Reliability of pulse oximetry during exercise in pulmonary patients

To evaluate the reliability of pulse oximetry during exercise, we studied 101 patients primarily with chronic pulmonary diseases. Three devices were used on different patients. Radial arterial blood was sampled at rest and maximal exercise simultaneously to pulse oximetric determination. Measured blood oxygen saturation was significantly different from noninvasive saturation at rest and also at exercise for each device. Nevertheless, changes in pulse oximetry from rest to exercise were significantly correlated with measured saturation for all three devices. Direction of changes in saturation from rest to exercise was correctly evaluated by transcutaneous oximetry in all but six instances where changes were less than 4 percent. Although measured and transcutaneous saturations are significantly different, we conclude that pulse oximetry reliably estimates changes in arterial saturation between rest and exercise for a clinical purpose. None of the three tested devices was better compared with the others in estimating saturation changes at exercise.