Comparison of point-of-care versus central laboratory measurement of hematocrit, hemoglobin, and electrolyte concentrations

Abstract

Objectives: We aimed to investigate the accuracy of certain laboratory examinations obtained by the ABG analyzer (ROCHE AVL OMNI S) as compared to hospital central laboratory (CL).

Methods: We prospectively collected data obtained from the same arterial blood sample regarding hematocrit, hemoglobin, potassium, and sodium.

Results: ABG analyzer results were significantly lower (p < 0.0001) compared to CL values thus values between the two methods are not interchangeable. The mean bias for Hb, Na⁺ and K⁺ were within accepted by US Clinical Laboratory Improvement Amendment (USCLIA) differences (cut-off points) but not for Ht. In 8.0%, 17.5%, 37.5% and 56.0% of Hb, Na⁺, K⁺ and Ht measurements respectively and 29.75% in sum the differences were over the USCLIA accepted limits. ABG analyzer significantly underestimate the values of Hb, Ht, Na⁺ and K⁺, compared to CL and almost 30% of all examined parameters were beyond USCLIA accepted biases.

Conclusions: ABG analyzer significantly underestimates the values of Hb, Ht, Na⁺ and K⁺ compared to CL and almost 30% for all examined parameters are beyond USCLIA accepted biases. These data do not support widespread or even careful use of POCT for making diagnostic and treatment decisions until technology improves and results in improved outcomes.

Keywords: Accuracy; Bland–Altman; Electrolytes; Hematocrit; Hemoglobin; Intensive care; Point-of-care testing.