Certified Transport Registered Nurse Certification Practice Exam

What primarily causes the bends in divers?

1. Nitrogen narcosis

2. Carbon dioxide retention

3. Oxygen toxicity

4. Barometric pressure difference

The correct answer is: Nitrogen narcosis

The bends, also known as decompression sickness, primarily result from the formation of nitrogen bubbles in the bloodstream and tissues as a diver ascends too quickly after spending time at depths where nitrogen is compressed into the body. During deep dives, divers breathe in air that contains a significant amount of nitrogen. As they ascend, the pressure around them decreases, and nitrogen that was once dissolved in bodily fluids can come out of solution and form bubbles. While nitrogen narcosis is related to the effects of breathing nitrogen under high pressure and can impair cognitive function, it is not the direct cause of the bends. Oxygen toxicity and carbon dioxide retention are also additional risks modeled around underwater breathing but do not specifically relate to the formation of nitrogen bubbles that lead to decompression sickness. The significant factor here is the sudden alteration in pressure encountered as a diver ascends, which directly leads to the release of nitrogen gas—hence causing the bends.