護理師查閱一名接受持續靜脈輸注肝素 (heparin) 病人的病歷。哪項數值顯示治療達標（治療範圍內）？

核心概念：肝素（Heparin）靜脈輸注的治療監測。 為何正確答案對： B. 肝素的治療效果是透過監測活化部分凝血酶時間（Activated Partial Thromboplastin Time, aPTT）來評估。治療範圍通常是正常 aPTT 值的 1.5 至 2.5 倍。若正常 aPTT 值為 30-40 秒，則治療範圍約為 45-100 秒。 aPTT 值為 70 秒，處於此範圍內，表示肝素治療達到預期的抗凝血效果。 為何其他選項錯： A. aPTT 20 秒遠低於治療範圍，表示抗凝血效果不足，有血栓形成的風險。 C. 國際標準化比值（INR）主要用於監測口服抗凝血藥物 Warfarin 的效果，與肝素無關。 B. 凝血酶原時間（Prothrombin time, PT）也是評估 Warfarin 效果的指標，或用於評估外源性凝血途徑，與肝素的 aPTT 監測不同。 臨床思路（Pharmacological Therapies/Risk Management）：肝素輸注的目的是預防血栓形成，但過量則會導致出血。因此，精確監測 aPTT 值，確保其在治療範圍內，是平衡療效與安全性的關鍵。

Core concept: therapeutic monitoring of continuous IV heparin infusion. Why the correct answer is correct: B. The therapeutic effect of heparin is monitored by activated partial thromboplastin time (aPTT). The therapeutic range is typically 1.5 to 2.5 times the normal aPTT value. If the normal aPTT is 30–40 seconds, the therapeutic range is approximately 45–100 seconds. An aPTT of 70 seconds falls within this range and indicates that the heparin therapy is achieving the desired anticoagulant effect. Why the other options are wrong: A. An aPTT of 20 seconds is well below the therapeutic range, indicating insufficient anticoagulation and a risk of thrombus formation. C. The international normalized ratio (INR) is primarily used to monitor the effect of oral warfarin therapy and is not relevant to heparin. D. Prothrombin time (PT) is also used to monitor warfarin or to assess the extrinsic coagulation pathway and differs from the aPTT-based monitoring used for heparin. Clinical reasoning (Pharmacological Therapies/Risk Management): The goal of heparin infusion is to prevent thrombus formation, but excessive doses can lead to bleeding. Therefore, precisely monitoring the aPTT to ensure it remains within the therapeutic range is key to balancing efficacy and safety.