Abstract
OBJECTIVE:
This study aimed to quantify the sedative effects, detection rates and cardiovascular responses to xenon.
METHODS:
On three occasions, participants breathed xenon (FiXe 30%, for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) in a non-blinded design. Sedation was monitored by a board certified anesthesiologist. During 70% xenon, participants were also verbally instructed to operate a manual value with time to task failure being recorded. Beat-by-beat hemodynamics were measured continuously by ECG, photoplethysmography and transcranial Doppler. Over 48 hours post administration, xenon was measured in blood and urine by gas chromatography-mass spectrometry.
RESULTS:
Xenon caused variable levels of sedation and restlessness. Task failure of the self-operating value occurred at 60 - 90 seconds in most individuals. Over the first minute, 50 and 70% xenon caused a substantial reduction in total peripheral resistance (P<0.05). All dosages caused an increase in cardiac output (P<0.05). By the end of xenon inhalation, slight hypertension was observed after all three doses (P<0.05) with an increase in middle cerebral artery velocity (P<0.05). Xenon was consistently detected, albeit in trace amounts, up to 3 hours post all three doses of xenon inhalation in blood and urine with variable results thereafter.
DISCUSSION:
Xenon inhalation caused sedation incompatible with self-operation of a breathing apparatus, thus causing a potential life threatening condition in the absence of an anesthesiologist. Yet, xenon can only be reliably detected in blood and urine up to 3 hours post acute dosing.