| Summary: | Objective: This study aimed to determine if pulse oximetry could reliably be used after immersion in water, and if so, which of the finger, earlobe or nose most reliably produced a functional waveform. Method: Pulse oximetry data was recorded from the ear, nose and finger before and after 30 min of immersion in water. The primary outcome was the ability to measure pulse oximetry at any of the sites. Results: A total of 119 participants were enrolled (with a median age of 16 years, 55% male). A useful pulse oximetry waveform was obtained after immersion from at least one of the measurement sites in 118 (99.2%) participants. Waveforms were usable after immersion in 96% of participants at the nostril, compared to 92% at the finger, and 41% at the ear lobe. The likelihood of success at the ear was significantly lower than either the finger or the nose (41% vs 92% and 96% respectively, p < 0.0001 for both comparisons). The finger and nostril were similar. Oxygen saturations were not significantly different after immersion at the nostril (100% vs 100%, p = 0.537) and finger (100% vs 100%, p = 0.032) sites but were different at the ear (100% vs 96%, p < 0.0001). Conclusion: This study demonstrates that pulse oximetry is feasible and reliable in a large cohort of participants who have been immersed in water for 30 min. The results support the nostril as the most reliable location. Only pulse oximeters registered for clinical use should be employed for patient care.
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