病人服用毛地黃（Digoxin）。出現下列何種情形應暫停給藥？

毛地黃（Digoxin）具有正性肌力作用（增加心肌收縮力）與負性變時作用（減慢心跳速率）。由於其治療窗（Therapeutic window）狹窄，極易發生毛地黃中毒（Digoxin toxicity），心搏過緩（Bradycardia）常是中毒的早期徵象之一。臨床常規規定，給予毛地黃前必須先測量心尖脈（Apical pulse）滿一分鐘，若心跳小於 60 bpm，則必須暫停給藥並通知醫師，以防心律過慢導致心輸出量不足或危及生命的心律不整。

Digoxin has both a positive inotropic effect (increased myocardial contractility) and a negative chronotropic effect (decreased heart rate). Because its therapeutic window is narrow, digoxin toxicity occurs readily, and bradycardia is often an early sign of toxicity. Standard clinical practice requires measuring the apical pulse for a full minute before administering digoxin; if the heart rate is below 60 bpm, the medication must be withheld and the physician notified to prevent inadequate cardiac output or life-threatening dysrhythmias from slow heart rates.

在美國臨床，護理師給藥前評估心跳 < 60 bpm 停藥是標準 Protocol；在台灣臨床，部分醫院針對心衰竭病人可能有不同的心跳下限設定（如 < 50 或 < 60 bpm），務必遵照單位醫囑（Standing order）執行。