Section 862.1120 - Blood gases (P[CO2], P[O2]) and blood pH test system(a)Identification. A blood gases (PCO2, PO2) and blood pH test system is a device intended to measure certain gases in blood, serum, plasma or pH of blood, serum, and plasma. Measurements of blood gases (PCO2, PO2) and blood pH are used in the diagnosis and treatment of life-threatening acid-base disturbances.(b)Classification. Class II.