# What is partial pressure of oxygen in arterial blood?

At sea level, the arterial oxygen partial pressure (${P}_{a} {O}_{2}$) is 11 – 13 kPa or 75 -100 Torr.
A low ${P}_{a} {O}_{2}$ indicates that the patient has inadequate oxygen supply.
At a ${P}_{a} {O}_{2}$ of less than 26 Torr, the patient is at risk of death.