Decompression Illness | 1

Decompression illness

Access emergency medical services immediately and administer oxygen (if specifically trained).

Decompression illness results from a reduction in the ambient pressure surrounding a person’s body. It is commonly caused by pressure changes that occur in scuba diving, a very popular sport in many parts of the world. Decompression illness includes two conditions: decompression sickness and arterial gas embolism. Decompression sickness is thought to result from bubbles growing in the tissue and causing local damage. Arterial gas embolism results from bubbles entering the circulation, collecting together and travelling through the arteries and causing tissue damage by blocking blood flow to the small vessels.

Guidelines

Good practice points

In the case of suspected decompression illness, specifically trained first aid providers should administer oxygen at the highest concentration available (such as a non-rebreather mask) which may reduce the symptoms substantially. The oxygen should be continued until medical care is accessed. First aid providers should access emergency medical services (EMS) immediately, as well as the Divers Alert Network (see Access help section below) and indicate the likelihood of decompression illness so that transport of the person to a recompression chamber can be arranged as soon as possible. Definitive treatment is usually oxygen therapy provided in a recompression chamber. In cases of cardiac arrest after resurfacing, CPR should be administered with rescue breaths. See Unresponsive and abnormal breathing (baby and child) or (adolescent and adult). In locations requiring extended or complicated transport to a recompression chamber, rapid transport to a nearby emergency department capable of International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 1 Decompression illness | 2

resuscitation should be prioritised for stabilisation prior to transport to the chamber.

Chain of survival behaviours

Prevent and prepare

Be aware of and actively reduce the risk factors including deep or long dives, cold water, hard exercise at depth and rapid ascents.

Early recognition

Symptoms of decompression illnesses usually appear 15 minutes to 12 hours after surfacing, but in severe cases, may appear before surfacing or immediately afterwards.

Decompression sickness

Symptoms include the following:

unusual fatigue skin itch pain in joints and muscles of the arms, legs or body dizziness, vertigo, ringing in the ears numbness, tingling, paralysis shortness of breath.

Arterial gas embolism

Symptoms include the following:

dizziness chest pain disorientation bloody froth from the mouth or nose paralysis or weakness

International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 2 Decompression illness | 3

convulsions becoming unresponsive.

First aid steps

1. If specifically trained, administer oxygen to the person. (See Oxygen administration.) 2. Access EMS. If possible, call the Divers Alert Network +1-919-684-9111. 3. Monitor the person’s level of response, breathing and circulation until EMS arrives.

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NOTE

If the person becomes unresponsive, open their airway and check for breathing. (See Unresponsiveness.) If the person becomes unresponsive with abnormal breathing after resurfacing, CPR should be administered with rescue breaths. See Unresponsive and abnormal breathing (baby and child) or (adolescent and adult).

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Access help

Phone EMS immediately. They will be able to tell you what to do and arrange help. The Divers Alert Network is an international not-for-profit organisation with a helpline which can be reached 365 days a year, 24 hours a day, by phone: +1-919-684-9111. This network provides assistance with managing injured scuba divers, helps decide if recompression is needed, provides the location of the closest appropriate recompression facility and helps arrange transport for the person.

International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 3 Decompression illness | 4

Education considerations

Context considerations

In some countries, laws make it mandatory for professional diving operations to have oxygen readily available (e.g. diving training institutions). Therefore, the likelihood of oxygen being available is high at dive sites, and likely immediately available if called for by the first aid provider. Learners should be informed about any national first aid guidelines for decompression illness, including the local procedures for care in the country where they are diving. Programme designers should obtain information on local resources for diving emergencies and access to hyperbaric oxygen therapy facilities, to include in programmes. Decompression-related injuries can happen in open water as well as in deep swimming pools, so education on this topic may be applicable to learners without local access to open water.

Learner considerations

This topic is usually targeted at professional responders (e.g., paramedics, lifeguards) who have a specific duty to respond, strong assessment skills, and access to resources such as oxygen. Consideration should be given to the technical nature of this topic and the programme designer should match the content to the skill level of the learners using appropriate terminology.

Facilitation tips

Explain that decompression sickness is the result of rapid decompression after exposure to increased pressure. During a dive, the body tissues absorb nitrogen from the breathing gas in proportion to the surrounding pressure (which is elevated during diving). As long as the diver remains at pressure, the gas presents no problem. But if the pressure is reduced too quickly, the nitrogen comes out of solution and forms bubbles in the tissues and bloodstream. Diving tables provide scientific protocols to decompress safely, with a low chance of bubbles forming. However, decompression sickness can International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 4 Decompression illness | 5

still occur despite following accepted guidelines. Explain that an arterial gas embolism happens if a scuba diver surfaces without exhaling. Air trapped in the lungs expands on the ascent and may rupture lung tissue (called pulmonary barotrauma), which releases gas bubbles into the arterial circulation. The bubbles are distributed and may impair the circulation wherever they become lodged. Because the brain receives the highest proportion of blood flow, it is the main organ where bubbles lodged in small arteries can interfere with circulation. Emphasise that if learners will be responding to suspected decompression illness hours after the person has resurfaced (and is presumably in a different environment), they will need to use a detailed assessment process to identify the symptoms as being related to decompression illness and not another condition. This topic is best suited to be covered after foundational concepts of first aid so that learners are able to draw from a range of skills and knowledge.

Facilitation tools

National Societies may contact the Global First Aid Reference Centre for water rescue and drowning prevention first aid training programmes. There is an opportunity in this topic to include critical thinking and application of learning: > Option 1: Explore using a scenario and role-play. This allows the learners to experience the varied roles among a team when responding and preparing for transport, exercise decision making, practise their communication skills, and apply first aid skills. > Option 2: Explore this topic using case-based learning. Have the learners create their own case study (and then have a peer review the case study) or solve a case which has already been developed. > Using either method you can further challenge the learners by extending the scenarios or cases over time so that they are required to identify the impact of time on the ill person’s condition or add constraints which may require them to change their first aid action plan.

International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 5 Decompression illness | 6

Learning connections

Connect this topic to safety for the ill person and the first aid provider, assessment of the person (initial and continual), and accessing further support. (See General approach for more on each of these). Explore the safe administration and handling of oxygen (see Oxygen administration). There is the potential this condition will result in cardiac arrest (See Unresponsive and abnormal breathing (baby and child) or (adolescent and adult).

Scientific foundation

No formal reviews were made on this topic. The recommendations are based on expert opinion. The Diver Alert Network (DAN), a specific medical network dealing with diving-related problems, was also a source for the information presented in these guidelines.

Non-systematic review

A large retrospective case study showed that scuba divers experiencing decompression injury require less recompression treatment and have a greater likelihood of complete recovery if first aid includes normobaric oxygen (Blatteau, 2011).

References

Non-systematic reviews Blatteau, J. E., Gempp, E., Simon, O., Coulange, M., Delafosse, B., Souday, V., … & Germonpre, P. (2011). Prognostic factors of spinal cord decompression sickness in recreational diving: retrospective and multicentric analysis of 279 cases. Neurocritical care, 15(1), 120-127.

Mitchell, S. J., Bennett, M. H., Bryson, P., Butler, F. K., Doolette, D. J., Holm, J. R., … & Lafère, P. (2018). Pre-hospital management of decompression illness: expert

International first aid, resuscitation, and education guidelines 2020. https://www.globalfirstaidcentre.org/ Decompression illness | 6 Decompression illness | 7 review of key principles and controversies. Diving and hyperbaric medicine, 48(1), 45.

Moon, R. E., & Sheffield, P. J. (1997). Guidelines for treatment of decompression illness. Aviation, space, and environmental medicine, 68(3), 234-243.

Navy Department. (2016). US Navy Diving Manual. Diving Medicine and Recompression Chamber Operations. Naval Sea Systems Command. Washington, DC. 7(5): NAVSEA 0910-LP-115-1921.

Vann, R. D., Butler, F. K., Mitchell, S. J., & Moon, R. E. (2011). Decompression illness. The Lancet, 377(9760), 153-164.