Effects of hyperbaric oxygen therapy on circulating interleukin-8, nitric oxide, and insulin-like growth factors in patients with type 2 diabetes mellitus

Efficacy and safety of hyperbaric oxygen therapy in the management of diabetic foot ulcers: A systematic review and meta-analysis

Diabetic foot ulcers (DFUs) represent a major health concern for diabetic patients, often leading to debilitating complications. Hyperbaric oxygen therapy (HBOT) has been posited as an adjunctive therapeutic strategy to augment the healing rates of these ulcers. This systematic review and meta-analysis sought to critically evaluate the efficacy and safety of HBOT in the context of DFUs management. A rigorous search, adhering to PRISMA guidelines, was conducted across multiple electronic databases. Randomized controlled trials (RCTs) assessing the impact of HBOT on DFUs were included. Outcome measures were complete ulcer healing, major and minor amputation rates and adverse reactions. The analysis employed both fixed and random-effects models, contingent on the heterogeneity levels detected. Seven studies met the inclusion criteria. HBOT was found to significantly improve the complete healing rates of DFUs with a risk ratio (RR) of 3.59 (95% CI: 1.56-8.29, p < 0.001). However, HBOT's impact on both major and minor amputation rates did not yield statistically significant results. The sensitivity analysis underscored the robustness of the principal outcomes, and the publication bias assessment suggested the absence of any significant bias. Hyperbaric oxygen therapy stands out as a potent therapeutic tool in promoting the complete healing of diabetic foot ulcers, offering a promising adjunct to standard care protocols, while ensuring patient safety.

Hyperbaric oxygen rapidly improves tissue-specific insulin sensitivity and mitochondrial capacity in humans with type 2 diabetes: a randomised placebo-controlled crossover trial

AIMS/HYPOTHESIS

Hyperbaric oxygen (HBO) therapy may improve hyperglycaemia in humans with type 2 diabetes, but underlying mechanisms are unclear. Our objective was to examine the glucometabolic effects of HBO on whole-body glucose disposal in humans with type 2 diabetes.

METHODS

In a randomised placebo-controlled crossover trial located at the German Diabetes Center, 12 male individuals with type 2 diabetes (age 18-75 years, BMI <35 kg/m², HbA_1c 42-75 mmol/mol [6-9%]), randomly allocated by one person, underwent 2-h HBO, once with 100% (240 kPa; HBO) and once with 21% oxygen (240 kPa; control, CON). Insulin sensitivity was assessed by hyperinsulinaemic-euglycaemic clamps with D-[6,6-²H₂]glucose, hepatic and skeletal muscle energy metabolism were assessed by ¹H/³¹P-magnetic resonance spectroscopy, while high-resolution respirometry measured skeletal muscle and white adipose tissue (WAT) mitochondrial capacity. All participants and people assessing the outcomes were blinded.

RESULTS

HBO decreased fasting blood glucose by 19% and increased whole-body, hepatic and WAT insulin sensitivity about one-third (p<0.05 vs CON). Upon HBO, hepatic γ-ATP concentrations doubled, mitochondrial respiratory control doubled in skeletal muscle and tripled in WAT (p<0.05 vs CON). HBO increased myocellular insulin-stimulated serine-473/threonine-308 phosphorylation of Akt but decreased basal inhibitory serine-1101 phosphorylation of IRS-1 and endoplasmic reticulum stress (p<0.05 vs CON).

CONCLUSIONS/INTERPRETATION

HBO-mediated improvement of insulin sensitivity likely results from decreased endoplasmic reticulum stress and increased mitochondrial capacity, possibly leading to low-dose reactive oxygen species-mediated mitohormesis in humans with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04219215 FUNDING: German Federal Ministry of Health, German Federal Ministry of Education and Research, North-Rhine Westfalia Ministry of Culture and Science, European-Regional-Development-Fund, German-Research-Foundation (DFG), Schmutzler Stiftung.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

The Effects of Hyperbaric Oxygenation on Oxidative Stress, Inflammation and Angiogenesis

Hyperbaric oxygen therapy (HBOT) is commonly used as treatment in several diseases, such as non-healing chronic wounds, late radiation injuries and carbon monoxide poisoning. Ongoing research into HBOT has shown that preconditioning for surgery is a potential new treatment application, which may reduce complication rates and hospital stay. In this review, the effect of HBOT on oxidative stress, inflammation and angiogenesis is investigated to better understand the potential mechanisms underlying preconditioning for surgery using HBOT. A systematic search was conducted to retrieve studies measuring markers of oxidative stress, inflammation, or angiogenesis in humans. Analysis of the included studies showed that HBOT-induced oxidative stress reduces the concentrations of pro-inflammatory acute phase proteins, interleukins and cytokines and increases growth factors and other pro-angiogenesis cytokines. Several articles only noted this surge after the first HBOT session or for a short duration after each session. The anti-inflammatory status following HBOT may be mediated by hyperoxia interfering with NF-κB and IκBα. Further research into the effect of HBOT on inflammation and angiogenesis is needed to determine the implications of these findings for clinical practice.

Hyperbaric Oxygen Exposure Attenuates Circulating Stress Biomarkers: A Pilot Interventional Study

Hyperbaric oxygen therapy (HBOT) has been used to provide oxygen to underperfused organs following ischemia or carbon monoxide intoxication. Various beneficial consequences of HBOT have been reported, including wound healing, anti-inflammatory action, and cell survival; however, the molecular mechanisms underlying these effects have not been elucidated yet. We applied a single HBOT program consisting of administration of 2.8 atmospheres absolute (ATA) for 45 min, followed by 2.0 ATA for 55 min, to 10 male volunteers without any metabolic disease. Within 1 week of HBOT, there was no alteration in serum biochemical variables, except for an increase in triglyceride content. As a mitochondrial stress indicator, the serum concentration of growth differentiation factor 15 was reduced by HBOT. The circulating level of γ–glutamyltransferase was also decreased by HBOT, suggesting an attenuation of oxidative stress. HBOT increased adiponectin and reduced leptin levels in the serum, leading to an elevated adiponectin/leptin ratio. This is the first study to investigate the effect of HBOT on serum levels of metabolic stress-related biomarkers. We suggest that HBOT attenuates mitochondrial and oxidative stresses, and relieves metabolic burdens, indicating its potential for use in therapeutic applications to metabolic diseases.

Hyperbaric oxygen therapy as an adjuvant to standard therapy in the treatment of diabetic foot ulcers

Background and Aims:

Chronic diabetic foot ulcers pose a major problem because of associated limb threatening complications. The aim of the present study was to evaluate the efficacy of hyperbaric oxygen therapy (HBOT) as an adjuvant to standard therapy for treatment of diabetic foot ulcers.

Material and Methods:

A total of 54 patients with diabetic foot ulcer of Wagner grade II–IV were recruited in this prospective, randomized, double blind study. Patients were randomized to receive HBOT along with standard therapy (group H; n = 28) or standard therapy alone (group S; n = 26). Patients were given 6 sessions per week for 6 weeks and followed up for 1 year. Outcomes were measured in terms of healing, and need for amputation, grafting or debridement. Parametric continuous variables were analyzed using Student unpaired t-test and categorical variables were analyzed using Chi square test.

Results:

The diabetic ulcers in 78% patients in Group H completely healed without any surgical intervention while no patient in group S healed without surgical intervention (P = 0.001). 2 patients in group H required distal amputation while in Group S, three patients underwent proximal amputation.

Conclusion:

The present study shows that hyperbaric oxygen therapy is a useful adjuvant to standard therapy and is a better treatment modality if combined with standard treatment rather than standard treatment alone for management of diabetic foot ulcers.

Hyperbaric oxygen treatment in thromboangiitis obliterans: a retrospective clinical audit

INTRODUCTION

Wounds refractory to standard treatment in patients with thromboangiitis obliterans (TAO, Buerger's disease) are associated with amputation, other morbidity and mortality. The purpose of this study was to investigate the effect of hyperbaric oxygen treatment (HBOT) in patients with TAO.

MATERIALS AND METHODS

Ninety-seven patients with TAO with ischaemic wounds treated between January 2007 and July 2016 were included in this dual-centre, non-randomised, retrospective study. Patients receiving HBOT in addition to conventional treatment were enrolled in an HBOT group (n = 47) and those receiving conventional treatment alone in a non-HBOT group (n = 50). All patients were Rutherford grade III at the time of enrolment.

RESULTS

Significant improvement in the major amputation rate was observed in the HBOT group 10 months after starting treatment (2/47 vs. 13/50, P = 0.007). Numbers of patients progressing to Rutherford grade I (27/47 vs. 17/50, P = 0.035), numbers of patients healing completely (21 vs. 11, P = 0.031 and pain scores (visual analogue scale; 1, range 0-8 vs. 6, range 0-9, P < 0.001) were also significantly improved in the HBOT group.

CONCLUSION

The addition of HBOT to conventional treatment in TAO patients with non-healing ischaemic wounds and severe extremity pain, conferred significant benefits in terms of wound healing and rest pain control. Multi-centre, prospective, randomized studies with blinded outcome analysis are now needed to elicit more reliable results.

Amputation predictors in diabetic foot ulcers treated with hyperbaric oxygen

OBJECTIVE

Although hyperbaric oxygen therapy (HBOT) has long been used for diabetic foot ulcers (DFUs), its effectiveness is still controversial. The aim of this study was to investigate the efficacy of HBOT in the management of DFUs and identify amputation predictors.

METHOD

Patients with chronic DFUs (Wanger grade 2-5) were included in the study, which took place between January 2010 and December 2012. HBOT, 100% oxygen, 2.4 atmosphere absolute (ATA) for 120 minutes, was administered to all patients in addition to standard treatment. DFUs were monitored for at least 3 years, or until healing or amputation occurred.

RESULTS

Patients with a total of 146 chronic DFUswere recruited. Complete healing (69.6%) and significant improvement (17.9%) was observed in 87.5% of the patients. The cases with no improvement resulted in amputation (minor amputation: 15.0%; major amputation: 8.2%). The duration of diabetes (p=0.037), new wound formation (p=0.045), C-reactive protein (p=0.001) and Wagner grade (p=0.0001) were correlated with amputation in multiple regression analysis. Mortality was higher in the amputation group than in the non-amputation group (47.1 % versus 21.4 %, p=0.007).

CONCLUSION

The inclusion of HBOT with standard treatment and a multidisciplinary approach may be useful in the treatment of DFUs. We found the most important predictors of amputation to be Wagner grade and wound infection. Multicentre, prospective, randomised studies are needed to provide more evidence.

Hyperbaric Environment: Oxygen and Cellular Damage versus Protection

The elevation of tissue pO2 induced by hyperbaric oxygen (HBO) is a physiological stimulus that elicits a variety of cellular responses. These effects are largely mediated by, or in response to, an increase in the production of reactive oxygen and nitrogen species (RONS). The major consequences of elevated RONS include increased oxidative stress and enhanced antioxidant capacity, and modulation of redox-sensitive cell signaling pathways. Interestingly, these phenomena underlie both the therapeutic and potentially toxic effects of HBO. Emerging evidence indicates that supporting mitochondrial health is a potential method of enhancing the therapeutic efficacy of, and preventing oxygen toxicity during, HBO. This review will focus on the cellular consequences of HBO, and explore how these processes mediate a delicate balance of cellular protection versus damage. © 2017 American Physiological Society. Compr Physiol 7:213-234, 2017.

Hyperbaric Oxygen Therapy in the Treatment of Fontaine Stage IV Thromboangiitis Obliterans

Ischemic wounds unresponsive to standard treatment in thromboangiitis obliterans are associated with amputation, morbidity, and mortality. In this study, hyperbaric oxygen therapy was added to standard treatment of 36 patients with thromboangiitis obliterans with ischemic ulcerated wounds in the extremities. Full recovery was observed in 52.7% of cases (25% at discharge, 27.7% during follow-up). Resting pain after treatment decreased significantly compared to pretreatment levels based on visual analog scale scores (7.1 ± 1.7 vs 2.2 ± 3.0, P = .0001). Mean wound area also decreased significantly after treatment (22.6 ± 17.5 vs 13.02 ± 16.5, P = .0001). The number of patients requiring no assistance during routine daily activities increased significantly (25% vs 55.5%, P = .001). All patients were at Fontaine stage IV before hyperbaric oxygen therapy. The number of patients at stage IIB increased significantly after treatment, while that of patients at stage IV decreased significantly (0% vs 47.2%, P = .0001, and 100% vs 47.2%, P = .0001, respectively). None of our patients was able to walk without pain before treatment; however, walking distance was significantly extended in 16 patients who were capable of walking (0 vs 190.6 ± 129.4 meters, P = .0001). In addition, 11.1% of patients underwent major amputation during follow-up.

A novel technique for increasing skin oxygenation

OBJECTIVE

To develop a novel technique for increasing skin oxygenation based on diffusion principles and Fick's laws of diffusion.

METHODS

A device that allows the creation of an oxygen-depleted environment immediately to the skin while simultaneously allowing measurement of the transcutaneous oxygen tension (TcPo2) levels was created. This device forms an oxygen gradient from the capillary bed of the subcutaneous tissue, through the skin's semipermeable membrane, and toward the oxygen-depleted enclosed environment. A healthy adult subject was fitted with the device. Once baseline TcPo2 levels were recorded, the oxygen concentration within the device was lowered, and TcPo2 levels were monitored. Effects were also studied when subjects breathed 100% oxygen for 5 minutes.

RESULTS

Oxygen levels in the device decreased in accordance with increases in skin TcPo2 levels measured within the device.

CONCLUSIONS

The application of this technique results in an increase in oxygen concentration in the skin and subcutaneous tissue in healthy subjects with normal, well-perfused skin. Whether this novel technique produces an increase in the skin oxygenation of subjects with inappropriate tissue oxygenation and chronic wounds requires further study.

Is combined therapy more effective than growth hormone or hyperbaric oxygen alone in the healing of left ischemic and non-ischemic colonic anastomoses?

OBJECTIVE

Our aim was to investigate the effects of growth hormone (GH), hyperbaric oxygen and combined therapy on normal and ischemic colonic anastomoses in rats.

METHODS

Eighty male Wistar rats were divided into eight groups (n = 10). In the first four groups, non-ischemic colonic anastomosis was performed, whereas in the remaining four groups, ischemic colonic anastomosis was performed. In groups 5, 6, 7, and 8, colonic ischemia was established by ligating 2 cm of the mesocolon on either side of the anastomosis. The control groups (1 and 5) received no treatment. Hyperbaric oxygen therapy was initiated immediately after surgery and continued for 4 days in groups 3 and 4. Groups 2 and 6 received recombinant human growth hormone, whereas groups 4 and 8 received GH and hyperbaric oxygen treatment. Relaparotomy was performed on postoperative day 4, and a perianastomotic colon segment 2 cm in length was excised for the detection of biochemical and mechanical parameters of anastomotic healing and histopathological evaluation.

RESULTS

Combined treatment with hyperbaric oxygen and GH increased the mean bursting pressure values in all of the groups, and a statistically significant increase was noted in the ischemic groups compared to the controls (p<0.05). This improvement was more evident in the ischemic and normal groups treated with combined therapy. In addition, a histopathological evaluation of anastomotic neovascularization and collagen deposition showed significant differences among the groups.

CONCLUSIONS

Combined treatment with recombinant human growth hormone and hyperbaric oxygen resulted in a favorable therapeutic effect on the healing of ischemic colonic anastomoses.

Effect of growth hormone, hyperbaric oxygen and combined therapy on the gastric serosa

AIM: To investigate the role of growth hormone (GH), hyperbaric oxygen therapy (HBOT) and combined therapy on the intestinal neomucosa formation of the gastric serosa.

METHODS: Forty-eight male Wistar-albino rats, weighing 250-280 g, were used in this study. The rats were divided into four groups (n = 12): Group 1, control, gastric serosal patch; Group 2, gastric serosal patch + GH; Group 3, gastric serosal patch + HBOT; and Group 4, gastric serosal patch + GH + HBOT. Abdominal access was achieved through a midline incision, and after the 1-cm-long defect was created in the jejunum, a 1 cm × 1 cm patch of the gastric corpus was anastomosed to the jejunal defect. Venous blood samples were taken to determine the insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) basal levels. HBOT was performed in Groups 3 and 4. In Groups 2 and 4, human GH was given subcutaneously at a dose of 2 mg per kg/d for 28 d, beginning on the operation day. All animals were sacrificed 60 d after surgery. The jejunal segment and the gastric anastomotic area were excised for histological examination. The inflammatory process, granulation, collagen deposition and fibroblast activity at the neomucosa formation were studied and scored. Additionally, the villus density, villus height, and crypt depth were counted and recorded. The measurements of villus height and crypt depth were calculated with an ocular micrometer. New vessel growth was determined by calculatingeach new vessel in a 1 mm² area.

RESULTS: In the histological comparison of groups, no significant differences were observed between the control group and Groups 2 and 3 with respect to epithelialization, granulation, fibroblastic activity and the inflammatory process, but significant differences were present between the control group and all others groups (Groups 2-4) with respect to angiogenesis (P < 0.01) and collagen deposition (P < 0.05, P < 0.01). Significant differences between the control group and Group 4 were also observed with respect to epithelialization and fibroblastic activity (P < 0.01 and P < 0.05, respectively). There were significant differences in villus density in all of groups compared with the control group (P < 0.05). Crypt depth was significantly greater in Group 4 than in the control group (P < 0.05), but no other groups had deeper crypts. However, villus height was significantly longer in Groups 2 and 4 than in the control group (P < 0.05). The comparison of groups revealed, significant difference between control group and Groups 2 and 4) with respect to the levels of IGF-1 and IGFBP-3 (P < 0.01) 3 wk after the operation.

CONCLUSION: HBOT or GH and combined therapy augmented on neomucosal formation. The use of combined therapy produced a synergistic effect on the histological, morphological and functional parameters.

Serum leptin levels decrease after permanent MCAo in the rat and remain unaffected by delayed hyperbaric oxygen therapy

Hyperbaric oxygen therapy (HBOT), referring to the medical use of oxygen at a level higher than atmospheric pressure, exerts neuroprotective effects after ischemic stroke via various mechanisms. It has been demonstrated that HBOT modulates the synthesis and degradation of hormones. Leptin, an adipose derived hormone, has been found to confer neuroprotection following experimental stroke. However, it is not known whether HBOT alters leptin concentrations after permanent middle cerebral artery occlusion (pMCAo) in the rat. In this present study, we aimed to investigate the effect of HBOT on the serum concentration of leptin in rats subjected to pMCAo. HBOT was initiated 48 hrs after experimental pMCAo, at 2.5 atmospheres absolutes with 100% oxygen, 1 hr a day for 10 consecutive days. Body weight, neurobehavioral deficits and infarct size were evaluated. Blood was collected on day 1 and day 16 following HBOT. Serum leptin concentrations were measured with ELISA. Delayed HBOT reduced infarct size and improved neurobehavioral scores. Decreased serum levels of leptin were found in treated and untreated pMCAo animals, compared to the sham group on day 1 (P > 0.05) and day 16 (P < 0.05). However, no statistical significance was found between HBOT and the air group. We concluded that the neuroprotective effects of delayed HBOT in pMCAo rats were unlikely to be exerted through changes in the serum concentration of leptin.

IGF-1 Increases with Hyperbaric Oxygen Therapy and Promotes Wound Healing in Diabetic Foot Ulcers

Objectives. To investigate insulin-like growth factor I (IGF-1) levels in response to hyperbaric oxygen therapy (HBOT) for diabetic foot ulcers and to determine whether IGF-1 is a predictive indicator of wound healing in patients with diabetic foot ulcers. Design and Methods. We treated 48 consecutive patients with diabetic foot ulcers with HBOT. Alterations of IGF-1 levels in patients whose wound healed with HBOT were compared with those in patients who did not benefit from HBOT. Results. There was no significant difference in initial IGF-1 levels between the two groups (P = 0.399). The mean IGF-1 level increased with HBOT (P < 0.05). In the healed group, the mean IGF-1 increase and the final values were significantly higher (P < 0.05). In the nonhealed group, the mean IGF-1 increase was minus and the final values were not significantly different (P < 0.05). The increase in IGF-1 level with HBOT was significantly higher in the healed group (P < 0.001). Conclusions. IGF-1 increased significantly in the healed group. We believe that HBOT is effective in the treatment of diabetic foot ulcers, with an elevation of IGF-1. This alteration seems to be a predictive factor for wound healing in diabetic foot ulcers treated with HBOT.

Does treatment affect the levels of serum interleukin-6, interleukin-8 and procalcitonin in diabetic foot infection? A pilot study

AIMS

To investigate about serum PCT, IL-6 and IL-8 levels and how they are affected by the treatment in diabetic foot patients.

METHODS

Fifty patients' blood samples were taken to study ESR and CRP, IL-6, IL-8 and PCT before and at the 14th day of the treatment.

RESULTS

The pretreatment results of the 50 patients showed positive correlations between PCT and either ESH (r=0.49, p<0.001), or CRP (r=0.56, p<0.001). Similarly, there was a positive correlation between IL-6 and ESH (r=0.46, p=0.001), just like as it was between IL-6 and CRP (r=0.54, p<0.001). At the 14th day, the levels of ESR (70 ± 30.2 and 58.4 ± 26.2, p=0.02), CRP (63.8 ± 73.1 and 18.1 ± 19.7, p<0.001) and PCT (0.6 ± 2.1 and 0.05 ± 0.02, p=0.007) were significantly decreased while IL-6 was decreased at a close range to statistical significancy at healing patients (97.5 ± 147.2 and 47.1 ± 77.6; p=0.05), but they did not at nonhealing patients. IL-8 levels were not changed anyhow.

CONCLUSIONS

PCT was significantly decreased such as ESR and CRP were in the early phase of healing; IL-6 and IL-8 levels were also decreased by the treatment, but not statistically significantly. IL-6 and PCT were affected in correlation with the other inflammatory parameters in the beginning, but IL-8 was not. PCT and IL-6 may be useful like CRP and ESR in the diagnosis and follow up of diabetic foot infection, but IL-8 is not. Further investigation is needed.

Hyperbaric oxygen: its mechanisms and efficacy

BACKGROUND

This article outlines therapeutic mechanisms of hyperbaric oxygen therapy and reviews data on its efficacy for clinical problems seen by plastic and reconstructive surgeons.

METHODS

The information in this review was obtained from the peer-reviewed medical literature.

RESULTS

Principal mechanisms of hyperbaric oxygen are based on intracellular generation of reactive species of oxygen and nitrogen. Reactive species are recognized to play a central role in cell signal transduction cascades, and the discussion will focus on these pathways. Systematic reviews and randomized clinical trials support clinical use of hyperbaric oxygen for refractory diabetic wound-healing and radiation injuries; treatment of compromised flaps and grafts and ischemia-reperfusion disorders is supported by animal studies and a small number of clinical trials, but further studies are warranted.

CONCLUSIONS

Clinical and mechanistic data support use of hyperbaric oxygen for a variety of disorders. Further work is needed to clarify clinical utility for some disorders and to hone patient selection criteria to improve cost efficacy.

Mathematical model of hyperbaric oxygen therapy applied to chronic diabetic wounds

The failure of certain wounds to heal (including diabetic foot ulcers) is a significant socioeconomic issue for countries worldwide. There is much debate about the best way to treat these wounds and one approach that is shrouded with controversy is hyperbaric oxygen therapy (HBOT), a technique that can reduce the risk of amputation in diabetic patients.In this paper, we develop a six species mathematical model of wound healing angiogenesis and use it to investigate the effectiveness of HBOT, compare the response to different HBOT protocols and study the effect of HBOT on the healing of diabetic wounds that fail to heal for a variety of reasons. We vary the pressure level (1 atm-3 atm), percentage of oxygen inspired by the patient (21%-100%), session duration (0-180 minutes) and frequency (twice per day-once per week) and compare the simulated wound areas associated with different protocols after three weeks of treatment.We consider a variety of etiologies of wound chronicity and show that HBOT is only effective in treating certain causes of chronic wounds. For a wound that fails to heal due to excessive, oxygen-consuming bacteria, we show that intermittent HBOT can accelerate the healing of a chronic wound but that sessions should be continued until complete healing is observed. Importantly, we also demonstrate that normobaric oxygen is not a replacement for HBOT and supernormal healing is not an expected outcome. Our simulations illustrate that HBOT has little benefit for treating normal wounds, and that exposing a patient to fewer, longer sessions of oxygen is not an appropriate treatment option.

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.

Oxidative stress is fundamental to hyperbaric oxygen therapy

The goal of this review is to outline advances addressing the role that reactive species of oxygen and nitrogen play in therapeutic mechanisms of hyperbaric oxygen. The review will be organized around major categories of problems or processes where controlled clinical trials have demonstrated clinical efficacy for hyperbaric oxygen therapy. Reactive species are now recognized to play a major role in cell signal transduction cascades, and the discussion will focus on how hyperbaric oxygen acts through these pathways to mediate wound healing and ameliorate postischemic and inflammatory injuries.

Can major amputation rates be decreased in diabetic foot ulcers with hyperbaric oxygen therapy?

Although hyperbaric oxygen therapy has been used for diabetic foot ulcer since the 1980s, there is little information on its efficacy. The aim of this study is to evaluate whether hyperbaric oxygen can decrease major amputation rates and to determine the predictive factors. A total of 184 consecutive patients were treated with hyperbaric oxygen therapy as an adjunct to standard treatment modalities for their diabetic foot ulcer. Of these patients, 115 were completely healed, 31 showed no improvement and 38 underwent amputation. Of the amputations, nine (4.9%) were major amputations (below knee) and 29 were minor. Major amputations were associated with the Wagner grade (p < 0.0001), with the age of the patients (p = 0.028) and with the age of the wounds (p = 0.018). Hyperbaric oxygen therapy can help to reduce the major amputation rates in diabetic foot ulcer. However, further large, multicentre, randomised controlled studies are needed to make more accurate conclusions.

The use of hyperbaric oxygen therapy to treat chronic wounds: A review

Chronic wounds, defined as those wounds which fail to proceed through an orderly process to produce anatomic and functional integrity, are a significant socioeconomic problem. A wound may fail to heal for a variety of reasons including the use of corticosteroids, formation of squamous cell carcinoma, persistent infection, unrelieved pressure, and underlying hypoxia within the wound bed. Hypoxia appears to inhibit the wound healing process by blocking fibroblast proliferation, collagen production, and capillary angiogenesis and to increase the risk of infection. Hyperbaric oxygen therapy (HBOT) has been shown to aid the healing of ulcerated wounds and demonstrated to reduce the risk of amputation in diabetic patients. However, the causal reasons for the response of the underlying biological processes of wound repair to HBOT, such as the up-regulation of angiogenesis and collagen synthesis are unclear and, consequently, current protocols remain empirical. Here we review chronic wound healing and the use of hyperbaric oxygen as an adjunctive treatment for nonhealing wounds. Databases including PubMed, ScienceDirect, Blackwell Synergy, and The Cochrane Library were searched for relevant phrases including HBOT, HBO/HBOT, wound healing, and chronic/nonhealing wounds/ulcers.

Topical oxygen therapy induces vascular endothelial growth factor expression and improves closure of clinically presented chronic wounds

1. Chronic wounds, especially in diabetics, represent a serious threat to human health. 2. Correcting a compromised state of tissue oxygenation by the administration of supplemental O(2) is known to benefit wound healing. Beyond its role as a nutrient and antibiotic, O(2) supports wound healing by driving redox signaling. 3. Hyperbaric oxygen (HBO) therapy is widely used and approved by Center for Medicare and Medicaid Services to treat specific ulcerations. The current literature supports the notion that approaches to topically oxygenate wounds may be productive. 4. Here, we present the results of two simultaneous studies testing the effects of HBO and portable topical oxygen (TO) therapies. These two therapeutic approaches have several contrasting features. 5. In total, 1854 patients were screened in outpatient wound clinics for non-randomized enrolments into the HBO (n = 32; 31% diabetic) and TO (n = 25; 52% diabetic) studies. 6. Under the conditions of the present study, HBO treatment seemed to benefit some wounds while not benefiting others. Overall, HBO did not result in statistically significant improvements in wound size in the given population over the time monitored in the present study. 7. However, TO significantly improved wound size. Among the three O(2)-sensitive genes (VEGF, TGFbeta1 and COL1A1) studied in wound edge tissue biopsies, TO treatment was associated with higher VEGF165 expression in healing wounds. Expression of the other genes mentioned was not affected by TO. There was no significant change in the expression levels of any of genes studied in patients in the HBO study. This establishes a link between VEGF gene expression and healing outcome for TO therapy. 8. Taken together, the present study provides evidence demonstrating that TO treatment benefits wound healing in patients suffering from chronic wounds. Treatment with TO is associated with an induction of VEGF expression in wound edge tissue and an improvement in wound size.