pHi monitoring of the sigmoid colon after aortoiliac surgery.: A five-year prospective study

Objectives: to determine whether sigmoid-pHi diagnose colon ischaemia after aortoiliac surgery? Design: single-centre, non-randomised, prospective study. Patients and Methods: of 83 patients operated on between 1994 and 1998, 41 with risk factors for the development of colon ischaemia were monitored peri- and/or postoperatively with sigmoid-pHi. Peri-operative mortality was 26% (8/31) after operation for a ruptured abdominal aortic aneurysm (AAA), nil after operation for non-ruptered AAA. Thirty-five postoperative colonoscopies were performed. All non-survivors were examined post-mortem. Results: of six patients developing colon ischaemia after emergency operations (five for ruptured AAA) all had pHi-values <7.1 for 16-80 h. In two patients with transmural gangrene, and who had pHi-values below 6.6, pHi-monitoring permitted early diagnosis, colectomy and recovery. Three patients with mucosal gangrene were treated conservatively and recovered. Nine patients without ischaemic lesions had pHi-values <7.1, during 16 h, without adverse outcome. Bilateral ligation of the internal iliac arteries increased the risk of colon ischaemia (p < 0.0001). Conclusions: pHi-monitoring was diagnostic for colon ischaemia. Mucosal and transmural gangrene were distinguished. The importance of the internal iliac circulation was demonstrated. The low mortality rate, and the fact that no patient died from bowel ischaemia, suggests that sigmoid pHi-monitoring may improve survival after ruptured AAA.