title: Blood volume determination in obese and normal-weight gravidas: the hydroxyethyl starch method.
abstract: OBJECTIVE
  The impact of obesity on maternal blood volume in pregnancy has not been reported. We compared the blood volumes of obese and normal-weight gravidas using a validated hydroxyethyl starch (HES) dilution technique for blood volume estimation.
  
  
  METHODS
  Blood volumes were estimated in 30 normal-weight (pregravid body mass index [BMI] <25 kg/m(2)) and 30 obese (pregravid BMI >35 kg/m(2)) gravidas >34 weeks' gestation using a modified HES dilution technique. Blood samples obtained before and 10 minutes after HES injection were analyzed for plasma glucose concentrations after acid hydrolysis of HES. Blood volume was calculated from the difference between glucose concentrations measured in hydrolyzed plasma.
  
  
  RESULTS
  Obese gravidas had higher pregravid and visit BMI (mean [SD]): pregravid (41 [4] vs 22 [2] kg/m(2), P = .001); visit (42 [4] vs 27 [2] kg/m(2), P = .001), but lower weight gain (5 [7] vs 12 [4] kg, P = .001) than normal-weight women. Obese gravidas had similar estimated total blood volume to normal-weight women (8103 ± 2452 vs 6944 ± 2830 mL, P = .1), but lower blood volume per kilogram weight (73 ± 22 vs 95 ± 30 mL/kg, P = .007).
  
  
  CONCLUSIONS
  Obese gravidas have similar circulating blood volume, but lower blood volume per kilogram body weight, than normal-weight gravidas near term.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Case Western Reserve University-MetroHealth Medical Center, Cleveland, OH; Department of Obstetrics and Gynecology, Mercy Hospital, St Louis, MO. Electronic address: lpvricella@gmail.com.
authors.forename: Laura K
authors.initials: LK
authors.lastname: Vricella
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Morsani College of Medicine, University of South Florida, Tampa, FL.
authors.forename: Judette M
authors.initials: JM
authors.lastname: Louis
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Case Western Reserve University-MetroHealth Medical Center, Cleveland, OH.
authors.forename: Edward
authors.initials: E
authors.lastname: Chien
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Case Western Reserve University-MetroHealth Medical Center, Cleveland, OH.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Mercer
mesh_terms: D000293:Adolescent; D000328:Adult; D001811:Blood Volume Determination / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives; D009765:Obesity / Q000503:physiopathology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D006895:Hydroxyethyl Starch Derivatives
keywords: blood volume; hydroxyethyl starch; obesity; obstetric anesthesia