title: Patients with sickle cell anemia on simple chronic transfusion protocol show sex differences for hemodynamic and hematologic responses to transfusion.
abstract: BACKGROUND
  Chronic transfusion therapy (CTT) is a mainstay for stroke prophylaxis in sickle cell anemia, but its effects on hemodynamics are poorly characterized. Transfusion improves oxygen-carrying capacity, reducing demands for high cardiac output, while decreasing hemoglobin (Hb)S%, reticulocyte count, and hemolysis. We hypothesized that transfusion would improve oxygen-carrying capacity, but that would be counteracted by a decrease in cardiac output due to increased hematocrit (Hct) and vascular resistance, leaving oxygen delivery unchanged.
  
  
  METHODS
  To test this hypothesis, we examined patients on CTT immediately before transfusion and again 12 to 120 hours after transfusion, using echocardiography and near infrared spectroscopy.
  
  
  RESULTS
  Comparable increases in Hb and Hct and decreases in reticulocyte count and HbS with transfusion were observed in all patients, but males had a larger rebound of HbS%, reticulocyte count, and free Hb levels between transfusions. In males, transfusion decreased heart rate by 12%, stroke volume by 15%, and cardiac index by 24% while estimates for pulmonary and systemic vascular resistance increased, culminating in 6% decrease in oxygen delivery. In contrast, stroke volume and cardiac index and systemic and pulmonary vascular resistance did not change in women after transfusion, such that oxygen delivery improved 17%.
  
  
  CONCLUSIONS
  In our sample population, males exhibit a paradoxical reduction in oxygen delivery in response to transfusion because the increase in vascular resistance is larger than the increase in oxygen capacity. This may result from an inability to adequately suppress their HbS% between transfusion cycles.
authors.affiliation: Division of Cardiology, Division of Pediatric Pulmonology, Division of Hematology, Children's Hospital Los Angeles, Los Angeles, California 90027, USA. jdetterich@chla.usc.edu
authors.forename: Jon A
authors.initials: JA
authors.lastname: Detterich
authors.forename: Suvimol
authors.initials: S
authors.lastname: Sangkatumvong
authors.forename: Roberta
authors.initials: R
authors.lastname: Kato
authors.forename: Ani
authors.initials: A
authors.lastname: Dongelyan
authors.forename: Adam
authors.initials: A
authors.lastname: Bush
authors.forename: Michael
authors.initials: M
authors.lastname: Khoo
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Meiselman
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Coates
authors.forename: John C
authors.initials: JC
authors.lastname: Wood
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood / Q000000981:diagnostic imaging / Q000628:therapy*; D015415:Biomarkers / Q000097:blood; D001772:Blood Cell Count; D001803:Blood Transfusion; D002648:Child; D002985:Clinical Protocols; D003430:Cross-Sectional Studies; D004452:Echocardiography; D005260:Female; D006400:Hematocrit; D006439:Hemodynamics; D006451:Hemoglobin, Sickle / Q000378:metabolism; D006801:Humans; D016014:Linear Models; D008297:Male; D011446:Prospective Studies; D012156:Reticulocytes / Q000378:metabolism; D012737:Sex Factors; D019265:Spectroscopy, Near-Infrared; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006451:Hemoglobin, Sickle