Sleep Apnea in Sickle Cell Disease (DREPAPNEE)

Effects of Obstructive Sleep Apnea on the Frequency of Vaso-occlusive Crises Events and Bio-physical Markers in Sickle Cell Disease

Despite the fact that obstructive sleep apnoea (OSA) is highly prevalent in the sickle cell population, studies focusing on the associations of the two diseases and their common pathophysiological mechanisms are scarce. OSA is one of the most common conditions responsible for hemoglobin desaturation. The nocturnal hemoglobin desaturation occurring in some sickle cell disease (SCD) patients with OSA could trigger hemoglobin S polymerization and red blood cell (RBC) sickling, leading to further blood rheological alterations, hence increasing the risks for VOC. Moreover, OSA has been demonstrated to increase oxidative stress and inflammation in non Sickle Cell Disease (SCD) patients, which, in SCD patients, could increase the risk for complications. Finally, OSA is accompanied by impaired vascular function and autonomic nervous system dysfunction in the general population. Indeed, the presence of OSA in SCD could increase the clinical severity of patients and the frequency of VOC.

Homozygous sickle cell patients Each patient will undergo the following: polysomnography and oxygen saturation exam calculation of VOC rate within the two previous years Blood samples Physiological measurements

Homozygous sickle cell patients after one year of continuous positive airway pressure treatment Each patient will undergo the following: polysomnography and oxygen saturation exam calculation of VOC rate within the two previous years Blood samples Physiological measurements

calculation of VOC frequency between the first polysomnography and the end of the first year of continuous positive airway pressure treatment

calculation of VOC rate within the two previous years or between first polysomnography and one year of continuous positive airway pressure treatment

Blood samples with measurements of hematological, hemorheological, inflammatory and blood coagulation markers

Calculated over a 2 years period before inclusion. VOC requiring hospitalizations will be recorded. Measured at day 1

Blood inflammatory markers : C Reactive Protein (CRP, mg/L) The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

Biological risk factors of VOC : prothrombin time (PT, s), D-dimer (µg/L), Fibrinogen (g/L), Activated Thromboplastin Time (APPT, s), protein C and protein S (%) The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

prothrombin time (PT, s), D-dimer (µg/L), Fibrinogen (g/L), Activated Thromboplastin Time (APPT, s), protein C and protein S (%)

Biological risk factors of VOC : Blood cell counts and markers of hemolysis : red blood cell count (G/L), neutrophil count (G/L), hemoglobin concentration (g/dL), hematocrit (%), mean corpuscular volume (MCV, fl), mean corpuscular hemoglobin concentration (MCHC, pg), platelet count (G/L), lactate dehydrogenase (LDH, IU), bilirubin (µg/L), aspartate transaminase (AST, U/L). The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

Blood cell counts and markers of hemolysis : red blood cell count (G/L), neutrophil count (G/L), hemoglobin concentration (g/dL), hematocrit (%), mean corpuscular volume (MCV, fl), mean corpuscular hemoglobin concentration (MCHC, pg), platelet count (G/L), lactate dehydrogenase (LDH, IU), bilirubin (µg/L), aspartate transaminase (AST, U/L).

Biological risk factors of VOC : markers of nitric oxide production nitrites, nitrate, nitrotyrosine The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

Biological risk factors of VOC : protein oxidation marker (advanced oxidation protein products), markers of lipid peroxidation (malondialdehyde), antioxidant enzymatic activities (super oxide dismutase, catalase, glutathione peroxidase), antioxidant power (ferric reducing ability of plasma) The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

protein oxidation marker (advanced oxidation protein products), markers of lipid peroxidation (malondialdehyde), antioxidant enzymatic activities (super oxide dismutase, catalase, glutathione peroxidase), antioxidant power (ferric reducing ability of plasma)

blood viscosity (cP) measured with a cone plate viscometer at several shear rates, red blood cell deformability (a.u) measured by ektacytometry at several shear stresses, red blood cell aggregation (%) properties measured by laser backscatter method. The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

Biological risk factors of VOC : blood viscosity (cP) measured with a cone plate viscometer at several shear rates, red blood cell deformability (a.u) measured by ektacytometry at several shear stresses, red blood cell aggregation (%) properties measured by laser backscatter method.

Biological risk factors of VOC : oxygen and carbon dioxide pressure (mmHg), pH The morning after the polysomnography blood samples will be collected (M1 +/- 15 days)

Physiological risk factors of VOC : A laser Doppler flowmeter (Periflux 5000 Perimed) will be used to measure skin blood flow in resting condition and during a local thermal hyperemia (LTH) test (temperature will be increased from 33 °C to 42 °C) for 35 min. The peak response during the LTH reflects vasodilatation caused by axonal reflex while the delayed plateau response of the LTH test is mainly dependent on the ability to produce nitric oxide to promote vasodilation.

A laser Doppler flowmeter (Periflux 5000 Perimed) will be used to measure skin blood flow in resting condition and during a local thermal hyperemia (LTH) test (temperature will be increased from 33 °C to 42 °C) for 35 min. The peak response during the LTH reflects vasodilatation caused by axonal reflex while the delayed plateau response of the LTH test is mainly dependent on the ability to produce nitric oxide to promote vasodilation.

Physiological risk factors of VOC : electrocardiographic signals acquired by the polysomnographic machine will be extracted and the R-R intervals will be used for time domain spectral analyses to calculate several indices reflecting the activity of the autonomic nervous system activity. The ratio between the low frequency and the high frequency powers (LF/HF) will be used to characterize the autonomic imbalance.

electrocardiographic signals acquired by the polysomnographic machine will be extracted and the R-R intervals will be used for time domain spectral analyses to calculate several indices reflecting the activity of the autonomic nervous system activity. The ratio between the low frequency and the high frequency powers (LF/HF) will be used to characterize the autonomic imbalance.

Inclusion Criteria: Homozygous HbS (Hemoglobin S) (SS) patients, aged between 15 and 3 months and 50 years old, in steady state (i.e. without vaso-occlusive crisis or recent blood transfusion), followed by the sickle cell center of the Hospices Civils de Lyon, and showing symptoms of OSA. Exclusion Criteria: Patients receiving treatment of OSA, recent blood transfusion (less than 2 months), patients not at steady state (VOC or acute chest syndrome less than 2 months), pregnancy.

Stauffer E, Poutrel S, Cannas G, Gauthier A, Fort R, Bertrand Y, Renoux C, Joly P, Boisson C, Hot A, Peter-Derex L, Pialoux V, PetitJean T, Connes P. Nocturnal Hypoxemia Rather Than Obstructive Sleep Apnea Is Associated With Decreased Red Blood Cell Deformability and Enhanced Hemolysis in Patients With Sickle Cell Disease. Front Physiol. 2021 Sep 24;12:743399. doi: 10.3389/fphys.2021.743399. eCollection 2021.