What is the treatment for ketamine-induced bronchospasm?

Treatment for Ketamine-Induced Bronchospasm

Ketamine-induced bronchospasm is paradoxical and extremely rare, as ketamine is actually a bronchodilator used to treat bronchospasm; however, if it occurs (likely due to hypersensitivity or anaphylaxis), treat immediately with IV epinephrine as first-line therapy, followed by inhaled beta-agonists and supportive measures. 1

Immediate Management Algorithm

First-Line Treatment: Epinephrine

• Administer IV epinephrine 50 mcg (0.05 mg) if no other vasopressors or bronchodilators have been given 1
• If unresponsive to initial dose, escalate to IV epinephrine 100 mcg at 2-minute intervals 1
• For life-threatening bronchospasm with cardiovascular collapse, use IV epinephrine 1 mg as per advanced life support protocols 1

Critical caveat: This represents a likely allergic/anaphylactic reaction rather than a direct pharmacologic effect of ketamine, since ketamine has intrinsic bronchodilator properties through direct bronchial smooth muscle relaxation and catecholamine potentiation 1, 2, 3, 4

Second-Line Bronchodilators

• Nebulized albuterol 2.5-5 mg in 3 mL saline, repeat as necessary 1, 5
• Consider combining with ipratropium bromide 0.5 mg via nebulizer for severe cases 1, 5
• Inhaled volatile anesthetics (sevoflurane or isoflurane) if in operating room setting and unresponsive to initial therapy 1

Refractory Bronchospasm (After 10 Minutes)

If bronchospasm persists despite adequate epinephrine and inhaled bronchodilators:

• IV magnesium sulfate 2 g over 20 minutes for severe refractory bronchospasm 1, 6
• Epinephrine infusion 0.05-0.1 mcg/kg/min if more than three boluses required 1
• Consider IV salbutamol as alternative bronchodilator 1

Supportive Measures

• Rapid crystalloid bolus 1 L and repeat if inadequate response to address potential anaphylaxis-related hypotension 1
• IV corticosteroids (methylprednisolone 1-2 mg/kg) after adequate resuscitation to prevent protracted reactions 1
• IV antihistamines (diphenhydramine 25-50 mg plus ranitidine 50 mg) as second-line adjuncts, never as monotherapy 1

Important Clinical Considerations

Paradoxical nature: Ketamine is documented as an effective bronchodilator in status asthmaticus 7, 3, 4, 8, so bronchospasm during ketamine administration strongly suggests:

• Anaphylactic/allergic reaction to ketamine itself 2
• Reaction to preservatives or additives in the formulation
• Unrelated concurrent bronchospasm from another trigger

Avoid confusion with therapeutic use: Multiple studies demonstrate ketamine's efficacy in treating bronchospasm, with improvements in PaO2/FiO2 ratios and dynamic compliance 3, 4, 8. The question addresses the rare scenario where ketamine paradoxically causes bronchospasm, not its therapeutic bronchodilator use.

Monitoring requirements:

• Continuous pulse oximetry and capnography 1
• Blood pressure monitoring every 1-2 minutes during acute phase 1
• Observe in monitored setting for minimum 6 hours due to potential biphasic reactions 1

Special populations:

• Patients on beta-blockers: add IV glucagon 1-2 mg if inadequate response to epinephrine 1
• Pediatric dosing: epinephrine 0.01 mg/kg (maximum 0.5 mg), albuterol 0.15-0.3 mg/kg 1, 5

Post-Event Management

• Obtain mast cell tryptase levels at 1 hour and 2-4 hours after reaction onset, with baseline sample at 24 hours 1
• Refer to allergy/immunology for formal testing to confirm ketamine hypersensitivity 1
• Document in medical record as drug allergy to prevent future exposure 1