Anesthetic management of the head trauma patient

Abstract

Objective: To describe the optimal anesthetic management of patients with brain injury, with emphasis on the support of oxygen delivery to the brain, and the effects of anesthetic agents on cerebral perfusion. Data sources: Clinical and experimental studies from both the human and veterinary neuroanesthesia literature. Summary: The management of patients following primary traumatic brain injury (TBI) significantly impacts outcome. Outcome can be improved by strategies that improve oxygen delivery to the brain and prevent cerebral ischemia. Anesthetic agents have widely variable effects on the blood supply to the brain and, therefore, choice of anesthetic agent can influence neurological outcome. Although in the past, anesthetic agents have been selected for their neuroprotective properties, it is increasingly being recognized that the support of cerebral perfusion during anesthesia contributes more significantly to a positive outcome for these patients. Support of cardiorespiratory function is, therefore, highly important when anesthetizing patients with TBI. Conclusion: Choice of anesthetic agent is determined by the extent of brain injury and intracranial pressure (ICP) elevation. Factors that should be considered when anesthetizing head trauma patients include the effects of anesthetic agents on the cardiac and respiratory systems, their effects on cerebral blood flow (CBF), ICP, and possible neuroprotective benefits offered by certain agents.

Intracranial variables in propofol or sevoflurane-anesthestized dogs subjected to subarachnoid administration of iohexol

“…Thus, in this study PE´CO 2 was recorded, because these values can be used as a noninvasive measure of arterial CO 2 and in the absence of significant pulmonary disease or reduction in cardiac output, the difference between PaCO 2 and PE´CO 2 will be less than 5 mmHg (Armitage-Chan et al, 2007). In this study, the dogs were healthy and CO did not decrease during the whole study in both groups.…”

“…These values were slightly higher than ICP means at T0. This difference is probably due to mechanical ventilation used by Rezende (2004), because the application of positive pressure ventilations may increase ICP by decreasing venous return from the head (Armitage-Chan et al, 2007). Besides, at T0, ICP decreased possibly due to interference in the cerebral autoregulation caused by the alteration in transmural pressure related to the withdrawal of CSF and iohexol administration (Bagley et al, 1995).…”

“…Besides, at T0, ICP decreased possibly due to interference in the cerebral autoregulation caused by the alteration in transmural pressure related to the withdrawal of CSF and iohexol administration (Bagley et al, 1995). Although the most volatile anesthetics have dose-related effects on ICP (Armitage-Chan et al, 2007), in this study, sevoflurane did not change ICP because this drug does not impair pressure auto-regulation until concentrations exceed 1.5 MAC (3.3%) with normal PaCO 2 (McCulloch et al, 2000). The anesthetic protocols were adjusted to maintain the animals in stage III, plane 2/3 according to Guedel planes, and the 1.5 MAC of sevoflurane was sufficient for it.…”

Bispectral index in dogs with high intracranial pressure, anesthetized with propofol and submitted to two levels of FiO2

“…This can be confirmed by the stability of ICP and CPP. Moreover, in patients with intracranial disease, comparisons of propofol and volatile anesthetics (sevoflurane and isoflurane) have demonstrated improved cerebral perfusion and better maintenance of pressure auto regulation when total intravenous anesthesia was used (Armitage-Chan et al, 2007).…”

“…In patients with increased ICP, the mechanical positive pressure ventilation should be immediately available and instituted at induction, being recommended to maintain the normocapnia (Armitage-Chan et al, 2007;Harvey et al, 2007). However, there is no consideration about which is the best inspired oxygen fraction to use in these cases.…”