Contraindications to Ketamine Use
According to the FDA label, ketamine is contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard. 1
Primary Contraindications
- Ketamine produces a dose-dependent increase in heart rate, blood pressure, and cardiac output through stimulation of the sympathetic nervous system 2
- The European Society of Cardiology recommends avoiding ketamine in patients with ischemic heart disease, cerebrovascular disease, or hypertension due to its potential cardiovascular stimulant effects 2
- Ketamine is also contraindicated in patients with known hypersensitivity to ketamine or to any excipient 1
Hemodynamic Effects and Considerations
- Ketamine causes transient increases in blood pressure, heart rate, and cardiac index, though decreases in blood pressure, heart rate, arrhythmias, and cardiac decompensation have also been observed 1
- Vital signs and cardiac function must be monitored during ketamine administration 1
- In patients with sepsis or critical illness, the hemodynamic response to ketamine may be blunted or even reversed 2
Head Injury and Ketamine
- Historically, there were concerns about using ketamine in patients with head injury due to risks of increased intracranial pressure, but these concerns are now considered of little practical significance 2
- Recent evidence shows ketamine administration was not associated with worse survival or disability in traumatic brain injury patients 2, 3
- A 2023 retrospective analysis found that ketamine-exposed TBI subjects had significantly fewer instances of elevated intracranial pressure compared to ketamine-unexposed subjects 3
Respiratory Considerations
- Respiratory depression may occur with ketamine overdosage or rapid administration, requiring adequate oxygenation and ventilation 1
- Ketamine causes bronchodilation, which may be beneficial for patients with COPD, especially during acute exacerbations 4
- Ketamine does not suppress pharyngeal and laryngeal reflexes, so it should be avoided as a sole anesthetic agent during procedures of the pharynx, larynx, or bronchial tree 1
Other Important Precautions
- Ketamine increases upper airway secretions, which can potentially worsen respiratory symptoms in COPD patients 4
- Premedication with anticholinergics (atropine or glycopyrrolate) is recommended to reduce secretions when using ketamine in COPD patients 4
- Emergence delirium occurs in approximately 12% of patients during recovery, which can be reduced by using lower dosages of ketamine in conjunction with an intravenous benzodiazepine 1
Answer to the Multiple Choice Question
Based on the FDA label and clinical guidelines, the correct answer is: (a) hypotension
This is because ketamine is specifically contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard 1. Ketamine typically causes an increase in blood pressure, not hypotension 2, 1.
Head injury (b) is not a contraindication; recent evidence supports ketamine use in TBI patients 2, 3.
Asthma (c) is not a contraindication; ketamine's bronchodilatory effects may actually be beneficial 4.
Hypoventilation (d) requires caution but is not a specific contraindication; respiratory depression is a potential side effect of ketamine that requires monitoring 1.