Quadriceps muscle oxygenation parameters during exercise in ILD patients

Background: Poor exercise capacity was related the impaired quadriceps muscles function in patients with interstitial lung diseases (ILD). In normal subjects, tissue oxygen saturation (StO 2 ) in Quadriceps muscle related exercise capacity. ILD patients have severe hypoxia during exercise. We hypothesized that the SpO 2 - StO 2 which was considered exercise induced hypoxia would be usefulmuscle oxygenation parameter than the StO 2 . The purpose of the present study was to compare the SpO 2 - StO 2 and the StO 2 in relation to exercise capacity, pulmonary functional, dyspnea and health status in ILD patients. Methods : Forty ILD patients (%VC: 88.8±19.0%) were measured cardiopulmonary exercise test (CPET), pulmonary functional test (%VC, %DLco), dyspnea (Baseline dyspnea index: BDI), health status (St. George9s Respiratory Questionnaire: SGRQ), muscle strength tests. During CPET, we continuously monitored SpO 2 , and measured StO 2 in Quadriceps muscle with continuous-wave near-infrared spectroscopy. We calculated Pearson correlation coefficients to examine the relationships between the StO 2 , the SpO 2 - StO 2 and measurements. Results: At the end of CPET, the StO 2 was 52.9%, the SpO 2 - StO 2 was 35.5%. StO 2 was significantly correlated only with %DLco (p 2 - StO 2 was significantly correlated with peakVO 2 , %VC, %DLco, BDI, SGRQ, and SpO 2 (p Conclusion: In ILD patients, our study showed that the SpO 2 - StO 2 may be useful muscle oxygenation parameter than the StO 2 .