A 44-year-old man is scuba diving at 60 feet and loses track of the time. Upon return to the surface he notices pain in his knees. What is the cause of this pain?

Question

Quizplus · Accepted Answer

The pain in the knees is a symptom of decompression sickness, also known as "the bends". This occurs when a scuba diver ascends too quickly from a deep dive, causing nitrogen bubbles to form in their tissues and bloodstream. The knee joint is a common site for these bubbles to accumulate and cause pain. Nitrogen narcosis is a different condition in which an excessive amount of nitrogen in the bloodstream can cause disorientation and impaired judgment at depths greater than 100 feet. Excess generation of oxygen free radicals can occur during lengthy, deep dives when excessive oxygen is delivered to tissues, but this is typically only seen in experienced technical divers. An increase in arterial pCO₂ may occur as a result of retained carbon dioxide from a poorly functioning rebreather, but this is unlikely to cause knee pain.

A 44-Year-Old Man Is Scuba Diving at 60 Feet and Loses