Contraindications to Ketamine Use
According to the FDA drug label, ketamine is contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard, not in hypotension, head injury, asthma, or hypoventilation. 1
Primary Contraindications
- Ketamine is specifically contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard, such as those with ischemic heart disease, cerebrovascular disease, or hypertension 2, 1
- Ketamine is also contraindicated in patients with known hypersensitivity to ketamine or to any excipient 1
Hemodynamic Effects
- Ketamine produces a dose-dependent increase in heart rate, blood pressure, and cardiac output through stimulation of the sympathetic nervous system 2
- These hemodynamic effects make ketamine contraindicated in patients where blood pressure elevation would be dangerous 1
- Transient increases in blood pressure, heart rate, and cardiac index are frequently observed following ketamine administration 1
Common Misconceptions About Ketamine Contraindications
Head Injury
- Historically, ketamine was thought to be contraindicated in patients with head injury due to concerns about increased intracranial pressure (ICP) 2
- Recent evidence shows these concerns are of little practical significance, and ketamine is now frequently used in pre-hospital emergency anesthesia in patients with head injury 2
- A 2023 retrospective analysis found that ketamine administration was not associated with worse survival or disability in traumatic brain injury patients 3
Respiratory Function
- While respiratory depression may occur with ketamine overdosage or rapid administration, this is a warning rather than a contraindication 1
- Ketamine actually causes bronchodilation, which may be beneficial for patients with conditions like COPD, especially during acute exacerbations 4
Hypotension
- Ketamine is associated with relative hemodynamic stability, making it an attractive induction drug for trauma care 2
- In some settings, ketamine is specifically chosen for its ability to maintain blood pressure in hemodynamically compromised patients 4
Important Precautions When Using Ketamine
- Monitor vital signs and cardiac function during ketamine administration 1
- Be aware that ketamine increases upper airway secretions, which may require premedication with anticholinergics 4
- Consider that emergence delirium occurs in approximately 12% of patients during recovery, which can be reduced by using lower doses in conjunction with benzodiazepines 1
- Avoid ketamine as a sole anesthetic agent during procedures of the pharynx, larynx, or bronchial tree, as it does not suppress pharyngeal and laryngeal reflexes 1
In conclusion, the correct answer is (a) hypotension, as ketamine is actually contraindicated in conditions where elevation of blood pressure would be dangerous, not where hypotension is present.