On intestinal ischaemia after aortoiliac surgery : Epidemiological, clinical and experimental studies

Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

Sammanfattning: An important cause of death among patients undergoing surgery of the abdominal aorta is intestinal ischaemia. In the Swedish Vascular Registry 2930 aortoiliac operations were identified. The complication was studied in a combined cohort and case-control study, and multivariate analysis performed. The incidence of intestinal ischaemia was 2.8% overall, 1.1% after elective surgery and 7.3% after shock for a ruptured abdominal aortic aneurysm (AAA). One-fourth of the patients who died after operation on aruptured AAA, and one-tenth of those who died after operation for other indications, suffered intestinal ischaemia. The cardinal symptoms and signs of early, bloody diarrhea and peritonitis were often absent. Sigmoidoscopy was potentially diagnostic in 95% of cases. Important risk factors for the complication were preoperative shock or renal insufficiency, emergency surgery, ligation of one or both internal iliac arteries, aortobifemoral grafting, prolonged operation or cross-clamping time and operation at aregional hospital.In a clinical study on 34 patients, sigmoid colon intramucosal pH (pHi) was diagnostic for ischaemic colitis with both sensitivity and specificity of 100% when <6.86 for >4 hours, and for death or life-threatening complications with sensitivity 100% and specificity 92% when <7.10 for >2 hours. Gastric pHi had inferior predictive values.An experimental model of non-occlusive colonic ischaemia was established in the pig. All ischaemic animals had colonic pHi 6.9-7.1 and suffered mucosal ischaemic injury. Controls had no mucosal injury. In a non-randomised study no beneficial effect of dextran was observed. In a randomised study pigs were subjected to ischaemia for 7 hours. In the 12 animals receiving dobutamine, cardiac output was increased by 14% compared to baseline and by 59%o compared to nine controls, but blood flow of the superior mesenteric artery and colonic pHi were unaffected.In conclusion: the.importance of intestinal ischaemia after aortoiliac surgery was verified. Significant risk factors, avoidable by modifications in surgical technique, were identified. High-risk situations were described and the diagnostic value of sigmoidoscopy and of sigmoid pHi monitoring were suggested. An experimental model relevant for testing pharmacological influence was developed and proven reproducible.

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