Hemorheological alterations, decreased cerebral microvascular oxygenation and cerebral vasomotion compensation in sickle cell patients

Abstract

Sickle cell anemia (SS) is characterized by a reduced cerebral microvascular oxygen saturation (cerebral TOI), which is not associated with hemoglobin concentration. Cerebral TOI has never been studied in sickle cell-hemoglobin C disease (SC). We focused on the relationships between hemorheological alterations and cerebral TOI in sickle cell patients with no cerebral vasculopathy and on the usefulness of TOI variability to assess the cerebral vasomotion activity. The blood rheological profile, the level of cerebral TOI (spatial resolved spectroscopy) and the cerebral TOI variability, which reflects vasomotion activity, were compared between 20 healthy subjects (AA), 21 SC patients, and 21 SS patients. Cerebral TOI exhibited the following order: AA > SC > SS. The low cerebral TOI in SS patients was related to red blood cell aggregation and deformability properties. The cerebral TOI variability of SS and SC patients was increased above healthy values and vasomotion activity was negatively associated with the reduced cerebral TOI in SS patients. We demonstrated that (1) blood rheology could be involved in the reduced cerebral TOI in SS patients but not in SC patients; (2) vasomotion activity is increased in SS and SC patients to compensate for the reduced cerebral TOI. Am. J. Hematol. 87:1070Hematol. 87: -1073Hematol. 87: , 2012

Hematological and hemorheological Determinants of the Six-Minute Walk Test Performance in Children with Sickle Cell Anemia

“…Ours results support the fact that having higher RBC deformability contributes to a greater 6MWT distance in SCA children. A reduction of RBC deformability increases blood flow resistance into the microcirculation [6] and affects tissue oxygenation [11,15] because RBC with poor deformability cannot easily deform to enter into and flow through the microcirculation and bring oxygen to tissues. Based on these results, it is tempting to hypothesize that medication increasing RBC deformability, such as hydroxyurea, could increase physical capacity in SCA children.…”

“…. Recently, associations between blood rheological alterations and decreased tissue oxygenation, both at the muscle and cerebral level, have been described in sickle cell patients [15,16]. Based on these previous studies, one could suggest that the degree of hemorheological abnormalities, in association with the degree of anemia, could affect the 6MWT performance in SCA population.…”

Hematologic and hemorheological determinants of resting and exercise-induced hemoglobin oxygen desaturation in children with sickle cell disease

“…20,22,23,39 Therefore, SC and SS children were analyzed separately. Part of the results described here were previously included in a report on the initial SAPOTILLE cohort.…”

“…2,6,11 Sickle cell disease is characterized by severe hemorheological abnormalities that play a role in the pathophysiology of several acute and chronic complications. [16][17][18][19][20][21][22][23][24] Experimental work in non-SCD subjects and mathematical modeling strongly suggest that hemorheological impairment may contribute to hemoglobin oxygen desaturation at rest. 25 Hematocrit and red blood cell (RBC) deformability have been demonstrated to modulate pulmonary diffusing capacity.…”

Is there a relationship between the hematocrit-to-viscosity ratio and microvascular oxygenation in brain and muscle?

“…This study is a part of the SPIR project [33,34] and was performed on sixty-two age-and ethnicitymatched volunteers: 20 healthy subjects with no hemoglobinopathy (AA; 10 males and 10 females; 34.7 ± 11.9 yrs), 21 patients with sickle cell-hemoglobin C disease (SC; 10 males and 11 females; 35.9 ± 12.2 yrs) and 21 patients with sickle cell anemia (SS; 11 males and 10 females; 33.6 ± 11.9).…”