Differences in glucose values obtained from point-of-care glucose meters and laboratory analysis in critically ill patients.
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.
Cook
Anjannette
A
Providence Portland Medical Center, Portland, Oregon 97213, USA.
Laughlin
Delyla
D
Moore
Margery
M
North
Doreen
D
Wilkins
Kathleen
K
Wong
Gay
G
Wallace-Scroggs
Allyson
A
Halvorsen
Lisa
L
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
D001786:Blood Glucose