Performance evaluation of a blood gas system in a central and satellite laboratory

In many hospitals blood gases are performed in several laboratories. It is important to establish that values obtained in all laboratories are identical and that the same quality control program is used. Evaluation of the performance of blood gas apparatus has been made in two of our laboratories. Result reproducibility was assessed by means of gas analyzer system control. Measurements were made in duplicate of patients' specimens in the same instrument and duplicate measurements of patient samples with both instruments. A13 day evaluation using this system was carried out in both laboratories during all shifts and showed excellent agreement with the manufacturer's reported values. The combined standard deviation for pH at all levels was 0.009,pCO2 -0.83 mmHg and pO2 - 3.9 mmHg. Patients' samples analyzed in the same instrument showed an absolute average difference between duplicates for pH of 0.003, pCO2 - 0.62 mmHg and pO2 -0.87 mmHg. The comparison of duplicate samples in the two instruments in the different laboratories showed an absolute average difference for pH of 0.009,pCO2-1.7mmHg and pO2 - 1.6 mmHg.