Intraoperative calf blood pressure measurements for the detection of early lower extremity ischemia following endovascular aneurysm repair

Background: Access vessel complications during endovascular aneurysm repair (EVAR) remain a concern and has been reported to occur in 3–10% of cases. The purpose of this study is to report our experience with intraoperative, non-invasive calf blood pressure (BP) measurements and ankle brachial indexes (ABIs) before and immediately following EVAR, in evaluating the perfusion of the lower extremities and detecting early lower extremity ischemia (LEI). Methods: We performed a retrospective review of all consecutive patients who underwent EVAR at our institution between the years 2019 and 2021. All patients had blood pressure cuffs placed on their calves prior to the procedure. Calf BP measurements and ABIs were obtained prior to and immediately after the surgery. Based on the BP measurements, patients were categorized into two groups. Group 1: patients with unchanged ABIs at the end of the procedure. Group 2: patients who experienced a decrease in ABIs at the end of the procedure (no BP obtained or decrease of ABI >0.3 from preoperative measurement). Patients in group 2 underwent exploration of the access vessel. Based on these, the positive and negative predictive values of the study were calculated. Results: During the study period we performed 113 EVAR procedures for abdominal, thoracic, and thoracoabdominal aortic aneurysms, in which 226 femoral arteries were accessed. Mean age was 71 years and 88% were males. In 219 (97%) of the limbs, there was no change in calf BP measurements and ABIs immediately after the procedure, when compared to the preoperative measurements, and none suffered a decrease in follow up ABIs. In 7 limbs (3%), there was a decrease in the calf BP (group 2), and all underwent exploration of the femoral artery. In 5 of these, a pathology was found within the artery. The positive predictive value of the intraoperative calf BP measurement was 71%. The negative predictive value of the study was 100%. Conclusion: Intraoperative calf BP and ABIs is a simple method to assess the lower limb perfusion and detect LEI following EVAR. The exam is particularly accurate in ruling out LEI as it has a very high negative predictive value. However, an abnormal measurement does not necessarily confirm LEI.