What Clinical Trials, Guidelines, and Real-World Outcomes Actually Show About Hyperbaric Wound Healing
Patients and referring clinicians often ask for the success rate of hyperbaric oxygen therapy, commonly abbreviated as HBOT, in chronic wounds. The most accurate answer is that no single percentage applies across all wounds or patients.
A chronic wound may result from diabetes, ischemia, venous hypertension, pressure, infection, radiation damage, surgery, trauma, or several of these factors at once. Each wound type has a different pathophysiology, treatment pathway, and definition of success.
Even within diabetic foot ulcer research, reported results vary substantially. One well-designed trial found complete healing at one year in 52 percent of HBOT-treated patients compared with 29 percent of patients receiving sham treatment. Another sham-controlled trial found healing at 12 weeks in 20 percent of HBOT patients and 22 percent of controls. These results cannot be reconciled into a universal success rate without accounting for differences in patient selection, wound severity, ischemia, treatment completion, follow-up, and standard wound care. (PubMed)
HBOT should therefore be discussed in terms of the probability of achieving a defined outcome in a carefully selected patient, not as a treatment with one advertised cure rate.
What Counts as HBOT Success?
Success can mean several different things in chronic wound care:
- Complete wound closure
- Reduction in wound area or depth
- Development of healthy granulation tissue
- Control of refractory infection
- Preservation of a graft or flap
- Avoidance of major amputation
- Reduction in the required level of amputation
- Successful preparation for reconstructive surgery
- Durable healing without early recurrence
These outcomes are not interchangeable.
A wound that becomes smaller but remains open is not completely healed. A diabetic foot wound that closes temporarily and reopens several weeks later has not achieved sustained healing. A minor toe amputation that removes infection and preserves a functional foot may represent successful limb salvage, even though an amputation occurred.
For chronic osteomyelitis, success is generally measured through remission of infection rather than closure of a surface wound. For radiation injury, meaningful improvement may include reduced bleeding, healing of an ulcer, improved tissue quality, or successful reconstruction.
Any reported success percentage should therefore identify the outcome measured, the follow-up period, and the population treated.
Diabetic Foot Ulcers Have the Most Studied Wound Outcomes
The largest chronic wound evidence base concerns diabetes-related foot ulcers. HBOT is not intended for every diabetic ulcer. The patients studied and covered for treatment generally have advanced wounds that have failed comprehensive standard care.
The 2023 International Working Group on the Diabetic Foot, or IWGDF, conditionally recommends considering HBOT for neuro-ischemic or ischemic diabetes-related foot ulcers when standard care alone has failed and the treatment resources are available. The recommendation is rated as low certainty because the trials have produced conflicting findings and many have a high risk of bias.
The guideline found that the better-quality evidence suggested a possible improvement in complete wound healing and reduction in ulcer area. It did not find good evidence that HBOT reliably prevents amputation across the studied population. Differences in ischemia, wound definitions, treatment protocols, and follow-up periods made comparison difficult.
This is a more clinically responsible interpretation than claiming that HBOT heals a fixed percentage of diabetic wounds.
The HODFU Trial Reported Higher One-Year Healing
The HODFU study remains one of the most frequently cited HBOT wound trials. It was randomized, double-blinded, and placebo controlled, involving selected patients with chronic diabetes-related foot ulcers.
At one year, complete healing occurred in:
- 25 of 48 patients assigned to HBOT, or 52 percent
- 12 of 42 patients assigned to sham treatment, or 29 percent
The difference was statistically significant. Among patients who completed at least 36 of the planned 40 sessions, reported healing was approximately 61 percent with HBOT and 27 percent with placebo. (PubMed)
These figures show that HBOT improved the probability of healing in that specific trial. They do not mean that every patient beginning treatment has a 52 or 61 percent chance of healing.
The participants were selected for a controlled study, received structured wound care, and were followed for one year. Results may differ in patients with uncontrolled infection, uncorrected arterial disease, inadequate offloading, severe frailty, or an inability to complete the treatment course.
Other Randomized Trials Found Little or No Added Benefit
The Fedorko trial also used a randomized, double-blind, sham-controlled design. At 12 weeks, 10 patients in the HBOT group, or 20 percent, had healed compared with 12 patients in the sham group, or 22 percent. The study did not find that HBOT reduced the number of patients meeting criteria for amputation. (PubMed)
The DAMO2CLES multicenter trial studied patients with diabetes and ischemic lower-extremity ulcers. It did not demonstrate significant improvement in complete healing or limb salvage across the overall population assigned to adjunctive HBOT. Treatment completion was also a challenge, which reflects an important limitation in real clinical practice. (PubMed)
These negative trials do not prove that HBOT is ineffective for every chronic diabetic wound. They demonstrate that results depend heavily on which patients are treated, whether they complete treatment, and whether the wound’s principal barriers are responsive to oxygen therapy.
Meta-Analyses Often Report Stronger Pooled Effects
Meta-analyses combine results from multiple trials to estimate an overall treatment effect. Several recent reviews have reported improved healing with adjunctive HBOT.
A 2024 meta-analysis of seven randomized trials reported that complete healing was more frequent with HBOT, with a pooled relative risk of 3.59. The confidence interval was wide, indicating uncertainty about the exact size of the effect. (PubMed)
Another 2024 systematic review organized by Wagner grade reported an overall relative risk for ulcer healing of 2.39. The analysis also had substantial statistical heterogeneity, meaning the included study results differed considerably from one another. (PubMed Central (PMC))
Relative risk should not be confused with an absolute success rate. If 10 percent of a comparison group heals, doubling the healing probability would produce a 20 percent treatment-group rate. If 30 percent of the comparison group heals, the same relative effect would produce a much higher absolute rate.
Pooled estimates are also only as reliable as the studies included. Small samples, inconsistent wound classifications, variable standard care, and differences in treatment dose can produce a result that does not accurately predict outcomes in one hospital or one patient.
Success Is More Likely in Properly Selected Wounds
HBOT is most biologically plausible when the wound contains viable but hypoxic tissue and enough circulation remains to deliver oxygenated plasma.
Features that may support a favorable response include:
- A recognized hyperbaric indication
- A neuro-ischemic or ischemic diabetic foot ulcer
- Wagner grade III or higher disease
- Failure to heal despite appropriate standard care
- Corrected or maximally treated arterial disease
- Effective pressure offloading
- Adequate debridement and infection control
- A realistic reconstructive or limb-salvage objective
- Ability to complete the planned treatment course
HBOT is less likely to succeed when the principal barrier remains untreated. Examples include an occluded artery requiring revascularization, an undrained abscess, necrotic bone requiring removal, continued weight bearing on a plantar ulcer, or a wound bed that cannot support reconstruction.
Oxygen can strengthen healing biology. It cannot compensate indefinitely for absent blood flow, repeated trauma, uncontrolled infection, or irreversible necrosis.
Medicare Criteria Reflect Selective Use
Medicare coverage for diabetes-related lower-extremity wounds requires all of the following:
- Type 1 or type 2 diabetes
- A lower-extremity wound caused by diabetes
- Wagner grade III or higher
- Failure of an adequate course of standard wound therapy
HBOT is covered as an adjunct only after the wound has shown no measurable healing for at least 30 days despite appropriate care. Continued treatment is not covered when measurable improvement is not demonstrated within a subsequent 30-day treatment period. (Noridian Medicare)
These rules are coverage requirements rather than a complete clinical guideline, but they reinforce two essential principles. HBOT should not be the first treatment applied to an uncomplicated wound, and the course should not continue without objective evidence of benefit.
HBOT Is Not Established for Every Chronic Wound Type
The phrase chronic wound includes several conditions for which HBOT evidence is limited or absent.
For venous leg ulcers, the primary treatment is compression after appropriate arterial evaluation. HBOT research has not established a reliable complete-healing advantage for routine venous ulcer treatment.
Pressure injuries require pressure redistribution, repositioning, moisture control, nutrition, debridement, and management of contributing illness. There is insufficient controlled evidence to calculate a meaningful HBOT success rate for pressure ulcers.
Evidence is also inadequate for routine HBOT treatment of chronic arterial ulcers when arterial inflow has not been restored. A completely ischemic wound requires vascular evaluation, not an attempt to force oxygen through an absent circulation.
The major Cochrane review of HBOT for chronic wounds found that most randomized evidence involved diabetic foot ulcers. It found insufficient evidence to support routine treatment of venous, arterial, or pressure ulcers. (Cochrane)
A center should not apply diabetic foot ulcer outcome percentages to every wound referred for treatment.
Chronic Refractory Osteomyelitis Uses a Different Success Measure
Chronic refractory osteomyelitis is a recognized hyperbaric indication when infection persists or recurs despite appropriate surgery and antimicrobial treatment.
Published clinical reports have described remission rates of approximately 81 to 85 percent at two to three years. These figures are derived primarily from older observational series rather than modern randomized trials, so they should not be presented with the same certainty as a large controlled study. (AAFP)
A later systematic review found supportive results across published reports, but the evidence remained limited by nonrandomized designs and differences in surgical care, infection site, pathogens, and outcome definitions. (PubMed)
Success in refractory osteomyelitis requires more than chamber attendance. It generally depends on:
- Removal of infected or necrotic bone when feasible
- Deep cultures
- Appropriate antimicrobial therapy
- Stable fixation
- Management of infected hardware
- Adequate soft-tissue coverage
- Correction of vascular insufficiency
Current clinical guidance describes courses of approximately 20 to 40 sessions when the patient is improving. Failure to show an early clinical response should prompt reassessment of source control and the overall treatment plan rather than indefinite continuation of the same regimen. (PubMed)
Radiation Wounds Also Require Diagnosis-Specific Outcomes
Delayed radiation injury may cause chronic ulcers, exposed bone, fibrosis, bleeding, or failure of surgical tissue within a previous treatment field.
Success may involve:
- Closure of a radiation-associated ulcer
- Reduced tissue bleeding
- Improved wound-bed quality
- Healing after debridement
- Successful graft or flap reconstruction
- Remission of osteoradionecrosis symptoms
These patients should not be grouped with diabetic foot ulcer trials. Radiation injury has a different mechanism, treatment course, and outcome profile.
The tissue may require 30 to 40 or more HBOT sessions, sometimes coordinated around surgery. Complete recovery is less likely when radiation injury has caused extensive structural destruction, a fistula, pathologic fracture, or severe loss of organ function.
A reported improvement rate in radiation cystitis, for example, cannot be used as the expected closure rate for a chest wall ulcer or mandibular osteoradionecrosis.
Treatment Completion Influences Outcomes
Chronic wound protocols commonly require treatment five days per week over several weeks. This creates a substantial burden for patients who may already have limited mobility, transportation barriers, employment obligations, or multiple medical appointments.
Treatment interruptions may occur because of:
- Ear or sinus pressure difficulty
- Hospitalization
- Surgery
- Glucose instability
- Transportation problems
- Claustrophobia
- Acute illness
- Financial or caregiving demands
The HODFU results were stronger among patients who completed at least 36 sessions than in the full intention-to-treat population. This suggests that treatment completion may influence outcomes, although patients who complete therapy may also be healthier or more adherent in other aspects of wound care. (Wiley Online Library)
A success estimate should therefore specify whether it applies to all patients who started treatment or only to those who completed a minimum number of sessions.
Standard Wound Care Determines Much of the Outcome
HBOT does not operate independently of the rest of the treatment plan.
For a diabetic foot wound, standard care may include:
- Vascular testing and revascularization
- Surgical debridement
- Infection and osteomyelitis treatment
- Pressure offloading
- Glucose management
- Nutritional support
- Appropriate dressings
- Reconstruction when necessary
The IWGDF defines high-quality standard care as including debridement, offloading, revascularization, and infection treatment where appropriate. HBOT was evaluated as an adjunct to these interventions, not as a replacement for them. (IWGDF Guidelines)
A hyperbaric program reporting high closure rates may have excellent vascular, podiatric, surgical, infectious disease, and offloading services. The result should not automatically be attributed to the chamber alone.
Conversely, a low healing rate may reflect late referral, severe disease, limited access to revascularization, or poor treatment completion rather than a failure of oxygen physiology.
Early Wound Improvement Is More Useful Than a Marketing Percentage
The most valuable success estimate is often the patient’s own trajectory after treatment begins.
The care team should monitor:
- Wound area
- Wound depth
- Tissue quality
- Granulation
- Drainage
- Necrosis
- Infection findings
- Exposed bone or tendon
- Perfusion
- Offloading adherence
- Need for further surgery
A wound that demonstrates progressive granulation, reduced depth, and measurable area reduction may justify continued therapy. A wound that remains unchanged or deteriorates requires reassessment.
Potential explanations for nonresponse include:
- Recurrent or persistent ischemia
- Undiagnosed osteomyelitis
- Inadequate debridement
- Continued pressure
- Uncontrolled edema
- Malnutrition
- Tobacco or nicotine exposure
- Incorrect diagnosis
- Irreversible tissue loss
Continuing HBOT without addressing these factors is unlikely to convert a failing treatment plan into a successful one.
Complete Closure Is Not the Only Meaningful Benefit
Some advanced wounds do not close during the chamber course but still improve enough to permit a successful operation, graft, flap, or delayed closure.
Clinically meaningful intermediate outcomes may include:
- Development of a vascular granulation bed
- Coverage of exposed structures
- Reduced necrotic tissue
- Control of chronic drainage
- Reduced wound dimensions
- Transition to a simpler reconstruction
- Preservation of a functional portion of the foot
- Avoidance of a major amputation
These outcomes should be documented honestly. A wound should not be counted as healed when it merely becomes smaller, but partial progress can still have substantial value.
The final assessment should consider whether the improvement was durable and whether the patient’s function, treatment burden, and quality of life improved.
How Clinicians Should Discuss Expected Results
A balanced discussion might explain that:
- HBOT improves healing in some selected advanced wounds.
- Clinical trials report substantially different results.
- One strong diabetic foot ulcer trial reported 52 percent healing at one year compared with 29 percent after sham treatment.
- Other well-designed trials did not find an added healing benefit.
- Current international guidance supports selective use with low certainty.
- Success depends on blood flow, infection control, offloading, surgery, treatment completion, and wound severity.
- HBOT does not guarantee closure or prevent every amputation.
This approach gives patients meaningful evidence without replacing uncertainty with a misleading percentage.
Evaluating a Hyperbaric Program’s Reported Success Rate
When a center reports a wound-healing success rate, physicians and hospital leaders should ask:
- Which diagnoses were included?
- Was success defined as complete and sustained closure?
- What was the follow-up period?
- Were patients who discontinued treatment included?
- Were wounds measured consistently?
- Were major and minor amputations reported separately?
- How severe were the wounds at baseline?
- Was revascularization available?
- Were outcomes independently reviewed?
- Were recurrence and mortality reported?
A rate calculated only among patients who completed every treatment will usually appear better than a rate including everyone who began therapy. A program that excludes high-risk patients may also report stronger results than a tertiary center treating the most severe cases.
Transparent outcomes are more valuable than impressive but poorly defined percentages.
A Realistic Interpretation of HBOT Success
HBOT can meaningfully improve healing for selected chronic wounds, particularly some advanced neuro-ischemic or ischemic diabetic foot ulcers. The evidence does not support a single universal success rate.
For diabetic foot ulcers, individual randomized trials have reported complete-healing rates ranging from approximately 20 percent to more than 50 percent in HBOT groups, with comparison groups also varying substantially. Meta-analyses generally favor HBOT for healing, but heterogeneity and trial quality limit confidence in the exact magnitude of benefit. (PubMed)
The most defensible definition of success is not whether a patient completed a predetermined number of chamber sessions. It is whether HBOT contributed to a measurable, durable clinical outcome within a comprehensive wound-care plan.
That outcome may be complete closure, infection remission, successful reconstruction, or preservation of a functional limb. The probability depends less on a generalized percentage than on selecting the right wound, correcting its major barriers, beginning treatment while viable tissue remains, and stopping or revising the plan when objective progress is absent.
