Management of Ketamine Overdose
In ketamine overdose, the primary intervention is supportive care with mechanical ventilation for respiratory depression, as there is no specific antidote. 1
Immediate Airway and Respiratory Management
The FDA drug label explicitly states that respiratory depression may occur with ketamine overdosage or too rapid administration, and mechanical support of respiration is preferred over analeptics. 1
Key respiratory interventions:
- Provide supportive ventilation immediately if respiratory depression develops 1
- Prepare for airway management with adjuncts (oro/nasopharyngeal airways) or bag-mask ventilation, as these are required in 11.8% and 5.5% of cases respectively 2
- Monitor for hypoxia (occurs in 15.4% of cases) and airway compromise (14.8% of cases) 2
- Manage increased secretions and emesis (7% of cases) which can lead to aspiration risk 2
- Advanced airway placement may be necessary in severe cases 2
Cardiovascular Monitoring
Cardiac function must be continuously monitored throughout the overdose period 1, particularly given ketamine's dose-dependent increases in heart rate, blood pressure, and cardiac output through sympathetic stimulation. 3, 4
- Tachycardia is the most common physical finding in ketamine intoxication 5
- Cardiac arrest has been reported in severe overdoses, though rare 6, 2
- Arrhythmias can occur 3
Management of Neuropsychiatric Effects
Benzodiazepines are the recommended first-line treatment for agitation, hallucinations, and excess neuromuscular activity 7, which occur in 10-30% of adults. 8
Common neuropsychiatric presentations include:
- Dysphoria, hallucinations, anxiety, disorientation, and feelings of detachment 3
- Impaired consciousness, dizziness, and irrational behavior 7
- Severe agitation requiring pharmacologic intervention 5
Additional Complications to Monitor
Watch for rhabdomyolysis, which is one of the most frequent complications after ketamine abuse 5:
- Monitor creatine kinase levels
- Ensure adequate hydration
- Monitor renal function
Other potential complications include:
Timeline and Disposition
Most patients recover within 5 hours of presentation, with average recovery time after IV ketamine approximately 84 minutes (range 22-215 minutes). 3, 5
- Symptoms are typically short-lived 5
- Ketamine has a half-life of 1.5-5 hours 7
- Prolonged awakening may be the only sign of significant overdose in some cases 9
Critical Pitfalls to Avoid
- Do not rely on analeptics for respiratory support—mechanical ventilation is preferred 1
- Do not assume absence of vital sign abnormalities rules out significant overdose—one case series showed no hemodynamic or CNS perturbations despite 10-fold overdose 9
- Remember that ketamine is frequently combined with other substances, increasing the risk of adverse effects 6, 7
- Be aware that unpleasant flashbacks can occur weeks after elimination from the body 6