title: A comparative study of hematocrits drawn from a standard venipuncture and those drawn from a saline lock device.
abstract: BACKGROUND
  Most trauma patients in the emergency department have multiple hematocrits drawn to monitor hypovolemia. These venipunctures are painful to the patient and frustrating for hospital staff when venipuncture sites are difficult to locate.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether the hematocrit values of blood samples obtained with saline lock devices agree or are different from those blood specimens obtained by standard venipuncture. If they agree, can the traditional venipuncture route of blood collection be replaced by collection from a saline lock device?
  
  
  METHODS
  The study used a quasiexperimental, repeated measures design. The research was conducted at a teaching, regional level I trauma center with annual ED visits of 65,000. Each subject had hematocrit samples obtained by venipuncture (control) according to standard trauma protocols. Within 5 minutes of obtaining each control specimen, a hematocrit sample was obtained with a saline lock device (experimental) after a 5 ml discard volume was obtained.
  
  
  RESULTS
  Results were analyzed by measures of central tendency and paired t test. There were no differences in mean hematocrit values in blood obtained by saline locks (41.1 +/- 4.4) and those drawn from direct venipunctures (41.0 +/- 3.9).
  
  
  CONCLUSIONS
  Obtaining samples for determination of hematocrit values from a saline look device is an accurate method of obtaining serial hematocrit values.
authors.affiliation: Emergency Department, University of California, Davis, Medical Center, Sacramento, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Sliwa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001800:Blood Specimen Collection / Q000379:methods*; D005260:Female; D006400:Hematocrit; D006801:Humans; D007262:Infusions, Intravenous / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy; D014111:Tourniquets