Background: Since the values of various parameters in arterial blood samples changes with time, they should be measured without delay. There are some situations, however, where it is quite difficult to carry out the measurement immediately. In this study, we aim to obtain a series of parameters by which we can estimate true values from stale blood samples.
Methods: Arterial blood gases (PaCO2, PaO2, pH), electrolytes, blood sugar and lactate were measured at 0 min, 30 min, 60 min after collecting the samples. Cytometry was done at 0 min. We calculated proton ion concentration ([H+]) and oxygen content (CaO2). Relationships between the change of various parameters in arterial blood samples and the numbers of red blood cell (RBC), white blood cell (WBC) and platelet were analyzed using multiple regression analysis.
Result: The values of PaCO2, lactate and [H+] increased, and those of PaO2, blood sugar and CaO2 decreased with time. Electrolytes changed little. There were significant relationships between the number of RBC and the change of blood sugar, and between the number of WBC and the change of CaO2 value.
Conclusion: From these result, we found a series of expression by which we can estimate appropriate values from stale blood samples.