title: Arterial blood sampling devices influence ionized calcium measurements.
abstract: OBJECTIVE
  To determine the effect of commercially available arterial blood sampling devices on ionized calcium measurements.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Neurosurgical and shock-trauma intensive care units (ICU) at a tertiary care teaching hospital.
  
  
  METHODS
  Fourteen patients admitted to the ICU. Each patient had an indwelling arterial catheter.
  
  
  METHODS
  Arterial blood sampling.
  
  
  RESULTS
  In 14 ICU patients, measurements of arterial blood ionized calcium concentrations were performed, using 12 different commercially available arterial blood sampling devices. Significant underestimation of ionized calcium in blood samples compared with the reference test tube (Vacutainer 45) was seen in seven of the devices. Arterial blood ionized calcium concentrations measured, using one commercially available syringe, were significantly higher compared with the reference test tube. There was no correlation between either the amount or type of heparin in the arterial blood sampling devices and arterial blood ionized calcium measurement.
  
  
  CONCLUSIONS
  This study demonstrates that various commercially available arterial blood sampling devices alter arterial blood ionized calcium measurements. These alterations are clinically important because ICU patients may be treated with inappropriate calcium supplementation.
authors.affiliation: Department of Anesthesiology, University of Texas Medical School at Houston 77030-1503, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Koch
authors.forename: U
authors.initials: U
authors.lastname: Mehlhorn
authors.forename: B A
authors.initials: BA
authors.lastname: McKinley
authors.forename: S L
authors.initials: SL
authors.lastname: Irby
authors.forename: R D
authors.initials: RD
authors.lastname: Warters
authors.forename: S J
authors.initials: SJ
authors.lastname: Allen
mesh_terms: D001158:Arteries; D001774:Blood Chemical Analysis / Q000295:instrumentation*; D002118:Calcium / Q000097:blood*; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D006801:Humans; D007362:Intensive Care Units; D011446:Prospective Studies
chemical_list: D002118:Calcium