Anesthesiological Management in a Non-accessible Environment Preparation of Volunteers for Investigations with Controlled Hypoxemia in a 3 Tesla Magnetic Field for Assessing Cerebral Energy Metabolism

Several centres worldwide have established con-trolled hypoxemia studies (CHS) for testing and calibrating pulse oximeters. Since the brain is, compared to the rest of the body, a highly demanding organ that requires nearly 20 % of the body's total oxygen supply, a period of hypoxemia may reduce the content of high energy phosphates such as phosphocreatine (PCr) with constant levels of adenosine triphosphate (ATP). To prove this hypothesis a controlled 30 minute hypoxemic state of 70 to75 % arterial oxygen saturation was induced in healthy subjects. ³¹P magnetic resonance spectroscopy (³¹P-MRS) performed in a 3Tesla (T)-MR-scanner was used for high energy phosphates measurement. The study protocol was based on a randomised trial including two groups of male volunteers, one with normal weight and one with a body mass index higher than 30 kg/m² in such a way that each person served as his own control in one session with normoxemia and one with hypoxemia. The knowledge of physiological adjustment to a hypoxemia as well as the volunteer management is the basis for a safe procedure.