A-358 Extended linearity studies for pO2, pCO2, K+ Cl- on GEM 5000 blood gas analyzers using a combination of verification materials

Abstract Background Blood gas analyzers (BGA) measure blood gases pO2,pCO2,O2Hb,COHb,MetHb, and several analytes in the workup and management of acid-base disorders. GEM 5000 BGA (Instrumentation Laboratory, a Werfen Company) have very broad reportable ranges for the measured analytes. However, manufacturer’s current linearity materials do not cover the entire reportable ranges claims. This poses challenge to clinical laboratories, especially for pO2 and pCO2 to comply with College of American Pathologists (CAP) requirements to verify instruments performance every six months through the entire reportable range. We evaluated secondary materials in combination with manufacturer’s primary linearity materials for pO2, pCO2, K+ and Cl- for an extended linearity verification. Methods Routine linearity studies was performed with PVP (5-levels), a primary material provided by the GEM 5000 analyzer manufacturer. Hypoxic (pO2: 5-25mmHg) and hyperbaric (pO2: 600-670mmHg) materials obtained from Eurotrol Inc. and VK-R5 linearity material (Radiometer America Inc.) for pCO2, K+ and Cl- were processed on GEM 5000. All materials at all levels were assayed in duplicate. Results from PVP, Eurotrol and VK-R5 were combined from low to high levels to assess linearity verification. Results Linearity range of 15-630mmHg with r2=0.99 was verified for pO2. Using a combination of VK-R5 with PVP, a linearity range of 14-127 mmHg (r2=0.99) for pCO2, 1.1-14.1 mmol/L (r2=1.00) for K+, and 51-153 mmol/L (r2=1.00) for Cl-were verified. See table for details. Conclusions A combination of BGA manufacturer’s primary linearity material with secondary vendors material was useful in addressing linearity verification for blood gases pO2, pCO2, and electrolytes K+Cl- over an extended range close to the manufacturer’s claims. We recommend other laboratories that experience similar BGA linearity verification challenges to consider this approach for verification of the manufacturer’s claims. It would have been very helpful if manufacturer can provide materials that cover both the lower and upper limits of their claims.