Lung function and exercise capacity in thalassaemia major

Abstract

Lung function abnormalities in thalassaemia major are various and complex; however, patients still die from cardiac lesions. This study aimed to investigate pulmonary and cardiac involvement at an early stage in thalassaemic patients and study their respective implications at rest and during exercise. Ten patients (five adults and five children) with thalassaemia major were investigated by echocardiography, lung function and exercise testing a few days after transfusion. All have had regular transfusions and chelation with deferoxamine and none had chronic pulmonary disease symptoms. Minor lung function abnormalities were found: two patients had moderate obstructive syndrome and two had a decreased carbon monoxide transfer factor. Hypoxaemia was never found at rest and no desaturation was observed at the end of exercise. Echocardiographic abnormalities were also moderate. Peak oxygen consumption (V'(O2)) was decreased in three adults and was lower in adults than children (means 27.7±4.6 and 41.1±4.8 mL·kg-1·min-1 respectively). The V'(O2)/cardiac frequency slope was lower in adults than children (0.25±0.06 versus 0.42±0.10 mL·kg-1·min-2), whereas end-exercise breathing reserve was >40% maximal voluntary ventilation for all patients. In conclusion, none of the patients had ventilatory limitations but older patients had cardiac limitations assessed by the relationship between oxygen consumption and cardiac frequency. Exercise testing may detect cardiac impairment in thalassaemia major earlier than investigations at rest.