Ambulatory monitoring of arterial oxygen saturation

We have developed a method of recording oxygen saturation over time using ambulatory equipment. A pulse oximeter was modified to be powered by battery, and values for oxygen saturation were recorded by an analog recorder. The unit is compact and functions for 30 hours between battery changes. The mean difference between oxygen saturation reported by the pulse oximeter and an IL 282 CO-oximeter was -1.12 percent, with a range of difference +/- 2.75 percent, indicating 95 percent confidence limits 5.5 percent either side of the mean. Continuous ambulatory recordings were obtained in 16 male subjects; six were healthy nonsnorers, five were healthy snorers, and five had sleep apnea. Of the average recording time, 19 +/- 5 hours, records contained 89 +/- 7 percent usable data. We conclude that ambulatory pulse oximetry is a feasible means of unsupervised long-term monitoring of oxygenation during daily activities.