Indirect and direct gas exchange at maximum exercise in beryllium sensitization and disease

To determine whether pulse oximetry accurately estimates arterial blood gas measurements during exercise in the assessment of chronic beryllium disease (CBD) and beryllium sensitization (BeS).

Participants underwent maximal exercise physiology testing in a clinical-practice setting. Oxygen saturation in the blood was measured through an indwelling arterial line and by pulse oximetry.

All exercise physiology tests were performed in the pulmonary physiology unit of the National Jewish Medical and Research Center (NJMRC) between December 1985 and November 1998.

We analyzed the exercise physiology data for 168 individuals who were referred to NJMRC for evaluation of possible CBD and underwent exercise testing. On evaluation, they subsequently received diagnoses of either CBD or BeS.

In BeS subjects, the percentage of oxygen saturation as measured by pulse oximetry (SpO(2)) often underestimated the percentage of arterial oxygen saturation (SaO(2)) (mean [+/- SD] underestimation, 0.88 +/- 4.6%) at maximum exercise and showed no significant correlation (r = -0.13; p = 0.3). The use of SpO(2) misclassified 14.9% of BeS subjects as having abnormal gas exchange levels (< 90%) that were normal by arterial blood gas measurement. In contrast, SpO(2) and SaO(2) values correlated at maximum exercise in CBD subjects (r = 0.55 [corrected]; p = 0.0001) without exhibiting SpO(2) underestimation of SaO(2), and misclassification occurred in only 5.9%.

These data suggest that pulse oximetry cannot be used reliably to distinguish between CBD and BeS and, thus, is not an adequate substitute for arterial blood gas analysis with exercise.