Hyperbaric oxygen: its mechanisms and efficacy

Highs and lows of hyperoxia: physiological, performance, and clinical aspects

Molecular oxygen (O₂) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O₂ delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O₂, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O₂ delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O₂ toxicity and future research directions are also considered.

Hyperbaric Oxygen Reduces Aspergillus fumigatus Proliferation In Vitro and Influences In Vivo Disease Outcomes

Recent estimates suggest that more than 3 million people have chronic or invasive fungal infections, causing more than 600,000 deaths every year. Aspergillus fumigatus causes invasive pulmonary aspergillosis (IPA) in patients with compromised immune systems and is a primary contributor to increases in human fungal infections. Thus, the development of new clinical modalities as stand-alone or adjunctive therapy for improving IPA patient outcomes is critically needed. Here we tested the in vitro and in vivo impacts of hyperbaric oxygen (HBO) (100% oxygen, >1 atmosphere absolute [ATA]) on A. fumigatus proliferation and murine IPA outcomes. Our findings indicate that HBO reduces established fungal biofilm proliferation in vitro by over 50%. The effect of HBO under the treatment conditions was transient and fungistatic, with A. fumigatus metabolic activity rebounding within 6 h of HBO treatment being removed. In vivo, daily HBO provides a dose-dependent but modest improvement in murine IPA disease outcomes as measured by survival analysis. Intriguingly, no synergy was observed between subtherapeutic voriconazole or amphotericin B and HBO in vitro or in vivo with daily HBO dosing, though the loss of fungal superoxide dismutase genes enhanced HBO antifungal activity. Further studies are needed to optimize the HBO treatment regimen and better understand the effects of HBO on both the host and the pathogen during a pulmonary invasive fungal infection.

Alterations in mitochondrial respiration and reactive oxygen species in patients poisoned with carbon monoxide treated with hyperbaric oxygen

Background

Carbon monoxide (CO) poisoning is the leading cause of poisoning mortality and morbidity in the USA. Carboxyhemoglobin (COHb) levels are not predictive of severity or prognosis. At this time, the measurement of mitochondrial respiration may serve as a biomarker in CO poisoning. The primary objective of this study was to assess changes in mitochondrial function consisting of respiration and generation of reactive oxygen species (ROS) in peripheral blood mononuclear cells (PBMCs) obtained from patients with CO poisoning.

Methods

PBMCs from patients having confirmed CO exposure treated with hyperbaric oxygen or HBO (CO group) and healthy controls (control group) were analyzed with high-resolution respirometry. PBMCs were placed in a 2-ml chamber at a final concentration of 3–4 × 10⁶ cells/ml to simultaneously obtain both respiration and hydrogen peroxide (H₂O₂) production. In the CO group, we performed measurements before and after patients underwent their first HBO treatment.

Results

We enrolled a total of 17 subjects, including 7 subjects with confirmed CO poisoning and 10 subjects in the control group. The CO group included five (71.4%) men and two (28.6%) women having a median COHb of 28%. There was a significant decrease in respiration as measured in pmol O₂ × s^− 1 × 10^− 6 PBMCs in the CO group (pre-HBO) when compared to the control group: maximal respiration (18.4 ± 2.4 versus 35.4 ± 2.8, P < 0.001); uncoupled Complex I respiration (19.8 ± 1.8 versus 41.1 ± 3.8, P < 0.001); uncoupled Complex I + II respiration (32.3 ± 3.2 versus 58.3 ± 3.1, P < 0.001); Complex IV respiration (43.5 ± 2.9 versus 63.6 ± 6.31, P < 0.05). There were also similar differences measured in the CO group before and after HBO treatment with an overall increase in respiration present after treatment. We also determined the rate of H₂O₂ production simultaneously with the measurement of respiration. There was an overall significant increase in the H₂O₂ production in the CO group after HBO treatment when compared to prior HBO treatment and the control group.

Conclusions

In this study, PBMCs obtained from subjects with CO poisoning have an overall decrease in respiration (similar H₂O₂ production) when compared to controls. The inhibition of Complex IV respiration is from CO binding leading to a downstream decrease in respiration at other complexes. PBMCs obtained from CO-poisoned individuals immediately following initial HBO therapy displayed an overall increase in both respiration and H₂O₂ production. The study findings demonstrate that treatment with HBO resulted in improved cellular respiration but a higher H₂O₂ production. It is unclear if the increased production of H₂O₂ in HBO treatment is detrimental.

The Effects of Short- and Long-Term Exposure to Hyperbaric Oxygen on Nasal Mucociliary Clearance

The aim of this study is to assess the effects of short- and long-term exposure to hyperbaric oxygen (HBO) on nasal mucociliary clearance (MCC). This study included 47 consecutive nondiabetic patients treated with hyperbaric oxygen therapy (HBOT). Participants were divided into 2 groups according to the taken number of HBOT sessions. Nineteen patients who received <11 HBOT sessions comprised short-term HBOT group, 28 patients who received more than 15 sessions comprised the long-term HBOT group. Mucociliary clearance was measured using a saccharin clearance test, which was performed 3 times on patients: prior to, at completion of, and 6 months after HBOT. The average number of HBOT sessions was 8 ± 1.9 in short-term HBOT group and 20 ± 4.8 in long-term group. Both short- and long-term exposure to HBO led to significant influence on MCC upon treatment completion (both P < 0.001). In addition, only long-term exposure to HBO caused significant elongation of MCC at long-term evaluation (6 months after HBOT). From these objective measurements, the authors can conclude that long-term exposure to HBO can cause irreversible damage to MCC compared with short-term exposure and HBOT appears to affect MCC in a dose-dependent manner. The clinical significance of this effect is of concern for patients undergoing HBOT for middle ear, sinonasal, or respiratory tract infections. Patients who undergo chronic HBOT should be monitored closely and informed about the possible negative effects.

An Injectable Oxygen Release System to Augment Cell Survival and Promote Cardiac Repair Following Myocardial Infarction

Oxygen deficiency after myocardial infarction (MI) leads to massive cardiac cell death. Protection of cardiac cells and promotion of cardiac repair are key therapeutic goals. These goals may be achieved by re-introducing oxygen into the infarcted area. Yet current systemic oxygen delivery approaches cannot efficiently diffuse oxygen into the infarcted area that has extremely low blood flow. In this work, we developed a new oxygen delivery system that can be delivered specifically to the infarcted tissue, and continuously release oxygen to protect the cardiac cells. The system was based on a thermosensitive, injectable and fast gelation hydrogel, and oxygen releasing microspheres. The fast gelation hydrogel was used to increase microsphere retention in the heart tissue. The system was able to continuously release oxygen for 4 weeks. The released oxygen significantly increased survival of cardiac cells under the hypoxic condition (1% O₂) mimicking that of the infarcted hearts. It also reduced myofibroblast formation under hypoxic condition (1% O₂). After implanting into infarcted hearts for 4 weeks, the released oxygen significantly augmented cell survival, decreased macrophage density, reduced collagen deposition and myofibroblast density, and stimulated tissue angiogenesis, leading to a significant increase in cardiac function.

Strategies to Restore Adenosine Triphosphate (ATP) Level After More than 20 Hours of Cold Ischemia Time in Human Marginal Kidney Grafts

Background

The persisting organ shortage in the field of transplantation recommends the use of marginal kidneys which poorly tolerate ischemic damage. Adenosine triphosphate (ATP) depletion during cold ischemia time (CIT) is considered crucial for graft function. We tested different strategies of kidney perfusion before transplantation in the attempt to improve the technique.

Material/Methods

Twenty human discarded kidneys from donors after brain death and with at least 20 hours of CIT were randomized to the following experimental groups (treatment time three-hours at 4°C): a) static cold storage (CS); b) static cold hyperbaric oxygenation (Hyp); c) hypothermic perfusion (PE); d) hypothermic perfusion in hyperbaric oxygenation (PE-Hyp); and e) hypothermic oxygenated perfusion (PE-O₂).

Results

Histological results showed that perfusion with or without oxygen did not produce any endothelial damage. A depletion of ATP content following the preservation procedure was observed in CS, PE, and Hyp, while PE-Hyp and PE-O₂ were associated with a net increase of ATP content with respect to baseline level. In addition, PE-Hyp was associated with a significant downregulation of endothelial isoform of nitric oxide synthase (eNOS) gene expression and of hypoxia inducible factor-1α (HIF-1α).

Conclusions

Hyperbaric or normobaric oxygenation with perfusion improves organ metabolic preservation compared to other methods. This approach may prevent the onset of delayed graft function, but clinical trials are needed to confirm this.

Hyperbaric Oxygen for Ischemia due to Injection of Cosmetic Fillers: Case Report and Issues

Natural and synthetic fillers have revolutionized aesthetic facial rejuvenation and soft-tissue augmentation. We present a case highlighting the dangers of filler self-injection. A 37-year-old woman self-injected a dermal filler around both temples. She immediately experienced left--side hearing loss, blanching over the left face, and pain. Prompt treatment with hyaluronidase, topical nitro paste, and warm compresses ensued. An emergency computed tomography angiogram showed occlusion of a superficial temporal artery branch. We treated her with enoxaparin, aspirin, dexamethasone, piperacillin-tazobactam, and intradermal lidocaine. After 6 hyperbaric oxygen therapy (HBO2) treatments in 3 days, the patient showed improvement in appearance with markedly decreased ischemic discoloration and her hearing returned to baseline. Algorithms for treating such injuries generally neglect HBO2. HBO2 is thought to be efficacious in these situations by a variety of mechanisms: oxygenation of ischemic tissues, reduction of edema, amelioration of ischemic/reperfusion injury, promotion of angiogenesis and collagen maturation. Her resolved hearing highlights the utility of HBO2 in sudden hearing loss as well. Injectors should have guidelines for using product, not only on patients but staff as well. Filler courses should include handling complications and include HBO2 in their guidelines. Clinicians should remind patients to seek treatment from qualified clinicians. The goal of a bargain price using self-injection may quickly become expensive and disfiguring.

Topical oxygen therapy & micro/nanobubbles: a new modality for tissue oxygen delivery

Up to 15 billion dollars of US health care expenditure each year is consumed by treatment of poorly healing wounds whose etiologies are often associated with aberrancies in tissue oxygenation. To address this issue, several modes of tissue oxygen delivery systems exist, including Hyperbaric Oxygen Therapy (HBOT) and Topical Oxygen Therapy (TOT), but their efficacies have yet to be fully substantiated. Micro/nanobubbles (MNBs), which range anywhere from 100 μm to <1 μm in diameter and are relatively stable for hours, offer a new mode of oxygen delivery to wounds. The aim of this article is to systematically review literature examining the use of TOT for wound healing and use of MNBs for tissue oxygenation using the MEDLINE database. The search yielded 87 articles (12 MNB articles and 75 TOT articles), of which 52 met the inclusion criteria for this literature review (12 MNB articles and 40 TOT articles). Additionally, we present an analysis on the efficacy of our MNB generating technology and propose its use as a wound healing agent.

Cerebral arterial gas embolism from attempted mechanical thrombectomy: recovery following hyperbaric oxygen therapy

Cerebral arterial gas embolism is a recognised complication of endovascular intervention with an estimated incidence of 0.08%. Its diagnosis is predominantly clinical, supported by neuroimaging. The treatment relies on alleviating mechanical obstruction and reversing the proinflammatory processes that contribute to tissue ischaemia. Hyperbaric oxygen therapy is an effective treatment and has multiple mechanisms to reverse the pathological processes involved in cerebral arterial gas embolism. Symptomatic cerebral arterial gas embolism is a rare complication of endovascular intervention for acute ischaemic stroke. Although there are no previous descriptions of its successful treatment with hyperbaric oxygen therapy following mechanical thrombectomy, this is likely to become more common as mechanical thrombectomy is increasingly used worldwide to treat acute ischaemic stroke.

Salvage of Unilateral Complete Ear Amputation with Continuous Local Hyperbaric Oxygen, Platelet-Rich Plasma and Polydeoxyribonucleotide without Micro-Revascularization

In many cases of complete ear amputation, microvascular surgery is required for tissue perfusion and organ survival. However, microvascular reconstruction is not always feasible in the absence of suitable vessels. Here, we present the case of a 76-year-old man who underwent complete amputation of the left ear after a collapse at home because of cardiogenic syncope. He was treated with primary replantation and underwent a postoperative salvage course including continuous local hyperbaric oxygen therapy (HBOT), platelet-rich plasma (PRP) injections, and polydeoxyribonucleotide (PDRN) injections. The ear was almost completely salvaged, with a tiny eschar at the mid-scapha on both the anterior and posterior aspects. This case demonstrates the efficacy of local HBOT with PRP and PDRN injections.

A Double-Blind, Randomized Trial on the Efficacy and Safety of Hyperbaric Oxygenation Therapy in the Preservation of Erectile Function after Radical Prostatectomy

PURPOSE

We evaluated the efficacy and safety of hyperbaric oxygenation therapy to preserve erectile function as part of penile rehabilitation after robot assisted bilateral nerve sparing radical prostatectomy for prostate cancer.

MATERIALS AND METHODS

We performed a prospective, randomized, double-blind study from January 2009 to April 2013. Men 40 to 65 years old who underwent robot assisted bilateral nerve sparing radical prostatectomy were randomized 1:1 to the control or the treatment group. Participants were exposed to air as the control or to 100% oxygen as the treatment in hyperbaric conditions. The primary outcome was erectile function at 18 months as measured by IIEF (International Index of Erectile Function). Secondary outcomes were 12-month urinary symptoms, and 18-month sexual, urinary, bowel and hormonal related symptoms as measured by EPIC-26 (Expanded Prostate Index Composite-26). Adverse events and long-term cancer outcomes were monitored. Primary and secondary outcomes in the 2 groups were compared by the independent group t-test, the Wilcoxon rank sum test and the chi-square test of proportion.

RESULTS

A total of 109 potent men were randomized to hyperbaric oxygenation therapy or the control group. A total of 43 men in the air group and 40 in the hyperbaric oxygenation therapy group completed the 18-month followup. No statistically significant differences were observed between the 2 groups on any outcome measure.

CONCLUSIONS

This study revealed no difference in erectile recovery in men treated with hyperbaric oxygenation therapy vs placebo. Larger studies involving more diverse comorbidities and different hyperbaric oxygenation therapy regimens are needed to better evaluate the usefulness of hyperbaric oxygenation therapy for penile rehabilitation after radical prostatectomy.

How biomarkers reflect the prognosis and treatment of necrotising soft tissue infections and the effects of hyperbaric oxygen therapy: the protocol of the prospective cohort PROTREAT study conducted at a tertiary hospital in Copenhagen, Denmark

INTRODUCTION

Not enough is known regarding the prognosis and treatment of necrotising soft tissue infections (NSTIs). Mortality has been shown to be 25%-35%, with survivors coping with amputations and prolonged rehabilitation. This study will evaluate soluble urokinase-type plasminogen activator receptor (suPAR) as a possible prognostic marker of NSTI severity and mortality, as well as whether hyperbaric oxygen therapy (HBOT) can modulate markers of endothelial damage during NSTI. We hypothesise that in patients with NSTI, suPAR can provide prognostic risk assessment on hospital admission and that HBOT can reduce the endothelial damage that these patients are exposed to.

METHODS AND ANALYSIS

This is a prospective observational study. Biomarkers will be measured in 150 patients who have been diagnosed with NSTI. On admission, baseline blood samples will be obtained. Following surgery and HBOT, daily blood samples will be obtained in order to measure endothelial and prognostic biomarkers (soluble thrombomodulin, syndecan-1, sE-selectin, vascular endothelial (VE)-cadherin, protein C and suPAR levels). Clinical data will be acquired during the first 7 days of stay in the intensive care unit. The primary outcomes in studies I and II will be endothelial biomarker levels after HBOT, and in study III suPAR levels as a marker of disease prognosis and severity.

ETHICS AND DISSEMINATION

The study has been approved by the Regional Scientific Ethical Committee of Copenhagen (H-16021845) and the Danish Data Protection Agency (RH-2016-199). Results will be presented at national and international conferences and published in peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier NCT03147352. (Pre-results).

Treatment of ulcerative compared to non-ulcerative interstitial cystitis with hyperbaric oxygen: a pilot study

Background

The etiology of interstitial cystitis (IC) is often idiopathic but can be due to Hunner's ulcers. Hyperbaric oxygen (HBO) is used to treat ulcerative disease of the superficial skin. We hypothesized that HBO can treat ulcerative IC (UIC) but would be less efficacious for non-ulcerative IC (NIC).

Methods

Patients with NIC and UIC enrolled in this study. Following informed consent, demographic information was collected. A visual analog pain scale and validated questionnaires were collected; each patient underwent cystoscopy prior to treatment. Each subject met with a hyperbaric specialist and after clearance underwent 30 treatments over 6 weeks. Adverse events were monitored. Patients repeated questionnaires, visual analog pain scale and global response assessment (GRA) immediately, 2 weeks, 3, 6 and 12 months after treatment. Patients also underwent cystoscopy 6 months after treatment. Differences before and after treatment were compared.

Results

Nine patients were recruited to this study. One was unable to participate, leaving two subjects with NIC and six with UIC. All patients completed HBO without adverse events. Three patients completed HBO but pursued other therapies 7, 8.5 and 11 months after treatment. On GRA, 83% of patients with UIC were improved. This treatment effect persisted, as 66% of UIC patients remained better at 6 months. In contrast, only one patient in the NIC group improved. Questionnaire scores improved in both groups. Pain scores improved by 2 points in the UIC group but worsened by 1.5 points in the NIC group. Two patients with ulcers resolved at 6-month cystoscopy.

Conclusion

HBO appeared beneficial for both UIC and NIC. Data shows slightly better benefit in patients with UIC compared to NIC; both groups showed improvement. Given the small sample size, it is difficult to draw definitive conclusions from these data. Larger studies with randomization would be beneficial to show treatment effect.

Managing Complications in Abdominoplasty: A Literature Review

Background

Abdominoplasty, with or without liposuction, is among the most frequently performed aesthetic procedures. Its main objective is to improve the body contour by means of excising redundant skin and fat tissue. Although abdominoplasty is considered a safe procedure with high satisfaction rates, intraoperative and postoperative complications can become a challenge for the surgical team. The aim of this article is to offer a synopsis of the most common complications arising after abdominoplasty, along with evidence-based guidelines about how to prevent and treat them.

Methods

A systematic MEDLINE search strategy was designed using appropriate Medical Subject Headings (MeSH) terms, and references were scanned for further relevant articles.

Results

According to the published case series, local complications are considerably more common than complications with systemic repercussions. Approximately 10% to 20% of patients suffer a local complication following abdominoplasty, while fewer than 1% suffer a systemic complication. Prevention and management strategies are critically discussed for complications including seroma, haematoma, infection, skin necrosis, suture extrusions, hypertrophic scars, neurological symptoms, umbilical anomalies, deep venous thrombosis and pulmonary thromboembolism, respiratory distress, and death.

Conclusions

The complications of abdominoplasty vary in severity and in the impact they have on the aesthetic outcomes. Recommendations for prevention and management are based on various levels of evidence, with a risk of observer bias. However, most complications can be treated appropriately following the current standards, with satisfactory results.

The efficacy of hyperbaric oxygen in hemorrhagic stroke: experimental and clinical implications

Hemorrhagic stroke, accounting for 10-30% of stroke cases, carries high rates of morbidity and mortality. This review presents the current knowledge on the efficacy of hyperbaric oxygen (HBO)-based modalities in the preclinical research on hemorrhagic stroke. Both preconditioning and post-treatment with HBO are considered as prospective therapeutic options. High efficacy of HBO therapy (HBOT) for brain hemorrhage has been noted. We found that moderate hyperbaric pressures appear optimal for therapeutic effect, while the therapeutic window of opportunity is short. HBO preconditioning offers more modest neuroprotective benefit as compared to HBO post-treatment for experimental intracerebral hemorrhage. We advocate for mandatory calculations of percent changes in the experimentally investigated indexes of HBO effectiveness and stress the need to design new clinical trials on HBO for hemorrhagic stroke.

Normal carboxyhaemoglobin level in carbon monoxide poisoning treated with hyperbaric oxygen therapy

Throughout the world both intentional and inadvertent exposure to carbon monoxide (CO) remains an important public health issue. While CO poisoning can be lethal, the morbidity is predominantly due to nervous system injury. A previously healthy 22-year-old woman was found unconscious at home by her sister. Her parents were found dead in the house with a recent history of a dysfunctional furnace. She was presumed to have CO poisoning despite an initial carboxyhaemoglobin level of 2.5%. Patient had both clinical and radiological evidence of neurological damage. However, with multiple sessions of hyperbaric oxygen (HBO) therapy she recovered to a near normal functional status. There is no consensus that exists among treating physicians about the role of hyperbaric oxygen in management of neurological injury. The case described here has significant neurological damage related to CO exposure but improved after HBO therapy.

Hyperbaric Oxygen Therapy for Wound Dehiscence After Intraoral Bone Grafting in the Nonirradiated Patient: A Case Series

PURPOSE

In maxillofacial surgery, hyperbaric oxygen treatment is used almost exclusively as adjunctive therapy for osteoradionecrosis of the mandible in irradiated patients. It also is used to prevent the occurrence of osteoradionecrosis in the irradiated patient when dental surgery is indicated. Theoretically, hyperbaric oxygen therapy should benefit the nonirradiated patient in maxillofacial surgery (eg, patients with persistent intraoral wound dehiscences after bone grafting).

MATERIALS AND METHODS

Six nonirradiated patients underwent hyperbaric oxygen therapy because of compromised wound healing after intraoral bone grafting of the maxilla as a preimplant procedure. All patients were treated 7 to 26 times with hyperbaric oxygen therapy at 2.5 ATA.

RESULTS

All patients healed uneventfully. In retrospect, almost all patients had a history of chronic maxillary sinusitis or trauma to the operated area.

CONCLUSION

Hyperbaric oxygen therapy seems to be an effective adjunctive therapy in the treatment of nonirradiated patients with compromised intraoral maxillary bone graft healing. Chronic maxillary sinus problems or a history of trauma could predispose to wound dehiscence after bone grafting.

Hyperbaric oxygen therapy of spinal cord injury

Spinal cord injury (SCI) is a complex disease process that involves both primary and secondary mechanisms of injury and can leave patients with devastating functional impairment as well as psychological debilitation. While no curative treatment is available for spinal cord injury, current therapeutic approaches focus on reducing the secondary injury that follows SCI. Hyperbaric oxygen (HBO) therapy has shown promising neuroprotective effects in several experimental studies, but the limited number of clinical reports have shown mixed findings. This review will provide an overview of the potential mechanisms by which HBO therapy may exert neuroprotection, provide a summary of the clinical application of HBO therapy in patients with SCI, and discuss avenues for future studies.

Re-operative urethroplasty after failed hypospadias repair: how prior surgery impacts risk for additional complications

PURPOSE

The primary aim of this report was to compare urethroplasty complications for primary distal and proximal repairs with those after 1, 2, 3, and 4 or more re-operations.

METHODS

Prospectively collected data on consecutive hypospadias repairs (tubularized incised plate (TIP), inlay, two-stage graft) from 2000 to 2015 were reviewed. Isolated fistula closures were excluded. Extracted information included patient age, meatal location, repair type, primary vs. re-operative surgery, number of prior operations, any testosterone use, glans width, and urethroplasty complications. Pre-operative testosterone stimulation was used during the study period until 2012. Initially, it was given for a subjectively small-appearing glans, but from 2008 to 2012 use was determined by glans width <14 mm. Patients initially managed elsewhere were queried for any testosterone treatment. The number of prior operations was determined by patient history and confirmed by review of records. Calibrations, dilations, cystoscopies, and/or isolated skin revisions were not considered as prior urethroplasty operations. Multiple logistic regression was performed for all patients, and for the subset of patients undergoing re-operation, using stepwise regression for the following potential risk factors: meatal location (distal vs. midshaft/proximal), number of prior surgeries (0, 1, 2, 3, ≥4), pre-operative testosterone use (yes/no), small glans (<14 vs. ≥14), surgery type (TIP, inlay and two-stage graft), and age (continuous in months), with P-values <0.05 considered statistically significant.

RESULTS

In contrast to the 135/1085 (12%) complication rate in patients undergoing primary distal and proximal TIP repair, re-operative urethroplasty complications occurred in 61/191 (32%) TIP, 16/46 (35%) inlay, and 49/124 (40%) two-stage repairs, P<0.0001. Data regarding testosterone use was available for 1490 (96%) patients. A total of 139 received therapy, of which 65 (46%) had urethroplasty complications vs. 229 of 1351 (16%) without treatment, P = 0.0001. Logistic regression in 1536 patients demonstrated that each prior surgery increased the odds of subsequent urethroplasty complications 1.5-fold (OR 1.51, 95% CI 1.25-1.83), along with small glans <14 mm (OR 2.40, 95% CI 1.48-3.87), mid/proximal meatal location (OR 2.54, 95% CI 1.65-3.92), and use of pre-operative testosterone (OR 2.57, 95% CI 1.53-4.31); age and surgery type did not increase odds (AUC = 0.739).

DISCUSSION

Urethroplasty complications doubled in people undergoing a second hypospadias urethroplasty compared with those undergoing primary repair. This risk increased to 40% with three or more re-operations. Logistic regression demonstrates that each surgery increases the odds for additional complications 1.5-fold. Mid/proximal meatal location, small glans <14 mm, and use of pre-operative testosterone also significantly increase odds for complications. These observations support the theory that previously operated tissues have less robust vascularity than assumed in a primary repair, and suggest additional adjunctive therapies are needed to improve wound healing in re-operations. The finding that even a single re-operative urethroplasty has twice the risk for additional complications vs. a primary repair emphasizes the need for hypospadias surgeons to 'get it right the first time'. The fact that 40% of the re-operative urethroplasties in this series followed distal repairs emphasizes that there is no 'minor' hypospadias.

CONCLUSIONS

A single re-operative hypospadias urethroplasty has twice the risk for additional complications vs. the primary repair, which increases to 40% with three or more re-operations. These results support a theory that vascularity of penile tissues decreases with successive operations, and suggest the need for treatments to improve vascularity. The higher risk for complications during re-operative urethroplasties also emphasizes the need to get the initial repair correct.

Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified

Significance: Hyperbaric oxygen therapy (HBOT) is an important advanced therapy in the treatment of problem wounds, including diabetic foot ulcers and late effect radiation injury. HBOT remains among the safest therapies used today. Nonetheless, there are side effects associated with HBOT. It is important for providers to be able to identify, understand, and quantify these side effects for prevention, management, and informed consent. Recent Advances: The past two decades have seen significant advancements in our understanding of the underlying mechanisms of HBOT. This has led to a better understanding of the underlying reason for clinical benefit. It has also led to a better understanding of its side effects. Moreover, more recent literature allows for better quantification of these side effects. This review will highlight these side effects. Critical Issues: Wound healing in the case of problem nonhealing wounds requires the use of various advanced treatment modalities, including HBOT. HBOT has been shown to significantly improve healing rates in certain problem wounds, including advanced diabetic foot ulcers and late effect radiation injury. It is provided in a variety of clinical settings by providers with varying levels of expertise. It is important for those providing this therapy to understand the potential side effects. Future Directions: Research in HBOT has led to significant advancements in the area of wound healing. At the same time, there remains a variety of treatment protocols used at different institutions. It is important to quantify risk and benefit at different treatment pressures and times to better standardize treatment and improve patient care.

Hyperbaric oxygen therapy for wound healing in diabetic rats: Varying efficacy after a clinically-based protocol

Hyperbaric oxygen therapy (HBOT) is a clinical treatment in which a patient breathes pure oxygen for a limited period of time at an increased pressure. Although this therapy has been used for decades to assist wound healing, its efficacy for many conditions is unproven and its mechanism of action is not yet fully clarified. This study investigated the effects of HBOT on wound healing using a diabetes-impaired pressure ulcer rat model. Seven weeks after streptozotocin-induced diabetes in rats (n = 55), a pressure ulcer was created on dorsal skin. Subsequently, animals received HBOT during 6 weeks following a standard clinical protocol (HBOT group with varying endpoints up to 42 days post-wounding) versus controls without HBOT. Capillary venous oxygen saturation (SO₂) showed a significant increase in the HBOT group on day 24; however, this increase was significant at this time point only. The quantity of hemoglobin in the micro-blood vessels (rHB) showed a significant decrease in the HBOT group on days 21 and 42, and showed a trend to decrease on day 31. Blood flow in the microcirculation showed a significant increase on days 17, 21 and 31 but a significant decrease on days 24 and 28. Inflammation scoring showed significantly decreased CD68 counts in the HBOT group on day 42, but not in the early stages of wound healing. Animals in the HBOT group showed a trend for an increase in mean wound breaking strength on day 42.

Hyperbaric Oxygen Therapy for the Treatment of Diabetic Foot Ulcers: A Health Technology Assessment

BACKGROUND

About 15% to 25% of people with diabetes will develop a foot ulcer. These wounds are often resistant to healing; therefore, people with diabetes experience lower limb amputation at about 20 times the rate of people without diabetes. If an ulcer does not heal with standard wound care, other therapeutic interventions are offered, one of which is hyperbaric oxygen therapy (HBOT). However, the effectiveness of this therapy is not clearly known. The objectives of this health technology assessment were to assess the safety, clinical effectiveness, and cost-effectiveness of standard wound care plus HBOT versus standard wound care alone for the treatment of diabetic foot ulcers. We also investigated the preferences and perspectives of people with diabetic foot ulcers through lived experience.

METHODS

We performed a review of the clinical and economic literature for the effectiveness and cost-effectiveness of hyperbaric oxygen therapy, as well as the budget impact of HBOT from the perspective of the Ministry of Health and Long-Term Care. We assessed the quality of the body of clinical evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. To better understand the preferences, perspectives, and values of patients with diabetic foot ulcers and their experience with HBOT, we conducted interviews and administered an online survey.

RESULTS

Seven randomized controlled trials and one nonrandomized controlled trial met the inclusion criteria. Comparing standard wound care plus HBOT with standard wound care alone, we found mixed results for major amputation rates (GRADE quality of evidence: low), a significant difference in favour of standard wound care plus HBOT on ulcers healed (GRADE quality of evidence: low), and no difference in terms of adverse events (GRADE quality of evidence: moderate). There is a large degree of uncertainty associated with the evaluation of the cost-effectiveness of standard wound care plus HBOT. However, results appear to suggest that this treatment results in lower costs and better outcomes than standard wound care alone. Funding HBOT will result in a budget impact of $4 million per year in immediate treatment costs for the Ontario Ministry of Health and Long-Term Care. This cost decreases to $0.5 million per year when downstream costs are considered. There is a substantial daily burden of care and emotional weight associated with living with diabetic foot ulcers, both of which are compounded by concern regarding possible amputation. Patients feel that HBOT is an effective treatment and reported that they were satisfied with how their ulcers healed and that this improved their quality of life.

CONCLUSIONS

The evidence makes it difficult to draw any definitive conclusions on the clinical and cost effectiveness of standard wound care plus HBOT versus standard wound care alone for the treatment of diabetic foot ulcers.

Cold Injuries

New treatments of frostbite have led to unprecedented salvage of extremities including fingers and toes. Success is predicated on prompt institution of time-sensitive protocols initiated soon after rewarming, particularly the use of thombolytics. Unfortunately, in the urban setting, most patients are not candidates for these treatment modalities. Triple-phase bone scans have allowed for early determination of devitalized parts that need amputation. Reconstructive surgical techniques are typically used to salvage limb length in these devastating injuries.

Medical perspective in testicular ischemia-reperfusion injury

Testicular torsion or torsion of the spermatic cord is one of the most serious urological conditions. It causes testicular injury, which potentially leads to male subfertility. The turning of the spermatic cord and spermatic structures around themselves results in biochemical and histological changes; however, following testicular detorsion, tissues undergo reperfusion that causes more severe damage than that induced by ischemia. Since the primary causes of testicular damage are reactive oxygen species production, an increase in intra-mitochondrial calcium concentration and an increased rate of cellular apoptosis, different medications may potentially be effective. It seems that several medications, experimentally and sometimes clinically, serve an adjuvant role in the cellular damage that occurs following ischemia-reperfusion. Antioxidants, calcium channel blockers, phytotherapeutical medicinals, anaesthetics, hormones and platelet inhibitors may potentially create a solid basis for an adjuvant restoring therapy and ameliorate testicular function following torsion. The current study aimed to review the relevant literature and discuss the actions of a number of molecules that may protect the testes during ischemia/reperfusion injury.

Is hyperbaric oxygen therapy indispensable for saving mutilated hand injuries?

Mutilated hand injuries are a profound challenge to the plastic surgeon, and such injuries often lead to limb loss and severe functional impairment. Hyperbaric oxygen therapy (HBOT) appears to counteract tissue hypoxia and stimulate acute wound healing. This study was performed to evaluate the efficacy of HBOT as an adjunctive therapy in patients with a mutilated hand injury. Between January 2006 and December 2014, 45 patients with a mutilated hand injury were enrolled. After reconstruction or revascularisation, patients underwent 120 minutes of HBOT with oxygen at 2·5 atmospheres absolute while breathing 100% oxygen. Outcomes such as amputee survival and surgery-related complications were recorded. The patients were 38 men and 7 women with average age of 37·2 years (range 18-62). The mean defect area was 131·5 cm² (range 40-300). Most patients experienced a pure crush injury (53%). The average number of operations from the initial debridement to the first reconstruction was 3·8 (range 1-6). A total of 33 patients (73%) underwent replantation during the initial reconstruction. For flap coverage, most patients received a free flap using an anterolateral thigh flap (18 patients) or local flap using an abdomen/groin flap (nine patients). The average time from the first reconstruction or revascularisation to the first HBOT was 6·5 hours (range 2-12). The average number of HBOT sessions was 9·1 (range 6-14 sessions). The survival rate of the replanted fingers was 81%, and the survival rate of the palms was 100%. Most complications in the initial reconstruction involved partial loss of an avulsed flap, and most complications in the chronic stage (≥3 months) involved scar contracture. When combined with delicate microsurgery, early intervention using adjunctive HBOT was effective in preserving partially viable tissue and restoring hand function in patients with a mutilated hand injury.

Regulation of Sterol Biosynthesis in the Human Fungal Pathogen Aspergillus fumigatus: Opportunities for Therapeutic Development

Sterols are a major component of eukaryotic cell membranes. For human fungal infections caused by the filamentous fungus Aspergillus fumigatus, antifungal drugs that target sterol biosynthesis and/or function remain the standard of care. Yet, an understanding of A. fumigatus sterol biosynthesis regulatory mechanisms remains an under developed therapeutic target. The critical role of sterol biosynthesis regulation and its interactions with clinically relevant azole drugs is highlighted by the basic helix loop helix (bHLH) class of transcription factors known as Sterol Regulatory Element Binding Proteins (SREBPs). SREBPs regulate transcription of key ergosterol biosynthesis genes in fungi including A. fumigatus. In addition, other emerging regulatory pathways and target genes involved in sterol biosynthesis and drug interactions provide additional opportunities including the unfolded protein response, iron responsive transcriptional networks, and chaperone proteins such as Hsp90. Thus, targeting molecular pathways critical for sterol biosynthesis regulation presents an opportunity to improve therapeutic options for the collection of diseases termed aspergillosis. This mini-review summarizes our current understanding of sterol biosynthesis regulation with a focus on mechanisms of transcriptional regulation by the SREBP family of transcription factors.

Reactive oxygen species (ROS) and wound healing: the functional role of ROS and emerging ROS-modulating technologies for augmentation of the healing process

Reactive oxygen species (ROS) play a pivotal role in the orchestration of the normal wound-healing response. They act as secondary messengers to many immunocytes and non-lymphoid cells, which are involved in the repair process, and appear to be important in coordinating the recruitment of lymphoid cells to the wound site and effective tissue repair. ROS also possess the ability to regulate the formation of blood vessels (angiogenesis) at the wound site and the optimal perfusion of blood into the wound-healing area. ROS act in the host's defence through phagocytes that induce an ROS burst onto the pathogens present in wounds, leading to their destruction, and during this period, excess ROS leakage into the surrounding environment has further bacteriostatic effects. In light of these important roles of ROS in wound healing and the continued quest for therapeutic strategies to treat wounds in general and chronic wounds, such as diabetic foot ulcers, venous and arterial leg ulcers and pressure ulcers in particular, the manipulation of ROS represents a promising avenue for improving wound-healing responses when they are stalled. This article presents a review of the evidence supporting the critical role of ROS in wound healing and infection control at the wound site, and some of the new emerging concepts associated with ROS modulation and its potential in improving wound healing are discussed.

Hyperbaric oxygen therapy for wound care

OBJECTIVE

To describe the most common types of wounds indicated for hyperbaric oxygen therapy and the results.

METHOD

Cross-sectional study at a Hyperbaric Centre in the city of Salvador, Bahia, Brazil. The medical records of 200 patients treated with hyperbaric oxygen were reviewed from January to November 2013. The variables of the persons, clinical, indications, number of sessions and wound care were analysed by means of descriptive statistics and the chi-square test of association incorporating Yates's correction with a level of 5%.

RESULTS

The wounds that were most frequently indicated for hyperbaric oxygen therapy were venous ulcers, traumatic injury and diabetic foot. Patients with chronic wounds had fewer sessions (61.1%) and their wounds healed or were reduced (62.0%) compared to those with acute wounds.

CONCLUSION

Hyperbaric oxygen therapy is an effective treatment for patients with chronic wounds.

Adjunctive hyperbaric oxygen therapy in severe burns: Experience in Taiwan Formosa Water Park dust explosion disaster

BACKGROUND

Despite major advances in therapeutic strategies for the management of patients with severe burns, significant morbidity and mortality is observed. Hyperbaric oxygen therapy (HBOT) increases the supply of oxygen to burn areas. The aim of this study was to determine whether HBOT is effective in the treatment of major thermal burns.

METHODS

On June 27, 2015 in New Taipei, Taiwan, a mass casualty disaster occurred as fire erupted over a large crowd, injuring 499 people. Fifty-three victims (20 women and 33 men) were admitted to Tri-Service General Hospital. Thirty-eight patients underwent adjunctive HBOT (HBOT group), and 15 patients received routine burn therapy (control group). Serum procalcitonin (PCT) level, a sepsis biomarker, was measured until it reached normal levels (<0.5μg/L). The records of all patients from June 2015 to March 2016 were analyzed retrospectively. Outcome measures that were compared between the groups included the use of tracheostomy and hemodialysis, total body surface area (TBSA) and the number of skin graft operations, length of hospital stay, infection status, and mortality.

RESULTS

The mean age of the patients was 22.4 years, and the mean TBSA was 43%. All the patients survived and were discharged without requiring limb amputation or being permanently disabled. Patient characteristics did not differ significantly between the groups. PCT levels returned to normal significantly faster (p=0.007) in the HBOT group.

CONCLUSION

Multidisciplinary burn care combined with adjunctive HBOT improves sepsis control compared with standard treatment without HBOT. Prospective studies are required to define the role of HBOT in extensive burns.

Effect of Hyperbaric Oxygen on the Growth of Intracranial Glioma in Rats

Background:

Numerous studies have confirmed that hyperbaric oxygen (HBO) in combination with radiotherapy or chemotherapy may increase the efficacy of radiotherapy or chemotherapy in patients with glioma. However, whether HBO therapy alone may inhibit or promote the growth of malignant tumors remains controversial. This study aimed to investigate the effect of HBO on the growth of glioma in rats, and the impact of HBO on the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-alpha (HIF-1α), angiogenesis, and apoptosis of glioma cells.

Methods:

Male Sprague–Dawley rats were treated with or without HBO after glioma cell inoculation and followed for up to 16 days postinoculation. Rats were randomized to receive bilateral forelimb function tests (n = 20 per group) and head magnetic resonance imaging (n = 5 per group). Differences between HBO and control groups were tested using 2-sample independent t-tests and changes over time within treatment groups were analyzed using a repeated measurement analysis of variance with Bonferroni correction. The effect of HBO on the expression of VEGF, HIF-1α, von Willebrand factor, angiogenesis, and tumor cell apoptosis were also examined (n = 5 per group).

Results:

Forelimb function scores were reduced in both HBO-treated and control groups. HBO-treated rats had significantly larger tumor volume and more water in the cerebellum compared with control rats. The intratumoral expression of VEGF was significantly higher in HBO-treated rats compared with control rats (23.2% vs. 13.3%, P = 0.002). HIF-1α was significantly increased in HBO-treated rats compared with controls in the expression of both intratumoral (72.7% vs. 54.9%, P = 0.001) and peritumoral (2.6% vs. 1.9%, P = 0.003) cells. The intratumoral microvessel density (MVD) was significantly higher in the HBO group (15.6 vessels/field vs. 4.4 vessels/field, P < 0.001), and the peritumoral MVD was not significantly different between the two groups (P > 0.05). Apoptosis was significantly lower in HBO-treated rats compared with controls (44.4% vs. 82.8% for intratumoral; 10.1% vs. 77.5% for peritumoral, both P < 0.001).

Conclusions:

The current results demonstrate that HBO alone may promote tumor growth, and is therefore not suitable to treat patients with gliomas with neurological deficits or disorders with HBO alone. If HBO must be used as a mean of rehabilitation, it is recommended that HBO should be combined with radiotherapy or chemotherapy.

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.

Effects of hyperbaric oxygen therapy combined with platelet-rich plasma on diabetic wounds: an experimental rat model

INTRODUCTION

Hyperbaric oxygen and platelet-rich plasma are used in the treatment of diabetic wounds. The aim of this study is to evaluate the effects of hyperbaric oxygen therapy and autologous platelet concentrates in healing diabetic wounds.

MATERIAL AND METHODS

Thirty-six female Wistar albino rats were used in this study. Diabetes mellitus was induced chemically with an intraperitoneal injection of streptozotocin. The rats were divided into a control group, a hyperbaric oxygen group, a platelet-rich plasma group, and a combined therapy group. Platelet-rich plasma was applied just after the creation of the wound; hyperbaric oxygen treatment was carried out daily over 7 days. Wound healing was evaluated according to four parameters: ulcerations, epidermal thickness, density of dermal collagen fibers, and proliferation of dermal blood vessels.

RESULTS

The number of active ulcers in the combined therapy group was fewer than in the control group (p = 0.039), and the wound area was greatest in controls (p < 0.001). The epidermal thickness in platelet-rich plasma and combined therapy groups was non-significantly greater than in the control group (p = 0.097 and p = 0.074, respectively). The amount of fibrous collagen in these two groups was greater than in the control group (p = 0.002).

CONCLUSIONS

Combined hyperbaric oxygen and platelet-rich plasma therapy was found to be successful in diabetic wound healing. The combination therapy had no additive effect in terms of angiogenesis and the development of new collagen fibers.

Hyperbaric oxygen therapy for people with autism spectrum disorder (ASD)

BACKGROUND

The rising prevalence of autism spectrum disorder (ASD) has increased the need for evidence-based treatments to lessen the impact of symptoms. Presently, no therapies are available to effectively treat individuals with all of the symptoms of this disorder. It has been suggested that hyperbaric oxygen therapy may alleviate the biochemical dysfunction and clinical symptoms of ASD.

OBJECTIVES

To determine whether treatment with hyperbaric oxygen:1. improves core symptoms of ASD, including social communication problems and stereotypical and repetitive behaviors;2. improves noncore symptoms of ASD, such as challenging behaviors;3. improves comorbid states, such as depression and anxiety; and4. causes adverse effects.

SEARCH METHODS

On 10 December 2015, we searched CENTRAL, Ovid MEDLINE, Embase, and 15 other databases, four of which were Chinese language databases. We also searched multiple trial and research registers.

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) and quasi-RCTs of any dose, duration, and frequency for hyperbaric oxygen therapy compared with no treatment or sham treatment for children and adults with ASD.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration, in that three review authors independently selected studies, assessed them for risk of bias, and extracted relevant data. We also assessed the quality of the evidence by using the GRADE approach.

MAIN RESULTS

We included one trial with a total of 60 children with a diagnosis of ASD who randomly received hyperbaric oxygen therapy or a sham treatment. Using GRADE criteria, we rated the quality of the evidence as low because of the small sample size and wide confidence intervals (CIs). Other problems included selection bias and short duration or follow-up.Overall, study authors reported no improvement in social interaction and communication, behavioral problems, communication and linguistic abilities, or cognitive function. With regard to the safety of hyperbaric oxygen therapy (adverse events), they reported minor-grade ear barotrauma events. Investigators found significant differences between groups in total number of side effect events (Peto odds ratio (OR) 3.87, 95% CI 1.53 to 9.82) and in the number of children who experienced side effects (Peto OR 4.40, 95% CI 1.33 to 14.48).

AUTHORS' CONCLUSIONS

To date, there is no evidence that hyperbaric oxygen therapy improves core symptoms and associated symptoms of ASD. It is important to note that adverse effects (minor-grade ear barotrauma events) can occur. Given the absence of evidence of effectiveness and the limited biological plausibility and possible adverse effects, the need for future RCTs of hyperbaric oxygen therapy must be carefully considered.

Signaling pathways involved in HSP32 induction by hyperbaric oxygen in rat spinal neurons

Spinal cord injury (SCI) is a debilitating disease, effective prevention measures are in desperate need. Our previous work found that hyperbaric oxygen (HBO) preconditioning significantly protected rats from SCI after stimulated diving, and in vitro study further testified that HBO protected primary cultured rat spinal neurons from oxidative insult and oxygen glucose deprivation injury via heat shock protein (HSP) 32 induction. In this study, underlying molecular mechanisms were further investigated. The results showed that a single exposure to HBO significantly increased intracellular levels of reactive oxygen species (ROS) and nitric oxide (NO) and activated MEK1/2, ERK1/2, p38 MAPK, CREB, Bach1 and Nrf2. The induction of HSP32 by HBO was significantly reversed by pretreatment neurons with ROS scavenger N-Acetyl-L-cysteine, p38 MAPK inhibitor or Nrf2 gene knockdown, enhanced by MEK1/2 inhibitors or gene knockdown but not by ERK1/2 inhibitor. CREB knockdown did not change the expression of HSP32 induced by HBO. N-Acetyl-L-cysteine significantly inhibited the activation of MEK1/2, ERK1/2, p38 MAPK, and Nrf2. Activation of Nrf2 was significantly inhibited by p38 MAPK inhibitor and the nuclear export of Bach1 was significantly enhanced by MEK1/2 inhibitor. The results demonstrated that HBO induces HSP32 expression through a ROS/p38 MAPK/Nrf2 pathway and the MEK1/2/Bach1 pathway contributes to negative regulation in the process. More importantly, as we know, this is the first study to delineate that ERK1/2 is not the only physiological substrates of MEK1/2.

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HBO induces HSP32 through ROS/p38 MAPK/Nrf2 pathway in rat spinal neurons.

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ROS but not RNS participates in HBO induced HSP32 expression.

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MEK1/2/Bach1 contributes to negative regulation in HBO induced HSP32 expression.

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MEK1/2 acts through pathways other than ERK1/2.

An Update on the Appropriate Role for Hyperbaric Oxygen: Indications and Evidence

BACKGROUND

Among advanced therapeutic interventions for wounds, hyperbaric oxygen therapy (HBOT) has the unique ability to ameliorate tissue hypoxia, reduce pathologic inflammation, and mitigate ischemia reperfusion injury. Most of the conditions for which it is utilized have few successful alternative treatments, and the morbidity and mortality associated with treatment failure are significant. Data on the efficacy and effectiveness of HBOT were reviewed, comparative effectiveness research of HBOT was explained, and a new paradigm for the appropriate use of HBOT was described.

METHODS

Systematic reviews and randomized controlled trials that have evaluated HBOT were reviewed.

RESULTS

Although numerous small randomized controlled trials provide compelling support for HBOT, the physics of the hyperbaric environment create significant barriers to trial design. The electronic health record infrastructure created to satisfy mandatory quality and registry reporting requirements as part of healthcare reform can be harnessed to facilitate the acquisition of real world data for HBOT comparative effectiveness studies and clinical decision support.

CONCLUSIONS

Predictive models can identify patients unlikely to heal spontaneously and most likely to benefit from HBOT. Although electronic health records can automate the calculation of predictive models making them available at the point of care, using them in clinical decision making is complicated. It is not clear whether stakeholders will support the allocation of healthcare resources using mathematical models, but the current patient selection process mandates a 30-day delay for all patients who might benefit and allows treatment for at least some patients who cannot benefit.

Alterations in taste perception as a result of hyperbaric oxygen therapy

The present study evaluates the effect of hyperbaric oxygen therapy on taste sensitivity, hedonic perception of taste, and food preferences. The studied groups included 197 people in total (79 in the study group; 118 in the control group). All patients from the study group were treated with hyperbaric oxygen therapy due to chronic non-healing wounds. The control group consisted of healthy people, who did not receive hyperbaric oxygen therapy. The taste intensity, recognition thresholds, and hedonic perception were examined using gustatory tests. The aqueous solutions of sucrose for sweet, sodium chloride for salty, citric acid for sour, quinine hydrochloride for bitter, and monosodium glutamate for umami taste were used. The participants fulfilled the questionnaire to examine pleasure derived from eating certain types of dishes. Gustatory tests and analyses of the pleasure derived from eating in the study group were carried out before the first exposure to hyperbaric oxygen and then at the end of therapy, after at least 25 sessions of treatment. In the control group, examination of perception of taste sensations was conducted only once. The results of comparing patients with non-healing wounds with healthy people are characterized by reduced taste sensitivity. After participation in hyperbaric oxygen therapy, the improvement in perception of taste sensations and changes in hedonic evaluation have occurred among patients with non-healing wounds. In terms of food preference, a decreased desire for eating sweet desserts, chocolate, and crisps was observed in those patients who received hyperbaric oxygen therapy.