Variability in oxygen saturation between oxygen conserving devices and continuous flow oxygen

Differences in resting and exercise pulse oxygen saturation (SpO₂) between four oxygen conserving devices (D1 through D4) set at "2," continuous oxygen via nasal cannula at 2 L/min, and room air. On room air, the subjects had a mean SpO₂ at rest of 94 percent, which increased by varying amounts with continuous oxygen and the four conserving devices. With exercise, the mean room air SpO₂ decreased to just below 92 percent. Continuous flow oxygen increased the SpO₂ to almost 98 percent, but the response to the conserving devices ranged from 93 to 95 percent. The variability between responses to continuous flow oxygen and the oxygen conserving devices emphasizes the need to evaluate the SpO₂ response to the particular oxygen conserving device at rest and with exertion.