Hyperventilation in Adult TBI Patients: How to Approach It?

Abstract

Hyperventilation is a commonly used therapy to treat intracranial hypertension (ICTH) in traumatic brain injury patients (TBI). Hyperventilation promotes hypocapnia, which causes vasoconstriction in the cerebral arterioles and thus reduces cerebral blood flow and, to a lesser extent, cerebral blood volume effectively, decreasing temporarily intracranial pressure. However, hyperventilation can have serious systemic and cerebral deleterious effects, such as ventilator-induced lung injury or cerebral ischemia. The routine use of this therapy is therefore not recommended. Conversely, in specific conditions, such as refractory ICHT and imminent brain herniation, it can be an effective life-saving rescue therapy. The aim of this review is to describe the impact of hyperventilation on extra-cerebral organs and cerebral hemodynamics or metabolism, as well as to discuss the side effects and how to implement it to manage TBI patients.

Keywords: cerebral ischemia; hyperventilation; hypocapnia; intracranial hypertension; traumatic brain injury.

Figure 1

A practical approach on how to manage controlled hyperventilation and hypocapnia in traumatic brain injury (TBI) patients. Acute intracranial hypertension (ICHT) = life-threatening elevation in ICP, in particular when signs of herniation (i.e., anisocoria, apnea, hypertension, bradycardia) are present. ICHT, intracranial pressure close to the critical threshold for therapy without signs of herniation; HV, controlled hyperventilation and hypocapnia. Green and red circles refers to the potential use (green) or contraindication (red) to the use of HV. NM, neuromonitoring. *In case of diffuse brain injury but with high potential risk of tissue hypoxia. **Adjusted on neuromonitoring.