Certified Transport Registered Nurse Certification Practice Exam

What physiologic effect may occur at an altitude of 10,000 ft?

1. Loss of night vision

2. Reduced fatigue

3. Increased hydration

4. Enhanced alertness

The correct answer is: Loss of night vision

At an altitude of 10,000 feet, the atmospheric pressure is lower, which can lead to a decrease in the partial pressure of oxygen. This reduction can result in hypoxia, a condition where the body does not receive enough oxygen. As a consequence, individuals may experience a loss of night vision because the eyes are particularly sensitive to changes in oxygen levels. Night vision requires sufficient oxygen to function optimally, and hypoxia can impair the ability of the eyes to adjust in low-light conditions, resulting in difficulties seeing in the dark. The other options reflect outcomes that are generally not associated with high altitudes. For instance, reduced fatigue is typically not experienced; rather, fatigue can increase due to exertion and lower oxygen availability. Increased hydration is usually not an effect of altitude, as the body often becomes more dehydrated at higher elevations due to increased respiratory water loss. Enhanced alertness is also not a widespread effect of altitude, as many individuals report feelings of fatigue, headaches, and decreased cognitive function due to reduced oxygen levels.