title: Differences in glucose values obtained from point-of-care glucose meters and laboratory analysis in critically ill patients.
abstract: BACKGROUND
  Blood for glucose analysis is often obtained interchangeably from indwelling catheters and fingersticks.
  
  
  OBJECTIVE
  To determine the level of agreement between glucose values obtained by laboratory analysis and with a point-of-care device for blood from 2 different sources: fingerstick and a central venous catheter.
  
  
  METHODS
  A method-comparison design was used. Point-of-care values for blood from fingersticks and catheters were compared with laboratory values for blood from catheters in a convenience sample of 67 critically ill patients. The effects of hematocrit level and finger edema on differences in glucose values between the 2 methods were also evaluated. A t test was used to determine differences in glucose values obtained via the 2 methods. Differences and limits of agreement were also calculated.
  
  
  RESULTS
  Laboratory glucose values for blood from a catheter differed significantly from point-of-care values for blood from the catheter (t(1,66) = -9.18; P < .001) and from a fingerstick (t(1,66) = 6.53; P < .001). Glucose values for the 2 methods differed by 20 mg/dL or more for 1 of 6 patients (15%) for catheter samples and for 1 of 5 (21%) for fingerstick samples. Point-of-care glucose values for fingerstick and catheter samples did not differ (P = .98). Hematocrit level significantly explained the difference in glucose values between the 2 methods for both catheter (R(2) = 0.288; P < .001) and fingerstick (R(2) = 0.280; P = .02) samples.
  
  
  CONCLUSIONS
  Use of a commonly used point-of-care device when precise glucose values are needed may lead to faulty treatment decisions.
authors.affiliation: Providence Portland Medical Center, Portland, Oregon 97213, USA.
authors.forename: Anjannette
authors.initials: A
authors.lastname: Cook
authors.forename: Delyla
authors.initials: D
authors.lastname: Laughlin
authors.forename: Margery
authors.initials: M
authors.lastname: Moore
authors.forename: Doreen
authors.initials: D
authors.lastname: North
authors.forename: Kathleen
authors.initials: K
authors.lastname: Wilkins
authors.forename: Gay
authors.initials: G
authors.lastname: Wong
authors.forename: Allyson
authors.initials: A
authors.lastname: Wallace-Scroggs
authors.forename: Lisa
authors.initials: L
authors.lastname: Halvorsen
mesh_terms: D000368:Aged; D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods*; D001786:Blood Glucose / Q000032:analysis*; D003422:Critical Care / Q000379:methods*; D006400:Hematocrit; D006801:Humans; D008875:Middle Aged; D019095:Point-of-Care Systems; D012044:Regression Analysis; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose