Decompression Illness (DCI): An In-Depth Exploration


Decompression illness (DCI), an overarching term often used in the world of scuba diving, covers a range of conditions that can occur as a result of rapid changes in pressure during ascent. The two primary forms of DCI are decompression sickness (DCS) and arterial gas embolism (AGE). Both DCS and AGE are serious medical conditions that demand immediate attention and treatment.

Decompression Sickness (DCS)

Decompression sickness, also known as “the bends,” is a condition that arises when divers ascend too quickly from a dive. The pressure change can cause dissolved gases in the tissues to come out of solution, forming bubbles. Nitrogen, a gas breathed in large quantities in compressed air, is the most common culprit.

These bubbles can block blood vessels and disrupt blood flow, leading to a multitude of symptoms. These range from mild (joint pain, rash, fatigue) to severe (paralysis, unconsciousness). The exact symptoms depend on where the bubbles form and how severe the DCS is.

Preventing DCS is a matter of carefully controlling ascent rate and, in the case of deep or long dives, performing staged decompression stops to allow gases to be expelled from the body gradually. Despite these precautions, DCS can still occur, and the need for prompt treatment, typically with hyperbaric oxygen therapy, is crucial to reduce long-term effects.

Arterial Gas Embolism (AGE)

Arterial gas embolism is another potential complication of scuba diving, closely related to DCS. AGE occurs when a rapid ascent causes a gas bubble to enter the arterial circulation. This often happens if a diver holds their breath during ascent, causing the lungs to over-expand and potentially rupture, releasing gas into the bloodstream.

These gas bubbles can travel to any part of the body, including the brain, causing symptoms such as chest pain, coughing up blood, seizures, stroke-like symptoms, or unconsciousness. Like DCS, AGE is a serious medical emergency requiring immediate hyperbaric oxygen therapy.

Hyperbaric Oxygen Therapy for DCI

Both DCS and AGE require immediate hyperbaric oxygen therapy. This treatment involves placing the patient in a pressurized chamber where they breathe pure oxygen. This process helps reduce the size of the gas bubbles and increase the oxygen supply to the affected tissues. In the case of AGE, it can also help heal any lung damage that may have occurred.

Prevention of Decompression Illness

Prevention is a key element in managing the risks associated with DCI. This includes proper dive planning, adhering to safe ascent rates, and avoiding breath-holding during ascent. Furthermore, divers should maintain good overall physical health and avoid diving when fatigued or ill. Adequate hydration and avoiding alcohol before diving can also help prevent DCI.

Recognition and Response to DCI

Recognizing the signs and symptoms of DCI is vital. Mild symptoms might include fatigue, skin itch, or joint pain. More severe symptoms can involve difficulty breathing, chest pain, paralysis, confusion, or unconsciousness.

If DCI is suspected, the affected diver should breathe 100% oxygen and seek medical attention immediately. The Divers Alert Network (DAN) operates a 24/7 hotline for diving emergencies and can assist with finding appropriate treatment.


Decompression illness is a serious risk associated with scuba diving. Understanding the conditions that contribute to its development and recognizing the signs and symptoms can help prevent long-term health consequences. Education, safe diving practices, and prompt treatment are essential in managing this risk. By understanding and respecting the physics and physiology involved in scuba diving, divers can safely

explore the underwater world while minimizing the risk of DCI.

DCI in the Context of Diving Practices

Scuba diving is an activity that requires both physical and mental preparation. The education of divers includes understanding DCI, its causes, symptoms, and prevention techniques. Divers are taught to ascend slowly and perform safety stops, particularly following deep or long dives. Dive computers and tables provide crucial guidance on safe ascent rates and decompression stops.

Risk Factors for DCI

There are multiple factors that can increase a diver’s risk of developing DCI. These include diving at high altitudes, diving in cold water, making multiple dives in a day, older age, obesity, dehydration, and pre-existing health conditions such as lung disease. Understanding these risk factors can help divers take additional precautions when needed.

Decompression Procedures and Technology

Over the years, decompression procedures and technology have evolved significantly, with modern dive computers now able to calculate complex decompression algorithms in real-time. These technological advances have made diving safer, but it’s important to remember that no technology can eliminate the risk of DCI completely. Divers must always adhere to safe diving practices.

The Role of Dive Professionals and Medical Personnel

Dive professionals, such as instructors and dive masters, play a critical role in preventing DCI. They are responsible for ensuring divers understand the risks of DCI, and they set the example for safe diving practices. Medical personnel, on the other hand, are trained to recognize and respond to DCI, providing prompt and appropriate treatment that can save lives and prevent long-term health consequences.

Long-Term Effects of DCI

If not treated promptly and effectively, DCI can have long-term effects on a diver’s health, including permanent damage to the nervous system, ongoing joint and muscle pain, and even paralysis. These potential outcomes underscore the seriousness of DCI and the importance of prevention, early recognition, and treatment.

Diving After DCI

A diver who has suffered from DCI should only return to diving after receiving clearance from a doctor experienced in diving medicine. Residual bubbles and tissue damage can increase the risk of subsequent DCI incidents. Further, some divers may experience residual symptoms, such as fatigue or difficulty concentrating, which could impact their diving safety.

Final Thoughts

Decompression illness, encompassing decompression sickness and arterial gas embolism, represents a significant hazard in scuba diving. However, with the proper knowledge, training, and adherence to safety protocols, divers can significantly reduce their risk. It is incumbent upon every member of the diving community, from the novice to the professional, to understand, respect, and mitigate the risks associated with DCI. By doing so, we can ensure that the marvels of the underwater world can be safely enjoyed by all who are called to explore its depths.