Certified Hyperbaric Technologist Practice Test

At a PO2 of 2000 mmHg, by how much does the oxygen diffusion distance increase compared to that at 1 ATA?

1. 2 times

2. 3 times

3. 4 times

4. 5 times

The correct answer is: 4 times

At a partial pressure of oxygen (PO2) of 2000 mmHg, the diffusion distance for oxygen increases significantly compared to conditions at 1 atmosphere absolute (ATA), where the PO2 is typically around 760 mmHg at sea level. This increase in diffusion distance can be explained by Fick's Law of Diffusion, which states that the rate of diffusion of a gas is proportional to the difference in partial pressures and inversely proportional to the distance the gas must travel. When the partial pressure of a gas increases, the concentration gradient becomes steeper, facilitating more efficient diffusion. However, as the distance over which oxygen must diffuse increases (due to elevated pressures leading to denser conditions), the time and energy required for oxygen to travel through that distance also increase. In hyperbaric conditions, the diffusion coefficient and effective diffusion distance for oxygen tend to double or even quadruple depending on the exact pressure conditions and physiological parameters. In scenarios where the pressure increases substantially, such as from 1 ATA to 2000 mmHg (approximately 3 ATA), the increase in oxygen diffusion distance can be approximated to quadruple (4 times) because the pressure directly affects the volume of gas and the diffusion capacity through tissue. This relationship