每日一题_2022.09.22

A 50-year-old man with no significant past medical history is status post Hartmann procedure for a perforated diverticulum with purulent peritonitis. Postoperative hemoglobin level dropped significantly, so he was given a transfusion of 2 units of packed red blood cells; there were “coffee grounds” in the nasogastric aspirate. No further bleeding has been noted and no additional investigations were undertaken. On postoperative day (POD) seven, he remains intubated because of severe alcohol withdrawal. He has been consistently febrile, although he was successfully weaned off vasopressors 72 hours ago. Renal and hepatic function are within normal limits. This morning his platelet count is 45,000 x 103/mm3. Platelet counts have shown the following trend: baseline, 350 x 103/mm3; POD 1, 254 x 103/mm3; POD 2, 214 x 103/mm3; POD 3, 185 x 103/mm3; POD 4, 132 x 103/mm3; POD 5, 109 x 103/mm3; POD 6, 72 x 103/mm3. Medications include ventilator-associated pneumonia prophylaxis with chlorhexidene, pantoprazole, piperacillin/tazobactam, enoxaparin, vancomycin, fentanyl, lorazepam, midazolam, haloperidol, parenteral nutrition. Doppler ultrasound of the lower extremities is negative.

In addition to discontinuing enoxaparin, which of the following is the most appropriate treatment to address his thrombocytopenia?

A. Argatroban

B. Aspirin

C. Fondaparinux

D. Mechanical prophylaxis

答案解析：

阿加曲班不正确。使用 4Ts 评分系统应用预测试概率评估表明，由于发病时间是在四天前开始使用低分子量肝素之前观察到的血小板下降趋势之后，因此发生时间与肝素诱导的血小板减少症 (HIT) 不一致（0 分）。尽管血小板下降的程度（大于 50%）为 2 分，但还有其他明确的血小板减少原因（哌拉西林/他唑巴坦、阴燃感染）（0 分）且没有新血栓形成的证据（0 分）。因此，4Ts 总分为 2，表示概率低，仅受血小板下降程度驱动。尽管该评分系统在识别危重患者的风险方面可能并不完全可靠，但这种差异是由于缺乏对既往肝素暴露以及 HIT 的替代原因的了解造成的。患者既往未接触过肝素，且有其他可能导致血小板减少的原因。正因为如此（建议以中等至高预测概率开始替代抗凝治疗）以及血小板计数低于 50 x 103/mm3（主要出血风险因素）和既往出血，阿加曲班治疗性抗凝治疗带来的风险大于益处。

阿司匹林是不正确的，因为目前的血小板水平使他处于高出血风险之中。 磺达肝癸钠 不正确，因为它禁用于血小板计数低于 50 x 103/mm3。 机械预防是正确的。 他的血小板计数低，低于 50 x 103/mm3（主要出血风险因素）和既往出血证实停止药物预防并开始机械方法直到血小板计数改善。

正确答案：D