ABSTRACT
Hemoglobin-Oxygen Dissociation Curve The reversible combination of hemoglobin with oxygen is defined by the hemoglobinoxygen dissociation curve.2 This curve is a plot of the partial pressure of oxygen (PO2) versus the percent saturation of hemoglobin. The majority of oxygen in the human body is transported in the blood bound to hemoglobin, although a small percentage is dissolved in the blood.2 The PO2, also abbreviated as PaO2, describes the partial pressure of oxygen because the air in the atmosphere is composed of several different gases, each having its own pressure, with each contributing to a single overall pressure. This pressure determines the movement of oxygen because gases, like particles in liquid solutions, move from regions of higher pressure to lower pressure. As long as the PO2 of oxygen in the gas phase (i.e., air) is greater than the PO2 in liquid (i.e., blood), a net diffusion of oxygen into blood takes place. The percent saturation (SpO2) describes the amount of oxygen molecules bound to hemoglobin.
