Atropine Protocol for Hypotension and Bradycardia
For symptomatic bradycardia with hypotension, administer atropine 0.5 mg IV every 3-5 minutes up to a maximum total dose of 3 mg, while preparing for transcutaneous pacing if the patient does not respond to atropine. 1, 2
Indications for Atropine
- Symptomatic sinus bradycardia (heart rate <50 bpm with hypotension, ischemia, or escape ventricular arrhythmia) 3
- Ventricular asystole 3
- Symptomatic AV block occurring at the AV nodal level (second-degree type I or third-degree with narrow-complex escape rhythm) 3
- Bradycardia with hemodynamic compromise (hypotension, altered mental status, chest pain, acute heart failure, shock) 1
Dosing Protocol
- Initial dose: 0.5 mg IV 1, 2
- Repeat every 3-5 minutes as needed 3, 1
- Maximum total dose: 3 mg 1, 2
- Titrate to achieve minimally effective heart rate (approximately 60 bpm) 3
- For patients with coronary artery disease, limit total dose to 0.03-0.04 mg/kg 2
Important Cautions
- Doses less than 0.5 mg may paradoxically worsen bradycardia due to parasympathomimetic effects 3, 1
- Use with caution in acute myocardial infarction as increased heart rate may worsen ischemia 3, 1
- Avoid in AV block occurring at infranodal level (usually associated with anterior MI with wide-complex escape rhythm) 3
- Use with caution in patients after cardiac transplantation as it may cause paradoxical AV block 3, 1
- Monitor for potential hypertensive response, which although rare, can be severe 4
When Atropine Fails
- Consider transcutaneous pacing for unstable patients not responding to atropine 3, 1
- Consider β-adrenergic support with dopamine (2-10 μg/kg/min) or epinephrine (2-10 μg/min) 3, 1
- Prepare for transvenous pacing if patient does not respond to drugs or transcutaneous pacing 3
Clinical Evidence of Effectiveness
- Atropine has been shown to significantly increase heart rate (from 46±14 to 79±12/min) and systolic blood pressure (from 70±15 to 105±13 mm Hg) in patients with bradycardia-hypotension syndrome 5
- In patients with acute myocardial infarction and sinus bradycardia, atropine has been shown to normalize blood pressure in 88% of hypotensive patients 6
- Prophylactic atropine administration before procedures that may induce bradycardia (such as carotid angioplasty) has been shown to decrease the incidence of intraoperative bradycardia and cardiac morbidity 7
Potential Adverse Effects
- Tachycardia, which may worsen ischemia in patients with acute coronary syndrome 1
- Ventricular tachycardia or fibrillation (rare) 6
- Central nervous system effects (hallucinations, fever) with repeated administration 1
- Adverse effects correlate with higher initial doses (≥1.0 mg) or cumulative doses exceeding 2.5 mg over 2.5 hours 6