title: Effect of the size of evacuated blood collection tubes on total carbon dioxide concentration in equine plasma.
abstract: OBJECTIVE
  To determine whether plasma total CO(2) concentrations would vary with the size of the evacuated tube used to collect blood samples.
  
  
  METHODS
  Randomized crossover study.
  
  
  METHODS
  Convenience sample of 20 healthy adult horses.
  
  
  METHODS
  Jugular venous blood was collected from horses in random order into 8 types of evacuated tubes: 2-mL glass, 2- or 3-mL plastic or plastic plasma separator, 4- or 6-mL plastic, and 10-mL glass or plastic. Total CO(2) concentrations in plasma were measured with a biochemistry analyzer. Data were analyzed via repeated-measures ANOVA and multivariate regression.
  
  
  RESULTS
  The air volume-to-blood volume ratio was significantly higher and consequently, plasma total CO(2) concentration was significantly lower when blood was collected into 2-mL glass tubes and 2- or 3-mL plastic tubes than when the other 5 types of evacuated tubes were used. Concentrations in the other tube types were statistically equivalent. A linear relationship was detected between total CO(2) concentration and air volume-to-blood volume ratio.
  
  
  CONCLUSIONS
  Blood samples should be collected into evacuated tubes with a small air volume-to-blood volume ratio whenever an accurate estimate of plasma total CO(2) concentration is required.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA. stinkler@purdue.edu
authors.forename: Stacy H
authors.initials: SH
authors.lastname: Tinkler
authors.forename: Laurent L
authors.initials: LL
authors.lastname: Couëtil
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Kennedy
authors.forename: Peter D
authors.initials: PD
authors.lastname: Constable
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis / Q000592:standards / Q000662:veterinary; D001800:Blood Specimen Collection / Q000295:instrumentation / Q000662:veterinary*; D002245:Carbon Dioxide / Q000097:blood*; D018592:Cross-Over Studies; D005260:Female; D006736:Horses / Q000097:blood*; D008297:Male; D013048:Specimen Handling / Q000295:instrumentation / Q000662:veterinary
chemical_list: D002245:Carbon Dioxide