What is the effect of ketamine on intracranial pressure (ICP)?

From the Guidelines

Ketamine is generally considered safe for use in patients with elevated intracranial pressure (ICP). While historical concerns suggested ketamine might increase ICP, current evidence, such as the 2017 guidelines from the Association of Anaesthetists of Great Britain and Ireland 1, indicates it can be safely administered in patients with head injuries or conditions causing increased ICP.

Key Points to Consider

• Ketamine may actually be beneficial in these patients due to its ability to maintain or even improve cerebral perfusion pressure through its sympathomimetic effects that preserve blood pressure.
• Ketamine provides analgesia and sedation without causing respiratory depression, which is advantageous since hypercarbia from respiratory compromise can worsen ICP.
• When using ketamine in patients with elevated ICP, it's essential to ensure adequate sedation before administration, considering co-administering a benzodiazepine like midazolam to mitigate potential emergence reactions, as suggested by the safer pre-hospital anaesthesia guidelines 1.

Clinical Application

Ketamine's neuroprotective properties, including NMDA receptor antagonism, may offer additional benefits in the setting of brain injury.

• Its hemodynamic stability makes it particularly valuable in traumatic brain injury patients who may be at risk for hypotension with other sedative agents.
• The typical dosing for ketamine in this context is 1-2 mg/kg IV for induction or 0.5-1 mg/kg for procedural sedation.

Safety and Efficacy

The use of ketamine in patients with elevated ICP is supported by recent guidelines and studies, which emphasize its safety and efficacy in pre-hospital and emergency settings 1.

• Small, frequent doses of sedatives, including ketamine, minimize haemodynamic side-effects and should be titrated against physiological variables.
• Infusions may be preferable for longer transfers, but infusion pumps may make transfer more complex, highlighting the need for careful consideration of the administration method.

From the FDA Drug Label

1. 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 may increase intracranial pressure (ICP). Patients with elevated ICP should be closely monitored with frequent neurologic assessments when administered ketamine hydrochloride 2.

From the Research

Ketamine and Intracranial Pressure (ICP)

• The relationship between ketamine and ICP has been a topic of discussion in various studies 3, 4.
• A scoping review found that ketamine bolus and infusions were not associated with increased ICP and may reduce the incidence of cortical spreading depolarization events 3.
• A retrospective observational study in pediatric patients with neurologic conditions at risk for intracranial hypertension found that the administration of ketamine as the primary induction agent prior to tracheal intubation was not associated with an increased risk of peri-intubation associated neurologic, hemodynamic or respiratory events compared with those who received other induction agents 4.

Management of Elevated ICP

• The management of elevated ICP is a critical aspect of neurointensive care, and various treatment paradigms have been explored 5, 6, 7.
• A review of the literature discusses commonly encountered pathologies associated with increased ICP, summarizes diagnostic approaches used in evaluating ICP, and presents evidence-based treatment paradigms that drive clinical care in intensive care units 5.
• The use of pharmacologic agents, such as hypertonic saline, propofol, and fentanyl, has been shown to reduce the duration and dose of intracranial hypertension 6.

Treatment Options for ICP Crisis

• A comprehensive management protocol for the treatment of ICP crises includes mechanical ventilation, fluid therapy, hemoglobin targets, and hypertonic saline infusion 7.
• ICP monitoring allows for the guidance of patient care, and advanced neuromonitoring devices are available at the bedside to diagnose impaired intracranial compliance and intracranial hypertension, assess brain function, and optimize cerebral perfusion 7.