Risk Factors of Thrombocytopenia After Cardiac Surgery with Cardiopulmonary Bypass

ABSTRACT Introduction: Postoperative thrombocytopenia is common in cardiac surgery with cardiopulmonary bypass, and its risk factors are unclear. Methods: This retrospective study enrolled 3,175 adult patients undergoing valve surgeries with cardiopulmonary bypass from January 1, 2017 to December 30, 2018 in our institute. Postoperative thrombocytopenia was defined as the first postoperative platelet count below the 10th quantile in all the enrolled patients. Outcomes between patients with and without postoperative thrombocytopenia were compared. The primary outcome was in-hospital mortality. Risk factors of postoperative thrombocytopenia were assessed by logistic regression analysis. Results: The 10th quantile of all enrolled patients (75×109/L) was defined as the threshold for postoperative thrombocytopenia. In-hospital mortality was comparable between thrombocytopenia and non-thrombocytopenia groups (0.9% vs. 0.6%, P=0.434). Patients in the thrombocytopenia group had higher rate of postoperative blood transfusion (5.9% vs. 3.2%, P=0.014), more chest drainage volume (735 [550-1080] vs. 560 [430-730] ml, P<0.001), and higher incidence of acute kidney injury (12.3% vs. 4.2%, P<0.001). Age > 60 years (odds ratio [OR] 2.25, 95% confidence interval [CI] 1.345-3.765, P=0.002], preoperative thrombocytopenia (OR 18.671, 95% CI 13.649-25.542, P<0.001), and cardiopulmonary bypass time (OR 1.088, 95% CI 1.059-1.117, P<0.001) were positively independently associated with postoperative thrombocytopenia. Body surface area (BSA) (OR 0.247, 95% CI 0.114-0.538, P<0.001) and isolated mitral valve surgery (OR 0.475, 95% CI 0.294-0.77) were negatively independently associated with postoperative thrombocytopenia. Conclusion: Positive predictors for thrombocytopenia after valve surgery included age > 60 years, small BSA, preoperative thrombocytopenia, and cardiopulmonary bypass time. BSA and isolated mitral valve surgery were negative predictors.

摘要
引言：体外循环（cardiopulmonary bypass）下心脏手术后血小板减少症较为常见，其危险因素尚不明确。
方法：本回顾性研究纳入2017年1月1日至2018年12月30日于本机构接受体外循环瓣膜手术的3175例成年患者。术后血小板减少症定义为所有入组患者术后首次血小板计数低于第10百分位数。比较伴与不伴术后血小板减少症患者的临床结局，主要结局为住院期间死亡率。采用logistic回归分析（logistic regression analysis）评估术后血小板减少症的危险因素。
结果：本研究将所有入组患者的第10百分位数血小板计数（75×10^9/L）定为术后血小板减少症的诊断阈值。血小板减少症组与非血小板减少症组患者的住院死亡率无显著差异（0.9% vs. 0.6%，P=0.434）。血小板减少症组患者术后输血率更高（5.9% vs. 3.2%，P=0.014），胸腔引流液量中位数更高（735 [550~1080] ml vs. 560 [430~730] ml，P<0.001），急性肾损伤发生率更高（12.3% vs. 4.2%，P<0.001）。Logistic回归分析显示，年龄>60岁（比值比（odds ratio, OR）2.25，95%置信区间（confidence interval, CI）1.345~3.765，P=0.002）、术前血小板减少症（OR 18.671，95%CI 13.649~25.542，P<0.001）以及体外循环时长（OR 1.088，95%CI 1.059~1.117，P<0.001）与术后血小板减少症呈独立正相关；体表面积（body surface area, BSA）（OR 0.247，95%CI 0.114~0.538，P<0.001）以及单纯二尖瓣手术（OR 0.475，95%CI 0.294~0.77）与术后血小板减少症呈独立负相关。
结论：瓣膜手术后血小板减少症的正向预测因素包括年龄>60岁、体表面积偏小、术前血小板减少症以及体外循环时长；体表面积与单纯二尖瓣手术为其负向预测因素。