Is ketamine the preferred induction agent in Advanced Trauma Life Support (ATLS), and does it increase intracranial pressure (ICP)?

Ketamine in ATLS and Intracranial Pressure

Ketamine is not specifically designated as the "preferred" agent in ATLS protocols, but current evidence strongly supports its use as a safe and potentially advantageous induction agent for trauma patients, including those with traumatic brain injury (TBI), and it does not increase intracranial pressure (ICP) in sedated, mechanically ventilated patients.

ATLS Preference Status

ATLS guidelines do not explicitly designate ketamine as the single preferred induction agent. The 2023 Society of Critical Care Medicine guidelines suggest no difference between etomidate and other induction agents (including ketamine) regarding mortality, hypotension, or vasopressor requirements 1. The choice of induction agent should be based on the patient's hemodynamic status and clinical context rather than a blanket preference.

Ketamine and ICP: Debunking the Myth

FDA Label Warning vs. Clinical Reality

The FDA label for ketamine includes a warning about increased cerebrospinal fluid pressure 2, stating that "an increase in intracranial pressure has been reported following administration of ketamine hydrochloride" and recommending monitored settings with frequent neurologic assessments for patients with elevated ICP 2. However, this warning is based on outdated data from non-intubated, spontaneously breathing patients and does not reflect contemporary evidence in mechanically ventilated TBI patients.

Contemporary Evidence on ICP

Multiple systematic reviews and meta-analyses demonstrate that ketamine does not increase ICP in sedated, mechanically ventilated TBI patients:

• A 2014 systematic review of 101 adult and 55 pediatric TBI patients found that ICP did not increase in any studies during ketamine administration; three studies actually reported significant ICP decreases with ketamine bolus (Oxford level 2b, GRADE C evidence) 3

• A 2026 meta-analysis found no statistically significant difference in ICP elevation between ketamine and no-ketamine groups in patients with baseline ICP < 20 mmHg (RR = 0.67; 95% CI [0.45,1.01]) 4

• A 2018 retrospective study of 148 trauma patients found lower mortality rates in the ketamine group after injury stratification 5

Advantages of Ketamine in Trauma

Ketamine offers several advantages that make it particularly suitable for trauma patients with potential brain injury:

• Hemodynamic stability: Maintains blood pressure through sympathomimetic properties, crucial for maintaining cerebral perfusion pressure 1, 6
• Neuroprotective properties: Preclinical studies demonstrate anti-neuroinflammatory effects and cellular protection 7, 8
• Preserved respiratory drive: Minimal respiratory depression compared to other agents 2
• Rapid onset and short duration: Ideal pharmacokinetics for emergency intubation 1

Critical Caveat: Hemodynamic Considerations

One important finding from recent meta-analysis: ketamine use was associated with increased hypotension episodes (RR = 1.47; 95% CI [1.22,1.78]) 4. This likely reflects its use in critically ill patients with depleted catecholamine stores 1. In hemodynamically unstable trauma patients with suspected catecholamine depletion, have vasopressors immediately available and consider dose reduction.

Clinical Algorithm for Induction Agent Selection in Trauma

For trauma patients requiring intubation with suspected TBI:

1. Hemodynamically stable patients: Ketamine (1-2 mg/kg) is safe and effective
2. Hemodynamically unstable patients: Ketamine remains advantageous due to sympathomimetic properties, but prepare vasopressors and consider lower dosing (1 mg/kg)
3. Patients with baseline ICP < 20 mmHg: Ketamine is safe and may actually decrease ICP
4. Patients requiring ongoing sedation: Ketamine can be used as continuous infusion (1 mg/kg/h) without ICP concerns 9

Common Pitfalls to Avoid

• Don't avoid ketamine based on outdated dogma: The historical teaching against ketamine in TBI was based on studies in spontaneously breathing patients without controlled ventilation 6, 10, 7
• Don't use ketamine alone for airway procedures: It does not suppress pharyngeal/laryngeal reflexes; always use with neuromuscular blockade 2
• Don't assume hemodynamic stability is guaranteed: Despite sympathomimetic properties, monitor closely for hypotension, especially in catecholamine-depleted patients 1, 4

The evidence strongly supports reconsidering ketamine as a first-line induction agent for trauma patients with potential brain injury, particularly those with hemodynamic instability 5, 6, 3.