Hyperbaric oxygen therapy employs a special airtight chamber to increase the atmospheric pressure surrounding a patient (ambient pressure). The pressure may be increased several times above normal atmospheric pressure. The chamber is compressed with air while the patient breathes 100 percent oxygen. With a normal cardiovascular system, this increases the total amount of oxygen delivered to the cells by the blood stream (Henry’s law). In addition, increases in pressure result in a decrease in the size of bubbles (Boyle’s Law).
Bubbles that have been formed in the body are made smaller by hyperbaric chamber pressure. Divers may acquire bubbles in their bodies when they ascend to the surface too rapidly or stay underwater too long. Divers develop a condition known as decompression sickness (the “bends”) as a result of these bubbles. Decreasing bubble size is a primary therapy for decompression sickness. Hyperbaric chamber pressure can reduce the size of these bubbles and bubbles from other sources as well.
Boyle’s law also has an effect on patients during pressurization and depressurization. During pressurization, a patient’s ears will feel full, similar to the feeling experienced when traveling in an airplane. The pressure in the ears must be relieved during pressurization and the staff employs several techniques to help patients manage this problem.
Normally, most of the oxygen circulating in the body is carried by the red blood cells called hemoglobin. Hyperbaric oxygen dissolves any extra oxygen into the plasma (Henry’s law). The total oxygen carried to the tissues is about 10 times more than breathing air at sea level. The increase in the oxygen concentration in the blood stream promotes the healing of certain wounds.
Hyperbaric oxygen therapy can help heal some types of wounds and infections in the following ways: