Decompression sickness is a type of injury that occurs when there’s a rapid decrease in pressure surrounding the body.

It usually occurs in deep-sea divers who ascend to the surface too quickly. But it can also occur in hikers descending from a high altitude, astronauts returning to Earth, or in tunnel workers who are in an environment of compressed air.

With decompression sickness (DCS), gas bubbles can form in the blood and tissues. If you believe you’re experiencing decompression sickness, it’s important to seek medical attention immediately. This condition can be fatal if it’s not treated quickly.

While DCS can affect anyone moving from high altitudes to low altitudes, such as hikers and those who work in aerospace and aviation flights, it’s most common in scuba divers.

Your risk for decompression sickness increases if you:

  • have a heart defect
  • are dehydrated
  • take a flight after diving
  • have overexerted yourself
  • are fatigued
  • have obesity
  • are elderly
  • dive in cold water

In general, decompression sickness becomes more of a risk the deeper you dive. But it can occur after a dive of any depth. That’s why it’s important to ascend to the surface slowly and gradually.

If you’re new to diving, always go with an experienced dive master who can control the ascent. They can make sure it’s done safely.

Common symptoms of DCS may include:

  • fatigue
  • weakness
  • pain in muscles and joints
  • headache
  • lightheadedness or dizziness
  • confusion
  • vision problems, such as double vision
  • stomach pain
  • chest pain or coughing
  • shock
  • vertigo

More uncommonly, you may also experience:

  • muscle inflammation
  • itching
  • rash
  • swollen lymph nodes
  • extreme fatigue

Experts classify decompression sickness with symptoms affecting the skin, musculoskeletal, and lymphatic systems as type 1. Type 1 is sometimes called the bends.

In type 2, a person will experience symptoms affecting the nervous system. Sometimes, type 2 is called the chokes.

The symptoms of decompression sickness may appear rapidly. For scuba divers, they may start within an hour after a dive. You or your companion may appear visibly ill. Look out for:

  • dizziness
  • a change in gait when walking
  • weakness
  • unconsciousness, in more serious cases

These symptoms indicate a medical emergency. If you experience any of these, contact your local emergency medical services immediately.

You can also contact the Diver’s Alert Network (DAN), which operates an emergency phone line 24 hours a day. They can assist with evacuation assistance and help you locate a recompression chamber nearby.

In more mild cases, you may not notice symptoms until a few hours or even days after a dive. You should still seek medical care in those cases.

Contact emergency services

Call local emergency services or DAN’s 24-hour emergency line at +1-919-684-9111.

If you move from an area of high pressure to low pressure, nitrogen gas bubbles can form in the blood or tissues. The gas is then released into the body if the outside pressure is relieved too quickly. This can lead to obstructed blood flow and cause other pressure effects.

Contact emergency services

Watch for symptoms of decompression sickness. These are a medical emergency, and you should seek emergency medical services immediately.

Contact DAN

You can also contact DAN, which operates an emergency phone line 24 hours a day. They can assist with evacuation assistance and help you locate a hyperbaric chamber nearby. Contact them at +1-919-684-9111.

Concentrated oxygen

In more mild cases, you may not notice symptoms until a few hours or even days after a dive. You should still seek medical care. In mild cases, treatment may include breathing 100 percent oxygen from a mask.

Recompression therapy

The treatment for more serious cases of DCS involves recompression therapy, which is also known as hyperbaric oxygen therapy.

With this treatment, you’ll be taken to a sealed chamber where air pressure is three times higher than normal. This unit may fit one person. Some hyperbaric chambers are larger and can fit several people at once. Your doctor may also order an MRI or a CT scan.

If recompression therapy is started promptly after a diagnosis, you may not notice any effects of DCS afterward.

However, there can be long-term physical effects, such as pain or soreness around a joint.

For severe cases, there may also be long-term neurological effects. In this case, physical therapy may be required. Work with your doctor, and keep them informed about any lasting side effects. Together, you can determine a care plan that’s right for you.

Do your safety stops

To prevent decompression sickness, most divers make a safety stop for a few minutes before ascending to the surface. This is usually done around 15 feet (4.5 meters) below the surface.

If you’re diving very deep, you may want to ascend and stop a few times to ensure your body has time to adjust gradually.

Talk to a dive master

If you’re not an experienced diver, you’ll want to go with a dive master who is familiar with safe ascents. They may follow the guidelines for air compression as outlined by the United States Navy.

Before you dive, talk to the dive master about an adjustment plan and how slowly you need to ascend to the surface.

Avoid flying that day

You should avoid flying or going up to high elevations for 24 hours after diving. This will give your body time to adjust to the change in altitude.

Additional preventive measures

  • Avoid alcohol 24 hours before and after diving.
  • Avoid diving if you have obesity, are pregnant, or have a medical condition.
  • Avoid back-to-back dives within a 12-hour period.
  • Avoid diving for 2 weeks to a month if you’ve experienced symptoms of decompression sickness. Return only after you’ve undergone a medical evaluation.

Decompression sickness can be a dangerous condition, and it needs to be treated immediately. Luckily, it’s preventable in most cases by following safety measures.

For scuba divers, there’s protocol in place to prevent decompression sickness. That’s why it’s important to always dive with a group led by an experienced dive master.