Definition
A form of decompression sickness in which nitrogen gas, previously dissolved in the body's tissues and blood under higher pressure, comes out of solution and forms bubbles when ambient pressure drops too quickly — typically during rapid ascent to altitude or after scuba diving followed by flying. Symptoms include deep joint pain (especially in the shoulders, elbows, and knees), and in severe cases neurological problems, breathing difficulty, or circulatory collapse.
Plain English
A painful and potentially dangerous condition that happens when a person climbs to altitude too fast — or flies too soon after scuba diving — and gas bubbles form inside the body because the pressure dropped faster than the body could handle.
Context Anchor
Seen in aeromedical discussions about altitude exposure, rapid loss of cabin pressure, and flying after scuba diving.
Derivation
Called 'the bends' because sufferers often double over or bend their joints in pain. The term originated with 19th-century construction workers in pressurized caissons (underwater work chambers) who developed the same condition when surfacing too quickly.
Why Pilots Care
Can incapacitate a pilot during or after high-altitude flight or cabin depressurization, requiring immediate descent and medical attention.
Analogy
Like opening a shaken soda bottle. While sealed, the gas stays dissolved in the liquid. Release the pressure too quickly and bubbles form everywhere. The body works the same way with dissolved nitrogen.
Grounding Statement
When outside pressure drops, gas that was safely dissolved in the body can come out as bubbles, much like bubbles appear when pressure is released from a sealed drink.
Intuition Check
Do not read “the bends” as anything about bending the airplane or changing direction. In aviation medical use, it means a pressure-related illness in the body.
Example Sentence 1
After a weekend of scuba diving, the pilot waited the recommended 24 hours before flying to avoid the bends.
Example Sentence 2
Pre-breathing pure oxygen before a high-altitude flight reduces the chance of developing the bends.