At sea level, the air we breathe is 21% oxygen at ~15 psi (pounds per square inch). Hyperbaric oxygen therapy refers to the medical provision of 100% oxygen while in a pressurized environment (typically 3 atmospheres or approximately 45 psi). This pressure is equivalent to that experienced by a scuba diver who has descended 66 feet below the surface of the ocean.
Conditions It Is Used For
The reasons this kind of therapy is employed are many. Chief among them is to help heal tissue that has been damaged by radiation and surgery, or gangrene, or a crush injury. An example might be necrosis (dying tissue) of a larynx (voicebox) or mandible (jawbone) after radiation therapy for cancer has damaged blood supply to an area. It might also be used in severe infections, sudden visual or hearing loss, carbon monoxide poisoning, and decompression sickness, aka “the bends.”
The Process
A patient is placed in a hyperbaric chamber in a hospital or outpatient hyperbaric oxygen facility. This can look like a windowed submarine “tube” that can accommodate two people. Occasionally, the hyperbaric chamber is a special room that can accommodate several people at the same time. A search for images of “hyperbaric oxygen therapy” will provide many examples.
As the pressure in the chamber is increasing gradually, the person may need to equalize pressure in the ears just as one has to do when landing after a commercial airline flight. Simultaneously, 100% oxygen is pumped into the chamber. Then the “dive” is maintained for anywhere from 45 minutes to a few hours. During that time, the patient’s tissues are “bathed” in very high oxygen levels in a high-pressure environment. High oxygen levels can be achieved temporarily not only through blood cell/hemoglobin transfer, but also by direct absorption into tissue fluids.
Usually, a person receiving hyperbaric oxygen therapy will undergo a series of up to 40 “dives.” The change of tissue oxygen levels up and down surrounding each dive seems to stimulate new blood supply and potentiate healing.
Side Effects
The single issue seen in the author’s experience is occasional difficulty with equalization of air pressure in the middle ear space (behind the eardrum). This is analogous to the trouble some people have with their ears when they fly or come down from the top of the Sears Tower. Most people can manage this, but occasionally the patient will require placement of temporary tympanostomy tubes (like those put in the eardrums of little children with persistent middle ear fluid).