一位病人被處方使用美托洛爾 (metoprolol)，一種 beta-阻斷劑。哪個評估發現是給予此藥物的禁忌？
A client is prescribed metoprolol, a beta-blocker. Which assessment finding is a contraindication for administering this medication?
- AHeart rate 48 beats/min✓ 正解心率 48 次/分
- BBlood pressure 110/70 mmHg血壓 110/70 mmHg
- CHeart rate 65 beats/min心率 65 次/分
- DHistory of hypertension有高血壓病史
美托洛爾 (Metoprolol) 為選擇性 Beta-1 受體阻斷劑，主要作用為降低心率 (Negative chronotropic effect) 與心肌收縮力。若病人本身心率過緩（通常界定在 50-60 bpm 以下），給予此藥將進一步抑制竇房結功能，可能導致嚴重心搏過緩，進而影響心輸出量導致暈厥或休克。
Metoprolol is a beta-blocker that decreases heart rate and myocardial contractility, making bradycardia a primary contraindication for its administration. A heart rate of 48 beats per minute indicates significant slowing that could be exacerbated by the medication, potentially leading to hemodynamic instability, whereas a blood pressure of 110/70 mmHg is generally acceptable.
美國臨床護理實務中，對於 Beta-阻斷劑的給藥心率門檻 (Heart rate parameter) 非常嚴格，通常在給藥前會由醫師明確定義門檻，護理師需嚴格遵守，若低於門檻則必須 hold 住藥物。