What are the guidelines for using ketamine (anesthesia medication) in patients with head trauma?

From the Guidelines

Ketamine can be safely used in patients with head trauma, as its benefits outweigh the risks, particularly in emergency settings. The use of ketamine in head trauma patients has been supported by recent guidelines, such as the 2017 Association of Anaesthetists of Great Britain and Ireland (AAGBI) guidelines on safer pre-hospital anaesthesia 1. According to these guidelines, the historical concerns about ketamine increasing intracranial pressure are of little practical significance, and the drug is now frequently used in pre-hospital trauma care for patients with head injury.

Some key points to consider when using ketamine in head trauma patients include:

• The recommended dose for induction is 1-2 mg/kg IV or 4-5 mg/kg IM
• Maintenance doses typically range from 0.5-1 mg/kg IV
• For procedural sedation, 0.5-1 mg/kg IV followed by 0.25-0.5 mg/kg as needed is appropriate
• Ketamine preserves respiratory drive, maintains or increases blood pressure, and preserves laryngeal reflexes
• It does not increase intracranial pressure (ICP) in properly ventilated patients and may have neuroprotective properties through NMDA receptor antagonism, as suggested by studies such as those referenced in the AAGBI guidelines 1.

To optimize safety, providers should:

• Ensure adequate airway management capabilities
• Monitor vital signs closely
• Consider reduced dosing in elderly or hemodynamically unstable patients
• Combine ketamine with a benzodiazepine (like midazolam 0.02-0.05 mg/kg) to reduce emergence reactions without compromising its hemodynamic benefits
• Use ketamine cautiously in patients with severe hypertension or known coronary artery disease due to its sympathomimetic effects, as noted in the AAGBI guidelines 1.

From the FDA Drug Label

5.7 Increase in Cerebrospinal Fluid Pressure An increase in intracranial pressure has been reported following administration of ketamine hydrochloride. Patients with elevated intracranial pressure should be in a monitored setting with frequent neurologic assessments.

Ketamine use in head trauma patients is approached with caution due to the potential for increased intracranial pressure.

• The FDA drug label warns of an increase in cerebrospinal fluid pressure following ketamine administration.
• Patients with head trauma may have elevated intracranial pressure, and ketamine could potentially exacerbate this condition.
• The label recommends that patients with elevated intracranial pressure should be in a monitored setting with frequent neurologic assessments 2. Therefore, ketamine should be used with caution in head trauma patients, and its administration should be carefully considered and monitored by experienced physicians.

From the Research

Guidelines for Using Ketamine in Head Trauma Patients

The use of ketamine in patients with head trauma has been debated due to its potential effects on intracranial pressure and cerebral perfusion. However, recent studies suggest that ketamine may be safe and effective in these patients.

• The Brain Injury and Ketamine (BIKe) study, a prospective multicentre double-blind placebo-controlled RCT, aims to evaluate the safety and effect of ketamine as an adjunct to a standard sedation regimen in patients with severe traumatic brain injury 3.
• A systematic review of 11 studies found no evidence of harm during ketamine use in patients suffering from acute brain injury, and only two studies found a small increase in intracranial pressure 4.
• Another study found that ketamine does not increase and may instead decrease intracranial pressure, and its safety profile makes it a reliable tool in the prehospital environment 5.
• A narrative review of 11 recent studies found that ketamine should be the first-choice drug in patients with traumatic brain injury at induction, and there was no evidence of harm from the ketamine's use in patients with TBI 6.
• A joint position statement from several medical organizations provides uniform guidance on the use of ketamine in trauma patients, including those with head trauma, in both the prehospital and hospital setting 7.

Key Considerations

• Ketamine may be used as an adjunct to a standard sedation regimen in patients with severe traumatic brain injury.
• The safety and efficacy of ketamine in these patients are being studied in ongoing clinical trials.
• Current evidence suggests that ketamine does not increase intracranial pressure and may be a reliable tool in the prehospital environment.
• Medical organizations have issued guidance on the use of ketamine in trauma patients, including those with head trauma.