title: Is there a relationship between the hematocrit-to-viscosity ratio and microvascular oxygenation in brain and muscle?
abstract: The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s(-1)), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r=0.28; p=0.03 and r=0.38; p=0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R2<0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
authors.affiliation: Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, 75015, Paris, France Université des Antilles et de la Guyane, Laboratoire ACTES (EA 3596), Département de Physiologie, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Waltz
authors.affiliation: Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, 75015, Paris, France.
authors.forename: Marie-Dominique
authors.initials: MD
authors.lastname: Hardy-Dessources
authors.affiliation: Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Lemonne
authors.affiliation: Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Danièle
authors.initials: D
authors.lastname: Mougenel
authors.affiliation: Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France CIC-EC 802 Inserm, Centre Hospitalier Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Lalanne-Mistrih
authors.affiliation: Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, 75015, Paris, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Lamarre
authors.affiliation: Centre de référence maladies rares pour la drépanocytose aux Antilles-Guyane, Centre Hospitalier et Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Tarer
authors.affiliation: CIC-EC 802 Inserm, Centre Hospitalier Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Tressières
authors.affiliation: Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire de Pointe-à-Pitre, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Maryse
authors.initials: M
authors.lastname: Etienne-Julan
authors.affiliation: Université des Antilles et de la Guyane, Laboratoire ACTES (EA 3596), Département de Physiologie, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Hue
authors.affiliation: Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, 75015, Paris, France Université des Antilles et de la Guyane, Laboratoire ACTES (EA 3596), Département de Physiologie, Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Connes
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000378:metabolism; D001809:Blood Viscosity; D001921:Brain / Q000098:blood supply*; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D055806:Microvessels / Q000378:metabolism*; D008875:Middle Aged; D009132:Muscles / Q000098:blood supply*; D010100:Oxygen / Q000378:metabolism*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Microvascular oxygenation; hemorheology; sickle cell syndromes