Blood gas analyses are needed to reveal any kind of acid-base imbalance in some patients. Traditionally, arterial punctures are performed to obtain the blood samples for blood gas analyses. Arterial puncture is not a completely safe procedure. It may cause serious problems including arterial thrombosis, arteriovenous fistula, pseudoaneurysms and hematoma. In this retrospective reviewing, it was aimed to yield novel formulations to predict the blood pH only from CtCO2 and HCO3 values which can easily be measured in venous blood samples obtained for other diagnostic and follow-up purposes.