Key Insights On HBOT For Diabetic Foot Ulcers

In the vast field of wound care, many treatment options exist. The main goal is to heal open ulcerations as quickly as possible. One popular treatment is the use of hyperbaric oxygen therapy (HBOT). Hyperbaric oxygen has a long history, over several hundred years, with mixed results over a myriad of applications.

The Centers for Medicare and Medicaid Services (CMS) and the Undersea and Hyperbaric Medical Society (UHMS) have noted a list of approved indications that include a total of 15 applications with precise guidelines for the application of HBOT.¹ Many laypeople ask why the use of HBOT is limited and the answer is that the current approved indications are based on research-driven results. Many HBOT centers offer treatment for non-CMS approved indications but insurance coverage is very limited.

Podiatric applications exist within the current CMS guidelines and treatment with HBOT occurs frequently with good results. Hyperbaric oxygen is an adjunct therapy and one should consider it as part of a treatment plan consisting of good wound care. The modality requires careful patient selection and education. Most typical podiatric applications of HBOT include diabetic foot ulcers (DFUs) of Wagner grade 3 or higher, chronic refractory osteomyelitis unresponsive to treatment and preservation of compromised skin grafts.

Hyperbaric oxygen is the use of 100 percent oxygen at high atmospheric pressures. There are two types of chambers: multiplace and monoplace. Patients breathe 100 percent oxygen while the sealed chamber slowly pressurizes to 2.0 to 2.5 ATA for one to two hours.

Many chronic and refractory diabetic wounds are hypoxic secondary to limited blood flow to lower extremities.² Hyperbaric oxygen increases partial pressure of oxygen in blood, plasma and tissues. This leads to increased angiogenesis, collagen production and modification (via oxygen-dependent fibroblast and hydroxylation processes), and epithelialization. Oxygen decreases infection and necrosis, increases leukocyte oxidative killing, and suppresses anaerobic bacterial growth.¹ Increased oxygen concentration also decreases inflammation by inhibiting prostaglandins, interferon gamma (IFNg), interleukin-1 (IL-1) and interleukin-6 (IL-6).³

A Closer Look At The Guidelines For HBOT For Diabetic Wounds

The use of transcutaneous oximetry testing can be helpful in identifying patients who may benefit from HBOT. Transcutaneous oxygen (TcPO₂) of less than 40 mmHg during 100 percent oxygen inhalation correlates with poor HBOT outcomes.^4,5 An increase of more than 10 mmHg and/or TcPO2 of more than 200 mmHg while the patient is in the chamber with 100 percent oxygen inhalation indicates a higher success rate for these patients.^5,6

The Agency for Healthcare Research and Quality’s National Guideline Clearinghouse makes the following recommendations in regard to HBOT.⁷

• In patients with Wagner Grade 2 or lower diabetic foot ulcers, the agency says clinicians should avoid using HBOT.
• In patients with Wagner Grade 3 or DFUs that have not shown significant improvement after 30 days of treatment, the agency suggests adding HBOT to the standard of care to reduce the risks of incomplete healing and major amputation.
• In patients with Wagner Grade 3 or higher DFUs who have just had a surgical debridement of an infected foot (e.g., partial toe or ray amputation; debridement of ulcer with underlying bursa, cicatrix or bone; foot amputation; incision and drainage of deep abscess; or treatment for necrotizing soft tissue infection), the committee suggests adding acute postoperative HBOT to the standard of care to reduce the risks of incomplete healing and major amputation.

In terms of HBOT coverage for lower extremity diabetic wounds, Medicare states that patients must meet all three of the following criteria:⁸

• have type 1 or type 2 diabetes, and a lower extremity wound that is due to diabetes;
• have a wound classified as Wagner grade 3 or higher; and
• have failed an adequate course of standard wound therapy.

In addition, Medicare does not cover continued HBOT if measurable signs of healing have not been apparent within any 30-day period of treatment.⁷

What You Should Know About Contraindications And Possible Complications

Not all patients are candidates for HBOT. The absolute contraindication for HBOT is untreated pneumothorax because compression and decompression during HBO therapy may lead to tension pneumothorax and gas emboli.⁹

Relative contraindications to HBOT include the use of certain medications such as bleomycin, cisplatin (Platinol, Teva Pharmaceuticals), disulfiram (Antabuse), doxorubicin and mafenide acetate (Sulfamylon). This is because HBOT may increase adverse effects (e.g., pulmonary toxicity, cardiotoxicity) but evidence in the literature is limited.⁹ Other relative contraindications include asthma, claustrophobia, congenital spherocytosis, chronic obstructive pulmonary disease, eustachian tube dysfunction, high fever, pacemakers/epidural pain pumps, pregnancy, seizures and upper respiratory infections.¹⁰

While most patients tolerate HBOT well, there are various complications clinicians should keep in mind.

Ear and sinus barotraumas are the most common complications. Middle ear barotrauma occurred in 2 percent of a study population having HBOT.⁹ This is caused by a failure to equalize internal pressure with the environment, and it is more common in those receiving multiple treatments. Treating physicians may employ autoinflation techniques or tympanostomy tubes to treat ear barotrauma. In regard to sinus barotrauma, clinicians may utilize nasal decongestants, steroids and antihistamines.¹⁰

Pulmonary barotrauma is rare but it manifests as cough, decreased pulmonary function and/or chest pain. Treating physicians can address this with increased decompression time and thoracostomy in pneumothorax.¹¹

Decompression sickness is a result of nitrogen dissolving in the blood and tissues forming bubbles in the blood during HBOT decompression. Symptoms include pruritus, fatigue, headache, sudden weakness, muscular pain, joint pain, dizziness, confusion and vision changes. One can reduce this risk through gradual decompression and having the patient breathe 100 percent oxygen. Treatments for decompression sickness are oxygen and recompression.¹²

Oxygen toxicity may manifest central nervous system symptoms such as seizures and pulmonary symptoms such as chest pain, cough and decreased vital capacity. For central nervous system toxicity, treating physicians remove the oxygen source and shorten treatment times. Decreasing oxygen exposure time is also key to addressing pulmonary toxicity.¹⁰

Myopia may also develop as a result of using HBOT. However, it is usually reversible and spontaneously resolves days to weeks after treatment.¹⁰

Reviewing The Current Evidence On HBOT

The current evidence shows that HBOT can, at least, aid in the short-term for chronic diabetic foot ulcerations along with standard wound care.

In 2016, Elraiyah and coworkers produced a systematic review and meta-analysis of HBOT as an adjunctive procedure for diabetic foot ulcers.¹³ They found that adding HBOT to conventional therapy (wound care/debridement and offloading) increases the healing rate and decreases the amputation rate. However, the authors note that currently available randomized controlled trials are of moderate quality due to lower methodological quality of the studies.

A 2015 Cochrane Report states that, for diabetic foot ulcers, HBOT improves short-term healing (up to six weeks) but does not have the same effect at longer term follow-up.¹⁴ The authors also note that HBOT may reduce the amount of amputations in chronic diabetic foot ulcers.

In terms of cost and mortality, Eggert and colleagues found that for Wagner grade 3 or 4 diabetic ulcerations, the average cost of a limb salvage protocol with HBOT is $33,100 with 35.4 percent mortality within 15 months in comparison to $66,000 to $73,000 with 47.2 percent mortality within 15 months for patients undergoing lower extremity amputation.¹⁵

It is important to note that while many studies support HBOT for wound management, the International Working Group on the Diabetic Foot did not find clear evidence to support HBOT to treat diabetic foot infections.¹⁶

In Conclusion
It is important to remember that HBOT cannot replace good wound care and debridement. However, HBOT can be an excellent adjunctive therapy for chronic diabetic foot ulcerations. Using transcutaneous oximetry testing can be helpful with appropriate patient selection for HBOT. Thoroughly evaluate patients for possible contraindications and complications. Trained staff and updated equipment should be available at all times when clinicians are administering HBOT. More high quality research is necessary to identify the full efficacy of HBOT but it is currently a contender for a place in optimal diabetic foot care.

Dr. Espensen is an Attending Physician and the Director of Resident Education for the Southern Arizona Limb Salvage Alliance (SALSA) Limb Salvage Clinic Banner/University of Arizona Hospital. He is also an Associate Professor in the Department of Surgery at the University of Arizona and an Associate Professor of Surgery at Western University of Health Sciences.

Dr. Song is a podiatric surgical resident at Jerry L. Pettis Memorial VA hospital in Loma Linda, Calif.

References

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