Effect of syringe type, storage temperature and time delay on venous blood gas values in newborn calves

The effects of storage temperature, storage duration and the type of syringe on blood gas and acid–base values in blood of newborn calves were investigated using commercial blood gas syringes coated with heparin (Monovette blood gas syringe, Mono) or heparinised injection syringes (HS). The pH, partial pressure of carbon dioxide (pCO₂), partial pressure of oxygen (pO₂), base excess (BE), bicarbonate concentration, oxygen saturation (sO₂), total carbon dioxide (TCO₂) and l-lactate concentration were determined immediately after blood collection. In addition, venous blood from 30 calves collected immediately after birth was stored for 12 h at 4 and 18 °C. Means that differed from baseline by more than ±3 SD of the intraserial precision of the blood gas analyser were considered effects of blood storage. There were very strong correlations between the two syringe types for pH, BE, bicarbonate concentration, TCO₂ and l-lactate concentration in blood assessed immediately after collection. The difference between the mean and baseline of pO₂ exceeded ±3 SD after 20 min of storage at 4 °C and after 180 min at 18 °C. At those time points, the means of pH and l-lactate concentration were also outside the ±3 SD range. In blood stored in HS, means exceeded the ±3 SD range after 120 min for l-lactate, after 180 min for pH and after 360 min for the pCO₂, pO₂, BE and bicarbonate concentration. Storage of venous blood samples at 4 °C preserved blood gas values except for pO₂. With the exception of l-lactate measurement, heparinised syringes are useful for storage of the blood at room temperature for up to 3 h.