Decompression Illness

Decompression Illness (DCI) is a condition directly associated with a reduction in the ambient pressure surrounding the body, and it encompasses two primary diseases: Decompression Sickness (DCS) and Arterial Gas Embolism (AGE). DCS results from gas bubbles in body tissues causing local damage, while AGE occurs when bubbles enter the arterial circulation, traveling through the arteries and potentially causing tissue damage by blocking blood flow at the small vessel level.

Who Gets Decompression Illness?

DCI affects scuba divers, aviators, astronauts, and compressed-air workers. The main risk factor for DCI is the reduction in ambient pressure, but other risk factors increase the likelihood of it occurring. The known risk factors for divers are deep or long dives, cold water, heavy exercise at depth, and rapid ascents. Rapid ascents contribute significantly to the risk of AGE. Other factors that may increase DCI risk, but lack conclusive evidence, include obesity, dehydration, heavy exercise immediately after surfacing, and pulmonary disease. It is important to note that almost any dive profile can result in DCI, no matter how safe it seems, and evaluation is always done on a case-by-case basis, considering the diver’s signs, symptoms, and dive profiles.

 Decompression Sickness (DCS)

DCS (also known as the bends or caisson disease) results from inadequate decompression following exposure to increased pressure. During a dive, the body tissues absorb inert gases like nitrogen from the breathing gas in proportion to the surrounding pressure. If this pressure is reduced too quickly, the nitrogen may come out of solution and form bubbles in the tissues and bloodstream. This can happen even when accepted guidelines are followed. Bubbles forming in or near joints are the presumed cause of the classic joint pain (the bends). In severe cases, the spinal cord and brain are affected, causing symptoms like numbness, paralysis, and impaired coordination. The most common manifestations of DCS are subtle, including joint pain and a tingling sensation (paraesthesia) in an extremity. Symptoms usually appear within 15 minutes to 12 hours after surfacing.

Arterial Gas Embolism (AGE)

AGE is considered the more serious form of DCI. It occurs if a diver ascends without exhaling, which causes air trapped in the lungs to expand and potentially rupture the lung tissue. This injury, called pulmonary barotrauma, releases gas bubbles into the arterial circulation. Because the brain receives the highest proportion of blood flow, it is the main organ where these bubbles interrupt circulation. This circulation interruption is AGE, and the diver may surface unconscious or lose consciousness within 10 minutes of surfacing. Symptoms are often immediate and severe, including dizziness, visual blurring, paralysis, and confusion.

Preventing and Treating DCI

Recreational divers should dive conservatively, especially when diving deep or in cold and strenuous conditions and are advised to avoid flying or exposure to altitude too soon after diving. To prevent AGE, divers must always relax and breathe normally during ascent. The primary treatment for DCI is recompression, and early oxygen first aid is essential for stabilization. Delays in seeking treatment significantly elevate the risk of residual symptoms and long-term damage. In case of suspected DCI, the response must be categorized as an Emergency (severe, immediate symptoms), Urgent (severe, unchanging pain only), or Timely (vague, slow-progressing symptoms) to ensure proper and prompt evacuation to a treatment facility. Following treatment, a conservative waiting period of several weeks, along with consultation from a physician trained in dive medicine, is required before considering a return to diving.