Safety, Detection and Hemodynamic Effects of Acute Xenon Inhalation

Abstract

PURPOSE: Xenon is an inhalation anesthetic, which has the potential to increase plasma erythropoietin, red cell mass and thus endurance performance. This study aimed to describe the sedative effects, detection rates and cardiovascular responses of an open circuit breathing system to deliver increasing concentrations of Xenon. METHODS: On three occasions, participants breathed increasing concentrations of xenon (Xenon, 30% for 20 min; Xenon, 50% for 5 min; Xenon, 70% for 2 min and oxygen, 21% with balance Nitrogen) in a non-blinded design. Xenon inhalation has been completed in 6 (30%), 5 (50%) and 4 (70%) subjects to date. The level of sedation was monitored by a board certified anesthesiologist (Richmond Agitation and Sedation Scale (RASS). Over 48 hours post administration, Xenon was measured in blood and urine by gas chromatography-mass spectrometry. All reported beat-by-beat hemodynamics were measured continuously by photoplethysmography (Nexfin; BMEYE, Netherlands) for 10 minutes prior to and throughout xenon administration. RESULTS: Xenon caused variable levels of sedation and restlessness between subjects (e.g. 50% xenon RAAS, -2, briefly awakens to voice to +2 frequent nonpurposeful movements), with the greatness symptoms occurring at 50 and 70%. Xenon was detected, albeit in trace amounts, up to 6 hours post xenon inhalation in blood (e.g. 30% 6 hours post, 2.2±2.7 nmol/mL) and urine (e.g. 30% 1.5±0.82 nmol/mL) in all subjects. Over the first minute, xenon cause a substantial reduction in total peripheral resistance ([INCREMENT]2.7±0.49,mmHg·L·min), which caused a reflex increase in cardiac output ([INCREMENT]2.7±0.54, L·min). By the end of xenon inhalation, hypertension was observed after all three dosages (MAP: 30%, [INCREMENT]7±11; 50% [INCREMENT]12±2; 70%, [INCREMENT]19±5 mmHg). CONCLUSIONS: We show that three different conceivable dosages of xenon inhalation cause a level of sedation incompatible with self-operation of breathing apparatus and a persistent hypertensive state. Dispute begin acute (<5 mins), high dosages (50 and 70%) of xenon caused near anesthesia and thus could present a life threatening condition in the absence of an anesthesiologist. Xenon can be reliability detected in blood and urine up to 6 hours post dosing. These studies were supported in part by funding from the Partnership for Clean Competition Research Collaborative.