Apport de l'etude des echanges gazeux respiratoires au cours de l'exercice dans le diagnostic d'une glycogenose musculaire

Background. - The diagnosis of muscular glycogen storage disease is usually difficult to demonstrate as symptoms normally consist of muscular cramps and exercise intolerance. Informations obtained from the study of the pulmonary, gas exchange during exercise in a young patient with a glycogen storage disease are reported. Case report. - The ventilatory and gas exchange responses to a cyclo-ergometer exercise were studied in a 17-year-old girl during a ramp-like test (5 W/min). The temporal profile of CO₂ production (V̇C0₂) response was clearly abnormal.' V̇CO₂ was always lower than oxygen consumption throughout the test, reflecting the lack of lactate buffering by the bicarbonates due to the absence of lactate production. The respiratory ratio was still around 0.75 at the peak of the test. In contrast, responses were perfectly normal in the other members of the family, allowing rejection of the diagnosis of glycogen storage disease without any blood sampling. Conclusion. - This case illustrates the benefit of studying pulmonary gas exchange during exercise for a non-invasive diagnosis of muscular glycogen storage disease and detection of the disease in the other members of family.