greater amounts of intraoperative crystalloid infusion (3495 mL vs 2628 mL; P = .029), and were more likely to return to the operating room (27.3% vs 3.6%; P = .016). Proximal clamp site was not associated with POI (P=.463). Patients with POI also had higher rates of postoperative vasopressor use (100% vs 61.1%; P = .014) and greater amounts of oral morphine equivalents in the first 3 postoperative days (488.0 ± 216.0 mg vs 203.8 ± 29.6 mg; P = .016). Patients who developed POI had longer lengths of stay (12.5 days vs 7.6 days; P < .001), a longer duration of nasogastric tube decompression (5.9 days vs 2.2 days; P < .001), and a longer period of time before diet tolerance (9.1 days vs 3.7 days; P < .001). Of those who developed a POI (n = 11), four (36.4%) required total parental nutrition during the admission.

Conclusions: POI is a morbid complication among patients undergoing elective open AAA surgery that prolongs hospital stay. Patients at risk for developing a POI are those with a lower body mass index, as well as those who had an operative repair via a transperitoneal approach, midline laparotomy, longer clamp times, larger amounts of intraoperative crystalloid infusion, a return to the operating room, postoperative vasopressor use, and higher amounts of oral morphine equivalents. These data highlight important perioperative opportunities to decrease the prevalence of POI.

Keywords: Abdominal aortic aneurysm; Gastrointestinal; Open repair; Postoperative ileus.