Introduction

Hyperbaric oxygen therapy involves the use of hyperbaric chambers, large cylindrical structures made of steel that can be pressurized and accomodate one or more patients. Patients are placed inside the chamber and the air pressure inside the chamber is typically increased to 2 to 3 ATM (atmospheres), which means the pressure inside the chamber becomes twice to three times the air pressure at sea level. Pressures higher than 3 ATM can potentially cause seizures, so it is usually avoided.

The patient inside the chamber is given oxygen by face mask or helmet, and it is the healing effect of this oxygen delivered at high pressures that makes hyperbaric oxygen therapy effective. The rate of oxygen delivery to the damaged tissues in the body is correlated with the pressure of the “dive”. So a 2 ATM dive will facilitate about double the oxygen delivery, and a 3 ATM drive will facilitate triple oxygen delivery.

Hyperbaric oxygen therapy is currently used as a treatment for many, many different ailments. In reality however, we only have evidence for certain conditions. Physiologically, hyperbaric oxygen therapy can induce healing by promoting growth of small blood vessels in damaged and chronically underperfused parts of the body. In patients who have suffered formation of air bubbles in their blood stream (air embolism) which can potentially cause strokes, myocardial infarction, and other problems, the increased pressures inside the hyperbaric chamber can shrink the air bubbles so it no longer becomes problematic.

Treatment sessions vary greatly depending on the attending physician, indication, and local protocols. They can involve one or a few dives lasting about 2 hours each, to over 60 dives with each dive lasting about 2 hours, one dive per day, 5 days a week for radiation enteritis.

Hyperbaric chambers are potentially dangerous. They have caught on fire or exploded in the past because the highly oxygenated and pressurized environment is a fire hazard. A small spark from static electricity generated on the patient’s clothes, for example, can trigger a fire and an explosion. The interior of the hyperbaric chamber must be depressurized before the door can be open, since the doors are sealed from the inside. This depressurization process can take minutes, which means that any emergencies happening inside the chamber may not be able to be dealt with right away. Patients have died in the past as a result of hyperbaric chamber fires and explosions. Many chambers are operated by private companies and may not adhere to high and strict standards of safety, such as the use of redundant fire suppression systems or protocols to reduce the likelihood of a static or electric discharge (e.g. mandatory use of 100% cotton garments while inside the chamber).

Indications for hyperbaric oxygen therapy

Ischemic damage

  • Post ischemic stroke
  • Arterial insufficiency
  • Diabetic foot ulcer
  • Compartment syndrome
  • Acute traumatic ischemias (e.g. crush injuries)
  • Severe anemia causing ischemia (e.g. unstable angina)

Radiation damage

  • Osteonecrosis of the bone from radiation therapy (e.g. jaw)
  • Chronic hematuria from radiation damage to the pelvis
  • Chronic ulcers post radiation therapy
  • Radiation-induced enteritis

Infections

  • Gas gangrene
  • Osteomyelitis
  • Intracranial abscess
  • Necrotizing fasciitis
  • Myositis (e.g. from Clostridium infections)

Chronic non-healing wounds

  • Poorly healing surgical grafts and flaps

Other

  • Air embolism
  • Gaseous embolism
  • Thermal burn injuries
  • Carbon monoxide poisoning
  • Decompression syndrome (“the bends”)
  • Idiopathic sudden sensorineural hearing loss (SSNHL)