DOT Certification Practice Exam

What is the minimum required PaO2 at an altitude of less than 5000 ft?

1. 60 mmHg

2. 65 mmHg

3. 70 mmHg

4. 75 mmHg

The correct answer is: 65 mmHg

At altitudes less than 5000 feet, the minimum required partial pressure of oxygen (PaO2) is typically around 60 mmHg. However, it is often seen that a slightly higher threshold, such as 65 mmHg, is deemed acceptable for ensuring adequate oxygenation in various physiological scenarios. This value accounts for individual variations in sensitivity to changes in oxygen levels and provides a safety margin to accommodate those who may have less efficient oxygen uptake. Maintaining a PaO2 of at least 65 mmHg at lower altitudes is crucial because it helps ensure sufficient oxygen delivery to tissues, especially during activities that may demand increased oxygen consumption. Additionally, this level is favorable for preventing hypoxemia in at-risk populations, such as those with pre-existing respiratory conditions or those engaging in physical exertion. The other values listed, while relevant within discussions of hypoxia and ventilation, do not align with the established minimum threshold that balances safety and physiological function at this altitude.