Certified Hyperbaric Technologist Practice Test

To determine the partial pressure of oxygen (PO2) when breathing oxygen at a depth of 33 feet of seawater (FSW), it is essential to understand how pressure changes with depth. At sea level, standard atmospheric pressure is approximately 760 mmHg. For every 33 feet of seawater, the pressure increases by about one atmosphere (or 760 mmHg), bringing the total pressure at 33 FSW to about 2 atmospheres (760 mmHg + 760 mmHg = 1520 mmHg). In a hyperbaric environment, when a patient is using an oxygen hood, they are typically receiving pure oxygen. To find the partial pressure of oxygen, we use the formula: PO2 = Total Pressure x Fraction of Inspired Oxygen (FiO2). Since the patient is breathing pure oxygen (FiO2 = 1), the equation simplifies to: PO2 = Total Pressure. At 33 FSW, the total pressure becomes 1520 mmHg due to the atmospheric pressure and the additional pressure from the water column above. Therefore, when the patient is breathing oxygen in this environment, the PO2 in the oxygen hood is correctly calculated as 1520 mmHg. This value reflects the increased partial pressure