2002 OPEN FORUM Abstracts
UTILIZING TOTAL BILIRUBIN MEASUREMENTS WITH POINT OF CARE TESTING IN THE NEONATAL ICU
Katherine L. Fedor CPFT, RRT Cleveland Clinic Foundation, The Childrens Hospital, Cleveland, Ohio.
Background: It is not uncommon for hospitals to utilize unit based point of care testing (POCT) to gain valuable clinical laboratory information as quickly and efficiently as possible. We wanted to evaluate the accuracy of the total bilirubin measurement available through whole blood unit based testing and the impact of the reduced blood loss. A review of the literature stongly suggested that there are large variations in bilirubin results from one analyzer to another making meaningful evaluations difficult. Some factors that can potentially alter the bilirubin results are fetal hemoglobin, presence of RBC in the plasma, hemolysis of the sample, the acid-base status of the patient, and the time interval from sampling to analysis. Whole blood analysis using the ABL 735 can factor in the acid-base status of the patient as well as the presence of fetal hemogobin.
Methods: Specifically we evaluated the total bilirubin measurements included in all routine blood gas samples using the Radiometer 735 blood gas analyzer, (Radiometer America, Westlake, Ohio). Results from the ABL 735 were compared to plasma results sent to the acute care lab. We enabled the feature on the Radiometer ABL 735 which detects and compensates for the presence of fetal hemoglobin. We then compared the whole blood total bilirubin results obtained in our POCT location with that of the plasma samples sent to the acute care laboratory (Diazo methodology).
Results: Our findings are outlined in Table 1.
Table 1 (n = 24 samples)
|WB||P||WB vs P||WB||P||WB vs P||WB||P||WB vs P|
|Average of Results: WB measurement = 4.72 mg/dL, Plasma measurement = 4.98 mg/dL|
WB Whole blood measurement in mg/dL
P Plasma measurement in mg/dL
WB vs P Whole blood to Plasma correlation
Conclusions: The whole blood to plasma correlations ranged from 0.22 1.16 (.22 found at the extreme low measurements) indicating the importance of consistent measuring techniques. It has been reported that variations of up to 14.8% exist within laboratories however, the overall acceptable analytical difference is 10%, our results reveal an average difference of 5.5%. Although POCT should not replace laboratory methodology, the rapid analysis may provide a reliable screening tool. The advantages of using whole blood POCT methods are that 1. results are obtained immediately allowing for appropriate interventions and 2. the sample size is 90% smaller than the amount required for a plasma measurement. Further studies are required to evaluate the full implications of the significantly reduced sample size on neonates.