Brain tissue oxygenation during transnasal endoscopic skull base procedures

We aimed to study brain tissue oxygenation during the period of controlled reduction of arterial blood pressure – a maneuver often used in extended endoscopic skull base surgery for bloodless operative field. Intracranial pressure, arterial blood pressure and the resultant cerebral perfusion pressure were measured during extended endoscopic skull base surgery in 5 patients with diagnosed tumors of the skull base and arterial hypertension. Simultaneously, in those patients, we measured partial pressure of oxygen in the brain parenchyma (PbtO2). Values of PbtO2 lower than 15 mm Hg (risk of brain ischemia) were observed in 3 patients for periods of 40 min, 110 min and 123 min, respectively. In 2 of these patients, no hypotension (mean arterial pressure