Comparison between Arterial Blood Gases and Oxygen Reserve Index™ in a SCUBA Diver: A Case Report.

Hypoxia and hyperoxia are both worrisome issues potentially affecting SCUBA divers, but validated methods to monitor these two conditions underwater are still lacking. In this experiment, a volunteer SCUBA diver was equipped with a pulse oximeter to detect peripheral oxygen saturation (SpO 2 ) and a device to monitor the oxygen reserve index (ORi™). ORi™ values were compared with arterial blood oxygen saturation (SaO 2 ) and the partial pressure of oxygen (PaO 2 ) obtained from the cannulated right radial artery at three steps: at rest out of water; at -15 m underwater after pedaling on a submerged bike; after resurfacing. SpO 2 and ORi™ mirrored the changes in SaO 2 and PaO 2 , confirming the expected hyperoxia at depth. To confirm the potential usefulness of an integrated SpO 2 and ORi™ device, further studies are needed on a broader sample with different underwater conditions and diving techniques.