What is the treatment for post spinal bradycardia?

Treatment of Post-Spinal Bradycardia

For bradycardia following spinal anesthesia, immediately administer atropine 0.5-1 mg IV as first-line therapy if the patient is symptomatic or hemodynamically unstable, repeatable every 3-5 minutes up to a maximum total dose of 3 mg. 1, 2

Immediate Assessment and Intervention

• Assess for signs of hemodynamic instability including altered mental status, hypotension (systolic BP <90 mmHg), chest pain, acute heart failure, or other signs of shock 1
• Establish continuous cardiac monitoring, obtain IV access, and measure pulse oximetry 1
• Obtain a 12-lead ECG to identify the underlying rhythm mechanism and exclude other causes of bradycardia 1, 3
• Bradycardia after spinal anesthesia is caused by unopposed parasympathetic stimulation from sympathetic blockade, particularly when the block extends to the upper thoracic levels (T1-T4) affecting cardiac accelerator fibers 4

First-Line Pharmacologic Management

• Atropine 0.5-1 mg IV push is the initial treatment, with a Class IIa recommendation from the American College of Cardiology 4, 2
• Repeat atropine every 3-5 minutes as needed, up to a maximum cumulative dose of 3 mg 1, 2, 5
• Atropine works by blocking muscarinic receptors and antagonizing parasympathetic effects on the heart 5
• Onset of action occurs within 7-8 minutes after IV administration, with peak heart rate effects delayed compared to plasma levels 5

Second-Line Agents When Atropine Fails

If bradycardia persists despite adequate atropine dosing:

• Dopamine 5-20 mcg/kg/min IV infusion, starting at 5 mcg/kg/min and titrating upward every 2 minutes based on heart rate response (Class IIb recommendation) 2
• Epinephrine 2-10 mcg/min IV infusion or 0.1-0.5 mcg/kg/min, titrated to effect (Class IIb recommendation) 1, 2
• Isoproterenol 1-20 mcg/min IV infusion may be considered, but should be avoided if coronary ischemia is suspected due to increased myocardial oxygen demand 1, 2

Temporary Pacing for Refractory Cases

• Transcutaneous pacing may be considered (Class IIb recommendation) as a bridge therapy if bradycardia remains hemodynamically unstable despite medical therapy 4, 1
• Transvenous pacing is reasonable (Class IIa recommendation) for persistent hemodynamic instability refractory to all medical interventions 4
• Temporary pacing should be used to stabilize the patient until the spinal anesthetic wears off and sympathetic tone returns 4

Critical Pitfalls and Caveats

• Patient positioning matters significantly: The Trendelenburg position (30 degrees head-down) increases the incidence of severe bradycardia to 60% compared to 20% in supine horizontal position 6
• The hammock position (trunk and legs elevated 30 degrees) has the lowest incidence of severe bradycardia at 10% and is the preferred recovery position 6
• Severe bradycardia can occur late—up to 320 minutes after admission to the post-anesthesia care unit—requiring extended monitoring 6
• Common triggers for bradycardia episodes include tracheal suctioning, turning the patient, and positional changes 4
• Do not rush to permanent pacemaker placement, as bradycardia from spinal anesthesia is typically self-limited and resolves as the block recedes 4

Special Considerations

• If the patient has a history of spinal cord injury, bradycardia may be refractory to atropine and adrenergic drugs due to autonomic dysfunction 4
• In spinal cord injury patients with persistent bradycardia, aminophylline or theophylline is reasonable (Class IIa recommendation) as these methylxanthines block adenosine receptors and target the underlying pathophysiology of unopposed parasympathetic stimulation 4
• Aminophylline 6 mg/kg IV over 20-30 minutes or oral theophylline can be effective and typically can be withdrawn after 4-6 weeks with rare side effects 4, 7, 8