Aerospace Decompression Illness

Excerpt

Aerospace decompression illness (ADI) can occur when the human body is exposed to low environmental barometric pressures when ascending while diving or at high altitudes. This activity rapidly releases the inert gas nitrogen, typically dissolved in bodily fluids and tissues, causing it to come out of solution in the bloodstream and form bubbles. These bubbles formed within the body can affect various organ systems, such as the joints, brain, skin, and lungs, leading to decompression sickness during aerospace activities. This condition can occur due to nonpressurized aircraft flights, flights experiencing cabin pressure fluctuations, flying shortly after diving, and using altitude chambers. Common symptoms involve joint pain, headaches, paresthesia, and visual changes, with severe consequences ranging from paralysis, seizures, loss of consciousness, or death.

Decompression illness during diving arises from nitrogen accumulation in tissues, leading to bubble formation upon returning to lower ambient pressure. In contrast, altitude decompression illness stems from nitrogen already saturated in tissue at ground level, emerging from solution at lower atmospheric pressures.

Decompression illness is initially classified into 2 types—type I and type II. Type I primarily affects the skin, joints, and lymphatic vessels, whereas type II involves the central nervous system (CNS) and is considered more severe. A prevalent classification system, as mentioned below, is based on the affected organ systems.

1. 'Cutaneous' refers to the skin and is also known as 'the Creeps.'

2. 'Arthropathy' is a medical condition that affects the joints and is also commonly referred to as 'the Bends.'

3. 'Cardiopulmonary' involves the heart and lungs and is also known as 'the Chokes.'

4. 'Neurology' involves the brain, spinal cord, and nerves and is also known as 'the Staggers.'

Decompression illness, often referred to as a 'great imitator,' presents with a diverse range of symptoms, with 44% to 67% of affected patients developing these symptoms within 2 hours of returning to ground level. The remaining cases may exhibit symptoms 20 hours or later. The mainstay of therapy is hydration and the administration of either 100% oxygen or hyperbaric oxygen, depending on the severity of symptoms. In situations involving fluctuating ambient pressure, such as scuba diving and flight-related illnesses, clinicians should always consider decompression illness due to its variable presentation.