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by Badash M
(Caisson Disease; Altitude Sickness; Dysbarism; The Bends; DCS)


Decompression sickness (DCS) occurs when the body is exposed to a sudden drop in surrounding pressure.


DCS is caused by the formation of gas bubbles in the blood and tissues. At normal altitudes, nitrogen and other gases are exhaled or dissolved in the blood and tissues. However, during severe changes in altitude and air pressure, nitrogen and other gases form gas bubbles. These bubbles block the flow of blood. This condition can be fatal if not treated quickly.

Risk Factors

This condition is more common in older adults.

The only risk factor that increases your chance of getting DCS is a sudden reduction in pressure. This occurs as a result of:

  • Rising too quickly to the surface from deep sea scuba diving
  • A fast ascent into a high altitude from a low altitude
  • Sudden exit from a high pressure or hyperbaric chamber
  • Increased risk with increased depth of dive
  • Long duration of dive
  • Multiple dives in one day
  • Flying after diving
  • Diving in cold water
  • Fatigue
  • Exertion
  • Dehydration
  • Obesity


The less severe type of DCS is called DCS I. It primarily results in inflammation of muscles, joints, and tendons, resulting in pain and swelling. This is commonly referred to as the bends. Although pain may occur anywhere in the body, it is most common in or near an arm or leg joint. The pain may become more severe over time. Itching, skin mottling, weakness, and fatigue also occur.

The more severe type of DCS is called DCS II. This results in more serious systemic effects, including neurological symptoms such as numbness and tingling. In the most severe form, numbness may lead to paralysis and even death. Other symptoms of DCS II include:

  • Stomach pain
  • Back pain
  • Headache
  • Lightheadedness
  • Confusion
  • Vision problems
  • Vertigo —the sensation of movement when standing still
  • Chest pain and severe coughing
  • Shock

If an individual dives occupationally and has regular exposure to increased pressure, a mild, chronic case of the bends may occur without detection. Over time, this can result in deterioration of affected joints and bones.

Progressive Joint Damage
Damaged Joint
Copyright © Nucleus Medical Media, Inc.


You will be asked about your symptoms and medical history. A physical exam will be done. When DCS is suspected, treatment is often started right away without any delay for examination or testing. Blood and other diagnostic tests are not usually helpful.


If you experience symptoms of DCS, it is extremely important to get treatment right away. In severe cases, delaying treatment may be fatal.

If you have DCS I, breathing 100% oxygen from a mask may be sufficient treatment. You should also be monitored carefully for other symptoms.

The treatment for DCS II is oxygen therapy in a hyperbaric chamber. This device works by gradually increasing and then decreasing air pressure around the body. This forces gas bubbles to dissolve. Oxygen should be given through an oxygen mask during transport to a hyperbaric chamber.

Treatment should be given even if initial symptoms are mild or disappear. Proper treatment given quickly should cure all symptoms of DCS.


DCS may be prevented by:

  • Limiting the depth and duration of deep sea dives
  • Following standard diving guidelines
  • Avoiding diving if you are obese, pregnant, have heart or lung problems, or have had a recent joint or limb injury
  • Avoiding excessive alcohol consumption for 24 hours before diving
  • Avoiding flying for 24 hours after deep sea diving
  • Avoiding repeated dives within a 12-hour period
  • Taking ibuprofen to help prevent altitude sickness when hiking
  • Avoiding flights in nonpressurized aircraft


Divers Alert Network  https://www.diversalertnetwork.org 

Undersea & Hyperbaric Medical Society  https://www.uhms.org 


Health Canada  https://www.canada.ca 

Nova Scotia Health Authority  http://www.nshealth.ca 


Altitude-induced decompression sickness. Federal Aviation Administration website. Available at: https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/dcs.pdf. Accessed March 23, 2018.

Decompression illness: what is it and what is the treatment? Divers Alert Network website. Available at: https://www.diversalertnetwork.org/medical/articles/Decompression%5FIllness%5FWhat%5FIs%5FIt%5Fand%5FWhat%5FIs%5FThe%5FTreatment. Accessed March 23, 2018.

Decompression illness. EBSCO DynaMed website. Available at:  https://www.dynamed.com/topics/dmp~AN~T115933/Decompression-illness  . Updated January 17, 2017. Accessed March 23, 2018.

Gertsch JH, Corbett B, Holck PS, et al. Altitude sickness in climbers and efficacy of NSAIDs trial (ASCENT): randomized, controlled trial of ibuprofen versus placebo for prevention of altitude illness. Wilderness Environ Med. 2012;23(4):307-315.

Revision Information

  • Reviewer: EBSCO Medical Review Board Marcin Chwistek, MD
  • Review Date: 03/2018
  • Update Date: 03/31/2014