Abdominal compartment syndrome and colonic ischaemia after abdominal aortic aneurysm repair in the endovascular era

Abdominal Compartment Syndrome (ACS) and colonic ischaemia (CI) are serious and potentially lethal complications after open (OSR) and endovascular repair (EVAR) of ruptured (rAAA) and intact (iAAA) abdominal aortic aneurysms. The aims of this thesis were to investigate the incidence, outcome, and risk factors associated with ACS (Papers I-III) and to evaluate extraluminal colonic tonometry for postoperative surveillance of colonic perfusion (Paper IV). Papers I-III combined data from the nationwide Swedish vascular registry (Swedvasc) (2008-2015) with case records and radiologic imaging. Paper I investigated incidence and outcome of ACS. The incidence was approximately 7% for both EVAR and OSR after rAAA and 1.6% after OSR and 0.5% after EVAR for iAAA. ACS was associated with a more than two-fold (59% vs 27%) 90-day mortality after rAAA and six-fold (19% vs 3%) after iAAA. Paper II investigated risk factors and outcome among subgroups. Risk of death could not be attributed to a specific main pathology of ACS: CI, postoperative bleeding and general oedema, nor to timing of decompressive laparotomy in relation to AAA surgery. However, the duration of intra-abdominal hypertension (IAH) predicted the need for renal replacement therapy. Paper III investigated risk factors after EVAR for rAAA. ACS was rare without pronounced pre- or intraoperative physiologic derangement associated with circulatory instability. Aortic morphology did not impact ACS development, nor did presence of a patent inferior mesenteric and lumbar arteries, known risk factors for type II endoleak. Paper IV studied patients operated on for iAAA/rAAA (n=27), and demonstrated extraluminal colonic tonometry safe, reliable and indicative of CI among all affected patients (n=4). In conclusion, ACS was common after rAAA repair, with poor outcome irrespective of AAA repair technique and indication for repair. Outcome did not differ depending on the main pathophysiological finding associated with ACS development, while a longer duration of IAH increased the risk of renal replacement therapy. ACS after EVAR for rAAA was largely associated with pre- and intraoperative physiologic factors. These findings highlight the importance of vigilant intra-abdominal pressure measurement after rAAA repair and in case of haemodynamic instability, as well as timely interventions to treat IAH. Extraluminal colonic tonometry appears promising for surveillance of postoperative colonic perfusion