This research project focuses on understanding at which time and distance oxygen is sufficiently dispersed to conduct advanced cardiac life support on top of a mattress that has been immediately removed from an oxygen-filled monoplace hyperbaric chamber. The research was conducted by taking oxygen readings using two monoplace hyperbaric chambers for 30 mattress height tests. Additional readings were conducted with oxygen levels recorded on the floor for 10 floor-level tests. Oxygen readings taken at 12 in. (0.3 m) on the mattress and the three floor distances showed a distinct oxygen percentage decrease from 30 to 60 s but little to no reduction from 60 to 90 s. The oxygen readings taken at 56 in. (1.4 m) and 78 in. (1.9 m) on the mattress showed little to no change from 30 to 90 s. Under the tested conditions, the results indicate that oxygen exiting the monoplace hyperbaric chamber remains above 21% on top of the chamber's gurney mattress when attached and on the floor with no gurney present until at least 90 s. For those who teach introductory hyperbaric medicine courses and hyperbaric safety director courses and those who work around large oxygen vessels or hyperbaric chambers, this information indicates where oxygen travels and the times associated with the travel path.