Independent Project HCAI 5221. Evaluation of Point of Care Bedside Glucose Monitors for Use in a Specialty & Transplant Hospital Mary A. Weidner, BS, MT(ASCP). Background. Methodist Specialty and Transplant Hospital is a 379 bed facility providing a variety of organ transplant services
Evaluation of Point of Care Bedside Glucose Monitors for Use in a Specialty & Transplant Hospital
Mary A. Weidner, BS, MT(ASCP)
Methodist Specialty and Transplant Hospital is a 379 bed facility providing a variety of organ transplant services
A Roche AccuCheck POC device is used post-operatively at our facility to monitor whole blood glucose in the ICU.
A positive bias has been observed for the Roche AccuChekwhole blood glucose meter (Fig 1 is an example of this observation)
A review of the medical literature revealed a number of substances (e.g., maltose, hematocrit, IVIG) can interfere with whole blood glucose meters.
This potential for interference and subsequent discordance with central lab methods led to concern by the clinical staff about accuracy of POCT results and exploration of alternative glucose monitors
Through regression analysis evaluate the accuracy, specificity, connectivity, and clinical performance of alternative POC glucose monitoring devices against the central laboratory for use within Methodist Specialty and Transplant Hospital
Prior to testing these devices in a clinical setting, in lab linearity and precision studies were performed (data not shown). Each monitor tested performed acceptably. To assess the potential for interference two glucose meters available at the time (AccuChek and Precision XP) were evaluated in patients typical of our hospital. Arterial whole blood from central lines was taken at the times indicated in Fig 1 and in parallel ran on each meter. In addition these specimens were spun down and the plasma ran on the Vista hexokinase method for comparison. Mean % bias was calculated relative to the Vista reference method. Fig 1 and 2 show the results of this comparison. A Nova StatStrip was acquired at a later time. Studies to evaluate the potential for known interferences such as hematocrit and maltose were assessed by testing samples of 3 different glucose concentrationsin which the hematocrit and maltose concentration was adjusted to varying levels (Fig 3). Finally whole blood specimens were spiked with increasing concentrations of glucose and then ran on each glucose monitor. These specimens were subsequently spun down and plasma ran on the Vista hexokinase central laboratory method. Regression analysis was performed to determine concordance between the two methods (Fig 4). The Point of Care team also evaluated connectivity options based on ability to support existing POC tests and the ability to expand as new POC tests are implemented.
Figure 1. Increased Bias Observed with Roche AccuChek. Arterial whole blood measurements were performed post-operatively as a function of time. Panel A shows a mean positive bias of 35% for the Roche AccuChekin a patient administered IVIG. Panel B also demonstrates a positive mean bias (16%) in a patient which underwent liver transplant procedure.
Figure 2. Bias Also Observed with Abbott Precision XP Glucose Monitor. PanelA shows a mean positive bias of 11% when the same specimens from the patient 1 below were ran on the Abbott Precision XP glucose meter. Panel B shows a mean positive bias of 3% when the specimens belowfor patient 2 are ran on the Abbott Precision XP. Relative to the Roche AccuChek, the Abbott Precision XP had a mean bias ~3x less for patient 1 and ~5x less for Patient 2.
Patient 1: IVIG Therapy
AccuCheck vs. Vista
Patient 2: Liver Recipient
AccuCheck vs. Vista
HCT INTERFERENCEFigure 3. Effects of Hct and Maltose on Whole Blood Measurement of Glucose. Three different glucose concentrations were measured under conditions in which the hematocrit and maltose concentration was adjusted to varying levels. In both instances the Nova StatStrip was not affected. However the AccuChekdevice was negatively affected by increasing Hct and positively affected by increasing maltose concentrations
at all glucose levels studied.
All three meters demonstrate good correlation with central lab, however both the Abbott Precision Xceed Pro (R2 = 0.98567) and the Nova StatStrip (R2 = 0.99790), had the acceptable CLSI correlation with slopes closest to 1 and lower y-intercept then the Roche AccuCheck meter.