Anemia causes hypoglycemia in intensive care unit patients due to error in single-channel glucometers: Methods of reducing patient risk

Heather F. Pidcoke, Charles E. Wade, Elizabeth A. Mann, Jose Salinas, Brian M. Cohee, John B. Holcomb, Steven Wolf

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Objective: Intensive insulin therapy in the critically ill reduces mortality but carries the risk of increased hypoglycemia. Point-of-care blood glucose analysis is standard; however, anemia causes falsely high values and potentially masks hypoglycemia. Permissive anemia is practiced routinely in most intensive care units. We hypothesized that point-of-care glucometer error due to anemia is prevalent, can be corrected mathematically, and correction uncovers occult hypoglycemia during intensive insulin therapy. Design: The study has both retrospective and prospective phases. We reviewed data to verify the presence of systematic error, determine the source of error, and establish the prevalence of anemia. We confirmed our findings by reproducing the error in an in vitro model. Prospective data were used to develop a correction formula validated by the Monte Carlo method. Correction was implemented in a burn intensive care unit and results were evaluated after 9 mos. Setting: Burn and trauma intensive care units at a single research institution. PATIENTS/Subjects: Samples for in vitro studies were taken from healthy volunteers. Samples for formula development were from critically ill patients who received intensive insulin therapy. Interventions: Insulin doses were calculated based on predicted serum glucose values from corrected point-of-care glucometer measurements. Measurements and Main Results: Time-matched point-of-care glucose, laboratory glucose, and hematocrit values. We previously found that anemia (hematocrit <34%) produces systematic error in glucometer measurements. The error was correctible with a mathematical formula developed and validated, using prospectively collected data. Error of uncorrected point-of-care glucose ranged from 19% to 29% (p <.001), improving to ≤5% after mathematical correction of prospective data. Comparison of data pairs before and after correction formula implementation demonstrated a 78% decrease in the prevalence of hypoglycemia in critically ill and anemic patients treated with insulin and tight glucose control (p <.001). Conclusions: A mathematical formula that corrects erroneous point-of-care glucose values due to anemia in intensive care unit patients reduces the prevalence of hypoglycemia during intensive insulin therapy.

Original languageEnglish (US)
Pages (from-to)471-476
Number of pages6
JournalCritical Care Medicine
Volume38
Issue number2
DOIs
StatePublished - Jan 1 2010
Externally publishedYes

Fingerprint

Point-of-Care Systems
Hypoglycemia
Intensive Care Units
Anemia
Insulin
Glucose
Critical Illness
Hematocrit
Monte Carlo Method
Therapeutics
Masks
Blood Glucose
Healthy Volunteers
Research Design
Mortality
Wounds and Injuries
Serum
Research

Keywords

  • Anemia
  • Critical care
  • Glucometer
  • Glucose
  • Glucose measurement
  • Glucose oxidase
  • Hematocrit
  • Insulin
  • Intensive care unit
  • Point-of-care systems

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

Cite this

Anemia causes hypoglycemia in intensive care unit patients due to error in single-channel glucometers : Methods of reducing patient risk. / Pidcoke, Heather F.; Wade, Charles E.; Mann, Elizabeth A.; Salinas, Jose; Cohee, Brian M.; Holcomb, John B.; Wolf, Steven.

In: Critical Care Medicine, Vol. 38, No. 2, 01.01.2010, p. 471-476.

Research output: Contribution to journalArticle

Pidcoke, Heather F. ; Wade, Charles E. ; Mann, Elizabeth A. ; Salinas, Jose ; Cohee, Brian M. ; Holcomb, John B. ; Wolf, Steven. / Anemia causes hypoglycemia in intensive care unit patients due to error in single-channel glucometers : Methods of reducing patient risk. In: Critical Care Medicine. 2010 ; Vol. 38, No. 2. pp. 471-476.
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AU - Salinas, Jose

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AU - Wolf, Steven

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N2 - Objective: Intensive insulin therapy in the critically ill reduces mortality but carries the risk of increased hypoglycemia. Point-of-care blood glucose analysis is standard; however, anemia causes falsely high values and potentially masks hypoglycemia. Permissive anemia is practiced routinely in most intensive care units. We hypothesized that point-of-care glucometer error due to anemia is prevalent, can be corrected mathematically, and correction uncovers occult hypoglycemia during intensive insulin therapy. Design: The study has both retrospective and prospective phases. We reviewed data to verify the presence of systematic error, determine the source of error, and establish the prevalence of anemia. We confirmed our findings by reproducing the error in an in vitro model. Prospective data were used to develop a correction formula validated by the Monte Carlo method. Correction was implemented in a burn intensive care unit and results were evaluated after 9 mos. Setting: Burn and trauma intensive care units at a single research institution. PATIENTS/Subjects: Samples for in vitro studies were taken from healthy volunteers. Samples for formula development were from critically ill patients who received intensive insulin therapy. Interventions: Insulin doses were calculated based on predicted serum glucose values from corrected point-of-care glucometer measurements. Measurements and Main Results: Time-matched point-of-care glucose, laboratory glucose, and hematocrit values. We previously found that anemia (hematocrit <34%) produces systematic error in glucometer measurements. The error was correctible with a mathematical formula developed and validated, using prospectively collected data. Error of uncorrected point-of-care glucose ranged from 19% to 29% (p <.001), improving to ≤5% after mathematical correction of prospective data. Comparison of data pairs before and after correction formula implementation demonstrated a 78% decrease in the prevalence of hypoglycemia in critically ill and anemic patients treated with insulin and tight glucose control (p <.001). Conclusions: A mathematical formula that corrects erroneous point-of-care glucose values due to anemia in intensive care unit patients reduces the prevalence of hypoglycemia during intensive insulin therapy.

AB - Objective: Intensive insulin therapy in the critically ill reduces mortality but carries the risk of increased hypoglycemia. Point-of-care blood glucose analysis is standard; however, anemia causes falsely high values and potentially masks hypoglycemia. Permissive anemia is practiced routinely in most intensive care units. We hypothesized that point-of-care glucometer error due to anemia is prevalent, can be corrected mathematically, and correction uncovers occult hypoglycemia during intensive insulin therapy. Design: The study has both retrospective and prospective phases. We reviewed data to verify the presence of systematic error, determine the source of error, and establish the prevalence of anemia. We confirmed our findings by reproducing the error in an in vitro model. Prospective data were used to develop a correction formula validated by the Monte Carlo method. Correction was implemented in a burn intensive care unit and results were evaluated after 9 mos. Setting: Burn and trauma intensive care units at a single research institution. PATIENTS/Subjects: Samples for in vitro studies were taken from healthy volunteers. Samples for formula development were from critically ill patients who received intensive insulin therapy. Interventions: Insulin doses were calculated based on predicted serum glucose values from corrected point-of-care glucometer measurements. Measurements and Main Results: Time-matched point-of-care glucose, laboratory glucose, and hematocrit values. We previously found that anemia (hematocrit <34%) produces systematic error in glucometer measurements. The error was correctible with a mathematical formula developed and validated, using prospectively collected data. Error of uncorrected point-of-care glucose ranged from 19% to 29% (p <.001), improving to ≤5% after mathematical correction of prospective data. Comparison of data pairs before and after correction formula implementation demonstrated a 78% decrease in the prevalence of hypoglycemia in critically ill and anemic patients treated with insulin and tight glucose control (p <.001). Conclusions: A mathematical formula that corrects erroneous point-of-care glucose values due to anemia in intensive care unit patients reduces the prevalence of hypoglycemia during intensive insulin therapy.

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