Increased ICP: induction agents

The utmost concern in managing patients with increased intracranial pressure (ICP) is to maintain cerebral perfusion and oxygenation. Therefore, emphasis should be placed upon the avoidance of cerebral ischemia and hypoxia when choosing anesthetic induction agents. Understanding the pathophysiology of cerebral hypertension and the systemic/cerebral physiological effects of induction agents is far more important than the choice of anesthetic agent. Attention should be paid to the following aspects during anesthesia induction in patients with increased ICP.

First, the systemic blood pressure should be maintained in order to maintain an adequate cerebral perfusion pressure. Hypotension should be treated accordingly.

Second, drugs which have the potential to increase cerebral metabolic rate of oxygen (CMRO₂) and ICP should be avoided. The typical example is ketamine, although this is becoming controversial – at least one study suggests that ketamine, in doses up to 5 mg/kg IV, does not increase ICP in intubated, sedated head-injury patients

Essentially, any common anesthetic induction agents, such as propofol, etomidate, or barbiturates, can be used as long their doses are titrated according to patient’s mental status and their effect on systemic and cerebral hemodynamics are considered and treated. Muscle relaxants should be considered especially when the dose of induction agent is low. Succinylcholine is not contraindicated if rapid airway securement is warranted or difficult airway is likely.