Desaturation after forced vital capacity measurement is suggested diffusing capacity disorder

Monitoring oxygen saturation (SpO2) in pulmonary functional testing (PFT) is useful to check for hypoxemia, especially in patients who performed home oxygen therapy. Although SpO2 is not part of PFT, assessing it allows testing to be performed more safely. The relationship between desaturation in the 6MWT and DLCO is known, but that between lower DLCO and mean desaturation in the PFT is unclear.

We performed a retrospective study to investigate the relationship between PFT parameters, SpO2 values, and patient characteristics. From April 2021 to July 2022, data from 311 patients were included in the study (male 210 patients, 67.5%).

The parameter most closely correlated with desaturation was %DLCO. Multiple linear regression indicated that HOT, %VC, FEV 1%, and %DLCO were significant predictors of desaturation. The best AUC for the relation of desaturation to %DLCO was for 3% desaturation (cut-off value, 53.0%; sensitivity, 0.691; specificity, 0.780).

Results showed that desaturation was one of the significant indicators. Monitoring SpO2 during the FVC measurement might help to identify patients with respiratory diseases and high-level diffusing capacity disorder. SpO2 desaturation might be one indicator of diffusing capacity for the patient who can not measure DLCO single breath method. Therefore, SpO2 might be useful not only for monitoring whether a patient has hypoxemia, but also as a predictor of diffusing capacity.