What exactly is decompression illness (DCI)?
The common term for decompression illness is the “bends” and DCI covers both DCS or decompression sickness and CAGE or Cerebral Arterial Gas Embolism. The “bends” is a condition primarily associated with scuba divers, such as those who work on oil rigs. However, the “bends” can also affect astronauts, high altitude pilots and people who work in controlled (or uncontrolled) environments where compressed air is used.
While it is not completely understood, the cause of the bends seems to be a sudden or incorrect decompression or rapid ascent from very deep water.
What happens to the body?
When a diver descend into the watery depths, pressure increases around them. This, in turn, increases the oxygen, carbon dioxide and nitrogen in bodily tissues. We can readily absorb oxygen and our lungs efficiently excrete carbon dioxide but nitrogen is another matter.
The body needs time to excrete nitrogen through the lungs and if the diver ascends too quickly without regular decompression stops, nitrogen bubbles are created and potentially released, thereby blocking blood flow or cutting off oxygen to the brain and other body parts.
This can cause paralysis, severe pain in the joints, nerve damage, and even death. It is not simply that the inert gas bubbles are dangerous but their size and location and the body’s ability (or lack of ability) to get rid of them which causes physiological damage.
Decompression Sickness Symptoms
When the body collects too many gas bubbles, breathing will be affected and the condition should be considered life-threatening – it could result in the fatal collapse of the respiratory system.
The general symptoms of decompression sickness include breathlessness, acceleration of the rate of breathing, coughing and chest pains. There are many other symptoms such as:
- weakness or fatigue
- vomiting, nausea
- itching, rash
- cutis marmorata (blue or purple “marbling” on the skin)
- diarrhoea, abdominal cramps
- chest pains
- muscle, joint pain or numbness
- confusion, memory loss
- lack of coordination, dizziness
- ringing in ears, hearing loss
- lower limb paralysis
- unconsciousnessEven if the person doesn’t exhibit obvious symptoms, DCI needs to be considered if the diver has been subjected to the relevant risks.
First aid for decompression illness should be given as soon as possible. Such treatment could include:
- giving 100% oxygen, using a tightly-fitting mask
- laying the diver horizontal to help prevent the bubbles going to the brain, keeping them comfortable
- putting the person in the recovery position if they lose consciousness
- giving fluids orally, but only if the person is able to take them unaided
- covering person with blanket or thermal shield to protect from hypothermia
- seeking medical help as soon as possible as recompression is the only effective treatment (but not in-water recompression)Recompression
A diver suffering DCI is usually treated with recompression, meaning they are placed inside a hyperbaric chamber which is pressurized to that equal to a sea depth of either 59 ft. or 98.5 ft. Using a mask or something like a plastic helmet, the person breathes pure oxygen for a set length of time, interspersed with “airbreaks” of 5 to 15 minutes. Known as treatment tables, the length of the treatments are usually between 2 and 5 hours but could be longer if DCI is severe.
The treatment tables are set by a trained doctor after an assessment of the diver’s medical and dive histories and neurological tests checking coordination, balance, sensation and strength. This could also include measuring breathing and heart rates and perhaps an ECG and/or X-ray, and blood tests.
Hyperbaric means “greater than ambient pressure” and hyperbaric medicine is treatment that uses oxygen at pressure higher than the normal atmosphere. Hyperbaric oxygen treatment (HBOT) is used for decompression illness to physically reduce the size of the bubbles as well as promote the elimination of excessive dissolved gas and bubbles from a diver’s body.There are other medical conditions for which hyperbaric oxygen treatment is also used, some of which are:
- severe anemia
- abscess of the brain
- air bubbles in blood vessels
- CO2 poisoning
- crush injuries
- sudden deafness
- gangrenous or infected tissue (skin or bone)
- wounds that won’t heal (diabetic ulcers)
- injury from radiation
- sudden but painless loss of vision
There are other illnesses or conditions for which HBOT may be used but evidence is insufficient to support claims of success.
Those involved in HBOT will have had hyperbaric chamber training and could be qualified as a hyperbaric technician or dive medic.
For more information on hyperbaric oxygen training certification, go to www.hyperbaricinternational.com