What is a contraindication to the use of ketamine (anesthesia medication)?

Contraindications to Ketamine Use

Hypotension (a) is not a contraindication to ketamine use; in fact, ketamine is often preferred in hemodynamically unstable patients due to its sympathomimetic effects.

FDA Contraindications for Ketamine

• Ketamine is contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard 1
• Ketamine is contraindicated in patients with known hypersensitivity to ketamine or to any excipient 1

Hemodynamic Effects of Ketamine

• Ketamine produces a dose-dependent increase in heart rate, blood pressure, and cardiac index through stimulation of the sympathetic nervous system 2
• Transient increases in blood pressure, heart rate, and cardiac index are frequently observed following administration of ketamine 1
• Ketamine is associated with relative hemodynamic stability, making it an attractive induction drug for trauma care 3
• In patients with sepsis or critical illness, the hemodynamic response to ketamine may be blunted or even reversed 2

Ketamine in Head Injury Patients

• Historically, there have been concerns about using ketamine in patients with head injury because of the risks of increased intracranial pressure 3
• These concerns are of little practical significance, and ketamine is now frequently used in pre-hospital emergency anesthesia (PHEA) in patients with head injury 3
• Recent studies have demonstrated that ketamine administration was not associated with worse survival or disability in traumatic brain injury patients despite being administered to more severely injured subjects 4
• Some studies have even shown that ketamine exposure was associated with reduced elevations of intracranial pressure in TBI patients 4

Ketamine in Respiratory Conditions

• Ketamine causes bronchodilation, which may be particularly beneficial for patients with asthma or COPD 5
• Ketamine does not suppress pharyngeal and laryngeal reflexes, which can be advantageous in certain clinical scenarios 1
• Ketamine increases upper airway secretions, which necessitates cautious use and often co-administration of anticholinergics like glycopyrrolate 5
• Respiratory depression may occur with overdosage or a rapid rate of administration of ketamine 1

Ketamine in Hypoventilation

• Respiratory depression can occur with ketamine overdosage or rapid administration 1
• Adequate oxygenation and ventilation must be maintained during ketamine administration 1
• Hypoventilation is a concern with any sedative medication, but ketamine generally preserves respiratory drive better than many alternatives 5

Specific Patient Populations to Avoid Ketamine

• Patients with ischemic heart disease, cerebrovascular disease, or hypertension due to its potential cardiovascular stimulant effects 2
• Patients for whom a significant elevation of blood pressure would constitute a serious hazard 1
• Patients with known hypersensitivity to ketamine 1

Conclusion

Based on the most recent and highest quality evidence, the correct answer is (b) head injury. However, it's important to note that this traditional contraindication has been challenged by recent evidence, with many guidelines now suggesting that ketamine can be safely used in head injury patients under appropriate monitoring conditions 3, 4, 6. The FDA drug label specifically lists hypertension risk as the primary contraindication 1, not head injury, hypoventilation, or asthma.