Which physical characteristic is NOT taken into account when calculating the transfer of oxygen in a blood gas exchange device?

In the context of blood gas exchange devices, the transfer of oxygen is influenced by several key physical characteristics that are critical for understanding gas exchange processes. Each element mentioned in the choices plays a significant role in this transfer.

The physical diffusion coefficient of a gas reflects how easily that gas molecules can move through a medium. This characteristic is paramount because it directly impacts the rate at which oxygen can diffuse into the blood from the device.

The coefficient of solubility is equally important as it indicates how much gas can dissolve in the liquid (in this case, blood) at a given pressure. This characteristic influences the availability of oxygen in the blood once it has crossed the gas exchange barrier.

The pressure gradient of a gas across the material is another crucial factor, as gas exchange primarily occurs when there is a difference in pressure between the two sides of a membrane. A higher pressure gradient leads to more efficient diffusion of oxygen into the blood.

Given that all the aforementioned characteristics are vital for the calculation and understanding of oxygen transfer in a blood gas exchange device, the assertion that none of these characteristics should be excluded is correct. Therefore, the correct response indicates that all physical characteristics listed are indeed relevant to calculating oxygen transfer.