Risk Factors for Abdominal Compartment Syndrome After Endovascular Repair for Ruptured Abdominal Aortic Aneurysm: A Case Control Study.

OBJECTIVE:Ruptured abdominal aortic aneurysms (rAAA) are treated by endovascular aneurysm repair (rEVAR) increasingly often. Despite rEVAR being a minimally invasive method, abdominal compartment syndrome (ACS) remains a significant post-operative threat. The aim of this study was to investigate risk factors for ACS after rEVAR, including aortic morphological features. METHODS:The Swedish vascular registry (Swedvasc) was assessed for ACS after rEVAR in the period 2008 - 2015. All patients identified were compared with controls (i.e., patients who did not develop ACS after rEVAR), matched by centre and repair date. Case records were reviewed, and radiology images analysed in a core laboratory. Comparisons were performed with respect to physiological and radiological risk factors. RESULTS:The study population consisted of 40 patients with ACS and 68 controls. Pre-operatively, patients with ACS had a lower blood pressure (BP) than controls (median 70 mmHg vs. 97 mmHg; p < .001). Intra-operatively, they had aortic balloon occlusion more often (55.0% vs. 10.3%; p < .001) and received more transfusions than controls (median nine units of packed red blood cells [pRBC] vs. two units; p < .001). Ninety-seven per cent of those who developed ACS had a pre-operative BP < 70 mmHg, aortic balloon occlusion, or received more than five pRBC unit transfusions. Treatment outside the instructions for use did not differ between patients and controls (57.5% vs. 54.4%; p = .84), and neither did the pre-operative patency of the inferior mesenteric artery (57.1% vs. 63.9%; p = .52) nor the number of visible lumbar arteries on pre-operative imaging (2 vs. 4; p = .014). In multivariable logistic regression, the number of intra-operative transfusions were predictive of ACS (p < .001), while pre-operative hypotension (p = .32) and aortic balloon occlusion (p = .018) were not. CONCLUSION:ACS after rEVAR is mainly associated with physiological factors and is unlikely to develop without the presence of a pre-operative BP < 70 mmHg, the need for an aortic occlusion balloon, or more than five intra-operative pRBC unit transfusions. Treatment outside the IFU or any other morphological factor were not associated with a risk of ACS.