Decompression-Related Emergencies

Breathing air under pressure while scuba diving or otherwise working in a pressurized environment can be hazardous. For detailed information about decompression sickness, go to eMedicine Medscape.

SCUBA diverTypes of Decompression Emergencies

The following conditions can occur.


Barotrauma is an injury due to the body’s inability to equalize its internal pressure. Common types of barotrauma involve a section of one or both ears. Other types of bartotrauma can affect the sinuses, gaps in tooth fillings, one or both lungs, the patient’s diving mask, etc.

The main symptoms of barotrauma are a feeling of fullness and pain in the ear (or area of the body with unequal pressure). Other signs and symptoms include bleeding from the ears or nose, dizziness, nausea, ringing in the ear, and injuries consistent with the type of barotrauma (e.g., bloodshot eyes and bruising on the face for mask squeeze, breathing difficulty and coughing up blood for pulmonary barotrauma, etc.).

Decompression sickness

Decompression sickness is caused by the expansion of air trapped in body tissues due to a rapid ascent while holding the breath. Signs and symptoms of decompression sickness include an itchy rash on parts of the body, pain in the joints, paralysis, bladder problems, and localized swelling. Signals of decompression sickness usually appear about 1 hour or so after diving, but they can be delayed up to about 6 hours (and, in rare cases, as much as 48 hours).

Nitrogen narcosis

Nitogen narcosis is the dissolving of nitrogen into brain nerve membranes, resulting in behavior similar to intoxication. This is a reversible condition that worsens as a diver descends deeper and deeper but dissipates when the diver ascends to shallower water. If a diver keeps descending, this condition can cause severe hallucinations, tunnel vision, memory loss, mental disorientation, blackout, and death.

Pulmonary overinflation syndrome (POIS)

POIS is the overexpansion of the lungs caused by rapid ascent while holding the breath, resulting in ruptured blood vessels in the lungs which allow gas bubbles to become trapped in the bloodstream. These gas bubbles—mostly nitrogen—expand during ascent and pass through the heart to obstruct bloodflow to the heart or brain.

This condition usually results in sudden loss of consciousness within 10 minutes of surfacing. Other signs and symptoms include paralysis, numbness, blindness, deafness, seizures, dizziness, confusion, and/or difficulty speaking.

Caring for Decompression-Related Emergencies

All barotrauma/decompression incidents should be checked out by a physician. Some, like localized barotrauma of the ear, tooth, sinus, etc. and nitrogen narcosis, may not require immediate medical attention, but the patient should be advised to see his or her doctor before diving again. If the incident results in bleeding (e.g., from the ear or nose); breathing difficulty; or lingering pain, dizziness or disorientation, do not delay obtaining medical care.

The most serious of these conditions are POIS, pulmonary barotrauma, and decompression sickness. If the patient suddenly loses consciousness, has extreme breathing difficulty, or shows signs similar to stroke or decompression sickness, do the following:

  1. Call 911 or the local emergency number. (If necessary, call the Diver’s Alert Network at Duke University to obtain the location of a recompression facility. The numbers are 919-684-8111 or 800-446-2671. For locations in Latin Americ, call 919-684-9111.)
  2. Maintain an open airway and administer oxygen, if available.
  3. Restore breathing and circulation, if necessary (see Airway and Ventilations and CPR).
  4. Care for shock by maintaining normal body temperature, stopping any bleeding, and staying with the patient for comfort and reassurance.

Preventing Decompression Sickness

Take the following precautions to prevent decompression-related emergencies:

  • If you have a heart condition, hypertension, asthma, or lung disease, consult your physician before diving.
  • Avoid dehydration by drinking plenty of fluids before diving.
  • Do not dive too deep. Stay in depths you have been certified to dive in.
  • Ascend slowly—no faster than 16 to 23 feet (5 to 7 meters) per minute.
  • Do not fly within 24 hours of diving.
  • If you have an episode of barotrauma/decompression sickness, do not dive for at least 4 weeks.