Definition
A form of decompression sickness caused by nitrogen gas bubbles forming in the blood and tissues when ambient pressure drops too rapidly. In aviation, it can occur during rapid climbs to high altitudes, particularly above 18,000 feet, or after scuba diving followed by flight. Symptoms include severe joint pain (especially in the elbows, shoulders, knees, and hips), often causing the affected person to bend over in pain, along with possible dizziness, numbness, or breathing difficulty.
Plain English
A painful condition caused by gas bubbles forming inside the body when outside pressure drops too quickly. It can hit pilots who climb to high altitudes too fast, or who fly soon after scuba diving.
Context Anchor
Seen in aviation medical discussions, high-altitude flight, pressurization problems, and rules about flying after scuba diving.
Derivation
The name comes from the visible symptom: people suffering from this condition often double over or bend their joints to ease the deep pain. The term first appeared among 19th-century construction workers building tunnels and bridge foundations under high pressure, who developed the same illness when returning to surface pressure.
Why Pilots Care
Symptoms such as joint pain, dizziness, or paralysis can incapacitate a pilot and require immediate descent plus medical care.
Analogy
Think of a sealed bottle of soda. While it is capped, the gas stays dissolved in the liquid. Pop the cap quickly and bubbles form everywhere. The body works the same way: nitrogen stays dissolved in the blood under normal pressure, but if pressure drops too fast, it bubbles out.
Grounding Statement
Picture a person climbing quickly to high altitude after diving, then developing deep joint pain because pressure around the body has dropped too fast.
Intuition Check
Do not read bends as ordinary bending or turning. In aviation medical use, bends means a pressure-related illness caused by gas bubbles forming in the body.
Example Sentence 1
After a cabin pressurization failure at 25,000 feet, the pilot descended quickly to avoid the risk of bends.
Example Sentence 2
Pre-breathing oxygen before flight reduces the risk of developing the bends at altitude.