10 Things to Know About Hyperbaric Oxygen Therapy

With two more indications approved by the FDA in 2021, hyperbaric oxygen (HBO) therapy continues to gain wide acceptance as an adjunct modality for problematic wounds. During the 2021 Symposium on Advanced Wound Care fall meeting, Jayesh B. Shah, MD, the president of South Texas Wound Associates, in San Antonio, shared the top 10 things that every provider should know about HBO therapy. They include the differences between topical and systemic HBO therapy, as well as various indications, contraindications and side effects.

10. HBO Is Old

HBO therapy has been around for more than 150 years in the United States, but its history spans much longer. In fact, the first record of a pressurized chamber used to treat medical conditions dates to 1662 in England. While the popularity of the technique has ebbed and flowed, Dr. Shah said, there are now more than 3,000 centers in the United States, and the list of indications approved by insurance plans continues to expand.

9. Life Can Exist Without Blood

In the 1960s, Boerma et al conducted an experiment that showed that life without blood is possible under hyperbaric conditions. Pigs breathing pure oxygen at 3 ATA (atmosphere absolute) were completely exsanguinated, but the volume of fluid in the circulatory system was maintained, and the oxygen supply remained sufficient (Ned Tijdschr Geneeskd. 1960;104:949-954). After being reinfused with their own blood, the pigs “lived happily ever after,” Dr. Shah said.

8. HBO Is More Than the Correction of Hypoxia

Research has demonstrated HBO’s mechanisms are more than the correction of hypoxia. Under normal atmospheric pressure, Dr. Shah explained, hemoglobin binds to oxygen. However, in a hyperbaric environment, resting cellular oxygen requirements can be met by plasma dissolved oxygen alone. As pressure increases, the number of molecules of oxygen in the plasma also increases, which can be extracted by the body to help heal hypoxic wounds.

“The rate at which wounds heal is oxygen dependent,” Dr. Shah said, who noted that all wounds have a hypoxic center of variable size. “Periwound hypoxia alters local responses to infection and local tissue reparative processes, but HBO leads to improved oxygen delivery.”

7. tcpO2 Predicts Failure to Heal Better Than ABI

The ankle brachial index (ABI) is the ratio of blood pressure at the ankle to blood pressure in the upper arm and is used to noninvasively check for peripheral artery disease. Transcutaneous oximetry (tcpO₂), on the other hand, is the only method to measure the local oxygen released from the capillaries through the skin.

“tcpO₂ measures oxygen molecules, not saturation,” Dr. Shah said. “It outperforms ABI in predicting the healing of foot ulcers and in predicting limb amputations.”

6. Infrared Spectroscopy to Monitor Oxygenation

According to Dr. Shah, infrared spectroscopy may be useful to monitor oxygenation within the wound beds and surrounding tissue. The effect of HBO therapy on diabetic foot ulcers can be documented via near-infrared spectroscopy, said Dr. Shah, who noted that the technology evaluates functional tissue oxygen saturation.

5. Most Approved Indications Are Emergency Indications

Although the majority of indications approved for HBO therapy are emergency indications, the number of HBO treatment centers treating emergency indications has decreased. Fewer than 10% of HBO centers with at least one chamber are available for emergency HBO therapy, said Dr. Shah, who noted that electively scheduled patients being treated for wound healing dominate most hospital-based and freestanding HBO facilities.

4. Only 1 Absolute Contraindication

The only absolute contraindication to HBO is untreated pneumothorax, which needs to be treated prior to HBO therapy. Relative contraindications include chemotherapy agents and active cancer, pregnancy, a history of middle ear surgery or optic neuritis, pulmonary pathologies, chronic sinusitis, seizure disorder, and viral infections. Physicians also should weigh the risk versus benefit of HBO therapy for patients with confinement anxiety before initiating treatment, Dr. Shah said.

3. HBO Therapy Is Extremely Safe

The safety of HBO therapy has long been demonstrated, but patients and providers should be aware of specific side effects. At the 2021 virtual American College of Surgeons Clinical Congress, Ernest S. Chiu, MD, the director of the Helen L. and Martin S. Kimmel Hyperbaric and Advanced Wound Healing Center at NYU Langone, in New York City, noted common and reversible adverse effects include barotrauma to the ear and myopia. Serious adverse events are rare but include seizures, congestive heart failure, pulmonary edema and retinal changes. Complications occur in less than 1% of HBO treatments, and the most common complication is ear pain, Dr. Chiu added.

2. Topical Oxygen Therapy Is Not HBO

Topical oxygen has gained traction as a technique to facilitate wound healing dynamics, and there is evidence to support its benefits, but the approach should not be confused with HBO therapy, Dr. Shah said. While the latter consists of breathing oxygen at increased atmospheric pressure, topical oxygen involves the placement of a local device that is pressurized with oxygen over an extremity. In the future, topical oxygen may be combined with HBO therapy to facilitate healing, he said.

1. The FDA Just Approved 2 New Indications

The FDA approved two new indications for HBO: acute central retinal artery occlusion and idiopathic sensorineural hearing loss. There are now 14 approved indications.

“If your healthcare provider recommends HBO therapy, the FDA advises receiving the treatment at a hospital or a facility that has been inspected and is accredited by the Undersea and Hyperbaric Medical Society,” Dr. Shah said.

This article is from the March 2022 print issue.