💊 药理学 · 第3课，共6课 · 7 min
Digoxin、Beta Blockers和Nitro：暂停参数和硬性停药点
Digoxin, Beta Blockers and Nitro: Hold Parameters and Hard Stops
❤️ 每次给予digoxin前，护士都要数满一分钟的心尖脉搏。如果是58，就暂停该剂量。考试会给你58、钾3.1和黄色视物模糊，并问你首先做什么。
❤️ Before every dose of digoxin, a nurse counts an apical pulse for a full minute. If it is 58, the dose is held. The exam will give you 58, a potassium of 3.1 and blurry yellow vision, and ask what you do first.
💡 核心要点
Digoxin：心尖脉搏数一分钟，低于60暂停，低钾会增加毒性。Beta blockers：切勿突然停药。Nitroglycerin：切勿与PDE-5抑制剂合用。
Digoxin: apical pulse one minute, hold under 60, low potassium raises toxicity. Beta blockers: never stop abruptly. Nitroglycerin: never with PDE-5 inhibitors.
🧠 为什么重要
Digoxin：数心尖脉搏满一分钟，成人低于60时暂停（婴儿按医嘱低于90至110时暂停）；治疗水平约0.5至2.0 ng/mL，心力衰竭时常采用较低目标（约0.5至1.0）；毒性表现为恶心、呕吐、食欲不振、心动过缓、意识模糊和视觉变化，如黄绿色光晕。低钾血症会增加毒性，因此要监测钾，尤其是在使用袢利尿剂时；解毒剂是digoxin immune Fab。Beta blockers（以-olol结尾）：按医嘱在心率低于60或收缩压低于90时暂停；切勿突然停药（会引起反跳性心动过速和心绞痛）；它们会掩盖糖尿病患者的低血糖症状，非选择性药物可加重哮喘。Nitroglycerin治疗心绞痛：每5分钟舌下含服一片，最多三剂，按当前指南在第一剂后疼痛未缓解时呼叫急救服务；预期会出现头痛；将药片保存在原来的深色瓶中；在使用PDE-5抑制剂（sildenafil、tadalafil）后24至48小时内绝对禁用，因为会导致严重低血压。ACE抑制剂（-pril）：干咳、血管性水肿、高钾血症；ARBs（-sartan）可作为替代。Calcium channel blockers：避免葡萄柚汁。AMIODARONE：肺毒性和甲状腺毒性、光敏性。
DIGOXIN: take an APICAL pulse for one full minute and hold for a rate under 60 in adults (under 90 to 110 in infants per order); therapeutic level about 0.5 to 2.0 ng/mL, with lower targets (about 0.5 to 1.0) often used in heart failure; toxicity shows as nausea, vomiting, anorexia, bradycardia, confusion and visual changes such as yellow-green halos. HYPOKALEMIA increases toxicity, so monitor potassium, especially with loop diuretics; the antidote is digoxin immune Fab. BETA BLOCKERS (ending in -olol): hold for heart rate under 60 or systolic pressure under 90 per order; never stop abruptly (rebound tachycardia and angina); they mask hypoglycemia symptoms in clients with diabetes, and non-selective agents can worsen asthma. NITROGLYCERIN for angina: one sublingual tablet every 5 minutes up to three doses, calling emergency services if pain is not relieved after the first dose per current guidance; expect a headache; keep tablets in the dark original bottle; absolutely contraindicated within 24 to 48 hours of PDE-5 inhibitors (sildenafil, tadalafil) because of profound hypotension. ACE INHIBITORS (-pril): dry cough, angioedema, hyperkalemia; ARBs (-sartan) as the alternative. CALCIUM CHANNEL BLOCKERS: avoid grapefruit juice. AMIODARONE: pulmonary and thyroid toxicity, photosensitivity.
🏥 真实场景
🟡 一名服用digoxin和furosemide的患者报告恶心，并看到灯光周围有黄色光晕。心尖脉搏54，钾3.0。护士暂停digoxin，报告这些发现，并预期会检查digoxin水平和做ECG；脉搏这么慢时，要避免钾盐，并可能医嘱给予digoxin immune Fab。利尿剂设下了陷阱；了解钾与digoxin相关联的护士会在心律失常发生前避开它。
🟡 A client taking digoxin and furosemide reports nausea and seeing yellow halos around lights. Apical pulse 54, potassium 3.0. The nurse holds the digoxin, reports the findings, and anticipates a digoxin level and an ECG; with a pulse this slow, potassium salts are avoided and digoxin immune Fab may be ordered. The diuretic set the trap; the nurse who knows that potassium and digoxin are linked springs it before the arrhythmia does.
📌 要点总结
- Digoxin毒性：胃肠道不适、心动过缓、视觉光晕；低钾会使其加重Digoxin toxicity: GI upset, bradycardia, visual halos; low potassium makes it worse
- HR低于60或SBP低于90时暂停beta blockers；切勿突然停药Hold beta blockers for HR under 60 or SBP under 90; never stop abruptly
- Nitroglycerin：最多3剂，间隔5分钟；与sildenafil合用禁忌Nitroglycerin: up to 3 doses 5 minutes apart; contraindicated with sildenafil
📖 本课术语
β受体阻滞剂（-olol） (Beta blockers (-olol)): 在心脏病发作后和心力衰竭中减慢心率并降低血压；心率低于60或收缩压低于90时按医嘱暂缓使用，切勿突然停药，并提醒糖尿病患者它们会掩盖低血糖症状。
钙通道阻滞剂（-dipine、verapamil、diltiazem） (Calcium channel blockers (-dipine, verapamil, diltiazem)): 舒张血管，用于高血压和心绞痛，verapamil或diltiazem还可减慢心率；预期会出现踝部肿胀和头痛，血压低或脉搏慢时按医嘱暂缓使用，避免饮用葡萄柚汁。
Digoxin: 在心力衰竭和心房颤动中增强心力并减慢心率；计数心尖脉搏整整一分钟，低于60时暂缓使用，注意恶心、呕吐和黄绿色光晕，记住低钾会增加毒性，解毒剂为digoxin immune fab。
Nitroglycerin和硝酸酯类 (Nitroglycerin and nitrates): 扩张血管以缓解心绞痛：舌下含服一片，每5分钟一次，最多三片，若第一片无效则呼叫急救服务；预期会出现头痛，将药片存放在避光瓶中，切勿在服用sildenafil或tadalafil后24到48小时内使用。
Amiodarone: 控制危险的室性和房性心律失常，但会损伤肺、甲状腺、肝脏和眼睛；出现新咳嗽或呼吸困难要立即报告，检查甲状腺和肝脏化验，静脉负荷期间预期心动过缓和低血压，并教导防晒以应对蓝灰色皮肤和光敏性。
Adenosine: 通过短暂停止心脏活动来复律室上性心动过速；快速推注超过1到2秒，随后立即用生理盐水冲洗至粗大的近端静脉，让患者保持监护，并告知数秒的胸部压迫感、面部潮红和心脏停搏是预期现象。
Nitroprusside: 用于高血压急症的快速IV血管扩张药，需持续监测血压（最好使用动脉管路）滴定；将输液袋包裹避光，并注意大剂量、长时间输注或肾衰竭时氰化物或硫氰酸盐毒性（意识模糊、代谢性酸中毒）。
Clonidine: 用于高血压（也用于ADHD和阿片类戒断）的中枢性α-2激动剂，会引起口干和嗜睡；其标志性危险是突然停药时反跳性高血压，因此要逐渐减量，切勿漏服，并按计划更换每周贴片。
✅ 自我测试
给予digoxin前，护士数得一名成人的心尖脉搏为每分钟56次。护士应该怎么做？Before administering digoxin, the nurse counts an apical pulse of 56 beats per minute in an adult. What should the nurse do?
- 暂停该剂量并通知医疗提供者Hold the dose and notify the provider
- 复查桡动脉脉搏，如果高于60就给予该剂量Recheck the radial pulse and give the dose if it is above 60
- 给予该剂量并记录心率Administer the dose and document the rate
- 给予一半剂量Give half the dose
答案: A · 暂停该剂量并通知医疗提供者
心尖心率低于60时暂停digoxin并报告。标准评估是心尖脉搏，而不是桡动脉脉搏。
Hold digoxin for an apical rate under 60 and report. The apical pulse, not radial, is the standard assessment.
一名胸痛患者在5分钟前舌下含服了一片nitroglycerin，但没有缓解。患者提到昨晚服用了sildenafil。护士的首要担忧是什么？A client with chest pain took one sublingual nitroglycerin tablet 5 minutes ago without relief. The client mentions taking sildenafil last night. What is the nurse's priority concern?
- 患者需要更高剂量The client needs a higher dose
- 严重低血压Profound hypotension
- nitroglycerin引起的头痛Headache from the nitroglycerin
- 药片可能已过期The tablet was probably expired
答案: B · 严重低血压
硝酸盐与PDE-5抑制剂合用会导致严重的、可能致命的低血压。这种组合是禁忌的。头痛是nitroglycerin的常见副作用，但并不危险；sildenafil使血压成为危及生命的担忧。
Nitrates with PDE-5 inhibitors cause profound, potentially fatal hypotension. The combination is contraindicated. Headache is a common nitroglycerin side effect, but it is not dangerous; the sildenafil makes blood pressure the life-threatening concern.
对于刚开始服用beta blocker（如metoprolol）的患者，哪项教导至关重要？Which teaching is essential for a client starting a beta blocker such as metoprolol?
- 如果感到疲倦，立即停药Stop the drug immediately if you feel tired
- 只在感觉血压高时服用Take it only when your blood pressure feels high
- 检查脉搏；不要突然停药Check your pulse; do not stop the drug abruptly
- 喝葡萄柚汁以改善吸收Drink grapefruit juice to improve absorption
答案: C · 检查脉搏；不要突然停药
突然停药会导致反跳性心动过速，并可能诱发心绞痛或MI。患者要监测脉搏和血压。疲倦是开始服用beta blocker时的常见副作用；因疲倦而停药会引发该药必须逐渐减量才能避免的反跳。
Abrupt withdrawal causes rebound tachycardia and can precipitate angina or MI. Clients monitor pulse and pressure. Fatigue is a common side effect when starting a beta blocker; stopping for it triggers the very rebound the drug must be tapered to avoid.
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