Hyperbaric oxygen therapy applied research in traumatic brain injury: from mechanisms to clinical investigation

Hyperbaric oxygen therapy for patients with fibromyalgia: a systematic review protocol

INTRODUCTION

Fibromyalgia (FM) is an unexplained chronic condition characterised by generalised pain, sleep disturbances, autonomic disturbances, anxiety, fatigue and cognitive impairment. FM is a prevalent chronic disease worldwide that imposes a significant burden on individuals and society. Emerging evidence suggests that environmental interventions, such as exposure to hyperbaric oxygen therapy (HBOT), can relieve pain and improve the quality of life in patients with FM. This study will systematically and comprehensively assess the effectiveness and safety of HBOT in patients with FM and provide evidence to support its implementation. We hope that the final review will be helpful in supporting the decision-making processes related to treatment programmes.

METHODS AND ANALYSIS

This protocol is reported in accordance with the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols guidelines. Ten key databases, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE (Excerpt Medica Database), PsycINFO, CINAHL (Cumulative Index to Nursing and Allied Health Literature), PEDro, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, WANFANG and VIP (Chinese Scientific Journal Database), will be searched from inception through December 2022 to identify relevant randomised controlled trials examining the effectiveness of HBOT in patients with FM published in English or Chinese. Two reviewers will independently complete the study screening, selection, and data extraction and assess the risk of bias in the included studies using the 0-10 PEDro Scale. Narrative or quantitative syntheses will be performed and a systematic review and meta-analysis will be performed using Review Manager V.5.3 statistical software.

ETHICS AND DISSEMINATION

Ethical approval was not required for this protocol. The results of the final review will be disseminated in a peer--reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022363672.

A Case Series of 39 United States Veterans with Mild Traumatic Brain Injury Treated with Hyperbaric Oxygen Therapy

Importance: The Defense and Veterans Brain Injury Center reported 358,088 mild traumatic brain injury (mTBI) among U.S. service members worldwide between the years 2000 and 2020. Veterans with mTBI have higher rates of Post-Traumatic Stress Disorder (PTSD), depressive disorder, substance use disorder, anxiety disorder, and suicide than their healthy counterparts. Currently, there is no effective treatment for mTBI. Objective: To assess the efficacy of hyperbaric oxygen therapy (HBOT) as a treatment option for mTBI. Design, Setting, Participants: This is a case series of 39 U.S. Veterans diagnosed with mTBI and treated with HBOT. Of these participants, 36 were men and 3 women, and their ages ranged between 28 and 69. The treatment was administered by The 22 Project (a veteran-centered nonprofit organization) using monoplace hyperbaric chambers located in Delray Beach, Florida. Neuroimaging using Single Photon Emission Computer Tomography (SPECT) brain scans performed pre- and post-HBOT were made available for secondary analysis. Nilearn Python Library was utilized to visualize the corresponding neuroimaging data. A two-sided paired t-test in R was used to compare the pre- and post-treatment results. Intervention: A full treatment of HBOT involved 40 sessions. Each session consisted of the administration of 100% oxygen at 1.5 atmospheres for 90 min, twice a day, for 20 days, Mondays to Fridays only. Main Outcome and Measure: Perfusion in the brain’s Brodmann Areas (BA) comparing pre- and post-HBOT using NeuroGam software analysis from brain SPECT scan neuroimaging and multi-symptom self-reports. Results: A comparison between the pre- and post-HBOT brain scans showed significant improvement in the brain perfusion, and the difference was statistically significant (p < 0.001). Separately, participants reported reduced pain, improved mood, and better sleep, an outcome that translated into an average of about 46.6% improvement in the measured symptoms. Conclusions and Relevance: This series demonstrated that HBOT could be a useful treatment for mTBI in U.S. veterans. The participants in the study showed marked improvement in both brain perfusion measured on SPECT scan imaging and measured mTBI symptoms. This is the first study to use brain SPECT scans with quantitative numerical measurements to demonstrate improvement in brain perfusion in veterans with mild TBI treated with HBOT and measured mTBI symptoms. Future research studies are currently being done to validate these important findings.

Hyperbaric oxygen therapy promotes consciousness, cognitive function, and prognosis recovery in patients following traumatic brain injury through various pathways

Objective

The aim of this study was to investigate the clinical curative effect of hyperbaric oxygen (HBO) treatment and its mechanism in improving dysfunction following traumatic brain injury (TBI).

Methods

Patients were enrolled into control and HBO groups. Glasgow coma scale (GCS) and coma recovery scale-revised (CRS-R) scores were used to measure consciousness; the Rancho Los Amigos scale-revised (RLAS-R) score was used to assess cognitive impairment; the Stockholm computed tomography (CT) score, quantitative electroencephalography (QEEG), and biomarkers, including neuron-specific enolase (NSE), S100 calcium-binding protein beta (S100β), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF), were used to assess TBI severity. The patients were followed up 6 months after discharge and assessed with the Glasgow outcome scale-extended (GOSE), functional independence measure (FIM), and the disability rating scale (DRS).

Results

The CRS-R scores were higher in the HBO group than the control group at 10 days after treatment. The RLAS-R scores were higher in the HBO group than the control group at 10 and 20 days after treatment. The Stockholm CT scores were significantly lower in the HBO group than the control group at 10 days after treatment. HBO depressed the (δ + θ)/(α + β) ratio (DTABR) of EEG, with lower δ band relative power and higher α band relative power than those in the control group. At 20 days after treatment, the expression of NSE, S100β, and GFAP in the HBO group was lower than that in controls, whereas the expression of BDNF, NGF, and VEGF in the HBO group was higher than that in controls. Six months after discharge, the HBO group had lower DRS scores and higher FIM and GOSE scores than the control group significantly.

Conclusions

HBO may be an effective treatment for patients with TBI to improve consciousness, cognitive function and prognosis through decreasing TBI-induced hematoma volumes, promoting the recovery of EEG rhythm, and modulating the expression of serum NSE, S100β, GFAP, BDNF, NGF, and VEGF.

The role of hyperbaric oxygen therapy in inflammatory bowel disease: a narrative review

Inflammatory bowel disease is a group of chronic recurrent diseases in the digestive tract, including ulcerative colitis and Crohn's disease. Over the past few decades, the treatment of IBD has made great progress but there is still a lot of room for improvement. Hyperbaric oxygen therapy (HBOT) was defined as the therapeutic effect of inhaling 100% oxygen higher than one atmosphere and reported to be used in stroke, decompression sickness and wound healing. Since several authors reported the role of HBOT as an adjunct to conventional medical treatment in patients with refractory IBD, the relevant research has shown an increasing trend in recent years. Clinical and experimental studies have revealed that HBOT may exert its therapeutic effect by inhibiting inflammation and strengthening the antioxidant system, promoting the differentiation of colonic stem cells and recruiting cells involved in repair. The purpose of this review is to summarize the past clinical and experimental studies and to understand the impact of HBOT in the treatment of IBD more deeply. In addition, we also hope to provide some ideas for future clinical and research work.

Hyperbaric oxygen therapy improves the effect of keloid surgery and radiotherapy by reducing the recurrence rate

OBJECTIVE

Keloids are exuberant cutaneous scars that form due to abnormal growth of fibrous tissue following an injury. The primary aim of this study was to assess the efficacy and mechanism of hyperbaric oxygen therapy (HBOT) to reduce the keloid recurrence rate after surgical excision and radiotherapy.

METHODS

(1) A total of 240 patients were randomly divided into two groups. Patients in the HBOT group (O group) received HBOT after surgical excision and radiotherapy. Patients in the other group were treated with only surgical excision and radiotherapy (K group). (2) Scar tissue from recurrent patients was collected after a second operation. Hematoxylin and eosin (H&E) staining was used to observe keloid morphology. Certain inflammatory factors (interleukin-6 (IL-6), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α), nuclear factor κB (NF-κB), and vascular endothelial growth factor (VEGF)) were measured using immunohistochemical staining.

RESULTS

(1) The recurrence rate of the O group (5.97%) was significantly lower than that of the K group (14.15%), P<0.05. Moreover, patients in the O group reported greater satisfaction than those in the K group (P<0.05). (2) Compared with the recurrent scar tissue of the K group, the expression levels of the inflammatory factors were lower in the recurrent scar tissue of the O group.

CONCLUSIONS

Adjunctive HBOT effectively reduces the keloid recurrence rate after surgical excision and radiotherapy by improving the oxygen level of the tissue and alleviating the inflammatory process.

Hypoxia and hyperbaric oxygen therapy: a review

Hypoxia causes a cascade of activity from the level of the individual down to the regulation and function of the cell nucleus. Prolonged periods of low oxygen tension are a core feature of several disease states. Advances in the study of molecular biology have begun to bridge the gap between the cellular response to hypoxia and physiology. Hyperbaric oxygen therapy is a treatment for hypoxic- and inflammatory-driven conditions, in which patients are treated with 100% oxygen at pressures greater than atmospheric pressure. This review discusses hypoxia, the physiologic changes associated with hypoxia, the responses that occur in the cells during hypoxic conditions, and the role that hyperbaric oxygen therapy can play as part of the treatment for many patients suffering from diseases with underlying hypoxia.

Annexin A7 Levels Increase in Rats With Traumatic Brain Injury and Promote Secondary Brain Injury

The incidence of traumatic brain injury (TBI) has been increasing annually. Annexin A7 is a calcium-dependent phospholipid binding protein. It can promote melting of the cell membrane. Recent studies have shown that it plays an important role in atherosclerosis, other cardiovascular diseases, and a variety of tumors. However, few studies of ANXA7 in TBI have been performed. We here observed how ANXA7 changes after TBI and discuss whether brain injury is associated with the use of ANXA7 antagonist intervention. Experimental Results: 1. After TBI, ANXA7 levels were higher than in the sham group, peaking 24 h after TBI. 2. The use of siA7 was found to reduce the expression of A7 in the injured brain tissue, and also brain edema, BBB damage, cell death, and apoptosis relative to the sham group. Conclusion: ANXA7 promotes the development of secondary brain injury (SBI) after TBI.

Hyperbaric oxygen therapy to improve cognitive dysfunction and encephalatrophy induced by N2O for recreational use: a case report

N₂O, or laughing gas, is generally used for anesthesia, especially in stomatology and pediatrics but is also commonly used recreationally. Cognitive dysfunction induced by the recreational use of N₂O is rare. Here, we present the case of an 18-year-old female with a history of having used N₂O recreationally for 5 months who suffered from encephalatrophy and severe cognitive dysfunction. All of the symptoms gradually subsided with ~20 days of treatment by hyperbaric oxygenation. We hypothesize that the long-term use of N₂O may have induced a chronic state of systemic hypoxia that further induced cerebral atrophy with impaired cognitive function. Hyperbaric oxygen therapy (HBOT) is reported here for the first time as an important therapeutic element for treating N₂O toxicity due to recreational use.

Predictive Value of CTA Spot Sign on Hematoma Expansion in Intracerebral Hemorrhage Patients

Hematoma expansion (HE) occurs in approximately one-third of patients with intracerebral hemorrhage and leads to high rates of mortality and morbidity. Currently, contrast extravasation within hematoma, termed the spot sign on computed tomography angiography (CTA), has been identified as a strong independent predictor of early hematoma expansion. Past studies indicate that the spot sign is a dynamic entity and is indicative of active hemorrhage. Furthermore, to enhance the spot sign's accuracy of predicting HE, spot parameters observed on CTA or dynamic CTA were used for its quantification. In addition, spot signs detected on multiphase CTA and dynamic CTA are shown to have higher sensitivity and specificity when compared with simple standardized spot sign detection in recent studies. Based on the spot sign, novel methods such as leakage sign and rate of contrast extravasation were explored to redefine HE prediction in combination with clinical characteristics and spot sign on CTA to assist clinical judgment. The spot sign is an accepted independent predictor of active hemorrhage and is used in both secondary intracerebral hemorrhage and the process of surgical assessment for hemorrhagic risk in patients with ischemic stroke. Spot sign predicts patients at high risk for hematoma expansion.

Hyperbaric oxygen alleviates the activation of NLRP‑3‑inflammasomes in traumatic brain injury

Growing evidence has demonstrated that the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP-3) inflammasome-mediated inflammatory pathways have been involved in the secondary injury of traumatic brain injury (TBI). In the present study, the authors investigated the effects of hyperbaric oxygen (HBO) therapy on the NLRP-3 inflammasome pathway following TBI. Following the evaluation of motor deficits and brain edema, the therapeutic effects of HBO on interleukin (IL)-1β and IL-18 expression were assessed, as well as NLRP-3 inflammasome activation following TBI. HBO may improve motor score and reduce brain edema, accompanied with the reduction of IL-1β and IL-18 during the 7-day observation period. Furthermore, HBO suppressed mRNA and protein expression of NLRP-3-inflammasome components, especially reducing NLRP-3 expression in microglia. Thus, these results suggested that HBO alleviates the inflammatory response in experimental TBI via modulating microglial NLRP-3-inflammasome signaling.

Stem cells and combination therapy for the treatment of traumatic brain injury

TBI is a nondegenerative, noncongenital insult to the brain from an external mechanical force; for instance a violent blow in a car accident. It is a complex injury with a broad spectrum of symptoms and has become a major cause of death and disability in addition to being a burden on public health and societies worldwide. As such, finding a therapy for TBI has become a major health concern for many countries, which has led to the emergence of many monotherapies that have shown promising effects in animal models of TBI, but have not yet proven any significant efficacy in clinical trials. In this paper, we will review existing and novel TBI treatment options. We will first shed light on the complex pathophysiology and molecular mechanisms of this disorder, understanding of which is a necessity for launching any treatment option. We will then review most of the currently available treatments for TBI including the recent approaches in the field of stem cell therapy as an optimal solution to treat TBI. Therapy using endogenous stem cells will be reviewed, followed by therapies utilizing exogenous stem cells from embryonic, induced pluripotent, mesenchymal, and neural origin. Combination therapy is also discussed as an emergent novel approach to treat TBI. Two approaches are highlighted, an approach concerning growth factors and another using ROCK inhibitors. These approaches are highlighted with regard to their benefits in minimizing the outcomes of TBI. Finally, we focus on the consequent improvements in motor and cognitive functions after stem cell therapy. Overall, this review will cover existing treatment options and recent advancements in TBI therapy, with a focus on the potential application of these strategies as a solution to improve the functional outcomes of TBI.

Hyperbaric oxygen therapy and preconditioning for ischemic and hemorrhagic stroke

To date, the therapeutic methods for ischemic and hemorrhagic stroke are still limited. The lack of oxygen supply is critical for brain injury following stroke. Hyperbaric oxygen (HBO), an approach through a process in which patients breathe in 100% pure oxygen at over 101 kPa, has been shown to facilitate oxygen delivery and increase oxygen supply. Hence, HBO possesses the potentials to produce beneficial effects on stroke. Actually, accumulated basic and clinical evidences have demonstrated that HBO therapy and preconditioning could induce neuroprotective functions via different mechanisms. Nevertheless, the lack of clinical translational study limits the application of HBO. More translational studies and clinical trials are needed in the future to develop effective HBO protocols.

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 experimental and clinical stroke

Stroke, which is defined as a neurologic deficit caused by sudden impaired blood supply, has been considered as a common cause of death and disability for decades. The World Health Organization has declared that almost every 5 seconds a new stroke occurs, placing immense socioeconomic burdens. However, the effective and available treatment strategies are still limited. Additionally, the most effective therapy, such as thrombolysis and stenting for ischemic stroke, generally requires a narrow therapeutic time window after the event. A large majority of patients cannot be admitted to hospital and receive these effective treatments for reperfusion timely. Hyperbaric oxygen therapy (HBOT) has been frequently applied and investigated in stroke since 1960s. Numerous basic and clinical studies have shown the beneficial efficacy for neurological outcome after stroke, and meanwhile many underlying mechanisms associated with neuroprotection have been illustrated, such as cerebral oxygenation promotion and metabolic improvement, blood-brain barrier protection, anti-inflammation and cerebral edema, intracranial pressure modulation, decreased oxidative-stress and apoptosis, increased vascular and neural regeneration. However, HBOT in human stroke is still not sufficiently evidence-based, due to the insufficient randomized double-blind controlled clinical studies. To date, there are no uniform criteria for the dose and session duration of HBOT in different strokes. Furthermore, the additional effect of HBOT combined with drugs and other treatment strategies are being investigated recently. Therefore, more experimental and clinical research is imperative to identify the mechanisms more clearly and to explore the best protocol of HBOT in stroke treatment.

Hyperbaric oxygen in chronic traumatic brain injury: oxygen, pressure, and gene therapy

Hyperbaric oxygen therapy is a treatment for wounds in any location and of any duration that has been misunderstood for 353 years. Since 2008 it has been applied to the persistent post-concussion syndrome of mild traumatic brain injury by civilian and later military researchers with apparent conflicting results. The civilian studies are positive and the military-funded studies are a mixture of misinterpreted positive data, indeterminate data, and negative data. This has confused the medical, academic, and lay communities. The source of the confusion is a fundamental misunderstanding of the definition, principles, and mechanisms of action of hyperbaric oxygen therapy. This article argues that the traditional definition of hyperbaric oxygen therapy is arbitrary. The article establishes a scientific definition of hyperbaric oxygen therapy as a wound-healing therapy of combined increased atmospheric pressure and pressure of oxygen over ambient atmospheric pressure and pressure of oxygen whose main mechanisms of action are gene-mediated. Hyperbaric oxygen therapy exerts its wound-healing effects by expression and suppression of thousands of genes. The dominant gene actions are upregulation of trophic and anti-inflammatory genes and down-regulation of pro-inflammatory and apoptotic genes. The combination of genes affected depends on the different combinations of total pressure and pressure of oxygen. Understanding that hyperbaric oxygen therapy is a pressure and oxygen dose-dependent gene therapy allows for reconciliation of the conflicting TBI study results as outcomes of different doses of pressure and oxygen.