Arterial oxygen saturation during breath-hold diving has not previously been measured continuously. We devised a submersible, waterproof, backpack computer to continuously record heart rate, depth, and arterial oxygen saturation (SPO2) as determined by earlobe pulse oximetry. Our measurements showed that one assisted (Funado) diver had reduced SPO2 values immediately after surfacing from 22 dives which lasted 23-76 s, from a mean of 99 +/- 1% SPO2 to 96 +/- 3% SPO2. SPO2 returned to 97 +/- 2% within 15 s after surfacing (P < 0.05 surface value differs from predive base line). Four unassisted (Cachido) divers showed no significant reduction of mean predive SPO2 below 98 +/- 2% at any time during the dive or recovery period in 92 routine dives lasting from 15 to 44 s. Upon surfacing from diving, mean SPO2 was 98 +/- 2% and the mean SPO2 15 s after surfacing was 97 +/- 3% for the unassisted divers. Three Cachido divers were asked to dive and breath hold for as long as possible. Mean SPO2 at the conclusion of breath holding was 73% after an average dive and breath hold lasting 69 s.
Adult Diving