RT Journal Article
SR Electronic
T1 Oxygen supplementation during exercise improves leg muscle fatigue in chronic fibrotic interstitial lung disease
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 672
OP 680
DO 10.1136/thoraxjnl-2020-215135
VO 76
IS 7
A1 Mathieu Marillier
A1 Anne-Catherine Bernard
A1 Samuel Verges
A1 Onofre Moran-Mendoza
A1 Denis E O'Donnell
A1 José Alberto Neder
YR 2021
UL http://thorax.bmj.com/content/76/7/672.abstract
AB Background Exercise-induced hypoxaemia is a hallmark of chronic fibrotic interstitial lung disease (f-ILD). It remains unclear whether patients’ severe hypoxaemia may exaggerate locomotor muscle fatigue and, if so, to what extent oxygen (O2) supplementation can ameliorate these abnormalities.Methods Fifteen patients (12 males, 9 with idiopathic pulmonary fibrosis) performed a constant-load (60% peak work rate) cycle test to symptom limitation (Tlim) while breathing medical air. Fifteen age-matched and sex-matched controls cycled up to patients’ Tlim. Patients repeated the exercise test on supplemental O2 (42%±7%) for the same duration. Near-infrared spectroscopy assessed vastus lateralis oxyhaemoglobin concentration ((HbO2)). Pre-exercise to postexercise variation in twitch force (∆Tw) induced by femoral nerve magnetic stimulation quantified muscle fatigue.Results Patients showed severe hypoxaemia (lowest O2 saturation by pulse oximetry=80.0%±7.6%) which was associated with a blunted increase in muscle (HbO2) during exercise vs controls (+1.3±0.3 µmol vs +4.4±0.4 µmol, respectively; p<0.001). Despite exercising at work rates ∼ one-third lower than controls (42±13 W vs 66±13 W), ∆Tw was greater in patients (∆Tw/external work performed by the leg muscles=−0.59±0.21 %/kJ vs −0.25±0.19 %/kJ; p<0.001). Reversal of exertional hypoxaemia with supplemental O2 was associated with a significant increase in muscle (HbO2), leading to a reduced decrease in ∆Tw in patients (−0.33±0.19 %/kJ; p<0.001 vs air). Supplemental O2 significantly improved leg discomfort (p=0.005).Conclusion O2 supplementation during exercise improves leg muscle oxygenation and fatigue in f-ILD. Lessening peripheral muscle fatigue to enhance exercise tolerance is a neglected therapeutic target that deserves clinical attention in this patient population.Data are available on reasonable request. Data available from the authors on request—unidentified patients in excel/SPSS files.