Cardiopulmonary exercise testing in male adolescent patients with thalassemia major after blood transfusion

Thalassemia major (TM) is characterized by anemia, and a synthesis defect occurs in both beta globin genes on the short arm of chromosome 11. Thalassemia patients suffer fatigue, and decreases in VO2max and aerobic exercise capacity are observed. Cardiopulmonary exercise test (CPET) data are valuable for interpreting the responses of the cardiovascular, respiratory, and locomotor systems to exercise. The main purpose of our study was to reveal the effects of transfusion on respiratory parameters, oxygen uptake, the ventilatory threshold, and maximal exercise capacity in the adolescent population.

Twelve boys with TM (age: 16.0 ± 0.6 years) participated in our study. Pulmonary function tests and incremental symptom-limited CPETs on cycle ergometers were performed before and after blood transfusion.

The exercise capacity (VO2max, mL kg-1min: 27.3 ± 1.9 vs 30.0 ± 2.1; P < 0.005) and maximal watt value (89.1 ± 5.1 and 101.6 ± 5.5 W; P < 0.001) were increased after transfusion. The changes in ventilatory equivalents and end-tidal CO2 - O2 partial pressures were compared before and after transfusion at five different stages. These stages are determined as rest (pre), VT, maximum (max) points, and exercise intensities corresponding to 50% of rest and VT (Mid1) and 50% of VT and maximum (Mid2). Compared with transfusion, transfusion significantly reduced the VE/VO2 Mid1 and VT values (P < 0.05). In addition, the VE/VCO2 values were significantly lower at Mid1 and VT than before transfusion (P < 0.05).

Although no significant change in the ventilatory threshold was detected after transfusions, the significant decrease in the minute ventilation to oxygen and carbon dioxide ratios may be interpreted as a sign that respiration is more efficient in these patients. The absence of a significant change in the VO2/work rate after transfusion suggests that patients can tolerate an increased workload. The ability of the cardiopulmonary system and skeletal muscle to cope with the increased workload indicates that these systems are not adversely affected in these patients. A well-tailored activity routine may be important to recommend for TM patients to prevent the adverse effects of a sedentary lifestyle, which may threaten their wellness during adulthood.