title: The relationship between vacuum and hemolysis during catheter blood collection: a retrospective analysis of six large cohorts.
abstract: BACKGROUND
  Blood collection through intravenous (IV) catheters is a common practice at emergency departments (EDs). This technique is associated with higher in vitro hemolysis rates and may even be amplified by the use of vacuum collection tubes. Our aim was to investigate the association of five different vacuum tubes with hemolysis rates in comparison to an aspiration system under real-life conditions and to propose an equation to estimate the amount of hemolysis, depending on the vacuum collection tube type.
  
  
  METHODS
  We retrospectively evaluated hemolysis data of plasma samples from our ED, where blood is drawn through IV catheters. Over the past 5 years, we compared 19,001 hemolysis index values amongst each other and against the respective vacuum pressure (Pv) of the collection tubes, which were used within the six observational periods.
  
  
  RESULTS
  The highest hemolysis rates were associated with full-draw evacuated tubes. Significantly reduced hemolysis was observed for two kinds of partial-draw tubes. The hemolysis rate of one partial-draw blood collection tube was comparable to those of the aspiration system. Regression analysis of Pv and mean free hemoglobin (fHb) values yielded the formula fHb (g/L)=0.0082*Pv2-0.1143*Pv+ 0.5314 with an R2 of 0.99.
  
  
  CONCLUSIONS
  If IV catheters are used for blood collection, hemolysis rates directly correlate with the vacuum within the tubes and can be estimated by the proposed formula. By the use of partial-draw vacuum blood collection tubes, hemolysis rates in IV catheter collections can be reduced to levels comparable with collections performed by aspiration systems.
authors.affiliation: .
authors.forename: Cornelia
authors.initials: C
authors.lastname: Mrazek
authors.affiliation: .
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Simundic
authors.affiliation: .
authors.forename: Helmut
authors.initials: H
authors.lastname: Wiedemann
authors.affiliation: .
authors.forename: Florian
authors.initials: F
authors.lastname: Krahmer
authors.affiliation: .
authors.forename: Thomas Klaus
authors.initials: TK
authors.lastname: Felder
authors.affiliation: .
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kipman
authors.affiliation: .
authors.forename: Uta
authors.initials: U
authors.lastname: Hoppe
authors.affiliation: .
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Haschke-Becher
authors.affiliation: .
authors.forename: Janne
authors.initials: J
authors.lastname: Cadamuro
mesh_terms: D001800:Blood Specimen Collection / Q000295:instrumentation*; D057785:Catheters; D015331:Cohort Studies; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis; D006801:Humans; D012189:Retrospective Studies; D014618:Vacuum
chemical_list: D006454:Hemoglobins
keywords: blood collection; emergency department; hemolysis; preanalytics