Study Questions Effectiveness Of Adjunctive HBOT For DFUs
A recent study in Diabetes Care casts doubt on the efficacy of hyperbaric oxygen therapy (HBOT) for reducing amputation risk in patients with diabetes although several physicians disagree with that assessment.
The prospective, double-blind, randomized controlled clinical trial included patients with diabetes who had foot lesions for at least four weeks. The treatment group had 30 daily HBOT treatments of 90 minutes each, breathing oxygen at 244 kPa. In the sham group, 13 of 54 patients met the criteria for major amputation while 11 of 49 in the HBOT group met that criteria, according to the study.
Researchers note 12 patients in the sham group and 10 in the HBOT group were healed at 12 weeks. The study authors concluded that HBOT is not an effective adjunct to comprehensive wound care in regard to reducing the risk of amputation or facilitating wound healing in patients with chronic diabetic foot ulcers (DFUs).
David Swain, DPM, believes if one uses HBOT with an appropriate patient, hyperbaric oxygen is an effective adjunctive therapy to help reduce the need for lower extremity amputations. Both he and Enoch Huang, MD, do not agree with the study’s conclusions and point out that researchers included patients with Wagner Grade 2 ulcers, which do not currently meet the Undersea and Hyperbaric Medical Society’s guidelines for HBOT use with DFUs.
Patients tolerate HBOT well and Dr. Swain says HBOT can facilitate fibroblast proliferation and angiogenesis, decrease inflammation, increase the flexibility of red blood cells, increase growth factors, mobilize stem cells within bone marrow, augment neutrophil bactericidal activity, limit clostridial exotoxins and spore production, kill certain anaerobes, and inhibit the growth of several other bacterial pathogens. Other published evidence supports the use of HBOT for diabetic foot ulcers, crush injuries and soft tissue infections, according to Dr. Swain, a certified wound specialist physician (CWSP) of the American Board of Wound Management.
Dr. Huang adds that clinical practice guidelines say HBOT for the acute DFU is most useful for ischemic, septic DFUs (Wagner grade 3 or 4) when oxygen is part of comprehensive care, which includes offloading, infection control, debridement, revascularization and diabetes control.
“I think that this study is going to muddy the waters and add to the polemics of HBOT supporters and detractors, but the unfortunate situation is that the (study) methodology is unsound,” says Dr. Huang, the Medical Director of Wound Healing and Hyperbaric Medicine at the Adventist Medical Center in Portland, Ore.
Both Drs. Huang and Swain note the study does not use actual amputation rates, but rather photographic adjudication by a vascular surgeon, who has not examined the actual patient, to recommend amputation.
“As we all know, the need for amputation is quite subjective and varies tremendously between practitioners,” says Dr. Swain.
Dr. Huang also says the study defines a transmetatarsal amputation as a major amputation whereas most would define major amputation as being above the ankle. Dr. Huang adds, “Equating a below-knee amputation with an amputation that retains a weightbearing limb biases the study against HBOT and does not help the clinician when making recommendations for patients.”
Could Acellular Human Reticular Dermis Be Beneficial For Chronic DFUs?
By Brian McCurdy, Managing Editor
An abstract submitted to the Symposium on Advanced Wound Care Spring/Wound Healing Society (SAWC Spring/WHS) notes that applying acellular human reticular dermis weekly can effectively treat non-healing diabetic foot ulcers (DFUs).
The abstract authors assessed 40 consecutive patients with non-healing ulcers between 1 and 25 cm2. If wounds did not reduce in size by 20 percent after two weeks of offloading and moist wound care, patients subsequently received either standard of care alginate wound therapy or weekly applications of wound size-specific acellular human reticular dermis.
At the end of the 12-week follow-up, the abstract authors note 16 of 20 patients healed completely with the human dermis in comparison to four of 20 patients with the standard of care dressing. The mean time to healing was 39.6 days for the human dermis cohort and 77 days for standard of care patients, according to the study abstract.
Abstract co-author Charles Zelen, DPM, notes that AlloPatch Pliable (Musculoskeletal Transplant Foundation), the main treatment modality in the study, is a novel acellular dermal matrix that is aseptically processed and derived from the reticular layer of the skin, a layer that has a more consistent, open architecture than the superficial layer with key matrix proteins (collagens and elastin) similar to those in unprocessed tissue. Dr. Zelen says the reticular dermal scaffold’s extracellular elements are naturally retained through the aseptic process that contributes to favorable interactions between the cell and extracellular matrix, regulating tissue function and supporting wound healing.
“Accordingly, I feel the deeper cut of the dermis is more advantageous to wound healing when compared to the many superficial dermal grafts that are on the market,” says Dr. Zelen, who is in private practice at Foot and Ankle Associates of Southwestern Virginia.
Another advantage of AlloPatch Pliable is the availability of the graft in multiple sizes in contrast to other grafts that only offer one size. Dr. Zelen says this allows “the clinician to choose the graft size most appropriate to the wound.” The study authors add that the mean cost to closure in the human dermis group was $1,475 per healed wound and Dr. Zelen says this is a considerable cost savings in comparison to cost to closure estimates cited for advanced grafts in other studies.
Dr. Zelen suggests considering use of the dermis graft for DFUs if wound size has not reduced by 50 percent after four weeks of standard wound care.
The SAWC Spring/WHS will be held April 13-17 in Atlanta. For more info, visit www.sawcspring.com .
Study Examines Acellular Fish Skin Graft For Post-Surgical DFUs
By Brian McCurdy, Managing Editor
An abstract submitted to the SAWC Spring/WHS suggests that a novel fish skin graft could be an effective adjunct for remodeling of significant soft tissue loss and immediate closure of diabetic foot ulcers (DFUs), and may provide an alternative to negative pressure wound therapy (NPWT).
Abstract authors note the acellular fish skin graft provides natural skin elements with bioactive lipids, antimicrobial and anti-inflammatory properties, and also acts as a scaffold for cell revascularization and repopulation. The abstract authors assessed 20 patients, who received fish skin grafts immediately after partial amputations or wound debridement. Patients treated in the OR with immediate application of fish skin grafting after bone and soft tissue resection had similar healing rates to a historic cohort treated with negative pressure wound therapy (NPWT), according to the abstract. Furthermore, researchers say seven of 20 patients achieved wound closure by their eighth fish skin graft application at a mean of 56 days.
Given that animal collagens are about 99 percent similar to that of human collagen, Kazu Suzuki, DPM, CWS, says it comes as no surprise that fish-based collagen performs similar to other animal-based skin substitutes currently on the market, such as porcine- or bovine-based products.
Dr. Suzuki speculates that fish skin grafts would come at a lower price than most skin substitute grafts on the market, especially if the grafts are utilizing the fish components that are discarded. For example, he says some of the porcine-based skin substitute grafts are made from porcine intestines or bladders that are commonly discarded and not considered for human consumption, and they are cheaper than bioengineered neonatal skins or human amniotic membrane grafts.
However, Dr. Suzuki questions if the fish skin substitute graft is therapeutically equivalent to NPWT, saying those are two “vastly different” modalities of wound therapy. Physicians most commonly use NPWT to fill in the soft tissue defect and promote granulation tissue while most skin substitute grafts facilitate wound coverage and wound closure, according to Dr. Suzuki, the Medical Director of the Tower Wound Care Center at the Cedars-Sinai Medical Towers.
