ACCURACY OF 3 PULSE OXIMETERS DURING EXERCISE AND HYPOXEMIA IN PATIENTS WITH CYSTIC-FIBROSIS

To evaluate the reliability of noninvasive oximeters during exercise i n patients with cystic fibrosis (CF), we studied 9 patients during exe rcise tests, using 3 devices (Hewlett-Packard 47201A, Biox-Ohmeda 3700 , Nellcor 100), comparing oximetry readings with arterial blood co-oxi metry. Fifty samples from preexercise, exercise, and recovery were col lected; and paired measurements were analyzed for bias (arterial blood gas SaO2 - noninvasive SaO2) and precision (I SD of the bias). Values were available for the Hewlett-Packard and the Biox-Ohmeda at all 50 collection times. The Nellcor failed to read on four occasions, all du ring exercise. The accuracy of the Biox-Ohmeda readings was significan tly worse during exercise than rest, while the Nellcor and the Hewlett -Packard performance did not differ significantly between exercise and rest. During hypoxemia (SaO2 <90 percent as determined by co-oximetry on arterial blood), the Biox-Ohmeda and Nellcor consistently overesti mated saturation, with mean bias of - 6.1 percent and - 3.0 percent, r espectively. The Hewlett-Packard was more reliable and valid during hy poxemia, with a mean bias of - 1.0 percent. The Nellcor read significa ntly more accurately in the six patients with severe digital clubbing than in the three patients with mild digital clubbing. It is important to be aware of possible limitations of noninvasive oximeters before a ccepting them as accurate.