Hyperbaric Oxygen Treatment-From Mechanisms to Cognitive Improvement

Hyperbaric Oxygen Therapy for the Treatment of Bone-Related Diseases

Hyperbaric oxygen therapy (HBOT) is a therapeutic modality that enhances tissue oxygenation by delivering 100% oxygen at pressures greater than 1 absolute atmosphere. In recent years, HBOT has shown considerable potential in the treatment of bone diseases. While excess oxygen was once thought to induce oxidative stress, recent studies indicate that when administered within safe limits, HBOT can notably promote bone healing and repair. Extensive basic research has demonstrated that HBOT can stimulate the proliferation and differentiation of osteoblasts and encourage bone angiogenesis. Furthermore, HBOT has been shown to exert a beneficial influence on bone metabolism by modulating the inflammatory response and redox status. These mechanisms are closely related to core issues of bone biology. Specifically, in the context of fracture healing, bone defect repair, and conditions such as osteoporosis, HBOT targets the key bone signaling pathways involved in bone health, thereby exerting a therapeutic effect. Several clinical studies have demonstrated the efficacy of HBOT in improving bone health. However, the optimal HBOT regimen for treating various bone diseases still requires further definition to expand the indications for its clinical application. This paper outlines the mechanisms of HBOT, focusing on its antioxidant stress, promotion of bone vascularization, and anti-inflammatory properties. The paper also describes the application of HBOT in orthopedic diseases, thereby providing a scientific basis for the development of precise and personalized HBOT treatment regimens in clinical orthopedics.

Effects of hyperbaric oxygen pre-exposure on the motor learning acquisition phase

Hyperbaric oxygen (HBO) exposure has recently been reported to be effective in spatial learning and memory. Additionally, HBO exposure considerably improves performance on motor tasks. These findings suggest that HBO exposure may facilitate motor learning. However, the specific effects of HBO exposure on motor learning remain largely unexplored. The present study aimed to investigate the effects of HBO exposure on motor learning tasks. In the experimental animal models (control n = 8, HBO n = 8), the HBO environment was exposed to 100 % oxygen with the chamber at 2.0 atmosphere absolute (ATA) for 90 min/day for 20 days. The motor learning task was an accelerated rotating bar task (bar width, 3 and 6 cm; rotation speed, 4-40 rpm; acceleration, 0.4, 0.6, and 0.8 rpm/s). The learning task was performed for 3 consecutive days. The HBO group showed a main effect of the day factor on the bar with a width of 6 cm, and significant differences were observed for each day comparison. However, no main effect of the day factor was observed in the control group. Additionally, significant differences were found in the bar with a width of 3 cm for both groups between days 1 and 2 and between days 1 and 3. In conclusion, these findings suggest that HBO exposure has a positive effect on more challenging motor learning tasks.

Hyperbaric Oxygen Therapy in Children with Brain Injury: A Retrospective Case Series

Introduction and Importance: Some experimental studies on brain injury associated with traumatic brain injury (TBI) and hypoxic-ischaemic encephalopathy (HIE) reveal a positive effect of hyperbaric oxygen therapy (HBOT). However, in clinical medicine, most of the scientific evidence available in the current literature relates only to TBI. Methods: The primary objective is to empirically assess the efficacy of HBOT in mitigating the symptoms of disability associated with brain injury in children, with a view to elucidating its therapeutic potential and clinical benefits. Outcomes: A total of 21 patients have been treated with HBOT. The mean age was 6±4.6 years. There were 12 cases (57%) of TBI, 8 cases (38%) of HIE and 1 case (5%) of ischaemic stroke. The mean initial Glasgow Coma Scale (GCS) at hospital admission immediately after accident was 3.3±0.9. The mean time from injury to HBOT was 5.2 ± 3.8 weeks. The mean number of HBOT exposures was 10±4.3. The mean GCS pre-HBOT was 10.7±3.7 and 12.3±3.4 (p=0.004) after post-HBOT, respectively. The mean Glasgow Outcome Scale (GOS) was 3.3±0.8 pre-HBOT, and 3.9±1.1 (p<0.001) after post-HBOT, respectively. Eighteen cases were included in response to HBOT assessment. Six cases (33%) were evaluated as large clinically significant response (CSR), 7 cases (39%) were evaluated as partial response with minimally important difference (MID). Five cases (28%) were evaluated as non-response. The results showed better response to HBOT in cases of starting HBOT up to 4 weeks (p=0.02) after the injury. There was no serious HBOT-related complication or injury. Conclusion: Results of our study demonstrate both clinical and statistically significant patient response to HBOT. Our data also suggest that the earlier HBOT started after diagnosis up to 4 weeks, the more pronounced patients' response to HBOT was achieved. The provision of HBOT to pediatric patients is feasible in large regional hyperbaric centers.

Hyperbaric oxygen therapy attenuates brain radiation-induced cognitive deficits in rats

Effective therapies for cognitive impairments induced by brain irradiation are currently lacking. This study investigated the therapeutic potential of hyperbaric oxygen therapy (HBOT) for radiation-induced brain injury in a randomized controlled experimental model using adult male Wistar rats. Adult male Wistar rats were divided into four experimental groups: 0 Gy whole brain radiotherapy (WBRT) with normal baric air (NBA) treatment, 0 Gy WBRT with HBOT, 10 Gy WBRT with NBA, and 10 Gy WBRT with HBOT. Behavioral tests and histochemical analyses were conducted four weeks post-WBRT to assess cognitive function, hippocampal microgliosis, apoptosis, and lipid peroxidation. Compared with the rats with 0 Gy WBRT on 28 days, the rats with 10 Gy WBRT on 28 days had significantly higher severity of spatial learning and memory dysfunction and hippocampal microgliosis, newborn neuronal apoptosis, and lipid peroxidation. HBOT significantly prevented and reversed WBRT-induced cognitive deficits, hippocampal microgliosis, newborn neuronal apoptosis, and lipid peroxidation. In addition, HBOT prevented and reversed the increased apoptosis among newborn neural stem cells and neuroblasts caused by 10 Gy WBRT on 7 days. The findings suggest that WBRT disrupts neurogenesis and enhance microgliosis, apoptosis of neuronal progenitors, and lipid peroxidation in the dentate gyrus, potentially leading to cognitive deficits and neuronal death. HBOT may offer a protective effect against these cognitive impairments and their underlying mechanisms in adult male rats following WBRT.

The current research status of the mechanisms and treatment of radioactive brain injury

Radioactive brain injury, a severe complication ensuing from radiotherapy for head and neck malignancies, frequently manifests as cognitive impairment and substantially diminishes patients' quality of life. Despite its profound impact, the pathogenesis of this condition remains inadequately elucidated, and efficacious treatments are notably absent in clinical practice. Consequently, contemporary interventions predominantly focus on symptom alleviation rather than achieving a radical cure or reversing the injury process. This article provides a comprehensive review of the various pathogenic mechanisms and therapeutic strategies associated with radioactive brain injury, offering insights that may guide the development of novel therapeutic strategies.

Is there a rationale for hyperbaric oxygen therapy in the patients with Post COVID syndrome? : A critical review

The SARS-CoV-2 pandemic has resulted in 762 million infections worldwide from 2020 to date, of which approximately ten percent are suffering from the effects after infection in 2019 (COVID-19) [1, 40]. In Germany, it is now assumed that at least one million people suffer from post-COVID condition with long-term consequences. These have been previously reported in diseases like Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS). Symptoms show a changing variability and recent surveys in the COVID context indicate that 10-30 % of outpatients, 50 to 70% of hospitalised patients suffer from sequelae. Recent data suggest that only 13% of all ill people were completely free of symptoms after recovery [3, 9]. Current hypotheses consider chronic inflammation, mitochondrial dysfunction, latent viral persistence, autoimmunity, changes of the human microbiome or multilocular sequelae in various organ system after infection. Hyperbaric oxygen therapy (HBOT) is applied since 1957 for heart surgery, scuba dive accidents, CO intoxication, air embolisms and infections with anaerobic pathogens. Under hyperbaric pressure, oxygen is physically dissolved in the blood in higher concentrations and reaches levels four times higher than under normobaric oxygen application. Moreover, the alternation of hyperoxia and normoxia induces a variety of processes at the cellular level, which improves oxygen supply in areas of locoregional hypoxia. Numerous target gene effects on new vessel formation, anti-inflammatory and anti-oedematous effects have been demonstrated [74]. The provision of intermittently high, local oxygen concentrations increases repair and regeneration processes and normalises the predominance of hyperinflammation. At present time only one prospective, randomized and placebo-controlled study exists with positive effects on global cognitive function, attention and executive function, psychiatric symptoms and pain interference. In conclusion, up to this date HBO is the only scientifically proven treatment in a prospective randomized controlled trial to be effective for cognitive improvement, regeneration of brain network and improvement of cardiac function. HBOT may have not only theoretical but also potential impact on targets of current pathophysiology of Post COVID condition, which warrants further scientific studies in patients.

Hyperbaric oxygen therapy as a neuromodulatory technique: a review of the recent evidence

Hyperbaric oxygen therapy (HBOT) has recently emerged as a promising neuromodulatory modality for treating several neurological and psychological disorders. Various studies indicate that HBOT can promote brain recovery and neuroplasticity through the modulation of key cellular and molecular mechanisms. HBOT affects multiple primary pathways and cellular functions including mitochondrial biogenesis and function (increased Bcl-2, reduced Bax, and enhanced ATP production), neurogenesis (upregulation of Wnt-3 and VEGF/ERK signaling), synaptogenesis (elevated GAP43 and synaptophysin expression), and anti-inflammatory responses (reduced TNF-α and IL-6). These mechanisms contribute to significant clinical benefits, such as enhanced cognitive function, improved recovery from traumatic brain injury and post-concussion syndrome, and symptom reduction in conditions like post-traumatic stress disorder and fibromyalgia. By influencing these molecular targets, HBOT offers a novel approach to neuromodulation that warrants further exploration. This review discusses the representative mechanisms of action of HBOT and highlights its therapeutic neuromodulatory effects and potential clinical applications across various neurological and psychiatric conditions.

Hyperbaric oxygen preconditioning rescues prolonged underwater exercise-induced hippocampal dysfunction by regulating microglia activation and polarization

Underwater exercise is becoming increasingly prevalent, during which brain function is necessary but is also at risk. However, no study has explored how prolonged exercise affect the brain in underwater environment. Previous studies have indicated that excessive exercise in common environment causes brain dysfunction but have failed to provide appropriate interventions. Numerous evidence has indicated the neuroprotective effect of hyperbaric oxygen preconditioning (HBO-PC). The objective of this study was to investigate the cognitive effect of prolonged underwater exercise (PUE) and to explore the potential neuroprotective effect of HBO-PC in underwater environment. Rats swimming for 3 h in a simulated hyperbaric chamber (2.0 ATA) was used to establish the PUE animal model and HBO-PC (2.5 ATA for 1, 3,5 times respectively) was administrated before PUE. The results demonstrated that PUE triggers anxiety-like behaviors, cognitive impairment accompanied by hippocampal dysfunction, microglia activation and neuroinflammation. Conversely, 3 HBO-PC rescued anxiety-like behaviors and cognitive impairment. Mechanistically, 3 HBO-PC reduced microglia activation and switched the activated microglia from a pro-inflammatory to neuroprotective phenotype. These findings illustrated that PUE induces anxiety-like behaviors and cognitive impairment and HBO-PC of proper frequency may provide an appropriate and less invasive intervention for protecting the brain in underwater exercise.

ROS exhaustion reverses the effects of hyperbaric oxygen on hemorrhagic transformation through reactivating microglia in post-stroke hyperglycemic mice

Acute ischemic stroke (AIS) is a major global health concern due to its high mortality and disability rates. Hemorrhagic transformation, a common complication of AIS, leads to poor prognosis yet lacks effective treatments. Preclinical studies indicate that hyperbaric oxygen (HBO) treatment within 12 h of AIS onset alleviates ischemia/reperfusion injuries, including hemorrhagic transformation. However, clinical trials have yielded conflicting results, suggesting some underlying mechanisms remain unclear. In this study, we confirmed that HBO treatments beginning within 1 h post reperfusion significantly alleviated the haemorrhage and neurological deficits in hyperglycemic transient middle cerebral arterial occlusion (tMCAO) mice, partly due to the inhibition of the NLRP3 inflammasome-mediated pro-inflammatory response in microglia. Notably, reactive oxygen species (ROS) mediate the anti-inflammatory and protective effect of early HBO treatment, as edaravone and N-Acetyl-L-Cysteine (NAC), two commonly used antioxidants, reversed the suppressive effect of HBO treatment on NLRP3 inflammasome-mediated inflammation in microglia. Furthermore, NAC countered the protective effect of early HBO treatment in tMCAO mice with hyperglycemia. These findings support that early HBO treatment is a promising intervention for AIS, however, caution is warranted when combining antioxidants with HBO treatment. Further assessments are needed to clarify the role of antioxidants in HBO therapy for AIS.

Increased oxygen stimulation promotes chemoresistance and phenotype shifting through PLCB1 in gliomas

Gliomas, the most common CNS (central nerve system) tumors, face poor survival due to severe chemoresistance exacerbated by hypoxia. However, studies on whether altered hypoxic conditions benefit for chemo-sensitivity and how gliomas react to increased oxygen stimulation are limited. In this study, we demonstrated that increased oxygen stimulation promotes glioma growth and chemoresistance. Mechanically, increased oxygen stimulation upregulates miR-1290 levels. miR-1290, in turn, downregulates PLCB1, while PLCB1 facilitates the proteasomal degradation of β-catenin and active-β-catenin by increasing the proportion of ubiquitinated β-catenin in a destruction complex-independent mechanism. This process inhibits PLCB1 expression, leads to the accumulation of active-β-catenin, boosting Wnt signaling through an independent mechanism and ultimately promoting chemoresistance in glioma cells. Pharmacological inhibition of Wnt by WNT974 could partially inhibit glioma volume growth and prolong the shortened survival caused by increased oxygen stimulation in a glioma-bearing mouse model. Moreover, PLCB1, a key molecule regulated by increased oxygen stimulation, shows promising predictive power in survival analysis and has great potential to be a biomarker for grading and prognosis in glioma patients. These results provide preliminary insights into clinical scenarios associated with altered hypoxic conditions in gliomas, and introduce a novel perspective on the role of the hypoxic microenvironment in glioma progression. Furthermore, the outcomes reveal the potential risks of utilizing hyperbaric oxygen treatment (HBOT) in glioma patients, particularly when considering HBOT as a standalone option to ameliorate neuro-dysfunctions or when combining HBOT with a single chemotherapy agent without radiotherapy.

A single exposure to 100% normo-baric oxygen therapy appears to improve sequence learning processes by increasing prefrontal cortex oxygen saturation

Previously, we showed that a normo-baric 100 % oxygen treatment (NbOxTr) enhances motor learning processes, e.g., visuomotor adaptation (VMA) and sequence learning (SL). However, this work was limited to behavioral outcomes and did not identify the physiological mechanistic underpinnings of these improvements. Here, we expand on this research to investigate the effects of a NbOxTr on the oxygen tissue saturation index (TSI) level of the prefrontal cortex (PFC) when performing a SL task and whether potential SL improvements relate to increased TSI levels in the PFC. Twenty four right-handed young, healthy adults were randomly assigned to a NbOxTr group (normo-baric 100 % oxygen, n = 12) or a control group (normal air, n = 12). They received their respective treatments via a nasal cannula during the experiment. Oxygen TSI levels of the right and left PFC were measured via near-infrared spectroscopy (NIRS) throughout different SL task phases (Baseline, Training, Testing). The NbOxTr increased the TSI of the PFC in the Training phase (p < 0.01) and positively affected SL retention in the Testing phase (p < 0.05). We also found a positive correlation between TSI changes in the right PFC during the gas treatment phase (3.4 % increase) and response time (RT) improvements in the SL task training and retention phase (all p < 0.05). Our results suggest that a simple NbOxTr increases the oxygenated hemoglobin availability in the PFC, which appears to mediate the retention of acquired SL improvements in healthy young adults. Future studies should examine treatment-related oxygenation changes in other brain areas involved and their relation to enhanced learning processes. Whether this NbOxTr improves SL in neurologically impaired populations should also be examined.

Intervention modalities for brain fog caused by long-COVID: systematic review of the literature

Individuals suffering from long-COVID can present with "brain fog", which is characterized by a range of cognitive impairments, such as confusion, short-term memory loss, and difficulty concentrating. To date, several potential interventions for brain fog have been considered. Notably, no systematic review has comprehensively discussed the impact of each intervention type on brain fog symptoms. We included studies on adult (aged > 18 years) individuals with proven long- COVID brain-fog symptoms from PubMed, MEDLINE, Central, Scopus, and Embase. A search limit was set for articles published between 01/2020 and 31/12/2023. We excluded studies lacking an objective assessment of brain fog symptoms and patients with preexisting neurological diseases that affected cognition before COVID-19 infection. This review provided relevant information from 17 studies. The rehabilitation studies utilized diverse approaches, leading to a range of outcomes in terms of the effectiveness of the interventions. Six studies described noninvasive brain stimulation, and all showed improvement in cognitive ability. Three studies described hyperbaric oxygen therapy, all of which showed improvements in cognitive assessment tests and brain perfusion. Two studies showed that the use of Palmitoylethanolamide and Luteolin (PEA-LUT) improved cognitive impairment. Noninvasive brain stimulation and hyperbaric oxygen therapy showed promising results in the treatment of brain fog symptoms caused by long-COVID, with improved perfusion and cortical excitability. Furthermore, both rehabilitation strategies and PEA-LUT administration have been associated with improvements in symptoms of brain fog. Future studies should explore combinations of interventions and include longer follow-up periods to assess the long-term effects of these treatments.

Analysis of Therapeutic Options for Noise-Induced Hearing Loss: Retroauricular Injection of Methylprednisolone Sodium Succinate Combined with Hyperbaric Oxygenation

OBJECTIVE

To evaluate the clinical effect of retroaural injection of methylprednisolone sodium succinate combined with hyperbaric oxygen (HBO) on the treatment of noise-induced hearing loss.

METHODS

Case data of 220 patients with hearing loss treated at the Zhongda Hospital Southeast University from January 1, 2019 to August 1, 2023 were obtained. As per the treatment plan, the recruited patients were divided into two cohorts: 158 cases in the combined-treatment group (retroaural injection of methylprednisolone sodium succinate combined with HBO) and 62 cases in the single-hormone group (retroaural injection of methylprednisolone sodium succinate). Comparison of the clinical efficacies and postoperative complication rates of the two groups was performed after treatment. MS-Excel was used to build a database for all data, and SPSS26.0 was utilized in the statistical analysis of recorded data.

RESULTS

For patients with low-frequency, high-frequency, and flat descending type, the combined-treatment group showed significantly higher clinical effective rate than the single-hormone group (P < 0.05). For patients with disease duration ≤7 days, the combined-treatment group attained a significantly higher clinical effective rate was than the single-hormone group (P < 0.05). The safety of patients in both groups was evaluated mainly through their adverse reactions. The total incidence of adverse reactions in the single-hormone group reached 9.68%, and that in the combined-treatment group was 8.23%. The two groups revealed no significant difference in terms of incidence of adverse reactions (P > 0.05).

CONCLUSION

HBO combined with retroaural injection of methylprednisolone sodium succinate has good clinical efficacy and safety in the treatment of hearing loss.

Early hyperbaric oxygen therapy through regulating the HIF-1α signaling pathway attenuates Neuroinflammation and behavioral deficits in a mouse model of Sepsis-associated encephalopathy

BACKGROUND

Sepsis-associated encephalopathy (SAE) presents a significant clinical challenge, associated with increased mortality and healthcare expenses. Hyperbaric oxygen therapy (HBOT), involving inhaling pure or highly concentrated oxygen under pressures exceeding one atmosphere, has demonstrated neuroprotective effects in various conditions. However, the precise mechanisms underlying its protective actions against sepsis-associated brain injury remain unclear. This study aimed to determine whether HBOT protects against SAE and to elucidate the impact of the hypoxia-inducible factor-1α (HIF-1α) signaling pathway on SAE.

METHODS

The experiment consisted of two parts. In the first part, C57BL/6 J male mice were divided into five groups using a random number table method: control group, sham surgery group, sepsis group, HBOT + sepsis group, and HBOT + sham surgery group. In the subsequent part, C57BL/6 J male mice were divided into four groups: sepsis group, HBOT + sepsis group, HIF-1α + HBOT + sepsis group, and HIF-1α + sepsis group. Sepsis was induced via cecal ligation and puncture (CLP). Hyperbaric oxygen therapy was administered at 1 h and 4 h post-CLP. After 24 h, blood and hippocampal tissue were collected for cytokine measurements. HIF-1α, TNF-α, IL-1β, and IL-6 expression were assessed via ELISA and western blotting. Microglial expression was determined by immunofluorescence. Blood-brain barrier permeability was quantified using Evans Blue. Barnes maze and fear conditioning were conducted 14 days post-CLP to evaluate learning and memory.

RESULTS

Our findings reveal that CLP-induced hippocampus-dependent cognitive deficits coincided with elevated HIF-1α and increased TNF-α, IL-1β, and IL-6 levels in both blood and hippocampus. Observable activation of microglial cells in the hippocampus and increased blood-brain barrier (BBB) permeability were also evident. HBOT mitigated HIF-1α, TNF-α, IL-1β, and IL-6 levels, attenuated microglial activation in the hippocampus, and significantly improved learning and memory deficits in CLP-exposed mice. Additionally, these outcomes were corroborated by injecting a lentivirus that overexpressed HIF-1α into the hippocampal region of the mice.

CONCLUSION

HIF-1α escalation induced peripheral and central inflammatory factors, promoting microglial activation, BBB impairment, and cognitive dysfunction. However, HBOT ameliorated these effects by reducing HIF-1α levels in Sepsis-Associated Encephalopathy.

Acupuncture for poststroke coma: A systematic review and meta-analysis

BACKGROUND

Despite being widely applied in clinical practice, the wake-promoting effect of acupuncture in poststroke coma patients remains controversial.

OBJECTIVE

This study aimed to evaluate the efficacy of acupuncture for the treatment of poststroke coma.

METHODS

Randomized controlled trials (RCTs) of acupuncture for treating poststroke coma were identified in PubMed, Cochrane Library, EMBASE, CNKI, WanFang and VIP up to 25 November 2023. The main outcomes were Glasgow Coma Scale (GCS) score, National Institute of Health Stroke Scale (NIHSS) score, awakening ratio and clinically effective ratio. Stata 17 and Review Manager 5.4 software were used for mate analysis.

RESULTS

A total of 34 RCTs involving 2757 patients were included. GCS (WMD = 1.78; 95% CI: 1.35 to 2.21) and NIHSS score (WMD = -2.84; 95% CI: -3.84 to -1.84) were significantly increased in acupuncture group compared with control group. Acupuncture combined with routine treatment may be better than routine treatment in improving the awakening ratio (RR= 1.65; 95% CI: 1.24 to 2.91) and the clinically effective ratio (RR= 1.20; 95% CI: 1.13 to 1.27). Some methodological flaws were identified in the included studies, including non-implementation of blinding, inappropriate disease assessment and heterogeneous interventions.

CONCLUSIONS

The existing evidence suggests that acupuncture combined with conventional treatment may be an effective treatment for poststroke coma patients. In the meantime, more high-quality RCTs are needed to demonstrate these findings due to methodological weaknesses like randomization, blinding, heterogeneous interventions and long-term follow-up.

Treating Alzheimer's disease using nanoparticle-mediated drug delivery strategies/systems

The administration of promising medications for the treatment of neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) is significantly hampered by the blood-brain barrier (BBB). Nanotechnology has recently come to light as a viable strategy for overcoming this obstacle and improving drug delivery to the brain. With a focus on current developments and prospects, this review article examines the use of nanoparticles to overcome the BBB constraints to improve drug therapy for AD The potential for several nanoparticle-based approaches, such as those utilizing lipid-based, polymeric, and inorganic nanoparticles, to enhance drug transport across the BBB are highlighted. To shed insight on their involvement in aiding effective drug transport to the brain, methods of nanoparticle-mediated drug delivery, such as surface modifications, functionalization, and particular targeting ligands, are also investigated. The article also discusses the most recent findings on innovative medication formulations encapsulated within nanoparticles and the therapeutic effects they have shown in both preclinical and clinical testing. This sector has difficulties and restrictions, such as the need for increased safety, scalability, and translation to clinical applications. However, the major emphasis of this review aims to provide insight and contribute to the knowledge of how nanotechnology can potentially revolutionize the worldwide treatment of NDDs, particularly AD, to enhance clinical outcomes.

Phase-Change Based Oxygen Carriers Improve Acute Cerebral Hypoxia

Stroke is the second leading cause of death worldwide, and hypoxia is a major crisis of the brain after stroke. Therefore, providing oxygen to the brain microenvironment can effectively protect neurons from damage caused by cerebral hypoxia. However, there is a lack of timely and effective means of oxygen delivery clinically to the brain for acute cerebral hypoxia. Here, a phase-change based nano oxygen carrier is reported, which can undergo a phase change in response to increasing temperature in the brain, leading to oxygen release. The nano oxygen carrier demonstrate intracerebral oxygen delivery capacity and is able to release oxygen in the hypoxic and inflammatory region of the brain. In the acute ischemic stroke mouse model, the nano oxygen carrier can effectively reduce the area of cerebral infarction and decrease the level of inflammation triggered by cerebral hypoxia. By taking advantage of the increase in temperature during cerebral hypoxia, phase-change oxygen carrier proposes a new intracerebral oxygen delivery strategy for reducing acute cerebral hypoxia.

Recent advances in the application of gasotransmitters in spinal cord injury

Spinal Cord Injury (SCI) is a condition characterized by complete or incomplete motor and sensory impairment, as well as dysfunction of the autonomic nervous system, caused by factors such as trauma, tumors, or inflammation. Current treatment methods primarily include traditional approaches like spinal canal decompression and internal fixation surgery, steroid pulse therapy, as well as newer techniques such as stem cell transplantation and brain-spinal cord interfaces. However, the above methods have limited efficacy in promoting axonal and neuronal regeneration. The challenge in medical research today lies in promoting spinal cord neuron regeneration and regulating the disrupted microenvironment of the spinal cord. Studies have shown that gas molecular therapy is increasingly used in medical research, with gasotransmitters such as hydrogen sulfide, nitric oxide, carbon monoxide, oxygen, and hydrogen exhibiting neuroprotective effects in central nervous system diseases. The gas molecular protect against neuronal death and reshape the microenvironment of spinal cord injuries by regulating oxidative, inflammatory and apoptotic processes. At present, gas therapy mainly relies on inhalation for systemic administration, which cannot effectively enrich and release gas in the spinal cord injury area, making it difficult to achieve the expected effects. With the rapid development of nanotechnology, the use of nanocarriers to achieve targeted enrichment and precise control release of gas at Sites of injury has become one of the emerging research directions in SCI. It has shown promising therapeutic effects in preclinical studies and is expected to bring new hope and opportunities for the treatment of SCI. In this review, we will briefly outline the therapeutic effects and research progress of gasotransmitters and nanogas in the treatment of SCI.

Hyperbaric oxygen therapy vs. pharmacological intervention in adults with fibromyalgia related to childhood sexual abuse: prospective, randomized clinical trial

Fibromyalgia syndrome (FMS) is a chronic pain syndrome characterized by disruptions in pain processing within the central nervous system. It exhibits a high prevalence among patients with a history of traumatic experiences, notably childhood sexual abuse (CSA). This study compared the efficacy of hyperbaric oxygen therapy (HBOT) to the current pharmacological standard of care for individuals suffering from CSA-related FMS. Forty-eight participants diagnosed with FMS and a history of CSA were randomly assigned to either the HBOT group (60 sessions of 100% oxygen at 2 ATA for 90 min, with air breaks every 5 min) or the medication (MED) group (FDA-approved medications, Pregabalin and Duloxetine). The primary endpoint was the Fibromyalgia impact questionnaire (FIQ) score, while secondary endpoints encompassed emotional status and daily functioning questionnaires, as well as pain thresholds and conditioned pain modulation tests. Brain activity was evaluated through single photon emission computed tomography (SPECT). Results revealed a significant group-by-time interaction for the FIQ score favoring HBOT over MED (p < 0.001), with a large effect size (Cohen's d = - 1.27). Similar findings were observed in emotional symptoms and functional measures. SPECT imaging demonstrated an increase in activity in pre-frontal and temporal brain areas, which correlated with symptoms improvement. In conclusion, HBOT exhibited superior benefits over medications in terms of physical, functional, and emotional improvements among FMS patients with a history of CSA. This associated with increased activity in pre-frontal and temporal brain areas, highlighting the neuroplasticity effect of HBOT.

Hyperbaric Oxygen Improves Long-Term Learning and Memory Impairment by Attenuating Neuronal Apoptosis in aMCI Rats

Background

With the aging of the population and the increasing incidence of neurological diseases, amnestic mild cognitive impairment (aMCI) has attracted attention. Hyperbaric oxygen (HBO) has gradually shown the potential in the treatment of aMCI as an emerging treatment method in recent times. This study is to observe the effect of HBO on the long-term learning memory of aMCI rats, and investigate the associated mechanisms.

Methods

Seventy-two male rats (4-month-old) were randomly divided into control (CON) group, aMCI group, HBO group, 24 rats in each group. Each group was randomly divided into CON1, CON7, CON28; aMCI1, aMCI7, aMCI28; HBO1, HBO7, HBO28, 8 rats in each group. The aMCI model rats were established in aMCI and HBO groups. HBO group was treated with HBO for 7 days. The ethological and cytopathology which include Morris water maze (MWM) test, HE staining, TUNEL staining and the expression of Fas/FasL on neuron membrane were conducted to evaluate the effects of HBO on day 1, day 7 and day 28 after HBO treatment.

Results

MWM test showed that the spatial learning and memory ability of the rats decreased in aMCI group, and recovered in HBO group; Compared with aMCI group, the pathological damage of hippocampal nerve cells was alleviated, the number of apoptotic cells was significantly reduced (P < 0.05), and the expression of Fas/FasL on the surface of nerve cell membrane was significantly weakened in HBO group (P < 0.05). There were no significant changes in the spatial learning and memory ability, pathological damage of hippocampal neurons, the number of apoptotic cells, and the changes of Fas/FasL on the surface of hippocampal neurons in HBO1, HBO7, and HBO28 groups (P > 0.05). However, in aMCI1, aMCI7, and aMCI28 groups gradually aggravated (P < 0.05).

Conclusion

1. HBO can improve the long-term learning and memory impairment by attenuating neuronal apoptosis in aMCI rats. 2. Fas/FasL mediated cell receptor death pathway is involved in the apoptosis of hippocampal neurons.

The effects of hyperbaric oxygen therapy on neuroprotection and recovery after brain resuscitation

OBJECTIVE

Analyze the impact of hyperbaric oxygen therapy on neuroprotection and recovery post severe traumatic brain injury (sTBI) resuscitation.

METHODS

Retrospective analysis of clinical data from 83 sTBI patients admitted between January 2022 to January 2024. Patients were divided into control (n = 41) and observation (n = 42) groups based on treatment received. Control received standard therapy, while the observation group received hyperbaric oxygen therapy. Effects on clinical outcomes, neuroinjury markers (S100β, GFAP, UCH-L1, NSE), neurotrophic factors (NGF, BDNF), neurological function indicators (NIHSS, CSS), and adverse reactions were compared.

RESULTS

The observation group showed a higher total effective rate (80.95%) compared to control (60.98%) (p < 0.05). Neuroinjury markers decreased post-treatment in both groups, with the observation group lower (p < 0.05). NGF and BDNF levels increased post-treatment in both groups, with the observation group higher (p < 0.05). NIHSS and CSS scores decreased post-treatment in both groups, with the observation group lower (p < 0.05). No significant difference in adverse reactions between groups (p > 0.05).

CONCLUSION

Hyperbaric oxygen therapy effectively treats sTBI by improving brain resuscitation success, reducing neuroinjury factors, enhancing neurotrophic factors, and promoting neurological function recovery, without increasing adverse reaction risk.

Therapeutic effects of long-term HBOT on Alzheimer's disease neuropathologies and cognitive impairment in APPswe/PS1dE9 mice

Alzheimer's disease (AD) is the most common neurodegenerative disorder with the pathological hallmarks of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. Although there is a hope that anti-amyloid monoclonal antibodies may emerge as a new therapy for AD, the high cost and side effect is a big concern. Non-drug therapy is attracting more attention and may provide a better resolution for the treatment of AD. Given the fact that hypoxia contributes to the pathogenesis of AD, hyperbaric oxygen therapy (HBOT) may be an effective intervention that can alleviate hypoxia and improve AD. However, it remains unclear whether long-term HBOT intervention in the early stage of AD can slow AD progression and ultimately prevent cognitive impairment in this disease. In this study we applied consecutive 3-month HBOT interventions on 3-month-old APPswe/PS1dE9 AD mice which represent the early stage of AD. When the APPswe/PS1dE9 mice at 9-month-old which represent the disease stage we measured cognitive function, 24-h blood oxygen saturation, Aβ and tau pathologies, vascular structure and function, and neuroinflammation in APPswe/PS1dE9 mice. Our results showed that long-term HBOT can attenuate the impairments in cognitive function observed in 9-month-old APPswe/PS1dE9 mice. Most importantly, HBOT effectively reduced the progression of Aβ plaques deposition, hyperphosphorylated tau protein aggregation, and neuronal and synaptic degeneration in the AD mice. Further, long-term HBOT was able to enhance blood oxygen saturation level. Besides, long-term HBOT can improve vascular structure and function, and reduce neuroinflammation in AD mice. This study is the first to demonstrate that long-term HBOT intervention in the early stage of AD can attenuate cognitive impairment and AD-like pathologies. Overall, these findings highlight the potential of long-term HBOT as a disease-modifying approach for AD treatment.

Effects of Hyperbaric Oxygen Therapy on Long COVID: A Systematic Review

The coronavirus disease (COVID-19) pandemic has resulted in an increasing population that is experiencing a wide range of long-lasting symptoms after recovery from the acute infection. Long COVID refers to this specific condition and is associated with diverse symptoms, such as fatigue, myalgias, dyspnea, headache, cognitive impairment, neurodegenerative symptoms, anxiety, depression, and a sense of despair. The potential of hyperbaric oxygen therapy (HBOT) to improve chronic fatigue, cognitive impairments, and neurological disorders has been established; therefore, the use of HBOT to treat long COVID has also been studied. We conducted a literature search between 1 January 2019 and 30 October 2023, focusing on the clinical efficacy and utility of HBOT for treating long COVID and found ten clinical studies that fit the review topic, including one case report, five one-group pretest-posttest design studies, one safety report from a randomized controlled trial (RCT), and three complete reports of RCTs. Most studies found that HBOT can improve quality of life, fatigue, cognition, neuropsychiatric symptoms, and cardiopulmonary function. Although HBOT has shown some benefits for long COVID symptoms, further rigorous large-scale RCTs are required to establish precise indications, protocols, and post-treatment evaluations.

Effects of hyperbaric oxygen therapy on autistic behaviors and GRIN2B gene expression in valproic acid-exposed rats

Introduction

Autism is a complex neurodevelopmental condition characterized by deficits in social interaction, communication, and restricted repetitive behaviors. Hyperbaric oxygen therapy (HBOT) has emerged as a potential treatment for autism, although its effects on behavior and gene expression are not well understood. The GRIN2B gene, known for its involvement in encoding a glutamate receptor subunit crucial for neuron communication and associated with autism, was a focus of this study.

Methods

Using a rat model induced by prenatal exposure to valproic acid, we examined the impact of HBOT on autism-like behaviors and GRIN2B gene expression. Male Wistar rats were categorized into four groups: control, VPA (valproic acid-exposed), VPA+HBOT [2 atmosphere absolute (ATA)], and VPA+HBOT (2.5 ATA). The rats underwent several behavioral tests to assess social behavior, anxiety, stereotype and exploratory behaviors, and learning. Following the behavioral tests, the HBOT groups received 15 sessions of HBOT at pressures of 2 and 2.5 (ATA), and their behaviors were re-evaluated. Subsequently, real-time PCR was employed to measure GRIN2B gene expression in the frontal lobe.

Results

Our results indicated that HBOT significantly increased social interaction and exploratory behaviors in VPA-exposed rats, alongside elevated GRIN2B gene expression in their frontal lobe.

Discussion

Our findings imply that HBOT might have a potential role in ameliorating autism-related behaviors in the VPA rat model of autism through potential modulation of GRIN2B gene expression. However, additional research is essential to fully comprehend the underlying mechanisms and refine the HBOT protocol for optimizing its effectiveness in improving autism-related symptoms.

Engineering tumor-oxygenated nanomaterials: advancing photodynamic therapy for cancer treatment

Photodynamic therapy (PDT), a promising treatment modality, employs photosensitizers to generate cytotoxic reactive oxygen species (ROS) within localized tumor regions. This technique involves administering a photosensitizer followed by light activation in the presence of oxygen (O2), resulting in cytotoxic ROS production. PDT's spatiotemporal selectivity, minimally invasive nature, and compatibility with other treatment modalities make it a compelling therapeutic approach. However, hypoxic tumor microenvironment (TME) poses a significant challenge to conventional PDT. To overcome this hurdle, various strategies have been devised, including in-situ O2 generation, targeted O2 delivery, tumor vasculature normalization, modulation of mitochondrial respiration, and photocatalytic O2 generation. This review aims to provide a comprehensive overview of recent developments in designing tumor-oxygenated nanomaterials to enhance PDT efficacy. Furthermore, we delineate ongoing challenges and propose strategies to improve PDT's clinical impact in cancer treatment.

Long term outcomes of hyperbaric oxygen therapy in post covid condition: longitudinal follow-up of a randomized controlled trial

In our previous randomized controlled trial, we documented significant improvements in cognitive, psychiatric, fatigue, sleep, and pain symptoms among long Coronavirus disease 2019 (COVID) patients who underwent hyperbaric oxygen therapy (HBOT). The primary objective of the present study was to evaluate the enduring 1 year long term effects of HBOT on long COVID syndrome. This longitudinal long-term follow-up included 31 patients with reported post COVID-19 cognitive symptoms, who underwent 40 daily sessions of HBOT. Participants were recruited more than one year (486 ± 73) after completion of the last HBOT session. Quality of life, assessed using the short form-36 (SF-36) questionnaire revealed, that the long-term results exhibited a similar magnitude of improvement as the short-term outcomes following HBOT across most domains. Regarding sleep quality, improvements were observed in global score and across five sleep domains with effect sizes of moderate magnitude during the short-term evaluation, and these improvements persisted in the long-term assessment (effect size (ES1) = 0.47-0.79). In the realm of neuropsychiatric symptoms, as evaluated by the brief symptom inventory-18 (BSI-18), the short-term assessment following HBOT demonstrated a large effect size, and this effect persisted at the long-term evaluation. Both pain severity (ES1 = 0.69) and pain interference (ES1 = 0.83), had significant improvements during the short-term assessment post HBOT, which persisted at long term. The results indicate HBOT can improve the quality of life, quality of sleep, psychiatric and pain symptoms of patients suffering from long COVID. The clinical improvements gained by HBOT are persistent even 1 year after the last HBOT session.

Efficacy and safety of hyperbaric oxygen therapy in acute ischaemic stroke: a systematic review and meta-analysis

OBJECTIVE

This study aims to evaluate the efficacy and safety of adjunctive hyperbaric oxygen therapy (HBOT) in acute ischaemic stroke (AIS) based on existing evidence.

METHODS

We conducted a comprehensive search through April 15, 2023, of seven major databases for randomized controlled trials (RCTs) comparing adjunctive hyperbaric HBOT with non-HBOT (no HBOT or sham HBOT) treatments for AIS. Data extraction and assessment were independently performed by two researchers. The quality of included studies was evaluated using the tool provided by the Cochrane Collaboration. Meta-analysis was conducted using Rev Man 5.3.

RESULTS

A total of 8 studies involving 493 patients were included. The meta-analysis showed no statistically significant differences between HBOT and the control group in terms of NIHSS score (MD = -1.41, 95%CI = -7.41 to 4.58), Barthel index (MD = 8.85, 95%CI = -5.84 to 23.54), TNF-α (MD = -5.78, 95%CI = -19.93 to 8.36), sICAM (MD = -308.47, 95%CI = -844.13 to 13227.19), sVCAM (MD = -122.84, 95%CI = -728.26 to 482.58), sE-selectin (MD = 0.11, 95%CI = -21.86 to 22.08), CRP (MD = -5.76, 95%CI = -15.02 to 3.51), adverse event incidence within ≤ 6 months of follow-up (OR = 0.98, 95%CI = 0.25 to 3.79). However, HBOT showed significant improvement in modified Rankin score (MD = 0.10, 95%CI = 0.03 to 0.17), and adverse event incidence at the end of treatment (OR = 0.42, 95%CI = 0.19 to 0.94) compared to the control group.

CONCLUSION

While our findings do not support the routine use of HBOT for improving clinical outcomes in AIS, further research is needed to explore its potential efficacy within specific therapeutic windows and for different cerebral occlusion scenarios. Therefore, the possibility of HBOT offering clinical benefits for AIS cannot be entirely ruled out.

Predicting acute brain lesions on magnetic resonance imaging in acute carbon monoxide poisoning: a multicenter prospective observational study

An acute brain lesion (ABL) identified by brain magnetic resonance imaging (MRI) after acute carbon monoxide (CO) poisoning is a strong prognostic factor for the development of delayed neuropsychiatric syndrome (DNS). This study aimed to identify predictors of ABLs on MRI in patients with acute CO poisoning. This was a multicenter prospective registry-based observational study conducted at two tertiary hospitals. A total of 1,034 patients were included. Multivariable logistic regression analysis showed that loss of consciousness (LOC) (adjusted odds ratio [aOR] 2.68, 95% Confidence Interval [CI]: 1.49-5.06), Glasgow Coma Scale (GCS) score < 9 (aOR 2.41, 95% CI: 1.49-3.91), troponin-I (TnI) (aOR 1.22, 95% CI: 1.08-1.41), CO exposure duration (aOR 1.09, 95% CI: 1.05-1.13), and white blood cell (WBC) (aOR 1.05, 95% CI: 1.01-1.09) were independent predictors of ABLs on MRI. LOC, GCS score, TnI, CO exposure duration, and WBC count can be useful predictors of ABLs on MRI in patients with acute CO poisoning, helping clinicians decide the need for an MRI scan or transfer the patient to an appropriate institution for MRI or hyperbaric oxygen therapy.

Hyperbaric oxygen treatment in carbon monoxide poisoning - Does it really matter?

Carbon monoxide (CO) is an odorless and colorless gas that can lead to fulminant and life-threatening intoxications. Besides an early diagnosis, an appropriate treatment of the intoxication is important. In this context the reduction of CO concentration in blood and tissues is crucial revealing hyperbaric oxygen treatment (HBO) as a highly promising tool. However, the benefit of HBO in CO intoxications is still considered controversial. In this review, we discuss the evidence of the role of HBO treatment in isolated CO intoxication.

Effect of hyperbaric oxygen on symptoms of dementia in patients with delayed encephalopathy after acute carbon monoxide poisoning

OBJECTIVES

Delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) is the most severe complication of carbon monoxide poisoning, which seriously endangers patients' quality of life. This study aims to investigate the efficacy of hyperbaric oxygen (HBO2) on improving dementia symptoms in patients with DEACMP.

METHODS

A retrospective analysis was performed on DEACMP patients, who visited Xiangya Hospital, Central South University from June 2014 to June 2020. Among them, patients who received conventional drug treatment combined with HBO2 treatment were included in an HBO2 group, while those who only received conventional drug treatment were included in a control group. HBO2 was administered once daily. Patients in the HBO2 group received 6 courses of treatment, with each course consisting of 10 sessions. The Hasegawa Dementia Scale (HDS) was used to diagnose dementia, and the Clinical Dementia Rating (CDR) was used to grade the severity of dementia for DEACMP. The Alzheimer's Disease Assessment Scale-Cognitive Section (ADAS-Cog), the Functional Activities Questionnaire (FAQ), the Neuropsychiatric Inventory (NPI), and the Clinician's Interview-Based Impression of Change-Plus Caregiver Input (CIBIC-Plus) were performed to assess cognitive function, ability to perform activities of daily living (ADL), behavioral and psychological symptoms, and overall function. The study further analyzed the results of objective examinations related to patients' dementia symptoms, including magnetic resonance imaging detection of white matter lesions and abnormal electroencephalogram (EEG). The changes of the above indicators before and after treatment, as well as the differences between the 2 groups after treatment were compared.

RESULTS

There was no significant difference in the HDS score and CDR grading between the 2 groups before treatment (both P>0.05). After treatment, the score of ADAS-Cog, FAQ, NPI, and CIBIC Plus grading of the 2 groups were significantly improved, and the improvement of the above indicators in the HBO2 group was greater than that in the control group (all P<0.05). The effective rate of the HBO2 group in treating DEACMP was significantly higher than that of the control group (89.47% vs 65.87%, P<0.05). The objective examination results (white matter lesions and abnormal EEG) showed that the recovery of patients in the HBO2 group was better than that in the control group.

CONCLUSIONS

Hyperbaric oxygen can significantly relieve the symptoms of dementia in patients with DEACMP.

Cardiopulmonary resuscitation during hyperbaric oxygen therapy: a comprehensive review and recommendations for practice

BACKGROUND

Cardiopulmonary resuscitation (CPR) during hyperbaric oxygen therapy (HBOT) presents unique challenges due to limited access to patients in cardiac arrest (CA) and the distinct physiological conditions present during hyperbaric therapy. Despite these challenges, guidelines specifically addressing CPR during HBOT are lacking. This review aims to consolidate the available evidence and offer recommendations for clinical practice in this context.

MATERIALS AND METHODS

A comprehensive literature search was conducted in PubMed, EMBASE, Cochrane Library, and CINAHL using the search string: "(pressure chamber OR decompression OR hyperbaric) AND (cardiac arrest OR cardiopulmonary resuscitation OR advanced life support OR ALS OR life support OR chest compression OR ventricular fibrillation OR heart arrest OR heart massage OR resuscitation)". Additionally, relevant publications and book chapters not identified through this search were included.

RESULTS

The search yielded 10,223 publications, with 41 deemed relevant to the topic. Among these, 18 articles (primarily case reports) described CPR or defibrillation in 22 patients undergoing HBOT. The remaining 23 articles provided information or recommendations pertaining to CPR during HBOT. Given the unique physiological factors during HBOT, the limitations of current resuscitation guidelines are discussed.

CONCLUSIONS

CPR in the context of HBOT is a rare, yet critical event requiring special considerations. Existing guidelines should be adapted to address these unique circumstances and integrated into regular training for HBOT practitioners. This review serves as a valuable contribution to the literature on "CPR under special circumstances".

Hyperbaric Oxygen Therapy Adjuvant Chemotherapy and Radiotherapy through Inhibiting Stemness in Glioblastoma

Glioblastoma multiforme (GBM) is the most common and deadliest primary brain tumor in adults. Despite the advances in GBM treatment, outcomes remain poor, with a 2-year survival rate of less than 5%. Hyperbaric oxygen (HBO) therapy is an intermittent, high-concentration, short-term oxygen therapy used to increase cellular oxygen content. In this study, we evaluated the effects of HBO therapy, alone or combined with other treatment modalities, on GBM in vitro and in vivo. In the in vitro analysis, we used a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to assess the effects of HBO therapy alone, a colony formation assay to analyze the effects of HBO therapy combined with radiotherapy and with temozolomide (TMZ), and a neurosphere assay to assess GBM stemness. In the in vivo analysis, we used immunohistochemical staining and in vivo bioluminescence imaging to assess GBM stemness and the therapeutic effect of HBO therapy alone or combined with TMZ or radiotherapy, respectively. HBO therapy did not affect GBM cell viability, but it did reduce the analyzed tumors' ability to form cancer stem cells. In addition, HBO therapy increased GBM sensitivity to TMZ and radiotherapy both in vitro and in vivo. HBO therapy did not enhance tumor growth and exhibited adjuvant effects to chemotherapy and radiotherapy through inhibiting GBM stemness. In conclusion, HBO therapy shows promise as an adjuvant treatment for GBM by reducing cancer stem cell formation and enhancing sensitivity to chemotherapy and radiotherapy.

Functional MRI evaluation of hyperbaric oxygen therapy effect on hand motor recovery in a chronic post-stroke patient: a case report and physiological discussion

Introduction

Impairments in activities of daily living (ADL) are a major concern in post-stroke rehabilitation. Upper-limb motor impairments, specifically, have been correlated with low quality of life. In the current case report, we used both task-based and resting state functional MRI (fMRI) tools to investigate the neural response mechanisms and functional reorganization underlying hyperbaric oxygen therapy (HBOT)-induced motor rehabilitation in a chronic post-stroke patient suffering from severe upper-limb motor impairment.

Methods

We studied motor task fMRI activation and resting-state functional connectivity (rsFC) in a 61-year-old right-handed male patient who suffered hemiparesis and physical weakness in the right upper limb, 2 years after his acute insult, pre- and post-treatment of 60 daily HBOT sessions. Motor functions were assessed at baseline and at the end of the treatment using the Fugl-Meyer assessment (FMA) and the handgrip maximum voluntary contraction (MVC).

Results

Following HBOT, the FMA score improved from 17 (severe impairment) to 31 (moderate impairment). Following the intervention during trials involving the affected hand, there was an observed increase in fMRI activation in both the supplementary motor cortex (SMA) and the premotor cortex (PMA) bilaterally. The lateralization index (LI) decreased from 1 to 0.63, demonstrating the recruitment of the contralesional hemisphere. The region of interest, ROI-to-ROI, analysis revealed increased post-intervention inter-hemispheric connectivity (P = 0.002) and a between-network connectivity increase (z-score: 0.35 ± 0.21 to 0.41 ± 0.21, P < 0.0001). Seed-to-voxel-based rsFC analysis using the right SMA as seed showed increased connectivity to the left posterior parietal cortex, the left primary somatosensory cortex, and the premotor cortex.

Conclusion

This study provides additional insights into HBOT-induced brain plasticity and functional improvement in chronic post-stroke patients.

Oxygen Variations-Insights into Hypoxia, Hyperoxia and Hyperbaric Hyperoxia-Is the Dose the Clue?

Molecular oxygen (O2) is one of the four most important elements on Earth (alongside carbon, nitrogen and hydrogen); aerobic organisms depend on it to release energy from carbon-based molecules [...].

The Mechanisms of Action of Hyperbaric Oxygen in Restoring Host Homeostasis during Sepsis

The perception of sepsis has shifted over time; however, it remains a leading cause of death worldwide. Sepsis is now recognized as an imbalance in host cellular functions triggered by the invading pathogens, both related to immune cells, endothelial function, glucose and oxygen metabolism, tissue repair and restoration. Many of these key mechanisms in sepsis are also targets of hyperbaric oxygen (HBO2) treatment. HBO2 treatment has been shown to improve survival in clinical studies on patients with necrotizing soft tissue infections as well as experimental sepsis models. High tissue oxygen tension during HBO2 treatment may affect oxidative phosphorylation in mitochondria. Oxygen is converted to energy, and, as a natural byproduct, reactive oxygen species are produced. Reactive oxygen species can act as mediators, and both these and the HBO2-mediated increase in oxygen supply have the potential to influence the cellular processes involved in sepsis. The pathophysiology of sepsis can be explained comprehensively through resistance and tolerance to infection. We argue that HBO2 treatment may protect the host from collateral tissue damage during resistance by reducing neutrophil extracellular traps, inhibiting neutrophil adhesion to vascular endothelium, reducing proinflammatory cytokines, and halting the Warburg effect, while also assisting the host in tolerance to infection by reducing iron-mediated injury and upregulating anti-inflammatory measures. Finally, we show how inflammation and oxygen-sensing pathways are connected on the cellular level in a self-reinforcing and detrimental manner in inflammatory conditions, and with support from a substantial body of studies from the literature, we conclude by demonstrating that HBO2 treatment can intervene to maintain homeostasis.

Oxidative Stress Response Kinetics after 60 Minutes at Different (1.4 ATA and 2.5 ATA) Hyperbaric Hyperoxia Exposures

Hyperbaric oxygen therapy (HBOT) is a therapeutical approach based on exposure to pure oxygen in an augmented atmospheric pressure. Although it has been used for years, the exact kinetics of the reactive oxygen species (ROS) between different pressures of hyperbaric oxygen exposure are still not clearly evidenced. In this study, the metabolic responses of hyperbaric hyperoxia exposures for 1 h at 1.4 and 2.5 ATA were investigated. Fourteen healthy non-smoking subjects (2 females and 12 males, age: 37.3 ± 12.7 years old (mean ± SD), height: 176.3 ± 9.9 cm, and weight: 75.8 ± 17.7 kg) volunteered for this study. Blood samples were taken before and at 30 min, 2 h, 24 h, and 48 h after a 1 h hyperbaric hyperoxic exposure. The level of oxidation was evaluated by the rate of ROS production, nitric oxide metabolites (NOx), and the levels of isoprostane. Antioxidant reactions were assessed through measuring superoxide dismutase (SOD), catalase (CAT), cysteinylglycine, and glutathione (GSH). The inflammatory response was measured using interleukine-6, neopterin, and creatinine. A short (60 min) period of mild (1.4 ATA) and high (2.5 ATA) hyperbaric hyperoxia leads to a similar significant increase in the production of ROS and antioxidant reactions. Immunomodulation and inflammatory responses, on the contrary, respond proportionally to the hyperbaric oxygen dose. Further research is warranted on the dose and the inter-dose recovery time to optimize the potential therapeutic benefits of this promising intervention.

Hyperbaric Oxygen Therapy versus placebo for post-concussion syndrome (HOT-POCS): A randomized, double-blinded controlled pilot study

Post-Concussion Syndrome (PCS) refers to the persistence of physical, cognitive, and emotional symptoms following mild traumatic brain injury (mTBI)/concussion, occurring in roughly 15-30% of individuals. Hyperbaric oxygen therapy (HBOT) has been suggested as a potential treatment for PCS; however, the evidence to date is mixed due to inconsistencies in the treatment protocol and focus on veterans with combat-related injuries, which may not be generalizable to the general population. The goal of Hyperbaric Oxygen Therapy for Post-Concussion Syndrome (HOT-POCS) is to assess the efficacy and safety of HBOT for the treatment of PCS in the civilian population. This randomized, controlled pilot study will be using a standardized HBOT protocol (20 sessions of 100% O₂ at 2.0 atm absolute [ATA]) compared with a true placebo gas system that mimics the oxygen composition at room air (20 sessions of 10.5% O₂ and 89.5% nitrogen at 2.0 ATA) in a cohort of 100 adults with persistent post-concussive symptoms 3-12 months following injury. Change in symptoms on the Rivermead Post-concussion Questionnaire (RPQ) will be the primary outcome of interest. Secondary outcomes include the rate of adverse events, change in the quality of life, and change in cognitive function. Exploratory outcome measures will include changes in physical function and changes in cerebral brain perfusion and oxygen metabolism on MRI brain imaging. Overall, the HOT-POCS study will compare the efficacy of a standardized HBOT treatment protocol against a true placebo gas for the treatment of PCS within 12 months after injury.

The effect of hyperbaric oxygen therapy on myocardial function in post-COVID-19 syndrome patients: a randomized controlled trial

Post-COVID-19 condition refers to a range of persisting physical, neurocognitive, and neuropsychological symptoms following SARS-CoV-2 infection. Recent evidence revealed that post-COVID-19 syndrome patients may suffer from cardiac dysfunction and are at increased risk for a broad range of cardiovascular disorders. This randomized, sham-control, double-blind trial evaluated the effect of hyperbaric oxygen therapy (HBOT) on the cardiac function of post-COVID-19 patients with ongoing symptoms for at least three months after confirmed infection. Sixty patients were randomized to receive 40 daily HBOT or sham sessions. They underwent echocardiography at baseline and 1-3 weeks after the last protocol session. Twenty-nine (48.3%) patients had reduced global longitudinal strain (GLS) at baseline. Of them, 13 (43.3%) and 16 (53.3%) were allocated to the sham and HBOT groups, respectively. Compared to the sham group, GLS significantly increased following HBOT (- 17.8 ± 1.1 to - 20.2 ± 1.0, p = 0.0001), with a significant group-by-time interaction (p = 0.041). In conclusion, post-COVID-19 syndrome patients despite normal EF often have subclinical left ventricular dysfunction that is characterized by mildly reduced GLS. HBOT promotes left ventricular systolic function recovery in patients suffering from post COVID-19 condition. Further studies are needed to optimize patient selection and evaluate long-term outcomes.This study was registered with ClinicalTrials.gov, number NCT04647656 on 01/12/2020.

Hyperbaric Oxygen Therapy in Orthopaedics: An Adjunct Therapy with an Emerging Role

Introduction

Hyperbaric oxygen therapy (HBOT) has emerged as an adjunct treatment modality in various orthopedic and rheumatological conditions. Undersea and Hyperbaric Medical Society (UHMS) defined the minimum number of HBOT cycles, dose, and frequency for various diseases. UHMS laid the 14 absolute indications for HBOT. This article deals with the mechanism of actions of HBOT and evidence of various musculoskeletal disorders where HBOT was utilized to accelerate the healing process of the diseases.

Materials and methods

The review literature search was conducted by using PubMed, SCOPUS, and other database of medical journals for identifying, reviewing, and evaluating the published clinical trial data, research study, and review articles for the use of HBOT in musculoskeletal disorders.

Results

Various clinical researchers documented cellular and biochemical advantages of HBOT which possess allodynic effects, anti-inflammatory, and prooxygenatory effects in patients with musculoskeletal conditions. Studies on the usage of HBOT in avascular necrosis and wound healing provide a platform for exploring the plausible uses of HBOT in other musculoskeletal conditions. Literature evidence states the complications associated with HBOT therapy.

Conclusion

The existing HBOT protocols have to be optimized for various musculoskeletal disorders. Large scale blinded RCTs have to be performed for demonstrating the level of evidence in the usage of HBOT in various musculoskeletal clinical scenarios.

Efficacy and association of hyperbaric oxygen therapy combined with butylphthalide and oxiracetam with serum levels of inflammatory markers in vascular cognitive impairment after acute ischemic stroke

Objectives

This study evaluated the efficacy of hyperbaric oxygen therapy (HBOT) combined with butylphthalide (NBP) and oxiracetam (OXR) for vascular cognitive impairment after acute ischemic stroke and investigated the association between such combination therapy and the serum levels of inflammatory markers.

Methods

This was a prospective study which included eighty patients with post-AIS cognitive impairment (PAISCI) treated in Dongguan City People's Hospital from January 2020 to January 2022. They were randomized into study group and control group. The control group was provided with conventional therapy consisting of NBP for intravenous transfusion and oral OXR, while the study group received combination therapy of HBOT, NBP, and OXR. A comparison was drawn between the two groups regarding clinical outcomes, levels of recovery of cognitive and neurological function and intelligence, changes in inflammatory markers, and incidence of adverse drug reactions (ADRs).

Results

The response rate of the study group was significantly higher than that of the control group (p=0.04). The cognitive function scores of the study group were significantly better than those of the control group at the end of treatment (p<0.05). The post-treatment levels of inflammatory markers were significantly reduced in the study group when compared with the control group (p<0.05). At two weeks after treatment, the ADR rate of study group was significantly lower than the control group (p=0.03).

Conclusions

The combination therapy of HBOT, NBP, and OXR demonstrates robust efficacy in patients with PAISCI. It is deemed to be a safe and effective treatment regimen.

The potential of hyperbaric oxygen as a therapy for neurodegenerative diseases

The World Health Organization estimates that by the year 2040, neurodegenerative diseases will be the second leading cause of death in developed countries, overtaking cancer-related deaths and exceeded only by cardiovascular disease-related death. The search for interventions has therefore become paramount to alleviate some of this burden. Based on pathways affected in neurodegenerative diseases, hyperbaric oxygen treatment (HBOT) could be a good candidate. This therapy has been used for the past 50 years for conditions such as decompression sickness and wound healing and has been shown to have promising effects in conditions associated with neurodegeneration and functional impairments. The goal of this review was to explore the history of hyperbaric oxygen therapy, its uses, and benefits, and to evaluate its effectiveness as an intervention in treating neurodegenerative diseases. Additionally, we examined common mechanisms underlying the effects of HBOT in different neurodegenerative diseases, with a special emphasis on epigenetics.

Hyperbaric Oxygen Therapy Alleviates Paclitaxel-Induced Peripheral Neuropathy Involving Suppressing TLR4-MyD88-NF-κB Signaling Pathway

Paclitaxel (PAC) results in long-term chemotherapy-induced peripheral neuropathy (CIPN). The coexpression of transient receptor potential vanilloid 1 (TRPV1) and Toll-like receptor 4 (TLR4) in the nervous system plays an essential role in mediating CIPN. In this study, we used a TLR4 agonist (lipopolysaccharide, LPS) and a TLR4 antagonist (TAK-242) in the CIPN rat model to investigate the role of TLR4-MyD88 signaling in the antinociceptive effects of hyper-baric oxygen therapy (HBOT). All rats, except a control group, received PAC to induce CIPN. Aside from the PAC group, four residual groups were treated with either LPS or TAK-242, and two of them received an additional one-week HBOT (PAC/LPS/HBOT and PAC/TAK-242/HBOT group). Mechanical allodynia and thermal hyperalgesia were then assessed. The expressions of TRPV1, TLR4 and its downstream signaling molecule, MyD88, were investigated. The mechanical and thermal tests revealed that HBOT and TAK-242 alleviated behavioral signs of CIPN. Immunofluorescence in the spinal cord dorsal horn and dorsal root ganglion revealed that TLR4 overexpression in PAC- and PAC/LPS-treated rats was significantly downregulated after HBOT and TAK-242. Additionally, Western blots showed a significant reduction in TLR4, TRPV1, MyD88 and NF-κB. Therefore, we suggest that HBOT may alleviate CIPN by modulating the TLR4-MyD88-NF-κB pathway.

Quercetin in combination with hyperbaric oxygen therapy synergistically attenuates damage progression in traumatic spinal cord injury in a rat model

BACKGROUND

Oxidative stress, inflammation and cell apoptosis are the most important destructive factors in the spread of damage following trauma to the spinal cord. Therefore, presently, we investigated the synergistic effects of quercetin along with hyperbaric oxygen therapy (HBOT) as strong antioxidant, anti-inflammatory and anti-apoptotic compounds in the recovery of traumatic spinal cord injury (TSCI) in a rat model.

MATERIAL AND METHODS

Seventy-five male mature Sprague-Dawley rats allocated into 5 groups, including: Sham group (SG), TSCI group, Quercetin group (underwent TSCI and received quercetin), HBOT group (underwent TSCI and received HBOT), and Quercetin+ HBOT group (underwent TSCI and received quercetin plus HBOT). Finally, the spinal cord samples at the traumatic site were harvested and various characteristics were evaluated, including the total volumes of the spinal cord and its central cavity as well as the numerical density of neuron and glial cells by stereological method, oxidant (malondialdehyde; MDA) and antioxidant (glutathione; GSH, superoxide dismutase; SOD and catalase; CAT) factors by biochemical method, molecular levels of IL-10, TNF-α and IL-1β by qRT-PCR method, and cell apoptosis by immunohistochemistry method against Caspase-3 antibody. Furthermore, Basso-Beattie-Bresnahan (BBB) and electromyography latency (EMG Latency) tests were performed to evaluate neurological functions.

RESULTS

Findings demonstrated that the stereological characteristics, biochemical factors (except MDA), expression of IL-10 gene and behavioral functions were significantly better in Quercetin, HBOT and Quercetin+HBOT groups than TSCI group, and were greater in Quercetin+HBOT ones (P < 0.05). While MDA levels, expression of TNF-α and IL-1β genes as well as the density of apoptotic cells significantly more decreased in Quercetin+HBOT group compared to other treated groups (P < 0.05).

CONCLUSION

Overall, co-administration of quercetin with HBOT has synergistic neuroprotective effects in animals underwent TSCI.

Hyperbaric Oxygen Therapy and Tissue Regeneration: A Literature Survey

By addressing the mechanisms involved in transcription, signaling, stress reaction, apoptosis and cell-death, cellular structure and cell-to-cell contacts, adhesion, migration as well as inflammation; HBO upregulates processes involved in repair while mechanisms perpetuating tissue damage are downregulated. Many experimental and clinical studies, respectively, cover wound healing, regeneration of neural tissue, of bone and cartilage, muscle, and cardiac tissue as well as intestinal barrier function. Following acute injury or in chronic healing problems HBO modulates proteins or molecules involved in inflammation, apoptosis, cell growth, neuro- and angiogenesis, scaffolding, perfusion, vascularization, and stem-cell mobilization, initiating repair by a variety of mechanisms, some of them based on the modulation of micro-RNAs. HBO affects the oxidative stress response via nuclear factor erythroid 2-related factor 2 (Nrf2) or c-Jun N-terminal peptide and downregulates inflammation by the modulation of high-mobility group protein B1 (HMGB-1), toll-like receptor 4 and 2 (TLR-4, TLR-2), nuclear factor kappa-B (NFκB), hypoxia-inducible factor (HIF-1α) and nitric oxide (NO•). HBO enhances stem-cell homeostasis via Wnt glycoproteins and mammalian target of rapamycin (mTOR) and improves cell repair, growth, and differentiation via the two latter but also by modulation of extracellular-signal regulated kinases (ERK) and the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathway. The HBO-induced downregulation of matrix metalloproteinases-2 and 9 (MMP-2/-9), rho-associated protein kinase (ROCK) and integrins improve healing by tissue remodeling. Interestingly, the action of HBO on single effector proteins or molecules may involve both up- or downregulation, respectively, depending on their initial level. This probably mirrors a generally stabilizing potential of HBO that tends to restore the physiological balance rather than enhancing or counteracting single mechanisms.

Effect of Hyperbaric Oxygen Therapy on Sleep Quality, Drug Dosage, and Nerve Function in Patients with Sleep Disorders after Ischemic Cerebral Stroke

Objective. To explore the effects of hyperbaric oxygen therapy (HOT) on sleep quality, drug dosage, and nerve function in patients with sleep disorders after ischemic cerebral stroke (ICS). Methods. A total of 120 patients with acute ICS and sleep disorders who came to our hospital for treatment from January 2019 to October 2021 were selected and divided into control and observation groups according to the random numbering method, with 60 cases in each group. Both groups were treated with sertraline and eszopiclone for treating insomnia. The control group was given routine treatment for ICS, and the observation group was additionally treated with HOT in addition to the control group. The sleep quality, the use of sleep medication, the neurological function score, and the levels of serum tumor necrosis factor-α (TNF-α), endothelin (ET), and neuropeptide Y (NPY) before and after treatment were compared between the two groups. Results. The levels of TNF-α, ET and NPY were not significantly different between the two groups of patients before treatment ( $P>0.05$ ), and all of the above indicators decreased significantly in both groups after treatment, with the observation group being lower than the control group ( $P<0.05$ ). There was no significant difference in the sleep quality scores of PSQI, ESS, and SBQ between the two groups before treatment ( $P>0.05$ ), and the above indicators decreased significantly in both groups after treatment, with the observation group being lower than the control group ( $P<0.05$ ). There was no significant difference in the dose of sleep medication used in the first day of treatment between the two groups ( $P>0.05$ ), and the amount of sleep medication used in the observation group was significantly less than that in the control group after 14 d of treatment ( $P<0.05$ ). There was no significant difference in the NIHSS scores between the two groups before treatment ( $P>0.05$ ), and the scores of both groups decreased after treatment, and the scores of the observation group were significantly lower than those of the control group ( $P<0.05$ ). Conclusion. Compared with routine treatment, the addition of HOT to treat patients with sleep disorders after ICS can significantly improve their sleep quality, reduce dosage of sleep drugs, reduce inflammatory level of brain tissue and nerve function damage, and improve their prognosis. Trial Registration. This study was registered in the EA2019056

Hyperbaric oxygen therapy in children with post-concussion syndrome improves cognitive and behavioral function: a randomized controlled trial

Persistent post-concussion syndrome (PPCS) is a common and significant morbidity among children following traumatic brain injury (TBI) and the evidence for effective PPCS treatments remains limited. Recent studies have shown the beneficial effects of hyperbaric oxygen therapy (HBOT) in PPCS adult patients. This randomized, sham-control, double blind trial evaluated the effect of hyperbaric oxygen therapy (HBOT) on children (age 8–15) suffering from PPCS from mild-moderate TBI events six months to 10 years prior. Twenty-five children were randomized to receive 60 daily sessions of HBOT (n = 15) or sham (n = 10) treatments. Following HBOT, there was a significant increase in cognitive function including the general cognitive score (d = 0.598, p = 0.01), memory (d = 0.480, p = 0.02), executive function (d = 0.739, p = 0.003), PPCS symptoms including emotional score (p = 0.04, d = – 0.676), behavioral symptoms including hyperactivity (d = 0.244, p = 0.03), global executive composite score (d = 0.528, p = 0.001), planning/organizing score (d = 1.09, p = 0.007). Clinical outcomes correlated with significant improvements in brain MRI microstructural changes in the insula, supramarginal, lingual, inferior frontal and fusiform gyri. The study suggests that HBOT improves both cognitive and behavioral function, PPCS symptoms, and quality of life in pediatric PPCS patients at the chronic stage, even years after injury. Additional data is needed to optimize the protocol and to characterize the children who can benefit the most.

Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial

Post-COVID-19 condition refers to a range of persisting physical, neurocognitive, and neuropsychological symptoms after SARS-CoV-2 infection. The mechanism can be related to brain tissue pathology caused by virus invasion or indirectly by neuroinflammation and hypercoagulability. This randomized, sham-control, double blind trial evaluated the effect of hyperbaric oxygen therapy (HBOT or HBO2 therapy) on post-COVID-19 patients with ongoing symptoms for at least 3 months after confirmed infection. Seventy-three patients were randomized to receive daily 40 session of HBOT (n = 37) or sham (n = 36). Follow-up assessments were performed at baseline and 1–3 weeks after the last treatment session. Following HBOT, there was a significant group-by-time interaction in global cognitive function, attention and executive function (d = 0.495, p = 0.038; d = 0.477, p = 0.04 and d = 0.463, p = 0.05 respectively). Significant improvement was also demonstrated in the energy domain (d = 0.522, p = 0.029), sleep (d = − 0.48, p = 0.042), psychiatric symptoms (d = 0.636, p = 0.008), and pain interference (d = 0.737, p = 0.001). Clinical outcomes were associated with significant improvement in brain MRI perfusion and microstructural changes in the supramarginal gyrus, left supplementary motor area, right insula, left frontal precentral gyrus, right middle frontal gyrus, and superior corona radiate. These results indicate that HBOT can induce neuroplasticity and improve cognitive, psychiatric, fatigue, sleep and pain symptoms of patients suffering from post-COVID-19 condition. HBOT’s beneficial effect may be attributed to increased brain perfusion and neuroplasticity in regions associated with cognitive and emotional roles.

Neurovascular Dysfunction in Diverse Communities With Health Disparities-Contributions to Dementia and Alzheimer's Disease

Alzheimer's disease and related dementias (ADRD) are an expanding worldwide crisis. In the absence of scientific breakthroughs, the global prevalence of ADRD will continue to increase as more people are living longer. Racial or ethnic minority groups have an increased risk and incidence of ADRD and have often been neglected by the scientific research community. There is mounting evidence that vascular insults in the brain can initiate a series of biological events leading to neurodegeneration, cognitive impairment, and ADRD. We are a group of researchers interested in developing and expanding ADRD research, with an emphasis on vascular contributions to dementia, to serve our local diverse community. Toward this goal, the primary objective of this review was to investigate and better understand health disparities in Alabama and the contributions of the social determinants of health to those disparities, particularly in the context of vascular dysfunction in ADRD. Here, we explain the neurovascular dysfunction associated with Alzheimer's disease (AD) as well as the intrinsic and extrinsic risk factors contributing to dysfunction of the neurovascular unit (NVU). Next, we ascertain ethnoregional health disparities of individuals living in Alabama, as well as relevant vascular risk factors linked to AD. We also discuss current pharmaceutical and non-pharmaceutical treatment options for neurovascular dysfunction, mild cognitive impairment (MCI) and AD, including relevant studies and ongoing clinical trials. Overall, individuals in Alabama are adversely affected by social and structural determinants of health leading to health disparities, driven by rurality, ethnic minority status, and lower socioeconomic status (SES). In general, these communities have limited access to healthcare and healthy food and other amenities resulting in decreased opportunities for early diagnosis of and pharmaceutical treatments for ADRD. Although this review is focused on the current state of health disparities of ADRD patients in Alabama, future studies must include diversity of race, ethnicity, and region to best be able to treat all individuals affected by ADRD.