Scuba diving sickness encompasses a range of medical conditions that can affect divers, stemming from the complex physiological interactions between the human body and the underwater environment. Understanding these risks is essential for any diver, from the novice to the experienced professional, as prevention and prompt recognition are paramount to safety. The most critical conditions include decompression illness, arterial gas embolism, and various forms of lung overpressure injuries, each requiring distinct management strategies.
Decompression Illness: The Core Concern
Decompression illness (DCI) is an umbrella term that describes two related but distinct syndromes caused by bubble formation in the tissues and bloodstream. These bubbles form when dissolved gases, primarily nitrogen, come out of solution too quickly during the ascent phase of a dive. The two main categories are arterial gas embolism (AGE) and decompression sickness (DCS), often referred to as "the bends." While the symptoms can overlap, the underlying mechanisms and urgency of treatment differ significantly, making accurate diagnosis a challenge for hyperbaric physicians.
Arterial Gas Embolism: A Sudden Emergency
Arterial gas embolism (AGE) is a acute, life-threatening event that typically occurs during or immediately after an ascent. It happens when a diver holds their breath while ascending, causing air trapped in the lungs to expand and rupture the alveolar tissue. This allows gas bubbles to enter the pulmonary veins and travel directly to the brain, heart, and other vital organs. Symptoms can manifest within minutes and include sudden unconsciousness, visual disturbances, chest pain, and a classic "marinoid" drunkenness, where the diver appears confused and uncoordinated without a history of alcohol consumption.
Decompression Sickness: The Delayed Reaction
Decompression sickness (DCS) occurs when the rate of ascent is too fast for the body to safely eliminate excess inert gas through the lungs. Unlike AGE, DCS symptoms often develop after the diver has completed the dive and is undergoing the decompression phase, or even hours after returning to the surface. The classic presentation involves joint pain, known as "the bends," due to nitrogen bubbles forming in the synovial fluid of the knees, elbows, and shoulders. Other symptoms can include skin itching, rashes, fatigue, and in severe cases, paralysis or respiratory distress.
Barotrauma and Lung Overpressure
Barotrauma refers to injuries caused by the inability to equalize pressure in air spaces within the body, such as the ears, sinuses, and lungs. While ear and sinus barotrauma are common and usually minor, pulmonary barotrauma is a serious concern. This occurs when a diver ascends too rapidly or holds their breath, causing the expanding air in the lungs to overdistend the delicate alveoli. This can lead to pneumothorax (collapsed lung), mediastinal emphysema (gas in the center of the chest), or subcutaneous emphysema (gas trapped under the skin), all of which require immediate medical evaluation.
Contamination and Environmental Illnesses
Not all diving illnesses are related to pressure changes. Divers are also at risk from environmental hazards that can lead to sickness. Swallowing contaminated water can cause gastrointestinal infections from bacteria like E. coli or parasites, leading to severe diarrhea and dehydration. Furthermore, exposure to marine life poses unique risks, including envenomation from jellyfish, lionfish, or stonefish stings, and infections from coral cuts, which can introduce bacteria like mycobacterium marinum into the wound.
