Traumatic brain injury remains a primary cause of disability and mortality in intensive care units globally. Managing these critically ill patients demands precise sedation to manage intracranial pressure while avoiding systemic hypotension. Conventional sedatives frequently compromise cardiovascular stability through profound vasodilation. Consequently, clinicians are actively exploring ketamine analgosedation as a hemodynamically stable alternative in neurocritical care. Historically, clinicians avoided ketamine in neurotrauma due to fears of drug-induced intracranial hypertension. However, modern physiological evidence challenges these traditional beliefs. A randomized controlled pilot study from India now provides essential insights into how ketamine affects cerebral dynamics, hemodynamics, and long-term functional recovery.

The Neurocritical Care Dilemma and Ketamine Analgosedation

Optimizing sedation in severe traumatic brain injury requires a careful physiological balancing act. Intensivists must suppress cerebral metabolic demands and control intracranial pressure. Simultaneously, they must preserve systemic blood pressure to guarantee adequate cerebral perfusion pressure. Traditional sedatives, including propofol, midazolam, and opioids, reliably cause dose-dependent vasodilation. Consequently, these medications frequently trigger arterial hypotension, which worsens secondary ischemic brain injury. To counteract hypotension, intensivists must frequently initiate potent vasopressor infusions. This intervention carries significant clinical risks, including peripheral tissue ischemia and cardiac arrhythmias. In contrast, ketamine functions as an N-methyl-D-aspartate receptor antagonist with distinct sympathomimetic properties. By stimulating central sympathetic outflow, ketamine effectively sustains mean arterial pressure and cardiac output. Furthermore, blocking N-methyl-D-aspartate receptors mitigates excitotoxic cascades caused by excessive extracellular glutamate. Preclinical studies also suggest that ketamine reduces cortical spreading depolarizations in injured cerebral cortex. Nevertheless, historical observational studies caused clinicians to fear that ketamine might elevate intracranial pressure. Modern neurointensivists recognize that those older reports examined non-ventilated patients with hydrocephalus. Therefore, controlled clinical trials remain crucial to redefine ketamine's true therapeutic role in neurotrauma.

Randomized Trial Design and Protocol Implementation

To evaluate ketamine rigorously in severe head injury, investigators conducted a prospective randomized controlled pilot study at the All India Institute of Medical Sciences. The research team enrolled sixty adult patients presenting with acute severe traumatic brain injury. All participants required mechanical ventilation and invasive intracranial pressure monitoring. The investigators allocated eligible patients randomly into two equal cohorts of thirty individuals each. The intervention cohort received a continuous intravenous infusion of ketamine at 3 mg/kg/h. Conversely, the control group received an equivalent rate of normal saline placebo. Both groups received standard background sedation comprising continuous infusions of fentanyl and midazolam. Throughout the monitoring phase, the clinical team systematically recorded arterial blood gas parameters, systemic hemodynamics, and intracranial pressure. Additionally, clinicians continuously tracked calculated cerebral perfusion pressure and jugular venous oxygen saturation. Vasopressor therapy was initiated according to standardized protocols whenever mean arterial pressure fell below target thresholds. Finally, an independent physician assessed functional neurological recovery at three months using the Glasgow Outcome Scale-Extended questionnaire. The study was prospectively recorded on the Central Trial Registry of India.

Hemodynamic Stability and Vasopressor Sparing Effects

The study results revealed striking hemodynamic benefits during the initial stages of ketamine infusion. Baseline cardiovascular parameters showed complete comparability between the two cohorts before drug administration. However, during the initial four to six hours, patients receiving ketamine exhibited significantly higher mean arterial pressures. Consequently, the ketamine group maintained significantly higher cerebral perfusion pressures during this critical early window. In contrast, control patients suffered frequent hypotensive episodes requiring active cardiovascular support. Therefore, intensivists initiated vasopressor therapy substantially more often in the control cohort. Specifically, 43.3% of control patients required vasopressor infusions, compared to only 16.6% of patients in the ketamine group. This difference represented a statistically significant reduction with a p-value of 0.02. Thus, ketamine demonstrated a clinically meaningful vasopressor-sparing effect in acute neurotrauma. Nevertheless, these hemodynamic advantages did not persist beyond the six-hour monitoring window. After six hours of infusion, systemic blood pressures and cerebral perfusion pressures converged between the cohorts. This attenuation suggests that receptor desensitization or drug redistribution limits sustained sympathomimetic drive. Nonetheless, early hemodynamic stabilization provided vital protection during the initial post-resuscitation period.

Intracranial Pressure Dynamics and Neuromonitoring

In addition to evaluating systemic hemodynamics, the investigators meticulously examined intracranial pressure dynamics throughout the trial. Historical teaching suggested that ketamine increases cerebral blood volume and triggers uncontrolled intracranial hypertension. However, this randomized trial completely refuted that classical dogma. Rather than increasing intracranial pressure, ketamine administration caused a statistically significant reduction in intracranial pressure between the fourth and sixth hours of infusion. During this specific window, the intervention cohort demonstrated improved intracranial elastance and superior compliance. Furthermore, the ketamine group maintained consistent trends toward higher cerebral perfusion pressure throughout monitoring. Nevertheless, these physiological differences ceased to demonstrate statistical significance after the initial six hours. Similarly, jugular venous oxygen saturation measurements remained comparable across both cohorts throughout the study period. This finding confirmed that ketamine did not compromise cerebral oxygen delivery or trigger uncoupled metabolic consumption. At three months, an independent evaluator recorded functional recovery scores using the Glasgow Outcome Scale-Extended. Ultimately, the distribution of functional outcomes showed no statistically significant differences between groups. Therefore, while ketamine established intracranial safety, its transient physiological benefits did not translate into enhanced long-term recovery.

Clinical Implications for Intensive Care Protocols

The clinical findings from this pilot study offer vital practical guidance for neurointensivists, anesthesiologists, and emergency physicians. First, the trial definitively establishes the intracranial safety of ketamine in mechanically ventilated patients with severe head injury. Consequently, clinicians can discard traditional contraindications that restricted ketamine administration during neurotrauma management. Second, ketamine provides crucial early hemodynamic stability by dampening the hypotensive effects of concurrent sedatives. Because ketamine reduced vasopressor utilization from 43.3% to 16.6%, it minimizes secondary complications associated with exogenous catecholamine administration. Therefore, intensivists can actively consider ketamine analgosedation as a valuable adjunct during early resuscitation and critical bedside interventions. However, clinicians must also recognize that ketamine does not improve three-month neurological outcomes. Because physiological benefits waned after six hours, continuous ketamine infusions cannot replace definitive intracranial pressure-lowering therapies or targeted neurosurgical decompression. Future research should investigate alternative administration regimens, including targeted bolus dosing and multimodal combinations with propofol. In summary, ketamine stands out as a safe, hemodynamically protective sedative that simplifies critical care management during acute traumatic brain injury.

How does ketamine impact intracranial pressure during acute neurotrauma?

Ketamine does not increase intracranial pressure in mechanically ventilated neurotrauma patients receiving background sedation. Instead, clinical evidence indicates that ketamine promotes transient intracranial pressure reductions and preserves cerebral perfusion pressure. Its non-competitive N-methyl-D-aspartate antagonism stabilizes cerebral vascular dynamics without triggering intracranial hypertension, effectively disproving historical neurosurgical concerns.

Why did ketamine reduce vasopressor requirements in this trial?

Ketamine stimulates the central sympathetic nervous system, promoting endogenous catecholamine release and maintaining peripheral vascular tone. Consequently, patients receiving ketamine infusions demonstrated significantly higher mean arterial pressures during early resuscitation. This intrinsic hemodynamic support prevented sedative-induced arterial hypotension, thereby significantly decreasing the need for concurrent vasopressor infusions compared to saline controls.

Does ketamine analgosedation improve long-term neurological recovery after severe TBI?

Current clinical trial data show that ketamine analgosedation does not produce statistically significant improvements in three-month neurological recovery. Although ketamine provides transient physiological benefits, including brief reductions in intracranial pressure and enhanced perfusion, these acute effects do not alter long-term Glasgow Outcome Scale-Extended scores compared to standard neurointensive care.

Disclaimer: This content is for informational and educational purposes only and should not be taken as professional medical advice. Clinical decisions must always rely on individual patient assessments and the judgment of qualified healthcare providers. Refer to the latest local and national guidelines for clinical practice.

References

1. Burman S et al. Effect of Ketamine Analgosedation on Neurological Outcome in patients with Severe Traumatic Brain Injury: A Randomized Controlled Pilot Study. Neurocrit Care. 2026 Feb. doi: 10.1007/s12028-025-02274-5. PMID: 40355795.
2. Gregers MCT, Mikkelsen S, Lindvig KP, et al. Ketamine as an anesthetic for patients with acute brain injury: a systematic review. Neurocrit Care. 2020;33(1):273-282.
3. Zeiler FA, Teitelbaum J, West M, Gilman LM. The ketamine effect on ICP in traumatic brain injury. Neurocrit Care. 2014;21(1):163-173.