North Carolina EMT State Practice Exam

In diving incidents, when is the risk of decompression sickness highest?

1. During the dive

2. After ascending

3. During surface intervals

4. While descending

The correct answer is: After ascending

The risk of decompression sickness is highest after ascending from a dive. Decompression sickness, often referred to as "the bends," occurs when a diver ascends too quickly, leading to the formation of nitrogen bubbles in the body due to changes in pressure. As a diver descends, the pressure increases, allowing more nitrogen to be absorbed by the body. However, the real risk arises during ascent when the pressure decreases, and if this ascent is rapid, the dissolved nitrogen can come out of solution too quickly, forming bubbles in the tissues or bloodstream. Proper ascent rates and safety stops during decompression are vital to prevent decompression sickness. While there are risks associated with other phases of diving, such as during the dive or while descending, the ascent phase is critically the moment when a diver is most susceptible to this condition, particularly if proper protocols are not followed. This is why monitoring ascent rates and adhering to diving tables or dive computers is essential for safety.