Anomalies des muscles squelettiques des BPCO en insuffisance respiratoire: Apport de la spectroscopie RMN ³¹P

³¹P magnetic resonance spectroscopy ( ³¹P MRS) is a non-invasive method to evaluate high energy compounds [adenosine triphosphate (ATP), phosphocreatin (PCr), inorganic phosphates (Pi)] and intracellular pH (pH(i)) of skeletal muscle during exercise and recovery. It is a clinically applicable method of investigation for severe COPD patients with respiratory failure since exercise is limited to a single group of muscle (calf). Pronounced alterations of muscular metabolism have been shown in these patients: (1) reduced aerobic capacity (as reflected by the ratio of Pi/PCr as a function of power and changes in recovery kinetics of PCr after exercise and (2) increased anaerobic metabolism (reflected by a decrease in intracellular pH). Four different studies reveal similar abnormalities. Acute oxygen administration partially improves these parameters, suggesting that other factors in addition to hypoxaemia may contribute to the metabolic impairment. The effects of increased physical activity on these abnormalities deserve further investigations.