Stability of pO2, pCO2 and pH in heparinized whole blood samples: influence of storage temperature with regard to leukocyte count and syringe material.

Influences of storage temperature and blood cell metabolism in different types of syringes were investigated. Experiments were performed on blood samples with normal and elevated leukocyte counts. After equilibration with gas mixtures at normal pO2 (86 mm Hg/11.5 kPa) and elevated pO2 (140 mm Hg/18.7 kPa), sequential blood gas analyses were done within one hour. Storage temperatures were 4 degrees C or 22 degrees C. In the first group of experiments we compared glass samplers with plastic syringes at different storage temperatures with regard to deviations of blood gas concentrations. The analysed samples had a normal cell count. Blood stored in glass syringes in ice water served as the reference, and it displayed virtually no changes. The deviations of pCO2 and pH were relatively small. In plastic syringes the greatest increases for pO2 occurred after storage at 4 degrees C, which can be explained by the increased solubility of oxygen and the higher O2 affinity of haemoglobin at 4 degrees C. When stored at room temperature, the deviations in plastic syringes were smaller. In a second group of experiments, the influence of cell metabolism was studied. Blood gases were analysed in samples with elevated leukocyte counts (20 x 10(9)/l, 40 x 10(9)/l, 60 x 10(9)/l), and only glass syringes were used. It was demonstrated that after storage at 22 degrees C considerable losses in pO2 occurred, while at 4 degrees C there was virtually no change. Deviations of pO2, pCO2 and pH are described in detail.(ABSTRACT TRUNCATED AT 250 WORDS)