Bends

Bends

The bends, also known as decompression sickness (DCS), is a condition that arises from dissolved gases coming out of solution into bubbles inside the body upon depressurization. It is most commonly associated with scuba diving, but can occur in other situations where rapid changes in pressure occur, such as in high-altitude or aerospace environments.

Pathophysiology

Decompression sickness occurs when inert gases, primarily nitrogen, that are dissolved in body tissues and blood under high pressure form bubbles as the pressure decreases. These bubbles can cause a variety of symptoms depending on their location in the body. The most common sites affected include the joints, skin, lungs, and central nervous system.

Nitrogen Absorption

During a dive, the increased pressure causes more nitrogen to dissolve in the blood and tissues. The longer and deeper the dive, the more nitrogen is absorbed. If the diver ascends too quickly, the pressure decreases rapidly, and the nitrogen comes out of solution, forming bubbles.

Bubble Formation

The formation of bubbles can lead to mechanical obstruction of blood vessels, inflammation, and activation of the coagulation cascade. This can result in a range of symptoms from mild joint pain to severe neurological deficits.

Symptoms

The symptoms of the bends can vary widely depending on the severity and location of the bubbles. Common symptoms include:

• Joint and muscle pain: Often referred to as "the bends" due to the characteristic posture divers assume to relieve pain.
• Skin rashes: Itching and rashes can occur due to bubbles in the skin.
• Neurological symptoms: Dizziness, confusion, paralysis, or unconsciousness can occur if bubbles affect the brain or spinal cord.
• Respiratory symptoms: Shortness of breath and chest pain can occur if bubbles form in the lungs.

Diagnosis

Diagnosis of decompression sickness is primarily clinical, based on the history of recent diving or exposure to pressure changes and the presence of characteristic symptoms. Imaging studies such as MRI can be used to assess neurological involvement.

Treatment

The primary treatment for decompression sickness is recompression therapy, usually in a hyperbaric chamber. This involves increasing the pressure to help dissolve the bubbles and then slowly decreasing the pressure to allow safe off-gassing of nitrogen.

Recompression Therapy

Recompression therapy is the definitive treatment and involves placing the patient in a hyperbaric chamber where the pressure is increased to simulate a depth of 18 meters (60 feet) of seawater. The pressure is then gradually reduced according to a specific protocol.

Supportive Care

Additional treatments may include oxygen therapy, intravenous fluids, and medications to manage symptoms such as pain or nausea.

Prevention

Preventing decompression sickness involves adhering to safe diving practices, such as:

• Following dive tables or dive computers: These tools help divers plan their ascents to avoid rapid pressure changes.
• Performing safety stops: Pausing at a shallow depth during ascent to allow excess nitrogen to be safely eliminated.
• Avoiding flying after diving: Waiting at least 12-24 hours before flying to prevent additional pressure changes.

Also see

• Scuba diving
• Hyperbaric medicine
• Nitrogen narcosis
• Barotrauma