Hyperbaric Chamber

Many medical establishments and institutions specializing in underwater medicine offer hyperbaric chamber therapy.

This page describes what a hyperbaric chamber is and how it can be used to improve tissue oxygenation. Medically approved uses, risks, contraindications and how it differs from other air-dispensing devices are also discussed below.

What is a Hyperbaric Chamber?

A hyperbaric chamber is a pressurized vessel or chamber used to administer hyperbaric oxygen therapy to a patient. All hyperbaric chambers are designed to house one or more patients who require extra tissue oxygenation or treatment for gas-related conditions, such as decompression sickness. As oxygen has antimicrobial properties and enhances healing, a hyperbaric chamber also has a role in treating injuries and necrotizing wounds.

Hyperbaric Therapy Basics. The hyperbaric chamber successfully increases whole-body oxygenation due to two key factors:

• Air Pressure. Henry’s Law is the founding principle for hyperbaric therapy, which states that the concentration of dissolved gases in a given liquid is directly proportional to the liquid’s pressure.^[1] The chamber is able to increase the internal air pressure by 2-3 times the ambient air pressure at sea level. This allows for the bloodstream to be saturated with a much higher concentration of oxygen than normal conditions would allow. The high blood oxygen content and smaller oxygen particle size allow for oxygen to move into muscle, organ and bone tissue with ease.
• Air Oxygen Content. The air fed into the chamber usually comprises 100% oxygen or an oxygen concentration substantially higher than that of ordinary air. Chambers that make use of normal air at an increased pressure are not considered appropriate for medical use.

Hyperbaric Oxygen Administration. Prior to therapy, the patient will be instructed to remove all jewelry and accessories. Once a patient is comfortably inside the chamber, the person operating the device will seal the chamber and increase the internal air pressure. The patient is usually asked to equalize their ears as needed until they have reached the destination pressure. Once acclimatized, the pressure difference is not usually felt by the patient, and nothing more than being inside the chamber is required of them. The treatment usually ranges from 1-2 hours, during which the patient can rest, relax, or entertain themselves. Patients are allowed to enter the hyperbaric chamber with electronic devices, games and books to help them pass the time.

Types of Hyperbaric Chambers

Hyperbaric chambers vary in size, shape, orientation and treatment coverage. They are usually categorized in accordance with the number of occupants they can house as well as the pressure intensities they offer.

Occupancy. Some chambers can only take one occupant at a time, while others can take several. Each type has different advantages and disadvantages, as briefly covered below:

• Multi-place Chambers can take more than one occupant at a time. They are usually found in large medical establishments and typically resemble large rooms, patient quarters or chambers lined with multiple seats or beds. Many of these chambers are equipped with modern amenities such as a television that enable a better overall patient experience. Multi-place chambers also have the added benefit of being able to treat claustrophobic patients.^[2]
• Mono-place chambers are able to house one patient at a time and are often far simpler than multi-place chambers. These can resemble soft-shelled body bags in which the patient lays down inside or capsules that house a bed or seat.

Pressure. Hyperbaric chamber designs may vary depending on whether they offer mild or intense hyperbaric therapy:

• Mild. Hyperbaric chambers designed for mild hyperbaric treatment are usually soft-shelled and, in some cases ,can even be rented or purchased for home use. The pressure selection on these is usually limited, and they are not able to administer the occupant with 100% oxygen.
• Intense. Chambers offering intensive therapy are not available for home use and are usually permanent fixtures offered in medical institutions that specialize in treating illnesses for which therapy is indicated. These chambers can administer 100% oxygen and offer a much wider pressure range that helps to tackle a larger variety of conditions. Unlike in mild therapy, these hyperbaric chambers also often come equipped with ventilators and oxygen masks in order to cover the specific needs of various patients. Oxygen may be administered through an internal ventilator in the pressurized chamber or ambiently.

How is a Hyperbaric Chamber Different from a Ventilator or Oxygen Mask?

A hyperbaric chamber supplies the user with more oxygen than either a ventilator or an oxygen mask. In most cases, hyperbaric therapy can be administered alongside oxygen masks and other kinds of ventilators.

The differences between a hyperbaric chamber and ventilators are described below:

Oxygen Masks. An oxygen mask is a non-invasive type of ventilator that is often preferred for enhancing breathing in those with respiratory ailments due to its portability and accessibility. Despite being able to enhance tissue oxygenation, hyperbaric therapy is not normally prescribed for improving breathing.^[3]

Mechanical Ventilation. Invasive ventilation that requires intubation (insertion of pipes into the windpipe to enable breathing) makes use of a machine that regulates every breath. This is used to help patients with mechanical respiration problems to breathe. Those making use of mechanical respirators may benefit from hyperbaric oxygen therapy, however, they would still need the ventilator to ensure they can breathe properly inside the chamber. Some indications of those with mechanical ventilators are contraindicated for hyperbaric therapy, such as lung collapse, while for other indications, hyperbaric therapy would be required with the ventilator, such as gas embolism or poisoning^[4].

Tracheostomy Ventilation. In situations of tracheostomy (windpipe surgery), mechanical ventilators are often surgically placed inside the windpipe. While preliminary studies suggest that hyperbaric therapy is beneficial for improving post-surgical recovery in these patients, the pressure gradient inside the chamber is known to promote airway constriction, patient distress and potential adverse effects. It is recommended that those with tracheostomy ventilation avoid hyperbaric therapy.^[5]

Medically Approved Uses for a Hyperbaric Chamber

Hyperbaric chambers are most commonly used in underwater medicine for treating decompression or diving sickness, however, there are over 10 other approved uses for oxygen therapy.

Approved hyperbaric chamber use includes the treatment of the following:

• Gas embolism
• Carbon monoxide or other similar types of gas poisoning
• Necrotizing injuries such as compromised surgical grafts, radiation injuries, gangrene or diabetic foot ulcers
• Necrotizing soft tissue infections
• Severe burns
• Retinal arterial occlusion
• Arterial insufficiency or severe blood loss
• Skeletal muscle compartment syndrome
• Intracranial abscesses
• Sudden hearing loss
• Chronic refractory osteomyelitis (inflammation and swelling of bone)

Dangers of Using a Hyperbaric Chamber

Under the right supervision, hyperbaric chambers are generally deemed very safe. This is especially true of those offering mild hyperbaric therapy. Those considering hyperbaric oxygen ought to consult with a healthcare professional beforehand to assess whether the treatment would be contraindicated in their case or not.^[6]

Risks associated with using a hyperbaric chamber include:

• Barotrauma due to heavily blocked ears, sinuses, infections, thoracic surgery or other internal wounds that create pockets of air (it is very important for a doctor to rule out pneumothorax prior to treatment)
• Exacerbation of congestive heart failure, pulmonary edema or lung collapse
• Claustrophobia or panic from entering a confined space (only applicable for a smaller chamber)

Contraindications. Hyperbaric chamber use may be contraindicated in patients with severe hypertension, diabetes, pregnancy, cancer, asthma, COPD, seizures or epilepsy, congenital spherocytosis, or an active infection with fever. A doctor is required to assess whether patients with these conditions would be suitable candidates for therapy or not.

Conclusion

A hyperbaric chamber is a specialized medical device that administers oxygen to a patient in a pressurized environment. It is mostly used to treat decompression sickness, necrotizing wounds and gas-related conditions such as gas embolisms. While they saturate tissues with oxygen, hyperbaric chambers are not meant to replace ventilators in treating critical respiratory conditions and may be contraindicated for those at risk of lung collapse. Hyperbaric therapy is generally considered safe, yet a healthcare professional ought to assess the state of the patient to ensure treatment is not contraindicated.

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