«Debilidad del cuadriceps relacionado con la capacidad de ejercicio en la fibrosis pulmonar idiopática.»
Osamu Nishiyama, MD; Hiroyuki Taniguchi, MD; Yasuhiro Kondoh, MD; Tomoki Kimura, MD; Tomoya Ogawa, PT; Fumiko Watanabe, PT and Shinichi Arizono, PT
* From the Departments of Respiratory Medicine and Allergy (Drs. Nishiyama, Taniguchi, Kondoh, and Kimura) and Rehabilitation (Mr. Ogawa, Ms. Watanabe, and Mr. Arizono), Tosei General Hospital, Seto, Aichi, Japan.
Correspondence to: Osamu Nishiyama, MD, Department of Respiratory Medicine and Allergy, Tosei General Hospital, 160 Nishioiwake-cho, Seto, Aichi, 489-8642 Japan; e-mail: email@example.com
Study objective: In COPD, it has been shown that peripheral muscle dysfunction is a factor determining exercise intolerance. We examined the hypothesis that exercise capacity of patients with idiopathic pulmonary fibrosis (IPF) is, at least in part, determined by peripheral muscle dysfunction.
Methods: Maximum oxygen uptake (O2max) was evaluated in 41 consecutive patients with IPF, along with potential determinants of exercise capacity, both in the lungs and in the peripheral muscles.
Results: Patients had reduced O2max (893 ± 314 mL, 46.0% predicted) and reduced quadriceps force (QF) [65% predicted]. Significant correlates of O2max reduction were vital capacity (VC) [r = 0.79], total lung capacity (r = 0.64), diffusion capacity (r = 0.64), QF (r = 0.62), maximum expiratory pressure (r = 0.48), and PaO2 at rest (r = 0.33). In stepwise multiple regression analysis, VC and QF were independent predictors of O2max. Furthermore, in subgroup analysis, QF was a significant contributing factor for O2max in patients who discontinued exercise because of dyspnea and/or leg fatigue.
Conclusions: We conclude that QF is a predictor of exercise capacity in IPF. Measures that improve muscle function might improve exercise tolerance.