Chronic Wounds

Hyperbaric Oxygen Therapy Approval Status

Yes Clearance by US Food and Drug Administration (FDA)

Yes Approval by the Undersea and Hyperbaric Medical Society (UHMS)

About Clearance and Approval


Definition and Causes

Chronic, complex, or problem wounds are skin ulcers or sores that do not heal without special treatment. Wounds that fail to heal in three months are usually considered chronic. Some take years to heal or never do. Common chronic wounds include venous ulcers (leg), arterial ulcers (foot), diabetic ulcers (leg and foot), and pressure ulcers (bedsores on elbows, back, ankles, hips, and heels). Wound care specialists classify chronic wounds into stages or grades.

Diabetic foot ulcers are classified using the Wagner Grade Scale (see Diabetic Ulcers).

Pressure ulcers are classified into stages developed by the National Pressure Ulcer Advisory Panel (NPUAP) as follows:

  • Suspected Deep Tissue Injury: Purple or maroon localized area of discolored intact skin or blood-filled blister due to damage of underlying soft tissue from pressure and/or shear. The area may be preceded by tissue that is painful, firm, mushy, boggy, warmer, or cooler as compared to adjacent tissue.
  • Stage I: Intact skin with nonblanchable redness of a localized area usually over a bony prominence. Darkly pigmented skin may not have visible blanching; its color may differ from the surrounding area.
  • Stage II: Partial thickness loss of dermis presenting as a shallow open ulcer with a red pink wound bed, without slough. May also present as an intact or open/ruptured serum-filled blister.
  • Stage III: Full thickness tissue loss. Subcutaneous fat may be visible but bone, tendon, or muscle are not exposed. Slough may be present but does not obscure the depth of tissue loss. May include undermining and tunneling.
  • Stage IV: Full thickness tissue loss with exposed bone, tendon or muscle. Slough or eschar may be present on some parts of the wound bed. Often include undermining and tunneling.
  • Unstageable: Full thickness tissue loss in which the base of the ulcer is covered by slough (yellow, tan, gray, green, or brown) and/or eschar (tan, brown, or black) in the wound bed.

Chronic wounds require a healthy, oxygenated wound bed to heal. A lack of sufficient oxygen (hypoxia) in the wound bed slows or stops the normal healing process. Healing is notably difficult in patients with poor general or circulatory health. Diabetes, in particular, may inhibit wound healing and increase the risk of infection and amputation. Wounds resulting from trauma, surgery, burns, skin grafting, and radiation therapy may also become problem wounds. Chronic wounds are especially prone to serious bacterial infections that threaten life and limb.

Evidence Index

FDA cleared, widely reimbursed
Strong body of evidence
Repeatedly favorable results
Early or mixed results
Unfavorable or no evidence
Strong evidence against HBOT

Treatment with Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy (HBOT) is an effective adjunct to traditional wound care therapies, including topical cleaning; surgical removal (debridement) of dead skin and tissue; application of dressings, ointments, and biologics; and use of compression boots or stockings, vacuum or negative pressure wound therapy (NPWT) pumps, ultrasound, laser, and other emerging technologies. HBOT helps repair wounds and enhance healing by improving blood circulation, encouraging the formation of new capillary blood vessels (angiogenesis), supplying more oxygen to tissue in the wound bed, and stimulating the growth and distribution of stem cells. Hyperbaric oxygen also helps kill the anaerobic bacteria that cause some of the worst infections in chronic wounds. Evidence for HBOT is especially strong in diabetic foot ulcers classified Wagner Grade 3 or higher, for which hyperbaric oxygen is widely considered standard therapy.

Read the Arterial Insufficiencies: Enhancement of Healing in Selected Problem Wounds page in the Undersea and Hyperbaric Medical Society resource library to learn more about wound evaluation, hypoxia, measures of wound oxygenation, the mechanisms and efficacy of hyperbaric oxygen, and future areas for research.

HyperbaricLink Commentary

Hyperbaric oxygen plays an increasingly important role in the treatment of problem wounds and limb salvage. But access to accredited hyperbaric facilities and certified hyperbaric physicians and technicians is a public health problem. In 2004 as many as two-thirds of nursing home patients with NPUAP Stage II or worse pressure ulcers were not enrolled in wound care treatment programs [ NCHS, 2009 ]. In diabetes-related wounds alone, US hospitals performed 66,000 toe, foot, and leg amputations in 2006 [ CDC, 2011 ], for which health economists have estimated a cost of $3 billion per year [ ACA, 2008 ].

More and more hospitals and health networks today are opening advanced wound care and hyperbaric centers to serve this unmet clinical need. Even if chronic wounds were its only indicated use, HBOT would be assured a place in evidence-based medicine for quality and cost-effective healthcare.

Patient Resources

HyperbaricLink recommends the following websites for anyone seeking authoritative information, patient advocacy, and community support for chronic wounds.


Presented by insurance company Aetna and reviewed by Harvard Medical School faculty, the InteliHealth foot ulcers page provides a good overview of symptoms, treatments, and prevention.

The Wound Institute

Presented by device manufacturer Smith & Nephew, this interactive program clearly explains diabetic foot care with easy-to-understand graphics, audio, and text.

Wikipedia: Chronic wound

The chronic wound entry in Wikipedia provides good basic information about the different types of wounds and their causes and treatments.

Clinical Resources

Start with the following resources to explore current research activities and the peer-reviewed medical literature on hyperbaric oxygen therapy for chronic wounds.

 Use the search buttons below to go directly to research on hyperbaric oxygen therapy.

American College of Hyperbaric Medicine (ACHM)

The ACHM is a professional organization working to develop an image of hyperbaric oxygen therapy as a distinct medical specialty, often requiring full-time practice. ACHM has a strong focus on wound care and offers a credentialing and fellowship track for physicians, a Certified Hyperbaric and Wound Specialist (CHWS) program for hyperbaric technologists, and a Wound Care Boot Camp online training course.

ACHM Profile

Association for the Advancement of Wound Care (AAWC)

The preeminent multidisciplinary organization for wound care, AAWC is a nonprofit association open to everyone involved in wound care. Its mission is to spread awareness by promoting excellence in education, clinical practice, public policy, and research.

American Professional Wound Care Association (APWCA)

A nonprofit organization welcoming all wound care professionals, the APWCA combines the structure of a credentialing college and a full-service medical association. Its mission is to decrease the rate of complications from wounds all types. APWCA provides ACHM-recognized physician and technician certification programs in conjunction with the Council for Medical Education and Testing (CMET).
US National Institutes of Health keeps the official list of human clinical trials currently enrolling, in progress, and recently completed. One may reasonably question the size and legitimacy of any study not listed here.



An independent, international, nongovernmental organization, the Cochrane Collaboration is a powerful force in evidence-based medicine. One may consider a Cochrane Reviews article on any HBOT topic required hyperbaric reading.

Read the 2015 Cochrane Intervention Review: Hyperbaric oxygen therapy for chronic wounds from the Cochrane Wounds Group, doi:10.1002/14651858.CD004123.pub4

Google Scholar

A specialized Google search engine, Google Scholar indexes scholarly articles, patents, and legal opinions and journals. Google Scholar may produce many search results, but entries provide easy access to full-text journal articles.

Search Google Scholar


HBOEvidence uses computerized tools to appraise the key randomized controlled trials (RCTs) in the hyperbaric medical literature. One may reasonably question the overall strength of HBOT evidence for any disease or condition not covered here.

Search HBOEvidence
US National Library of Medicine, US National Institutes of Health

PubMed keeps the official list of scientific papers published in reputable peer-reviewed medical journals. One may reasonably question the importance and legitimacy of any study not listed here.


Undersea and Hyperbaric Medical Society

An international nonprofit organization serving some 2,400 members in 50 countries, the UHMS is the chief accrediting body and the primary source of scientific information for diving and hyperbaric medicine physiology.

Read the UHMS statement on the Medicare Arterial Insufficiency ulcer issue.

UHMS Profile


News About Chronic Wounds and Hyperbaric Oxygen Therapy

One Last Post Re: Success with Hyperbaric Oxygen Therapy for Necrotizing Infections

Tuesday, 7/17

Before we take a break from this topic, here's one more quick but inspiring story about success with hyperbaric oxygen therapy for deadly soft tissue infections, or flesh-eating disease, sometimes including gas gangrene or bone read more...

HBOT for Necrotizing Fasciitis: South Carolina Mother of Twins Going Home with All Her Limbs

Monday, 7/16

Lana Kuykendall, this year's "other" high-profile victim of necrotizing fasciitis, or flesh-eating disease, underwent extensive hyperbaric oxygen therapy as part of her remarkable recovery at Greenville Memorial Hospital in Greenv read more...

Necrotizing Fasciitis Postcript: Aimee Copeland in Rehab, Set to Return Home Next Month

Thursday, 7/12

The young woman we wrote about in May has won her life-or-death battle against necrotizing fasciitis or flesh-eating disease. Hyperbaric oxygen therapy played some role—we don't know the details—in Aimee Copeland's recovery from read more...

More news from O2.0 – the HyperbaricLink blog

Complete radiation injury news archive from O2.0 — the HyperbaricLink blog

Further Reading

HyperbaricLink suggests Hyperbaric Nursing and Wound Care (ed. Valerie Larson-Lohr, Best Publishing, 2011) and Wound Care Practice, 2nd Edition (eds. Paul J Sheffield, PhD, and Caroline E. Fife, MD, Best Publishing, 2008).

Wound Care Practice cover

Related Terms

  • Amputation
  • Arterial ulcer
  • Bedsore
  • Bony necrosis
  • Clostridial myonecrosis
  • Clostridial myositis
  • Decubitus ulcer
  • Delayed radiation injury
  • Diabetes
  • Diabetic foot
  • Diabetic foot ulcer
  • Gas gangrene
  • Hypoxia
  • Leg ulcer
  • Limb salvage
  • Necrotizing fasciitis
  • Necrotizing infection
  • Nonhealing wound
  • Osteomyelitis
  • Osteonecrosis
  • Pressure ulcer
  • Radionecrosis
  • Selected problem wounds
  • Slow-healing wound
  • Soft tissue necrosis
  • Venous stasis ulcer
  • Venous ulcer
  • Wagner ulcer grade classification scale
Undersea and Hyperbaric Medical Society, Indications, Problem Wounds. Retrieved 02 May 2015.
Wound Healing, Chronic Wounds, Medscape. Retrieved 10 May 2011.
Page Data
Updated: 25 Jul 2015 03:50 PM
Created: 13 Jun 2009 12:00 AM
By: About the authors »