Is hyperbaric oxygen a useful adjunct in the management of problem lower extremity wounds?

Polymicrobial wound infections: pathophysiology and current therapeutic approaches

Acute and chronic wounds represent a very common health problem in the entire world. The dermal wounds are colonized by aerobic and anaerobic bacterial and fungal strains, most of them belonging to the resident microbiota of the surrounding skin, oral cavity and gut, or from the external environment, forming polymicrobial communities called biofilms, which are prevalent especially in chronic wounds. A better understanding of the precise mechanisms by which microbial biofilms delay repair processes together with optimizing methods for biofilm detection and prevention may enhance opportunities for chronic wounds healing. The purpose of this minireview is to assess the role of polymicrobial biofilms in the occurrence and evolution of wound infections, as well as the current and future preventive and therapeutic strategies used for the management of polymicrobial wound infections.

Hyperbaric oxygen therapy as adjunctive treatment of diabetic foot ulcers

The widespread use of HBO as an adjunctive treatment of diabetic foot ulcers has been founded on weak scientific evidence, but the consistency in positive outcomes in trials evaluating HBO on ulcer healing is noteworthy, not least as these results are in concert with data from in vitro and physiologic studies supporting the theoretical framework of HBO reversing hypoxia-induced abnormality. The long-term ulcer-healing rates of the nonrandomized controlled studies before the recent study by Margolis and colleagues, 77% with HBO versus 25% with standard treatment, are in concert with 1-year follow-up data from the 2 double-blind RCTs, 54% versus 25%. These 2 trials have put the use of HBO on firmer ground, but several issues, including health economics, developing robust selection criteria for treatment, optimizing treatment protocols, and identifying standards for when to start and stop treatment, remain to be elucidated. Not least, outcomes from further high-quality studies are needed. At present, HBO may be used as an adjunctive therapy in a select group of patients with diabetic foot ulcers that are difficult to heal.

A retrospective study of diabetic foot ulcers treated with hyperbaric oxygen therapy

A retrospective review of patient medical records was conducted to assess what factors influence the outcomes of diabetic foot ulcers treated with hyperbaric oxygen (HBO) therapy. Patients referred to the Diving Diseases Research Centre for HBO therapy for the treatment of diabetic foot ulcers during a 2-year period were included in this study. Data collected from 30 sets of patient records were entered into SPSS and statistical analysis was undertaken to investigate whether any underlying pathologies or confounding factors appeared to influence patient outcome. A 73.3% of patients achieved a successful outcome of partial healing, major amputation no longer required, amputation level lower than anticipated prior to HBO or healing at the end of HBO therapy and 70% remained successful 3 months later. A 13.3% of patients were lost to follow-up at 3 months and one patient (3.3%) had a major amputation. Steroid therapy, peripheral vascular disease, previous minor amputation, type of diabetes, previous HBO therapy, larvae therapy, the use of interactive dressings and haemoglobin A1c levels were all observed to have had a significant relationship with patient outcome (P < 0.05). These results were compared with data from other published research conducted in this area on similar patient groups. A larger scale study focussing on the factors found to be significant in this study is recommended. An improvement of patient documentation would allow patient outcomes to be more consistently monitored in the future.

Hyperbaric oxygen therapy as treatment of diabetic foot ulcers

Hyperbaric oxygen therapy (HBO) could be described as a short-term, high-dose oxygen inhalation and diffusion therapy, delivered systemically through airways and blood, achieved by having the patient breathing concentrated oxygen at a pressure higher than 1 absolute atmosphere. In clinical practice, monoplace or multiplace hyperbaric chambers are used to achieve this. Treatment is usually given as daily 90- to 120-min-long HBO sessions at pressures between 2.0 and 2.5 absolute atmosphere, aiming for 30-40 treatment sessions. The use of HBO as treatment of diabetic foot ulcers has been founded on weak scientific ground, although the outcomes from previous studies are in concert with the conclusions from preclinical studies and supports the theoretical framework of HBO reversing hypoxia-induced pathology. Two well-designed randomized double-blind trials have put HBO on firmer ground and may justify adjunctive HBO treatment to a selected group of patients with nonhealing diabetic foot ulcers. Some health economic studies suggest potential cost effectiveness, but these studies are limited by deficient primary clinical data and should be interpreted with caution. Several issues remain to be addressed, such as developing robust criteria to improve treatment protocols, determining which patients are likely to benefit, and when to start and stop treatment.

What is the role of hyperbaric oxygen in the management of diabetic foot disease?

Systemic hyperbaric oxygen (HBO) is accomplished when a patient is breathing 100% oxygen in an environment with increased barometric pressure. A typical HBO treatment protocol of diabetic foot ulcer involves 20 to 40 sessions. Treatment is usually given as daily 90- to 120-minute HBO sessions at pressures between 2.0 and 2.5 absolute atmospheres. The wide use of HBO as treatment of diabetic foot ulcers over the past decades has been founded on weak scientific ground (ie, few and small prospective studies with methodologic limitations on top of case series). However, the consistency in positive outcome in these trials evaluating HBO on ulcer healing is noteworthy because these findings are in concert with data from in vitro and physiologic studies supporting the theoretic framework of HBO reversing hypoxia-induced pathology. Two well-designed randomized double-blinded placebo-controlled studies have in recent years put HBO on firmer ground as treatment of a selection of diabetic patients with chronic foot. Some evidence indicates that microvascular parameters such as transcutaneous (partial) oxygen pressure (TcPO(2)) could be useful in predicting which patients will benefit from therapy. Health economic studies suggest potential cost-effectiveness of HBO. But because these analyses are limited by their deficient primary clinical data, they should be interpreted with caution. Thus, HBO is only indicated in a selected group of patients with chronic diabetic foot ulcers. Several key issues remain to be addressed such as developing robust criteria to determine which patients are likely to benefit and when to start and stop treatment.

Wound healing essentials: let there be oxygen

The state of wound oxygenation is a key determinant of healing outcomes. From a diagnostic standpoint, measurements of wound oxygenation are commonly used to guide treatment planning such as amputation decision. In preventive applications, optimizing wound perfusion and providing supplemental O(2) in the perioperative period reduces the incidence of postoperative infections. Correction of wound pO(2) may, by itself, trigger some healing responses. Importantly, approaches to correct wound pO(2) favorably influence outcomes of other therapies such as responsiveness to growth factors and acceptance of grafts. Chronic ischemic wounds are essentially hypoxic. Primarily based on the tumor literature, hypoxia is generally viewed as being angiogenic. This is true with the condition that hypoxia be acute and mild to modest in magnitude. Extreme near-anoxic hypoxia, as commonly noted in problem wounds, is not compatible with tissue repair. Adequate wound tissue oxygenation is required but may not be sufficient to favorably influence healing outcomes. Success in wound care may be improved by a personalized health care approach. The key lies in our ability to specifically identify the key limitations of a given wound and in developing a multifaceted strategy to specifically address those limitations. In considering approaches to oxygenate the wound tissue it is important to recognize that both too little as well as too much may impede the healing process. Oxygen dosing based on the specific need of a wound therefore seems prudent. Therapeutic approaches targeting the oxygen sensing and redox signaling pathways are promising.

alpha-Lipoic acid modulates extracellular matrix and angiogenesis gene expression in non-healing wounds treated with hyperbaric oxygen therapy

alpha-Lipoic acid (LA) has been found previously to accelerate wound repair in patients affected by chronic wounds who underwent hyperbaric oxygen (HBO) therapy. Because proteinases are important in wound repair, we hypothesized that LA may regulate matrix metalloproteinase (MMP) expression in cells that are involved in wound repair. Patients undergoing HBO therapy were double-blind randomized into two groups: the LA group and the placebo group. Gene expression profiles for MMPs and for angiogenesis mediators were evaluated in biopsies collected at the first HBO session, at the seventh HBO session, and after 14 days of HBO treatment. ELISA tests were used to validate microarray expression of selected genes. LA supplementation in combination with HBO therapy downregulated the inflammatory cytokines and the growth factors which, in turn, affect MMPs expression. The disruption of the positive autocrine feedback loops that maintain the chronic wound state promotes progression of the healing process.

Soft tissue complications following calcaneal fractures

Soft tissue complications following calcaneal fractures can be frustrating to the patient and present reconstructive challenges for the surgeon. Preoperative patient assessment may define a group of patients who are best treated nonoperatively in an effort to avoid disastrous soft tissue complications. Late sequelae will continue to be seen and through the use of differential injections, physical exam, and appropriate intervention, the practitioner can usually decrease symptoms and improve a patient's function. Further studies in the treatment of open calcaneal fractures are necessary to better define treatment algorithms. A working knowledge of these complications and their management is necessary for the surgeon treating calcaneal fractures.

A prospective study: hyperbaric oxygen therapy in diabetics with chronic foot ulcers

Research suggests that hyperbaric oxygen therapy may have beneficial effects on ulcer healing and amputation rates in diabetic patients. This paper describes the design of a study that is evaluating its effects on chronic diabetic foot ulcers.

Soft tissue coverage for posttraumatic reconstruction

Posttraumatic foot and ankle reconstruction requires careful preoperative planning to reduce wound complications. Systemic and local factors need to be considered. A careful surgical technique can avoid the need for surgical soft tissue coverage. Recognition of the need for coverage preoperatively improves outcomes. Often, dressings and time allow minor wound complications to heal. More severe wound issues require early soft tissue coverage by local or free flaps to prevent failure of the surgery.

Manifestations of cutaneous diabetic microangiopathy

The etiologies of a variety of skin conditions associated with diabetes have not been fully explained. One possible etiological factor is diabetic microangiopathy, which is known to affect the eyes and kidneys in patients with diabetes. There are many mechanisms by which diabetes may cause microangiopathy. These include excess sorbitol formation, increased glycation end products, oxidative damage, and protein kinase C overactivity. All of these processes occur in the skin, and the existence of a cutaneous diabetic microangiopathy has been well demonstrated. These microangiopathic changes are associated with abnormalities of skin perfusion. Because the skin plays a thermoregulatory role, there is significant capillary redundancy in normal skin. In diabetic patients, loss of capillaries is associated with a decrease in perfusion reserve. This lost reserve is demonstrable under stressed conditions, such as thermal stimulation. The associated failure of microvascular perfusion to meet the requirements of skin metabolism may result in diverse skin lesions in patients with diabetes. Many skin conditions peculiar to diabetes are fairly rare. Necrobiosis lipoidica diabeticorum (NLD) and diabetic bullae occur very infrequently as compared with diabetic retinopathy and nephropathy. Conversely, there is a correlation between diabetic microvascular disease and NLD. This correlation also exists with more common skin conditions, such as diabetic dermopathy. This relationship suggests that diabetic microangiopathy may contribute to these conditions even if it is not primarily causal. Clinically, the major significance of diabetic cutaneous microangiopathy is seen in skin ulceration which is very common and has a major impact on diabetic patients. Many factors contribute to the development of diabetic foot ulcers. Neuropathy, decreased large vessel perfusion, increased susceptibility to infection, and altered biomechanics all play a role, but there is no doubt that inadequate small blood vessel perfusion is a major cause of the inability to heal small wounds that eventually results in ulcer formation. The accessibility of skin capillaries makes cutaneous diabetic microangiopathy an attractive model for research on the evolution of microvascular disease in diabetic patients.

α-Lipoic acid supplementation inhibits oxidative damage, accelerating chronic wound healing in patients undergoing hyperbaric oxygen therapy

Hyperbaric oxygen (HBO) therapy is successfully used for the treatment of a variety of conditions. However, prolonged exposure to high concentrations of oxygen induces production of reactive oxygen species, causing damage to the cells. Thus, antioxidant supplementation has been proposed as an adjuvant to attenuate such deleterious secondary effects. We evaluated the effects of alpha-lipoic acid (LA) in patients affected by chronic wounds undergoing HBO treatment. LA supplementation efficiently reduces both the lipid and DNA oxidation induced by oxygen exposure. LA exerted its antioxidant activity by directly interacting with free radicals or by recycling vitamin E. An inhibitory effect of LA on the pro-inflammatory cytokine interleukin-6 was observed. Taken together, we demonstrated an adjuvant effect of LA in HBO therapy used for impaired wound healing treatment. We propose that LA may be used to further promote the beneficial effects of HBO therapy.

A retrospective study of patients with diabetes mellitus after partial foot amputation and hyperbaric oxygen treatment

A retrospective chart review was conducted of 35 patients (40 feet) who received hyperbaric oxygen (HBO) therapy after partial foot amputation between 1990 and 2000. Preoperative transcutaneous partial pressure of oxygen (tcPO2) levels, the number of hyperbaric treatments, time to final outcome, use of revascularization procedures, and postsurgical outcome were extracted from the charts. Seventy percent (n = 28) had a successful outcome, defined as complete healing and absence of ulceration at the amputation site, and lack of further surgical procedures to heal the amputation site; whereas 30% (n = 12) had a failed outcome, defined as lack of healing or the presence of an ulcer at the site of amputation or the need for further surgery to heal the amputation site. The level of amputation, use of revascularization procedures, time to final outcome, and number of hyperbaric treatments were not significantly different (P > .05) between the 2 postsurgical outcome groups. The mean preoperative tcPO2 levels were greater (P < .01) in the successful (24 +/- mm Hg) than in the failed (11 +/- mm Hg) outcome groups. All patients with a tcPO2 level > 29 mm Hg had a successful outcome. Patients with a successful postsurgical outcome had a mean of 20 HBO treatments and took 44 days to final outcome, while those with a failed postsurgical outcome had 16 HBO treatments and took 216 days to final outcome.

Hyperbaric oxygenation and wound healing

The purpose of this article is to review literature related to hyperbaric oxygenation and wound healing. The article discusses the role of oxygen in wound healing, as well as the effects of hyperbaric oxygenation to promote wound healing, and focuses on the use of hyperbaric oxygenation to treat foot wounds in patients with diabetes. A review of salient literature to support the use of hyperbaric oxygenation as a viable adjunct to healing foot wounds in patients with diabetes is provided. In addition, this article discusses appropriate patient selection for treatment with hyperbaric oxygenation. A discussion of the hyperbaric treatment, including preparation of the patient, contraindications, adverse effects, and treatment protocols, is provided. This article was designed to provide WOC nurses with information to provide appropriate referrals to technology that promises to increase the healing potential of foot wounds in patients with diabetes and subsequently reduce amputations in this population.

COST-EFFECTIVENESS OF ADJUNCTIVE HYPERBARIC OXYGEN IN THE TREATMENT OF DIABETIC ULCERS

Objectives: This study estimates the cost-effectiveness (CE) of the adjunctive use of hyperbaric oxygen (HBO2) therapy in the treatment of diabetic ulcers based on the payer's and societal perspectives.

Methods: The study population was a hypothetical cohort of 1,000 patients sixty years of age with severe diabetic foot ulcers. A decision tree model was constructed to estimate the CE of HBO2 therapy in the treatment of diabetic ulcers at years 1, 5, and 12. Scenario and one-way sensitivity analyses were also undertaken to identify parameters that may significantly influence the estimates.

Results: The CE model estimated that the incremental cost per additional quality-adjusted life year (QALY) gained at years 1, 5, and 12, was $27,310, $5,166, and $2,255, respectively.

Conclusions: The study results indicate that HBO2 therapy in the treatment of diabetic ulcers is cost-effective, particularly based on a long-term perspective. However, the results are limited by the clinical studies that provide the basis of the CE estimation.

Hyperbaric oxygen in the management of chronic wounds

This article reviews the role that hyperbaric oxygen therapy (HBOT) plays in the field of wound healing. HBOT, although not seen as a common method of wound management in the UK, can perhaps offer another avenue to managing recalcitrant wounds. In order for the healing of chronic wounds to progress, the practitioner must address all the factors impeding the healing process, one of which is oxygenation. HBOT is thought to improve many aspects of poor healing by supplying high levels of oxygen at normal atmospheric pressure. It has been suggested that increasing the availability of oxygen does not necessarily stimulate the healing process, but that perhaps the pressure at which the oxygen is delivered is the responsible stimulus.

Oxygen modulates the growth of skin fibroblasts

Elevated oxygen tensions are inhibitory to the growth of skin fibroblasts. Skin fibroblasts grow better at oxygen tensions below 137 mm Hg regardless of seeding density. A wide range of oxygen tensions, including those in the physiological range, strongly modulate the growth of human skin fibroblasts. There were no significant differences between the responses of fetal and postnatal cell lines to changes in ambient oxygen tension. In all cases, higher oxygen tensions significantly impeded cell growth. Seeding cells at 10(4) cells/cm(2) afforded some protection from the deleterious effects of hyperoxia. Oxygen tensions exceeding the amount present in ambient room air also impeded cell growth at this higher seeding density, but the effect did not become significant until the oxygen partial pressure reached 241 mm Hg. At lower oxygen tensions, cells seeded at 10(3) cells/cm(2) grew more rapidly than did cells seeded at 10(4) cells/cm(2). These findings may have implications for the treatment of poorly healing wounds with hyperbaric oxygen.

Peripheral arterial disease

Lower extremity peripheral arterial disease (PAD) most frequently presents with pain during ambulation, which is known as "intermittent claudication". Some relief of symptoms is possible with exercise, pharmacotherapy, and cessation of smoking. The risk of limb-loss is overshadowed by the risk of mortality from coexistent coronary artery and cerebrovascular atherosclerosis. Primary therapy should be directed at treating the generalised atherosclerotic process, managing lipids, blood sugar, and blood pressure. By contrast, the risk of limb-loss becomes substantial when there is pain at rest, ischaemic ulceration, or gangrene. Interventions such as balloon angioplasty, stenting, and surgical revascularisation should be considered in these patients with so-called "critical limb ischaemia". The choice of the intervention is dependent on the anatomy of the stenotic or occlusive lesion; percutaneous interventions are appropriate when the lesion is focal and short but longer lesions must be treated with surgical revascularisation to achieve acceptable long-term outcome.

Inpatient management of lower extremity amputations

The in-hospital care of the amputee is crucial; careful preoperative, intraoperative, and postoperative regimens set the stage for a successful clinical outcome. Caring for the patient undergoing amputation is much more than choosing the correct level at which to cut. Early aggressive rehabilitation; careful attention to postoperative complications; and appropriate physical therapy, occupational therapy, and counseling all play pivotal roles. Thorough knowledge of these issues helps to increase the likelihood of a successful outcome and to keep morbidity to a minimum.

Wound microbiology and associated approaches to wound management

The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.