Management of physiological variables in neuroanaesthesia: maintaining homeostasis during intracranial surgery

The recent literature on the perioperative maintenance of cerebral homeostasis was reviewed.

Several studies focused on the regulation of cerebral blood flow in patients without intracranial disease; therefore, further studies in neurosurgical patients are needed. High intracranial pressure and brain swelling can be controlled by the choice of anaesthetic agents, and also by optimal positioning of the patient. The use of positive end-expiratory pressure may impair cerebral blood flow, but the effects of positive end-expiratory pressure seem to depend on the respiratory system compliance. The international multicenter study failed to show any benefit from intraoperative hypothermia in patients with subarachnoid hemorrhage; similarly, the results on corticosteroid therapy in head-injured patients are discouraging. Corticosteroid therapy has prompted studies on the control of blood glucose levels. While tight glycemic control has been recommended, it can have untoward effects manifested as cerebral metabolic stress.

From the clinical point of view, the recent research has added only little to the knowledge on the management of physiological parameters in neurosurgery. More adequately powered studies focusing in specific problems, and having a meaningful aim relative to outcome, are needed also in neuroanaesthesia.