Aortic Clamping Time Is Associated With Postoperative Thrombocytopenia Following Elective Open Abdominal Aortic Surgery

<b>Objective:</b> The objective of this study was to evaluate the incidence of thrombocytopenia following elective abdominal aortic surgery and identify the associated risk factors. <b>Methods:</b> From 2009 to 2020, all consecutive patients undergoing elective open infrarenal abdominal aortic repair for aneurysms (AAAs) or aortic occlusive disease (AOD) were included in a prospectively maintained dedicated database and subsequently analyzed retrospectively. The perioperative dataset included the duration of surgery, aortic clamping time, graft configurations, blood loss, and blood products administered during the procedure. Univariate and multivariable analyses were conducted to identify risk factors for postoperative thrombocytopenia and assess its clinical consequences. <b>Results:</b> A total of 100 patients (male <i>n</i> = 81, mean age of 68 ± 9.3 years) were included in the present study. The AAA group showed a higher prevalence of hypertension (<i>n</i> = 58 [76%]) versus AOD (<i>n</i> = 12 [50%]) with <i>p</i> = 0.014 and the use of vancomycin presurgery prophylaxis, <i>n</i> = 36 (47%) and <i>n</i> = 7 (29%), respectively, with <i>p</i> = 0.033. The AOD group presented a higher number of active smokers (<i>n</i> = 19 [79%]) versus AAA group (<i>n</i> = 30 [39%]) with <i>p</i> < 0.001. The overall mean operative aortic clamping time was 91.6 ± 35 min, with a significantly longer time in the AAA group (96.0 ± 36.1 min vs. 78.8 ± 28.5 min in the AOD group) with <i>p</i> = 0.046. The mean estimated blood loss was 1383 ± 834 mL, with a higher average of 1546 ± 878 mL in the AAA group versus 933 ± 472 mL in the AOD group with <i>p</i> = 0.002. A decrease in the platelet count was observed immediately after surgery, with a mean reduction from baseline of 40.5% ± 16.3% in the AAA, 41.9 ± 16.4% compared to 35.9% ± 15.4% in the AOD group with <i>p</i> = 0.553, reaching its nadir on postoperative Days 2 and 3. No major bleeding events associated with thrombocytopenia during the postoperative period were recorded. In 54 patients (54%), the platelet count returned to baseline by postoperative Day 5 (POD 5). Five patients exhibited a sustained platelet count drop of > 50% from baseline on POD 5 and were tested for heparin-induced thrombocytopenia, all of which returned negative results. On multivariable analysis, the patient age (OR 1.125; 95% CI: 1.024-1.236; <i>p</i> = 0.014) and clamping time (OR 1.034; 95% CI: 1.011-1.058; <i>p</i> = 0.004) were independently associated with a decrease in the platelet count. <b>Conclusion:</b> Postoperative thrombocytopenia is common following an elective abdominal aortic surgery, but it was demonstrated that it typically resolves on its own by POD 5 without significant clinical consequences. The study identified the patient age, and aortic clamping time as independent risk factors for the development of thrombocytopenia. However, further research involving larger cohorts is needed to confirm these findings and better understand the underlying mechanisms and potential implications.