The power of oxygen

It may sound like something from the pages of a science-fiction novel, but hyperbaric oxygen therapy (HBOT) is a successful medical method that is widely respected throughout the industry. It is used for a wide variety of treatments, usually as a part of an overall medical care plan.

A unique treatment

The therapy enhances the body’s natural healing process by inhalation of 100% oxygen in a total body chamber, where the atmospheric pressure – which is greater than sea level – can be increased and controlled. In order to receive oxygen at these pressures, patients need to remain within a specially designed chamber, with each vessel accommodating one or two people.

The vessel is usually compressed with air and the patient breathes the oxygen via a transparent hood or mask. Some one-person chambers are compressed with 100% oxygen. By breathing the gas at high pressures, a large amount of oxygen dissolves into the body’s fluids, allowing it to be carried to areas where circulation is diminished or blocked.

According to Dr Caroline Fife of the Baylor College of Medicine in Texas, hyperbaric chambers represent some unique advantages.

“Among advanced therapeutic interventions for wounds, hyperbaric oxygen therapy has the unique ability to ameliorate tissue hypoxia, reduce pathologic inflammation and mitigate ischemia reperfusion injury,” she explains in her 2016 paper, ‘Appropriate Role for Hyperbaric Oxygen: Indications and Evidence’. “Most of the conditions for which it is used have few successful alternative treatments, and the morbidity and mortality associated with treatment failure are significant,” she continues. “Data on the efficacy and effectiveness of HBOT was reviewed, comparative effectiveness research of HBOT was explained, and a new paradigm for the appropriate use of HBOT was described.”

So, although the therapy is widely used, the jury is still out on its usefulness. It does not appear to do harm – but is it doing any good?

Diabetic challenges

Previously, hyperbaric chambers – formerly called decompression or recompression chambers – were used to treat complaints such as decompression sickness, carbon monoxide poisoning and wounds proving difficult to heal.

It is this last ailment that caught the interest of modern scientists. With the continual rise of diabetes worldwide, more research is focused on the treatment of the chronic wounds these patients suffer.

Education and prevention can only do so much; amputation is a last resort that many are unwilling to undergo, and management is fraught with problems for long-term patients if medical staff attempt more limited treatments.

While the application of HBOT in the management of decompression illness is well established, its application for other clinical conditions is less well known.

Approved uses as recommended by the Undersea and Hyperbaric Medical Society by its Hyperbaric Oxygen Therapy Committee report include:

• air or gas embolism
• carbon monoxide poisoning
• clostridial myositis and myonecrosis (gas gangrene)
• crush injury, compartment syndrome and other acute ischaemias
• decompression sickness
• enhancement of healing in selected problem wounds
• exceptional anaemia
• intracranial abscess
• necrotising soft tissue infections
• osteomyelitis (refractory)
• delayed radiation injury (soft tissue and bony necrosis)
• skin grafts and flaps
• thermal burns.

Many of these categories cover the issues confronted by those suffering with diabetes. However, despite evidence pointing towards the benefits, there is trepidation as to the overall effectiveness of HBOT on diabetic patients. It remains particularly controversial concerning those patients suffering from foot ulcers that are resistant to other treatments thanks to the dearth of consistent evidence, even though the procedure has been used for this issue for 35 years.

At loggerheads

At a American Diabetes Association’s Annual Science Session summit, Dr Magnus Löndahl from the department of endocrinology at Skane University Hospital and Lund University in Sweden, stated: “we do have two high-quality randomised controlled trials supporting the use of hyperbaric-oxygen therapy in treating chronic diabetic foot ulcers.”

Löndahl’s evidence comes from a study he led that discussed how chronic diabetic foot ulcers are a source of major concern for patients and healthcare systems. The aim of his study was to evaluate the effect of HBOT in the management of chronic diabetic foot ulcers.

The results of Löndahl’s study showed that adjunctive treatment with HBOT facilitates could heal chronic foot ulcers in selected diabetic patients.

In more detail, the study results showed that “In the intention-to-treat analysis, complete healing of the index ulcer was achieved in 37 patients at the one-year follow-up, 25 out of 48 (52%) in the HBOT group and 12 out of 42 (29%) in the placebo group.”

This means that twice as many patients with chronic diabetic foot wounds had improvement versus those in the placebo group.

“In the per-protocol analysis, complete healing of the index ulcer occurred in 23 out of 38 (61%) in the HBOT group, and ten out of 37 (27%) in the placebo group,” he explained. “The largest differences in healing rates between groups were seen at the nine-month follow-up.”

Löndahl’s presentation at the summit was met with more questions concerning the treatment, and failed to persuade all present as to the therapy’s effectiveness, despite the evidence.

When it comes to the effects of HBOT regarding amputation and mortality levels, the numbers in this study are less clear cut than one might expect. Three major amputations were performed in the HBOT group and one in the placebo group within the first year. In the HBOT group, two of the three amputations were done within two months after inclusion, and the third was done at 191 days. The amputation in the placebo group was performed 98 days after inclusion. All four patients had an arterial-toe blood pressure of less than 15mmHg in the affected lower limb. Two of these ulcers were classified as Wagner grade-four, and two were classified as grade-three ulcers. Four minor amputations were performed in each group in the first year of follow-up.

Löndahl admits that the procedure cannot yet be confidently termed ‘good’ or ‘bad’; “This partly reflects a general problem in evaluating the effects of different treatment methods for diabetic foot ulcers and is not unique for our study.” Meaning that, as with other studies, regardless of the progressive elements of the treatment, the medical community at large is hesitant to rely on the technology.

But with the huge numbers of diabetic patients around the world, HBOT’s time could be coming soon. More treatments for foot ulcers are being looked at all the time (catfish slime and leeches are having a brief moment in the sun), so expect the debate regarding HBOT’s efficacy to continue as the treatment develops.

HBOT in action

In a 2016 paper, Professor Radoslaw Litwinowicz and his team from the Jagiellonian University Medical College, and specialists from the Burns and Plastic Surgery Centre of Malopolska, Ludwik Rydygier Memorial Hospital in Krakow, worked together on a study for the use of hyperbaric therapy on deep, non-healing wounds.

Deep sternal wound infection (DSWI) is one of the most serious complications after cardiac surgery procedures, occurring in 5% of patients. Current standard medical therapy for deep sternal wounds includes antibiotics, surgical debridement, re-suturing or negative pressure wound therapy (NPWT). Unfortunately, in some cases these methods are insufficient, and additional therapeutic treatments are needed.

The aim of Litwinowicz’s study was to “assess the effects and usefulness of additional hyperbaric oxygen therapy (HBO2) in patients with DSWI after cardiac surgery procedures.”

To do so, a retrospective analysis of ten patients who developed deep sternal wounds following cardiac surgery was performed from 2010– 2012. After three months of ineffective conventional therapy, which included the use of targeted antibiotics and NPWT on the patients, those who qualified for additional HBO2 underwent the procedure. They received a total of 20 sessions, each 92 minutes long.

After 20 sessions of HBO2, seven patients presented complete wound healing with fibrous scar formation, equating to 70%. One patient was qualified for another cycle of HBO2 with 20 extra sessions and, following these, complete wound healing with fibrous scar formation was observed.

Litwinowicz says that as an additional therapy in deep sternal wound infection, “HBO2 was successful in 80% of cases.” And the procedure showed improved sternum stabilisation, wound sterilisation and final healing.

“No complications of HBO2 were observed,” says Litwinowicz. “HBO2 is an alternative method of treatment but definitely worth considering, especially in patients in whom standard pharmacotherapy and NPWT have failed. However, due to the small number of published studies on a very small number of patients, randomised clinical trials are needed to assess the clinical results of HBO2 in DSWI after cardiac-surgery procedures.”