Suitability of Capillary Blood Glucose Analysis in Patients Receiving Vasopressors

Abstract

Background Glycemic control in critically ill patients decreases infection and mortality. While capillary blood glucose values are accurate in normotensive patients and correlate with arterial samples, patients on vasopressors have altered peripheral perfusion that may affect accuracy of capillary blood glucose values tested using point of care devices. Objectives To compare capillary and arterial blood samples using point of care testing (POCT) with arterial blood samples using the clinical chemistry lab in patients following cardiothoracic surgery, and to determine if vasopressor medications or diminished peripheral perfusion influenced the accuracy of POCT values. Methods In a prospective, convenience sample (n=50) of adult post-operative cardiothoracic patients on insulin and vasopressors, samples (n=162) were obtained simultaneously from capillary and arterial sites during insulin infusion and tested on both POCT and clinical chemistry lab, respectively. Quality of peripheral perfusion was recorded using a standardized scale. Clarke error grid analysis and ISO 15197 were used to analyze the level of agreement between the three samples. Two-way ANOVA was used to analyze differences in blood glucose values with respect to vasopressor use and peripheral perfusion. Results An unacceptable level of agreement was found between the capillary POCT and arterial samples tested in the clinical chemistry lab (only 88.3% of values fell in Zone A, or within the ISO 15197 tolerance bands). Arterial POCT showed 94.4% agreement with the clinical chemistry lab. Vasopressor use demonstrated a statistically significant effect on the accuracy of arterial blood glucose values (F=15.01; p= .0001). Conclusions Capillary POCT is not within acceptable limits of agreement with the clinical chemistry lab. Even when using the more accurate arterial blood with POCT, patients with >2 vasopressors demonstrate significantly less accuracy as compared to patients on fewer vasopressors. Using the clinical chemistry lab may be safer for insulin titration in these patients.

An Academic‐Health Service Partnership in Nursing: Lessons From the Field

“…To date, DTNI point of care studies have improved care processes for patient and family decision making at the end of life care (Johnson et al, 2010), improved patient safety and use of prevention strategies for patients undergoing alcohol withdrawal in the setting of acute myocardial infarction (Fullwood et al, in review), and improved the reliability of blood glucose testing and subsequent safety of intravenous insulin dosing after cardiothoracic surgery (Ellis et al, in review). In each case, new scientific discoveries reached patients in the form of an evidence‐based practice review, a new practice recommendation, or through partnered mentoring of clinicians to read new science more effectively.…”

Accuracy of Capillary and Arterial Whole Blood Glucose Measurements Using a Glucose Meter in Patients under General Anesthesia in the Operating Room

“…A number of variables including hematocrit, PO 2 , PCO 2 , pH, and medications may interfere with or impact the accuracy of glucose meters 9,29–31 . The accuracy of capillary (fingerstick) glucose measurement in critically ill patients is of even greater concern; as previous studies have demonstrated potentially dangerous discrepancies in capillary glucose measurement in patients on vasopressor therapy 10,17 , patients in shock 18 or with poor tissue perfusion 19 , and other critically ill patient populations 20 . Studies have also found that systematic (mean or median) glucose meter bias differs for capillary glucose meter samples compared to arterial or venous whole blood samples 10,27,32 .…”

“…Though newer technologies may provide more accuracy 12–14 , there is still concern about the use of meters in the critically ill 15,16 . Studies have demonstrated potentially dangerous discrepancies in capillary glucose measurement in patients on vasopressor therapy 10,17 , patients in shock 18 or with poor tissue perfusion 19 , and in other critically ill patient populations 20 . Consequently, no glucose meter is currently approved by the U.S. Food and Drug Administration (FDA) for use with capillary samples in critically ill hospitalized patients.…”

Point-of-care testing in diabetes management

“…However, support in selecting appropriate system for specific patient has been issued recently (39). Several factors such as: edema, shock state, use of vasoconstrictors affect peripheral perfusion in ICU patients and disturb the accuracy of capillary glucose measurements (40,41). Moreover, glucose measurement in ICU is performed intermittently with the risk of undetected hypoglycemia, and the workload for the ICU nursing staff is considerable (42).…”