@article {Chuang353, author = {Ming-Lung Chuang and I-Feng Lin and Shih-Pin Chen}, title = {Kinetics of Changes in Oxyhemoglobin Saturation During Walking and Cycling Tests in COPD}, volume = {59}, number = {3}, pages = {353--362}, year = {2014}, doi = {10.4187/respcare.02494}, publisher = {Respiratory Care}, abstract = {BACKGROUND: The patterns and kinetics of changes in SpO2 in the 6-min walk test (6MWT) and cycling test have not been addressed in patients with COPD. METHODS: We studied 60 COPD subjects, with a mean {\textpm} SD FEV1 of 54 {\textpm} 18\% of predicted. We compared the changes in SpO2 (ΔSpO2) within and between the 2 tests, and the differences between the desaturators and non-desaturators. RESULTS: In the 6MWT there were 4 patterns of SpO2. Desaturation then resaturation was the most common (46\%). ΔSpO2 >= 3\% occurred at approximately 1.2 min, and the nadir was at 3.5 min where resaturation occurred thereafter. The ΔSpO2 between the start and the nadir (start-vs-nadir ΔSpO2) was greater than the start-vs-end ΔSpO2 (P \< .001). The desaturators had less inspiratory muscle strength, worse dyspnea, and shorter 6-min walk distance, whereas the resaturators had greater FEV1/FVC and less functional residual capacity (all P \< .05). In the cycling test there were 3 patterns of SpO2. Desaturation was the most common (57\%). The ΔSpO2 >= 3\% and nadir SpO2 occurred at 4.6 min and 6.6 min, respectively, of the 6.8-min cycling exercise duration. The desaturators had lower body mass index, lower oxygen-cost diagram score, less post-exercise inspiratory muscle strength, lower diffusing capacity, lower SpO2, lower work during 6MWT, and lower peak exercise performance (all P \< .05). In both tests, the start-vs-nadir ΔSpO2 during the 6MWT was greater (P = .02) but the start-vs-end ΔSpO2 was similar (P = .79). The desaturators in both tests had lower oxygen-cost-diagram scores (P \< .01) and poorer peak exercise performance. CONCLUSIONS: Measurement of start-vs-nadir ΔSpO2 rather than start-vs-end ΔSpO2 during the 6MWT is recommended, because start-vs-nadir ΔSpO2 is greater, and the nadir SpO2 is earlier. In both the 6MWT and the cycling exercise test, desaturation can be predicted with the oxygen-cost-diagram score, which has more capability to predict peak exercise performance than the 6MWT.}, issn = {0020-1324}, URL = {https://rc.rcjournal.com/content/59/3/353}, eprint = {https://rc.rcjournal.com/content/59/3/353.full.pdf}, journal = {Respiratory Care} }