Cardio-pulmonary exercise testing as a screening method in mitochondrial disorders

Cardiopulmonary exercise testing (CPX) is a non-invasive method of recordin g quantitative data from gas exchange and ventilation for the evaluation of oxidative metabolism at rest and during exercise. Determination of oxygen uptake (VO2) and carbon dioxide output (VCO2) describes the activity of ana erobic vs aerobic metabolism. An incremental exercise test measuring gas ex change, ventilation and lactate release was performed in healthy volunteers and in patients suffering from mitochondrial disorders. At rest as well as during exercise patients with mitochondrial disorders differ from healthy subjects with regard to gas exchange and ventilation parameters. During exe rcise, the decreased oxygen utilization of skeletal muscle and early activa tion of anaerobic metabolism in these patients are mirrored by a reduced an aerobic threshold, reduced maximal oxygen uptake and reduced oxygen pulse. Our study shows that CPX is a sensitive and practical clinical screening me thod of investigating mitochondrial disorders.