Bleeding in abdominal aortic aneurysm repair

Abstract

Background and aims: Massive bleeding in open abdominal aortic aneurysm (AAA) repair is associated with worse outcome. However, few studies have investigated specific problems related to perioperative bleeding and blood transfusion in elective or emergent AAA repair with open (OR) or endovascular (EVAR) aneurysm repair. The overall aim of this thesis project was to investigate the clinical problem of bleeding in open and endovascular repair in both ruptured and elective AAA, including treatment of bleeding and association to risk factors and outcome in this patient group.

Patients and Methods: The studies were retrospective and based on medical records (all) and regional and national registries (Papers II-IV). Paper I studied the Fascia Suture Technique (FST) as closure method for hemostasis in 160 femoral access sites after EVAR in AAA patients. Paper II investigated ruptured (rAAA) and non-rAAA cases undergoing EVAR in 525 patients. Perioperative bleeding and the association to mortality and morbidity was investigated. Paper III investigated preoperative coagulation tests and their association to preoperative hypotension and perioperative bleeding and outcome in 91 rAAA patients. Paper IV studied blood transfusion in 369 ruptured AAA (rAAA) patients undergoing OR or EVAR. Timing of blood transfusion and time dependent ratios of blood products were studied and related to method of repair and outcome.

Results: In Paper I FST was associated with a 91% success rate. Complications were two pseudoaneurysms (PA) at 30-day follow-up and nine <1cm PA at 1-year. No specific preoperative risk factor for failure of the method was found. In Paper II a perioperative bleeding of >2 liters was independently associated with increased mortality (non-rAAA patients odds ratio 30; 95% CI [3.6, 145], rAAA patients odds ratio 10.7; 95% CI [3.2, 36.1]) and morbidity in non- and rAAA cases. Open femoral access, branched EVAR and larger diameter introducers were associated with increased perioperative blood loss. In Paper III low preoperative fibrinogen concentration (<1.5 g/L) was significantly associated with preoperative hypotension (systolic blood pressure <70 mmHg), increased perioperative bleeding and worse outcome after rAAA. In Paper IV delayed platelet transfusion (>1h) was associated with increased mortality in rAAA patients requiring massive transfusion (>10 units within 24 h or 4 units within 1 h). Fifty-five percent of rAAA patients repaired by EVAR received massive transfusion. Transfusion ratios of 1:1 for fresh frozen plasma (FFP):red blood cells (RBC) were associated with lower mortality. Ratios of platelets (PLT):RBC increased significantly over the study period.

Conclusions: • Fascia Suture Technique proved feasible and safe with a low complication rate. Introducer size had no impact on outcome. No preoperative risk factors for failure were found. • A perioperative blood loss exceeding 2 liters in EVAR was independently associated with increased mortality and morbidity in both acute and elective AAA patients. Procedural risk factors for increased perioperative bleeding were open femoral access, fascia suture technique, branched stent grafts and aneurysm diameter. • Preoperative fibrinogen concentrations below 1.5 g/L were associated with a ten-fold increased risk of perioperative bleeding of more than 2 liters in rAAA. Low fibrinogen concentration should be suspected in patients with preoperative hypotension. • A ratio FFP: RBC close to 1:1 in EVAR and open repaired patients was associated with lower mortality. • Delayed (>1h) platelet transfusion was associated with significantly increased mortality. Ratios of PLT:RBC have increased over the last years. • Transfusion strategies in patients undergoing rAAA treatment with EVAR or open repair need further research. Also the definitive role of fibrinogen in patients with rAAA and hemodynamic shock need to be investigated in future studies.