One-Fifth of Children with Sickle Cell Anemia Show Exercise-Induced Hemoglobin Desaturation: Rate of Perceived Exertion and Role of Blood Rheology.

Valentine Brousse,Cecile Arnaud,Hélène Bourdeau,Benedicte Boutonnat-Faucher,Mariane De Montalembert,Corinne Pondarre,Suzanne Verlhac,Keyne Charlot,David Grévent,Annie Kamden,Philippe Connes,Lydie Da Costa

doi:10.3390/jcm9010133

Abstract

Perceived exertion is an important self-limiting factor influencing functional capacity in patients with sickle cell anemia (SCA). Exercise-related hemoglobin desaturation (EHD) may occur during a six-minute walking test (6MWT) and could influence the perceived rate of exertion. The aims of this study were (1) to compare the 6MWT responses (heart rate, perceived rate of exertion, and distance covered) between SCA children with and without EHD, and (2) to test the associations between EHD and several biological/physiological parameters. Nine of 51 SCA children (18%) at steady state (mean age 11.9 ± 3.8 years) exhibited EHD at the end of the 6MWT. The rate of perceived exertion increased with exercise in the two groups, but reached higher values in the EHD group. Heart rate and performance during the 6MWT did not differ between the two groups. The magnitude of change in SpO2 during the 6MWT was independently associated with the red blood cell (RBC) deformability and RBC aggregates strength. This study demonstrates that SCA children with EHD during a 6MWT have a higher rate of perceived exertion than non-EHD children despite a similar physiological demand, and that abnormal RBC rheology determinants appear to be significant contributors.

Highlights

Sickle cell anemia (SCA) is caused by a single mutation in the beta-globin gene responsible for the production of abnormal hemoglobin S (HbS)
The Exercise-related hemoglobin desaturation (EHD) group was significantly older than the non-EHD group
We looked for associations between ∆SpO2 and other parameters in the whole cohort, as follows: ∆SpO2 was positively correlated with age (r = 0.34; p < 0.05), RET count (r = 0.27; p < 0.05), PLT count (r = 0.31; p < 0.05), red blood cell (RBC) disaggregation threshold (r = 0.32; p < 0.05), and negatively with the

Summary

Introduction

Sickle cell anemia (SCA) is caused by a single mutation in the beta-globin gene responsible for the production of abnormal hemoglobin S (HbS). Abnormal RBC aggregation properties (increased RBC aggregates strength) have been reported in SCA patients, which may impair blood flow in the microcirculation and participate in the onset of vaso-occlusive events [5,6]. It was previously demonstrated that hemoglobin (Hb) and fetal hemoglobin (HbF) levels, as well as RBC deformability, were independent predictors of the 6MWT performance in SCA children [11]. Anthi et al [12] previously showed the usefulness of using the 6MWT distance as an index of pulmonary hypertension and cardiopulmonary function in adults with SCA. Minniti et al [14] demonstrated that hemoglobin oxygen desaturation during a 6MWT was more frequent in SCA children with pulmonary hypertension compared to those without

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