A decompression chamber is an enclosed, pressurized vessel designed to control atmospheric conditions for therapeutic or preventative purposes. This specialized equipment allows medical professionals to safely increase or decrease the pressure surrounding a patient. The original application was tied to deep-sea diving and pressurized work environments, where individuals were exposed to pressures greater than those at sea level. The technology is now broadly applied in medicine and is often referred to as hyperbaric oxygen therapy (HBOT).
The Physics of Pressure: Why Decompression is Necessary
Boyle’s Law explains that the volume of a gas is inversely proportional to the pressure exerted on it. As a diver descends, increasing water pressure causes the volume of air in the body’s gas-filled spaces, like the lungs and sinuses, to decrease. Conversely, an uncontrolled ascent causes these gas volumes to rapidly expand. This rapid expansion can lead to physical tissue trauma known as barotrauma.
Henry’s Law states that the amount of gas dissolved in a liquid is proportional to the partial pressure of that gas above the liquid. When diving, a person breathes air under high pressure, causing nitrogen to dissolve into the blood and tissues. If pressure is reduced too quickly, the dissolved nitrogen forms bubbles, similar to opening a carbonated drink. These gas bubbles cause decompression sickness, or “the bends,” making controlled decompression necessary.
Physical Structure and Operational Modes
Decompression chambers are sealed pressure vessels, typically constructed from steel or thick acrylic, designed to safely withstand high internal pressures. They include air locks and medical locks, which allow personnel or supplies to enter and exit without changing the pressure of the main chamber. A control panel, located outside, is used by a trained technician to precisely manage the rate of compression and decompression.
Chambers are broadly classified into two types: monoplace and multiplace designs. Monoplace chambers are clear, acrylic cylinders designed for a single patient, where the entire chamber is pressurized with 100% oxygen. Multiplace chambers are larger, room-like steel vessels that can accommodate multiple patients and medical staff simultaneously. In a multiplace chamber, the room is pressurized with compressed air, and patients breathe 100% oxygen through tight-fitting masks or hoods.
Treating Decompression Illness
The chamber’s original use is the treatment of Decompression Illness (DCI), which encompasses decompression sickness and arterial gas embolism (AGE). DCI occurs when nitrogen bubbles form in the body’s tissues and bloodstream following a rapid reduction in ambient pressure. The treatment, known as recompression therapy, involves quickly returning the patient to a pressure higher than the injury occurred, often between 2.5 and 3.0 atmospheres absolute (ATA).
This pressure increase reduces the volume of the gas bubbles (Boyle’s Law) and forces the nitrogen to dissolve back into the solution (Henry’s Law). The patient breathes 100% oxygen, which speeds up the removal of excess nitrogen while ensuring tissues remain well-oxygenated. Subsequent decompression is performed slowly over several hours, following standardized protocols, to allow the nitrogen to exit the body safely through the lungs.
Hyperbaric Oxygen Therapy
Modern decompression chambers are often referred to as Hyperbaric Oxygen Therapy (HBOT) chambers when used for a wide range of non-DCI medical conditions. HBOT involves delivering 100% oxygen to a patient at pressures two to three times greater than normal atmospheric pressure, typically between 1.5 and 3.0 ATA. The therapeutic benefit is primarily driven by hyperoxygenation, which is the saturation of the blood plasma with high concentrations of dissolved oxygen.
This super-oxygenated plasma can reach tissues with poor blood flow due to injury or infection, promoting healing and supporting the immune system. Conditions treated with HBOT include:
- Chronic non-healing diabetic wounds.
- Radiation injury.
- Serious infections like gas gangrene.
- Carbon monoxide poisoning.
In these applications, the goal is to leverage high oxygen levels to enhance cellular repair, reduce swelling, and stimulate the growth of new blood vessels.