The Science Journal of the American Association for Respiratory Care
Analysis of blood samples for blood gas, saturation, electrolytes, and metabolites plays a vital role in pulmonary and critical care medicine. With a goal to standardize testing throughout our health system and optimize purchasing power we examined five instruments.
Methods: Five vendors provided analyzers for two weeks including AVL Omni, Chiron 860, Instrumentation Laboratory Synthesis, Nova Stat Profile, and Radiometer 700. Each instrument was calibrated and maintained according to manufacturer's specification, using the vendor's QC. An identical evaluation included precision with quality control material (20 runs), precision utilizing whole blood samples run twice (100 samples), accuracy using QC material and tonometered samples, linearity using QC and tonometered samples (5 levels using IL 237), and comparison to the resident analyzers with split samples (100 samples). A mandatory data management system to network satellite labs was evaluated for each vendor. The evaluation process was performed by lab techs, a supervisor from the reference pulmonary lab and Respiratory Care Practitioners (RCPs) who utilize STAT satellite systems. Staff completed evaluation forms rating the maintenance, ease of use and noted technical difficulties encountered during the study.
Results: All instruments demonstrated excellent precision with correlation coefficients with the standard ranging from 0.997 to 0.999. All had good correlation with the existing system, IL 1640/682 in all parameters except for dyshemoglobins. High lipid samples affecting the older technology but not the new caused this variation. Linearity was good except for the highest PO2. Conclusions: Since all were close in precision, accuracy and linearity, the decision was influenced by sample size, maintenance issues, and data management. The process that was utilized to evaluate the five instruments was vital in providing data for the committee making decisions for purchase.