Is ketamine (anesthesia medication) risky in a patient with acute respiratory failure who refuses intubation (invasive mechanical ventilation)?

Ketamine in Acute Respiratory Failure Without Intubation Intent

Ketamine should NOT be used as adjunctive therapy in non-intubated patients with acute respiratory failure, as it provides no benefit over standard care and carries significant risks in this context. 1, 2

Evidence Against Ketamine in Non-Intubated Respiratory Failure

Lack of Efficacy

• The American Heart Association explicitly states that ketamine is NOT recommended as adjunctive therapy for acute respiratory exacerbations in non-intubated patients, as two published randomized trials in children found no benefit compared with standard care 1, 2
• A review of 68 non-intubated children showed no significant difference in respiratory rate, oxygen saturation, hospital admission rate, or need for mechanical ventilation between ketamine and placebo 2

Respiratory Risks in This Population

• The FDA label notes that ketamine can cause "transient and minimal respiratory depression" even in controlled settings 3
• Ketamine stimulates copious bronchial secretions, which can worsen airway management in patients already struggling with respiratory failure 1
• Without the ability to secure the airway via intubation, managing ketamine-induced secretions and potential respiratory depression becomes extremely hazardous 1

Critical Distinction: Intubation vs. Non-Intubation Context

When Intubation IS Planned

• Ketamine is the preferred induction agent for intubation in severe respiratory failure due to its bronchodilatory properties and maintenance of respiratory drive 2, 4
• Dose: 1-2 mg/kg IV for rapid sequence intubation, with pretreatment using glycopyrrolate or atropine to reduce secretions 2

When Intubation is NOT Planned (Your Scenario)

• This is the critical pitfall: Using ketamine without the safety net of definitive airway control exposes the patient to respiratory depression, secretions, and potential aspiration without rescue options 1, 3
• If the patient refuses intubation, sedation strategies must prioritize agents that do not compromise respiratory drive or airway protection 1

Alternative Approach for the DNI Patient

Sedation for NIV Tolerance

• The BTS/ICS guidelines recommend that if intubation is not intended should NIV fail, then sedation/anxiolysis is indicated for symptom control in the distressed or agitated patient 1
• Recommended approach: Intravenous morphine 2.5-5 mg (± benzodiazepine) may provide symptom relief and improve tolerance of NIV 1
• Sedation should only be used with close monitoring, and infused sedative/anxiolytic drugs should only be used in an HDU or ICU setting 1

Hemodynamic Concerns

• Ketamine can cause paradoxical hypotension in critically ill patients with depleted catecholamine stores, including those in prolonged respiratory failure 4, 5
• Post-intubation hypotension occurs in approximately 18% of emergency department patients receiving ketamine, requiring vasopressors to be immediately available 2
• In a patient refusing intubation, managing ketamine-induced hypotension becomes extremely problematic without the option of mechanical ventilation and full resuscitative measures 5

The Bottom Line

In a patient with acute respiratory failure who refuses intubation, ketamine is contraindicated for symptom management or respiratory support. The risk-benefit ratio is unacceptable because:

• No proven benefit in non-intubated respiratory failure 1, 2
• Risk of respiratory depression without airway rescue options 3
• Copious secretions that cannot be managed without intubation 1
• Potential hemodynamic instability in critically ill patients 4, 5

Instead, focus on optimizing NIV with careful sedation using opioids ± benzodiazepines in a monitored setting, while respecting the patient's wishes regarding intubation 1.