Hyperbaric-oxygen therapy

Mechanisms and therapeutic targets of carbon monoxide poisoning: A focus on reactive oxygen species

Carbon monoxide (CO) poisoning presents a substantial public health challenge that necessitates the identification of its pathological mechanisms and therapeutic targets. CO toxicity arises from tissue hypoxia-ischemia secondary to carboxyhemoglobin formation, and cellular damage mediated by CO at the cellular level. The mitochondria are the major targets of neuronal damage caused by CO. Under normal physiological conditions, mitochondria produce reactive oxygen species (ROS), which are byproducts of aerobic metabolism. While low ROS levels are crucial for essential cellular functions, including signal transduction, differentiation, responses to hypoxia and immunity, transcriptional regulation, and autophagy, excess ROS become pathological and exacerbate CO poisoning. This review presents the evidence of elevated ROS being associated with the progression of CO poisoning. Antioxidant treatments targeting ROS removal have been proven effective in mitigating CO poisoning, underscoring their therapeutic potential. In this review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in CO poisoning. We focus on cellular sources of ROS, the molecular mechanisms underlying mitochondrial oxidative stress, and potential therapeutic strategies for targeting ROS in CO poisoning.

The impact of hyperbaric oxygen treatment for cardiovascular implantable electronic devices

Introduction

The safety of hyperbaric oxygen treatment (HBO2) in patients with cardiovascular implanted electronic devices (CIED) remains unclear.

Methods

We conducted a retrospective analysis of seven CIED patients (median age 79 [73-83] years, five males [71.4%]), including five with pacemakers and two with implantable cardioverter defibrillators (ICD), who underwent HBO2 between June 2013 and April 2023. During the initial session, electrocardiogram monitoring was conducted, and CIED checks were performed before and after the treatment. In addition, the medical records were scrutinized to identify any abnormal CIED operations.

Results

All seven CIED patients underwent HBO2 within the safety pressure range specified by the CIED manufacturers or general pressure test by the International Organization for Standardization (2.5 [2.5-2.5] atmosphere absolute × 18 [5-20] sessions). When comparing the CIED parameters before and after HBO2, no significant changes were observed in the waveform amplitudes, pacing thresholds, lead impedance of the atrial and ventricular leads, or battery levels. All seven patients, including two with the rate response function activated, exhibited no significant changes in the pacing rate or pacing failure. Two ICD patients did not deactivate the therapy, including the defibrillation; however, they did not experience any arrhythmia or inappropriate ICD therapy during the HBO2.

Conclusion

CIED patients who underwent HBO2 within the safety pressure range exhibited no significant changes in the parameters immediately after the HBO2 and had no observable abnormal CIED operations during the treatment. The safety of defibrillation by an ICD during HBO2 should be clarified.

Hyperbaric Oxygenation Maintains Elevated Stromal Oxygen Availability During Corneal Collagen Crosslinking with and Without Epithelial Removal

PURPOSE

Corneal collagen cross-linking (CXL) can halt corneal ectasia. Leaving corneal epithelium intact during treatment may reduce the incidence of complications. However, it is under debate whether this reduces efficacy and if oxygen supplementation may be necessary to optimize the cross-linking effect. This study aimed to investigate the impact of hyperbaric oxygenation (HBO) on intracorneal oxygen concentrations during epi-off and epi-on CXL.

METHODS

CXL was performed using riboflavin and ultraviolet-A (UV-A) irradiance (3 mW/cm2 for 30 min) on porcine corneas under normobaric and hyperbaric conditions, with and without supplemented oxygen, with and without epithelium. Intracorneal oxygen concentrations were continuously monitored before and during irradiation. Biomechanical properties were assessed through tensile strength testing.

RESULTS

HBO alone did not cause perceivable changes in stromal oxygen concentrations. Oxygen supplementation resulted in higher oxygen concentration in corneal stroma during CXL. HBO may cause a further increase in oxygen levels, although this was not statistically significant in this study. Notably, a tendency of oxygen levels to rise continuously during UV-irradiation was observed using HBO. Biomechanical properties showend no statistically significant differences between any groups.

CONCLUSIONS

In this ex-vivo model, HBO increased stromal oxygen levels during CXL, regardless of the presence of corneal epithelium. The dynamics in oxygen concentrations in corneal stromal tissue during CXL suggest that time is an important factor to consider in modifications of established protocols. Also, we hypothesize that stromal levels of riboflavin and UV-A irradiance may be more critical to the CXL effect when oxygen is supplemented and epithelium is not removed.

The link between impaired oxygen supply and cognitive decline in peripheral artery disease

Although peripheral artery disease (PAD) primarily affects large arteries outside the brain, PAD is also associated with elevated cerebral vulnerabilities, including greater risks for brain injury (such as stroke), cognitive decline and dementia. In the present review, we aim to evaluate recent literature and extract information on potential mechanisms linking PAD and consequences on the brain. Furthermore, we suggest novel therapeutic avenues to mitigate cognitive decline and reduce risk of brain injury in patients with PAD. Various interventions, notably exercise, directly or indirectly improve systemic blood flow and oxygen supply and are effective strategies in patients with PAD or cognitive decline. Moreover, triggering protective cellular and systemic mechanisms by modulating inspired oxygen concentrations are emerging as potential novel treatment strategies. While several genetic and pharmacological approaches to modulate adaptations to hypoxia showed promising results in preclinical models of PAD, no clear benefits have yet been clinically demonstrated. We argue that genetic/pharmacological regulation of the involved adaptive systems remains challenging but that therapeutic variation of inspired oxygen levels (e.g., hypoxia conditioning) are promising future interventions to mitigate associated cognitive decline in patients with PAD.

Mechanical Improvement of Gas Monitoring System in Monoplace Hyperbaric Chamber to Advance the Safety and Efficacy

Introduction

A Monoplace hyperbaric chamber delivers oxygen to the patient's tissues through breathing. Gas monitoring inside the chamber is important because oxygen (O2) is consumed, and carbon dioxide (CO2) is increased because treatment is performed in a closed volume. This study aimed to advance the safety and efficacy of the monoplace hyperbaric chamber (MHC) through mechanical improvement in a gas monitoring system (GMS).

Methods

First, as the oxygen supply method was changed to the direction of the patient's face, it was compared the values of O2, CO2, humidity, and temperature were measured in the MHC and the GMS when operating at 2.0 atmosphere absolute (ATA) and 3.0 ATA. Second, to evaluate the effects of variables across measuring time, it was analyzed in a 3-way repeated measure ANOVA (10 min.×20 min.×30 min.). Lastly, the values before and after the optimization of the MHC were compared by applying a cooler to prevent temperature rise inside the MHC.

Results

In 2.0 ATA, the average humidity was higher in the MHC than in the GMS (p<0.001). Also, the average temperature was lower in the MHC than in the GMS (p<0.001). In 3.0 ATA, the average CO2 and humidity were higher in the MHC than in the GMS, respectively (p<0.001, p=0.004). The 3-way repeated measures ANOVA revealed a significant difference in most main and interacted factors (p<0.05). O2 and temperature, comparing before and after MHC optimization, revealed a significant difference (p<0.05).

Conclusion

Few studies have verified safety and effectiveness by evaluating the pressure, oxygen concentration, etc. of a monoplace hyperbaric chamber. Further research is expected to verify the effectiveness of providing comfort to patients receiving hyperbaric oxygen treatment and increase the treatment effect.

Hyperbaric Oxygen Post Established Stroke

BACKGROUND AND PURPOSE

Hyperbaric oxygen therapy (HBOT) has been reported to improve neurological function in the chronic phase of stroke in a single trial having significant limitations, including a lack of a sham control.

METHODS

We conducted a single-center, parallel-group, randomized trial to determine the effectiveness of HBOT compared with a sham control in adults who were 6 to 36 months post-ischemic stroke. The treatment group received 40 sessions of HBOT at the Vancouver General Hospital Hyperbaric Unit. The control group received 40 sessions of sham treatment designed to replicate an HBOT experience. Due to recruitment challenges and timeline/feasibility tracking by the research team, the control arm was altered after 20 months to a waitlist in the hope of increasing participation. In the second phase, participants were randomized to receive HBOT immediately or following an eight-week observation period. The primary outcome was the post-treatment Stroke Impact Scale-16 (SIS-16). Secondary outcomes included the National Institute of Health Stroke Scale, Berg Balance Test, Digit Symbol Substitution Test, 5-Metre Walk Test, 6-Minute Walk Test, Grip Strength, Montreal Cognitive Assessment, Box/Block Test, and Center for Epidemiological Studies - Depression and Short Form-36. Based on detecting a clinically important between-group difference of 10 on the SIS-16 score, our target sample size was 68 participants per arm.  Results: From January 5, 2016 to October 9, 2018, 34 participants were enrolled in the trial, 27 during the first phase and seven in the second phase. The study was stopped after 36 months, and prior to meeting the sample size target, due to low recruitment. At the end of treatment, the difference in the SIS-16 between groups was 5.5 (95% CI: 1.3 to 9.7, p = 0.01) in favor of the sham group.

CONCLUSIONS

Our results exclude a clinically important benefit of HBOT on the primary outcome of the SIS-16. These findings do not support the use of HBOT in chronic stroke survivors.

Topical oxygen therapy as a novel strategy to promote wound healing and control the bacteria in implantology, oral surgery and periodontology: A review

Globally, oral infections and inflammatory lesions persist as substantial public health concerns, necessitating the introduction of novel oral treatment protocols. Oral diseases are linked to various causative factors, with dental plaque/biofilm resulting from inadequate hygiene practices playing a predominant role. The strategic implementation of novel topical therapies holds promise for effectively controlling the biofilms, addressing oral infections and promoting enhanced oral wound healing. This review aims to providing a comprehensive overview of the available evidence pertaining to the potential efficacy of topical oxygen and lactoferrin-releasing biomaterials, exemplified by the blue®m formula, as novel oral care interventions within the scope of contemporary implantology, oral surgery and periodontology.

Hyperbaric oxygen therapy: future prospects in regenerative therapy and anti-aging

Hyperbaric Oxygen Therapy (HBOT) utilizes 100% oxygen at high atmospheric pressure for clinical applications. HBOT has proven to be an effective supplementary treatment for a variety of clinical and pathological disorders. HBOT's therapeutic results are based on the physiological effects of increased tissue oxygenation, or improved oxygen bioavailability. HBOT's current indications in illnesses like as wound healing, thermal or radiation burns, and tissue necrosis point to its function in facilitating the regeneration process. Various research has revealed that HBOT plays a function in vascularization, angiogenesis, and collagen production augmentation. Individual regeneration capacity is influenced by both environmental and genetic factors. Furthermore, the regenerating ability of different types of tissues varies, and this ability declines with age. HBOT affects physiological processes at the genetic level by altering gene expression, delaying cell senescence, and assisting in telomere length enhancement. The positive results in a variety of indications, ranging from tissue regeneration to better cognitive function, indicate that it has enormous potential in regenerative and anti-aging therapy.

Maternal exposure to hyperbaric oxygen at the preimplantation stages increases apoptosis and ectopic Cdx2 expression and decreases Oct4 expression in mouse blastocysts via Nrf2-Notch1 upregulation and Nf2 downregulation

BACKGROUND

The environmental oxygen tension has been reported to impact the blastocyst quality and cell numbers in the inner cell mass (ICM) during human and murine embryogenesis. While the molecular mechanisms leading to increased ICM cell numbers and pluripotency gene expression under hypoxia have been deciphered, it remains unknown which regulatory pathways caused the underweight fetal body and overweight placenta after maternal exposure to hyperbaric oxygen (HBO).

RESULTS

The blastocysts from the HBO-exposed pregnant mice revealed significantly increased signals of reactive oxygen species (ROS) and nuclear Nrf2 staining, decreased Nf2 and Oct4 expression, increased nuclear Tp53bp1 and active caspase-3 staining, and ectopic nuclear signals of Cdx2, Yap, and the Notch1 intracellular domain (N1ICD) in the ICM. In the ICM of the HBO-exposed blastocysts, both Nf2 cDNA microinjection and Nrf2 shRNA microinjection significantly decreased the ectopic nuclear expression of Cdx2, Tp53bp1, and Yap whereas increased Oct4 expression, while Nrf2 shRNA microinjection also significantly decreased Notch1 mRNA levels and nuclear expression of N1ICD and active caspase-3.

CONCLUSION

We show for the first time that maternal exposure to HBO at the preimplantation stage induces apoptosis and impairs ICM cell specification via upregulating Nrf2-Notch1-Cdx2 expression and downregulating Nf2-Oct4 expression.

[Hyperbaric oxygen therapy and eye disease: Review of the literature]

Hyperbaric oxygen therapy consists of breathing 100% oxygen continuously or intermittently in a chamber at a pressure equal to or greater than 1.4 absolute atmospheres. Indicated for the emergency treatment of carbon monoxide poisoning and other medical-surgical pathologies such as gas embolism or necrotizing soft-tissue infections, various studies have shown a beneficial effect of hyperbaric oxygen therapy in certain ocular pathologies, notably of microcirculatory origin, such as central retinal artery occlusion or macular edema linked to retinal vein occlusions. In addition, hyperbaric oxygen might represent an alternative treatment for ocular quinine toxicity and might also be useful as an adjuvant to surgery and antibiotics in cases of periorbital necrotizing fasciitis. On the other hand, oxygen in high concentrations has toxic ocular effects due to the production of reactive oxygen derivatives.

Hyperbaric Oxygen Therapy Attenuated the Motor Coordination and Cognitive Impairment of Polyglutamine Spinocerebellar Ataxia SCA17 Mice

Spinocerebellar ataxias (SCAs) are a large and diverse group of autosomal-dominant neurodegenerative diseases. No drugs have been approved for these relentlessly progressive and fatal SCAs. Our previous studies indicate that oxidative stress, neuroinflammation, and neuronal apoptosis are elevated in the SCA17 mice, which are the main therapeutic targets of hyperbaric oxygen treatment (HBOT). HBOT is considered to be an alternative and less invasive therapy for SCAs. In this study, we evaluated the HBOT (2.2 ATA for 14 days) effect and the persistence for the management of SCA17 mice and their wild-type littermates. We found HBOT attenuated the motor coordination and cognitive impairment of SCA17 mice and which persisted for about 1 month after the treatment. The results of several biochemistry and liver/kidney hematoxylin and eosin staining show the HBOT condition has no obvious toxicity in the mice. Immunostaining analyses show that the neuroprotective effect of HBOT could be through the promotion of BDNF production and the amelioration of neuroinflammation. Surprisingly, HBOT executes different effects on the male and female SCA17 mice, including the reduction of neuroinflammation and activation of CaMKII and ERK. This study suggests HBOT is a potential alternative therapeutic treatment for SCA17. Accumulated findings have revealed the similarity in disease pathomechanisms and possible therapeutic strategies in polyQ diseases; therefore, HBOT could be an optional treatment as well as the other polyQ diseases.

Revolutionizing Wound Healing: Exploring Scarless Solutions through Drug Delivery Innovations

Human skin is the largest organ and outermost surface of the human body, and due to the continuous exposure to various challenges, it is prone to develop injuries, customarily known as wounds. Although various tissue engineering strategies and bioactive wound matrices have been employed to speed up wound healing, scarring remains a significant challenge. The wound environment is harsh due to the presence of degradative enzymes and elevated pH levels, and the physiological processes involved in tissue regeneration operate on distinct time scales. Therefore, there is a need for effective drug delivery systems (DDSs) to address these issues. The objective of this review is to provide a comprehensive exposition of the mechanisms underlying the skin healing process, the factors and materials used in engineering DDSs, and the different DDSs used in wound care. Furthermore, this investigation will delve into the examination of emergent technologies and potential avenues for enhancing the efficacy of wound care devices.

Enriched oxygen improves age-related cognitive impairment through enhancing autophagy

Age-related cognitive impairment represents a significant health concern, with the understanding of its underlying mechanisms and potential interventions being of paramount importance. This study aimed to investigate the effects of hyperbaric oxygen therapy (HBOT) on cognitive function and neuronal integrity in aged (22-month-old) C57BL/6 mice. Male mice were exposed to HBOT for 2 weeks, and spatial learning and memory abilities were assessed using the Morris water maze. We employed transcriptome sequencing and Gene Ontology (GO) term enrichment analysis to examine the effects of HBOT on gene expression profiles, with particular attention given to synapse-related genes. Our data indicated a significant upregulation of postsynapse organization, synapse organization, and axonogenesis GO terms, likely contributing to improved cognitive performance. Moreover, the hyperphosphorylation of tau, a hallmark of many neurodegenerative diseases, was significantly reduced in the HBO-treated group, both in vivo and in vitro. Transmission electron microscopy revealed significant ultrastructural alterations in the hippocampus of the HBOT group, including an increase in the number of synapses and the size of the active zone, a reduction in demyelinated lesions, and a decreased number of "PANTHOS." Furthermore, Western blot analyses confirmed the upregulation of PSD95, BDNF, and Syn proteins, suggesting enhanced synaptic plasticity and neurotrophic support. Moreover, HBOT increased autophagy, as evidenced by the elevated levels of Beclin-1 and LC3 proteins and the reduced level of p62 protein. Finally, we demonstrated that HBOT activated the AMPK-mTOR signaling pathway, a critical regulator of autophagy. Notably, our findings provide novel insights into the mechanisms by which HBOT ameliorates age-related cognitive impairment, suggesting the potential therapeutic value of this approach.

Translational medicine for acute lung injury

Acute lung injury (ALI) is a complex disease with numerous causes. This review begins with a discussion of disease development from direct or indirect pulmonary insults, as well as varied pathogenesis. The heterogeneous nature of ALI is then elaborated upon, including its epidemiology, clinical manifestations, potential biomarkers, and genetic contributions. Although no medication is currently approved for this devastating illness, supportive care and pharmacological intervention for ALI treatment are summarized, followed by an assessment of the pathophysiological gap between human ALI and animal models. Lastly, current research progress on advanced nanomedicines for ALI therapeutics in preclinical and clinical settings is reviewed, demonstrating new opportunities towards developing an effective treatment for ALI.

Oxygen therapy attenuates neuroinflammation after spinal cord injury

Acute hyperbaric O2 (HBO) therapy after spinal cord injury (SCI) can reduce inflammation and increase neuronal survival. To our knowledge, it is unknown if these benefits of HBO require hyperbaric vs. normobaric hyperoxia. We used a C4 lateralized contusion SCI in adult male and female rats to test the hypothesis that the combination of hyperbaria and 100% O2 (i.e. HBO) more effectively mitigates spinal inflammation and neuronal loss, and enhances respiratory recovery, as compared to normobaric 100% O2. Experimental groups included spinal intact, SCI no O2 therapy, and SCI + 100% O2 delivered at normobaric pressure (1 atmosphere, ATA), or at 2- or 3 ATA. O2 treatments lasted 1-h, commenced within 2-h of SCI, and were repeated for 10 days. The spinal inflammatory response was assessed with transcriptomics (RNAseq) and immunohistochemistry. Gene co-expression network analysis showed that the strong inflammatory response to SCI was dramatically diminished by both hyper- and normobaric O2 therapy. Similarly, both HBO and normobaric O2 treatments reduced the prevalence of immunohistological markers for astrocytes (glial fibrillary acidic protein) and microglia (ionized calcium binding adaptor molecule) in the injured spinal cord. However, HBO treatment also had unique impacts not detected in the normobaric group including upregulation of an anti-inflammatory cytokine (interleukin-4) in the plasma, and larger inspiratory tidal volumes at 10-days (whole body-plethysmography measurements). We conclude that normobaric O2 treatment can reduce the spinal inflammatory response after SCI, but pressured O2 (i.e., HBO) provides further benefit.

Role of NMDA Receptor in High-Pressure Neurological Syndrome and Hyperbaric Oxygen Toxicity

Professional divers exposed to pressures greater than 11 ATA (1.1 MPa) may suffer from high-pressure neurological syndrome (HPNS). Divers who use closed-circuit breathing apparatus and patients and medical attendants undergoing hyperbaric oxygen therapy (HBOT) face the risk of CNS hyperbaric oxygen toxicity (HBOTx) at oxygen pressure above 2 ATA (0.2 MPa). Both syndromes are characterized by reversible CNS hyperexcitability, accompanied by cognitive and motor deficits, and N-methyl-D-aspartate receptor (NMDAR) plays a crucial role in provoking them. Various NMDAR subtypes respond differently under hyperbaric conditions. The augmented currents observed only in NMDAR containing GluN2A subunit increase glutamatergic synaptic activity and cause dendritic hyperexcitability and abnormal neuronal activity. Removal of the resting Zn2+ voltage-independent inhibition exerted by GluN2A present in the NMDAR is the major candidate for the mechanism underlying the increase in receptor conductance. Therefore, this process should be the main target for future research aiming at developing neuroprotection against HPNS and HBOTx.

On the treatment of melanoma: A mathematical model of oncolytic virotherapy

We develop and analyze a mathematical model of oncolytic virotherapy in the treatment of melanoma. We begin with a special, local case of the model, in which we consider the dynamics of the tumour cells in the presence of an oncolytic virus at the primary tumour site. We then consider the more general regional model, in which we incorporate a linear network of lymph nodes through which the tumour cells and the oncolytic virus may spread. The modelling also considers the impact of hypoxia on the disease dynamics. The modelling takes into account both the effects of hypoxia on tumour growth and spreading, as well as the impact of hypoxia on oncolytic virotherapy as a treatment modality. We find that oxygen-rich environments are favourable for the use of adenoviruses as oncolytic agents, potentially suggesting the use of complementary external oxygenation as a key aspect of treatment. Furthermore, the delicate balance between a virus' infection capabilities and its oncolytic capabilities should be considered when engineering an oncolytic virus. If the virus is too potent at killing tumour cells while not being sufficiently effective at infecting them, the infected tumour cells are destroyed faster than they are able to infect additional tumour cells, leading less favourable clinical results. Numerical simulations are performed in order to support the analytic results and to further investigate the impact of various parameters on the outcomes of treatment. Our modelling provides further evidence indicating the importance of three key factors in treatment outcomes: tumour microenvironment oxygen concentration, viral infection rates, and viral oncolysis rates. The numerical results also provide some estimates on these key model parameters which may be useful in the engineering of oncolytic adenoviruses.

Effects of hyperbaric oxygen therapy on human psychomotor performance: A review

Psychomotor performance is the coordination of a sensory or ideational (cognitive) process and a motor activity. All sensorimotor processes involved in planning and execution of voluntary movements need oxygen supply and seem to be significantly disrupted in states of hypoxia. Hyperbaric oxygen therapy has become a widely used treatment in routine medicine and sport medicine due to its beneficial effects on different aspects of human physiology and performance. This paper presents state-of-the-art data on the effects of hyperbaric oxygen therapy on different aspects of human psychomotor function. The therapy's influence on musculoskeletal properties and motor abilities as well as the effects of hyperbaric oxygenation on cognitive, myocardial and pulmonary functions are presented. In this review the molecular and physiological processes related to human psychomotor performance in response to hyperbaric oxygen are discussed to contribute to this fast-growing field of research in integrative medicine. Please cite this article as: Olex-Zarychta D. Effects of hyperbaric oxygen therapy on human psychomotor performance: A review. J Integr Med. 2023; 21(5): 430-440.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

Oxygen Therapy Part 2 - Indications and Toxicity

Oxygen Therapy Part 2: Indications and ToxicityWemple et al. continue their review of oxygen therapy, discussing the acute and chronic indications for oxygen and the delivery of supplemental oxygen (and its potential adverse effects and toxicity).

Recent advances in micro-sized oxygen carriers inspired by red blood cells

Supplementing sufficient oxygen to cells is always challenging in biomedical engineering fields such as tissue engineering. Originating from the concept of a 'blood substitute', nano-sized artificial oxygen carriers (AOCs) have been studied for a long time for the optimization of the oxygen supplementation and improvement of hypoxia environments in vitro and in vivo. When circulating in our bodies, micro-sized human red blood cells (hRBCs) feature a high oxygen capacity, a unique biconcave shape, biomechanical and rheological properties, and low frictional surfaces, making them efficient natural oxygen carriers. Inspired by hRBCs, recent studies have focused on evolving different AOCs into microparticles more feasibly able to achieve desired architectures and morphologies and to obtain the corresponding advantages. Recent micro-sized AOCs have been developed into additional categories based on their principal oxygen-carrying or oxygen-releasing materials. Various biomaterials such as lipids, proteins, and polymers have also been used to prepare oxygen carriers owing to their rapid oxygen transfer, high oxygen capacity, excellent colloidal stability, biocompatibility, suitable biodegradability, and long storage. In this review, we concentrated on the fabrication techniques, applied biomaterials, and design considerations of micro-sized AOCs to illustrate the advances in their performances. We also compared certain recent micro-sized AOCs with hRBCs where applicable and appropriate. Furthermore, we discussed existing and potential applications of different types of micro-sized AOCs.

The significance of quercetin-loaded advanced nanoformulations for the management of diabetic wounds

Quercetin is a well-known plant flavanol that exhibits multiple biological activities, including antioxidant, anti-inflammatory and anticancer activities. The role of quercetin in wound healing has been widely explored by a range of researchers in different models. However, the physicochemical properties, such as solubility and permeability, of this compound are low, which ultimately limits its bioavailability on the target site. To overcome these limitations for successful therapy, scientists have developed a range of nanoformulations that provide effective therapeutic potential. In this review, the broad mechanism of quercetin for acute and chronic wounds is covered. A compilation of recent advances on the horizon of wound healing via quercetin is incorporated with several advanced nanoformulations.

Reducing Risks for Local Skin Flap Failure

Local tissue flaps are a fundamental technique in cutaneous reconstruction. Reducing the risk of flap failure is of critical importance. The intrinsic vascularity of a flap is the most important determinant of success. Good surgical techniques, including flap design, delicate tissue handling, and tension-less closure, help reduce the risk of flap compromise. Determining the etiology of compromise, including arterial, venous, hematologic, or infectious, is the first step in salvaging a failing flap. Common causes include pedicle kinking, hematoma, pressure/tension, systemic patient factors, and poor surgical technique. Swift action to restore perfusion or venous outflow through numerous strategies is required.

The Role of Hyperbaric Oxygen Therapy in the Treatment of Surgical Site Infections: A Narrative Review

Surgical site infections (SSIs) are among the most prevalent postoperative complications, with significant morbidity and mortality worldwide. In the past half century, hyperbaric oxygen therapy (HBOT), the administration of 100% oxygen intermittently under a certain pressure, has been used as either a primary or alternative therapy for the management or treatment of chronic wounds and infections. This narrative review aims to gather information and evidence supporting the role of HBOT in the treatment of SSIs. We followed the Scale for the Quality Assessment of Narrative Review Articles (SANRA) guidelines and scrutinized the most relevant studies identified in Medline (via PubMed), Scopus, and Web of Science. Our review indicated that HBOT can result in rapid healing and epithelialization of various wounds and has potential beneficial effects in the treatment of SSIs or other similar infections following cardiac, neuromuscular scoliosis, coronary artery bypass, and urogenital surgeries. Moreover, it was a safe therapeutic procedure in most cases. The mechanisms related to the antimicrobial activity of HBOT include direct bactericidal effects through the formation of reactive oxygen species (ROS), the immunomodulatory effect of HBOT that increase the antimicrobial effects of the immune system, and the synergistic effects of HBOT with antibiotics. We emphasized the essential need for further studies, especially randomized clinical trials and longitudinal studies, to better standardize HBOT procedures as well as to determine its full benefits and possible side effects.

Clinically Translatable Transcrocetin Delivery Platform for Correction of Tumor Hypoxia and Enhancement of Radiation Therapy Effects

Improving the tumor reoxygenation to sensitize the tumor to radiation therapy is a cornerstone in radiation oncology. Here, the pre-clinical development of a clinically transferable liposomal formulation encapsulating trans sodium crocetinate (NP TSC) is reported to improve oxygen diffusion through the tumor environment. Early pharmacokinetic analysis of the clinical trial of this molecule performed on 37 patients orient to define the optimal fixed dosage to use in a triple-negative breast cancer model to validate the therapeutic combination of radiation therapy and NP TSC. Notably, it is reported that this formulation is non-toxic in both humans and mice at the defined fixed concentration, provides a normalization of the tumor vasculature within 72 h window after systemic injection, leads to a transient increase (50% improvement) in the tumor oxygenation, and significantly improves the efficacy of both mono-fractionated and fractionated radiation therapy treatment. Together, these findings support the introduction of a first-in-class therapeutic construct capable of tumor-specific reoxygenation without associated toxicities.

An overview of hyperbaric oxygen preconditioning against ischemic stroke

Ischemic stroke (IS) has become the second leading cause of morbidity and mortality worldwide, and the prevention of IS should be given high priority. Recent studies have indicated that hyperbaric oxygen preconditioning (HBO-PC) may be a protective nonpharmacological method, but its underlying mechanisms remain poorly defined. This study comprehensively reviewed the pathophysiology of IS and revealed the underlying mechanism of HBO-PC in protection against IS. The preventive effects of HBO-PC against IS may include inducing antioxidant, anti-inflammation, and anti-apoptosis capacity; activating autophagy and immune responses; upregulating heat shock proteins, hypoxia-inducible factor-1, and erythropoietin; and exerting protective effects upon the blood-brain barrier. In addition, HBO-PC may be considered a safe and effective method to prevent IS in combination with stem cell therapy. Although the benefits of HBO-PC on IS have been widely observed in recent research, the implementation of this technique is still controversial due to regimen differences. Transferring the results to clinical application needs to be taken carefully, and screening for the optimal regimen would be a daunting task. In addition, whether we should prescribe an individualized preconditioning regimen to each stroke patient needs further exploration.

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

AIMS/HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSIONS/INTERPRETATION

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

TRIAL REGISTRATION

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

The role of hyperbaric oxygen therapy in the management of perioperative peripheral nerve injury: a scoping review of the literature

Background/importance

Peripheral nerve injury is an uncommon but potentially catastrophic complication of anesthesia and surgery, for which there are limited effective treatment options. Hyperbaric oxygen therapy is a unique medical intervention which improves tissue oxygen delivery and reduces ischemia via exposure to oxygen at supra-atmospheric partial pressures. While the application of hyperbaric oxygen therapy has been evidenced for other medical conditions involving relative tissue ischemia, its role in the management of peripheral nerve injury remains unclear.

Objective

This scoping review seeks to characterize rehabilitative outcomes when hyperbaric oxygen therapy is applied as an adjunct therapy in the treatment of perioperative peripheral nerve injury.

Evidence review

The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines for scoping reviews, using a systematic screening and extraction process. The search included articles published from database inception until June 11, 2022, which reported clinical outcomes (in both human and non-human models) of peripheral nerve injury treated with hyperbaric oxygen therapy.

Findings

A total of 51 studies were included in the narrative synthesis. These consisted of animal (40) and human studies (11) treating peripheral nerve injury due to various physiological insults. Hyperbaric oxygen therapy protocols were highly heterogenous and applied at both early and late intervals relative to the time of peripheral nerve injury. Overall, hyperbaric oxygen therapy was reported as beneficial in 88% (45/51) of included studies (82% of human studies and 90% of animal studies), improving nerve regeneration and/or time to recovery with no reported major adverse events.

Conclusions

Existing data suggest that hyperbaric oxygen therapy is a promising intervention in the management of perioperative peripheral nerve injury, in which tissue ischemia is the most common underlying mechanism of injury, neurological deficits are severe, and treatment options are sparse. This positive signal should be further investigated in prospective randomized clinical trials.

Effects of Hyperbaric Oxygen Preconditioning on Doxorubicin Cardiorespiratory Toxicity

Cardiorespiratory dysfunction resulting from doxorubicin (DOX) chemotherapy treatment is a debilitating condition affecting cancer patient outcomes and quality of life. DOX treatment promotes cardiac and respiratory muscle pathology due to enhanced reactive oxygen species (ROS) production, mitochondrial dysfunction and impaired muscle contractility. In contrast, hyperbaric oxygen (HBO) therapy is considered a controlled oxidative stress that can evoke a substantial and sustained increase in muscle antioxidant expression. This HBO-induced increase in antioxidant capacity has the potential to improve cardiac and respiratory (i.e., diaphragm) muscle redox balance, preserving mitochondrial function and preventing muscle dysfunction. Therefore, we determined whether HBO therapy prior to DOX treatment is sufficient to enhance muscle antioxidant expression and preserve muscle redox balance and cardiorespiratory muscle function. To test this, adult female Sprague Dawley rats received HBO therapy (2 or 3 atmospheres absolute (ATA), 100% O₂, 1 h/day) for 5 consecutive days prior to acute DOX treatment (20 mg/kg i.p.). Our data demonstrate that 3 ATA HBO elicits a greater antioxidant response compared to 2 ATA HBO. However, these effects did not correspond with beneficial adaptations to cardiac systolic and diastolic function or diaphragm muscle force production in DOX treated rats. These findings suggest that modulating muscle antioxidant expression with HBO therapy is not sufficient to prevent DOX-induced cardiorespiratory dysfunction.

Determination of oxygen relaxivity in oxygen nanobubbles at 3 and 7 Tesla

OBJECTIVE

Oxygen-loaded nanobubbles have shown potential for reducing tumour hypoxia and improving treatment outcomes, however, it remains difficult to noninvasively measure the changes in partial pressure of oxygen (PO₂) in vivo. The linear relationship between PO₂ and longitudinal relaxation rate (R₁) has been used to noninvasively infer PO₂ in vitreous and cerebrospinal fluid, and therefore, this experiment aimed to investigate whether R₁ is a suitable measurement to study oxygen delivery from such oxygen carriers.

METHODS

T₁ mapping was used to measure R₁ in phantoms containing nanobubbles with varied PO₂ to measure the relaxivity of oxygen (r_1Ox) in the phantoms at 7 and 3 T. These measurements were used to estimate the limit of detection (LOD) in two experimental settings: preclinical 7 T and clinical 3 T MRI.

RESULTS

The r_1Ox in the nanobubble solution was 0.00057 and 0.000235 s^-1/mmHg, corresponding to a LOD of 111 and 103 mmHg with 95% confidence at 7 and 3 T, respectively.

CONCLUSION

This suggests that T₁ mapping could provide a noninvasive method of measuring a > 100 mmHg oxygen delivery from therapeutic nanobubbles.

[Hyperbaric oxygen therapy : Selected indications in the discipline of otorhinolaryngology]

Hyperbaric oxygenation (HBO) represents the controlled exposure to positive pressure with simultaneous inhalation of pure oxygen. It is considered to be an effective treatment option for diseases with restricted blood flow as oxygen not only binds chemically to hemoglobin but also physically dissolves in blood plasma. With the help of a hyperbaric chamber the ambient pressure of a patient can be modified and the physiological characteristics in positive pressure can be medically used. The indications relevant to otorhinolaryngology are necrotizing otitis externa and skull base osteomyelitis, other forms of osteomyelitis, gangrene, wound healing disorders and sudden loss of hearing. When choosing a treatment, not only the availability and costs of HBO treatment play a role but also the patient's tolerance of overpressure. The risks of treatment, e.g., due to oxygen toxicity or barotrauma of the middle ear or the paranasal sinuses, must be weighed up against the potential benefits.

Is There a Place for Hyperbaric Oxygen Therapy?

Hyperbaric oxygen therapy (HBOT) involves treating patients by providing 100% oxygen through inhalation while inside a treatment pressurized chamber. The oxygen acts as a drug and the hyperbaric chamber as the dosing device. The effect of hyperbaric hyperoxia is dose dependent and, therefore, treatment depth and duration are important when considering its use. HBOT can either be the primary method of treatment or used adjunctively to medications or surgical techniques. The underpinning physiology is to bring oxygen-rich plasma to hypoxic tissue, preventing reperfusion injury, strengthening immune responsiveness, and encouraging new collagen deposition as well as endothelial cell formation.

Advances and Controversies in the Management of Osteoradionecrosis After Head and Neck Cancer Treatment: A Narrative Review

Osteoradionecrosis (ORN) is a painful and debilitating serious late complication following treatment for head and neck cancer (HNC) often requiring surgical resection of the jaw and complex multidisciplinary management. An important aggravating factor for mandibular ORN is surgical trauma, commonly dental extractions or implant placement following head and neck radiotherapy. The evidence on the treatment protocols ranges from conservative management to more radical surgical strategies including the use of hyperbaric oxygen therapy. The available evidence on the preventive approaches for ORN includes prophylactic dental care prior to radiotherapy, the use of hyperbaric oxygen (HBO) treatment and prophylactic antibiotics for post-radiotherapy extractions. However, the efficacy of hyperbaric oxygen therapy has been questioned recently signifying poor understanding of the pathophysiology of the condition and therapies targeting the fibroatrophic process have become a focus of ORN treatment. Implementing recent IMRT radiation techniques has also shown evidence to reduce the incidence of ORN. This review provides an insight into the variations in definition and classification of the ORN, the controversies in its pathophysiology and the advances in the prevention and management.

Design, development, and evaluation of a registry system for hyperbaric oxygen therapy: A methodological study

Background and Aims

Hyperbaric oxygen therapy (HBOT), utilizes 100% oxygen at pressures greater than sea-level atmospheric pressure, for the treatment of conditions in which the tissues starve for oxygen. The Undersea and Hyperbaric Medical Society (UHMS) has granted HBOT approval for the treatment of various conditions. On the other hand, applying informatics registry systems can improve care delivery, ameliorate outcomes, and reduce the costs and medical errors for the patients receiving HBOT treatment. Therefore, we aimed to design, develop, and evaluate a registry system for patients undergoing HBOT.

Methods

In the first phase, the conceptual and logical models were designed after conducting symposiums with experts and having other experts review the models. In the second phase, the system was developed on the web using ASP.NET  and C# programming languages frameworks. The last phase involved Nielsen's heuristic evaluation method for the system's usability. Five experts evaluated the system, including three health information management specialists and two medical informatics specialists.

Results

The hyperbaric patient information registry system (HPIRS) interacts with three types of users-a specialist physician, a nurse, and a system administrator. A scenario for each predefined activity was designed, and all the information was stored in the SQL servers. The five experts independently found 152 issues, of which 84 were duplicates. The 68 distinct issues of the system were then resolved.

Conclusions

The design and development of such registry systems can make data available and stored carefully to improve clinical care and medical research and decrease costs and errors. These registries can provide the healthcare systems with E-health applications, improved data management, more secure data transfer, and support for statistical reporting. The implemented heuristic evaluation method can also provide a low-cost and readily available system to fix the issues of the designed systems.

Does hyperbaric oxygen therapy pressure reduce mechanical stability of implants?

Hyperbaric oxygen therapy (HBOT) has beneficial effects for patients complaining of poor bone healing such as related to diabetes mellitus. However, it is known that changing pressure conditions might cause dental barotrauma in the oral cavity. The aim of this study was to evaluate implant mechanical stability under HBOT pressure. Thirty-five implants were placed in bone blocks divided into five groups as control, 1, 3, 5, 7 HBOT cycles. In one cycle, 2.4 bar 100% oxygen pressure was performed. Implants' stabilities were measured with resonance frequency analysis (RFA) and removal torque (RT) meter device. Data were analyzed using Shapiro Wilk, ANOVA, and Tukey HSD tests for RFA and RT values considering p < 0.05 as the statistical significance level. RFA and RT values were compared by Pearson correlation coefficiency. RFA values of 5 and 7 HBOT cycles were significantly lower than 1, 3 HBOT and control group (p < 0.001). There was no statistical difference between 5 and 7 HBOT cycles RFA values. HBOT pressure simulation slightly but statistically decreased the stability for the implants exposed to 5 and 7 HBOT cycles. Graphical abstract.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

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

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.

Assessment of Nanoparticle-Mediated Tumor Oxygen Modulation by Photoacoustic Imaging

Photoacoustic imaging (PAI) is an invaluable tool in biomedical imaging, as it provides anatomical and functional information in real time. Its ability to image at clinically relevant depths with high spatial resolution using endogenous tissues as contrast agents constitutes its major advantage. One of the most important applications of PAI is to quantify tissue oxygen saturation by measuring the differential absorption characteristics of oxy and deoxy Hb. Consequently, PAI can be utilized to monitor tumor-related hypoxia, which is a crucial factor in tumor microenvironments that has a strong influence on tumor invasiveness. Reactive oxygen species (ROS)-based therapies, such as photodynamic therapy, radiotherapy, and sonodynamic therapy, are oxygen-consuming, and tumor hypoxia is detrimental to their efficacy. Therefore, a persistent demand exists for agents that can supply oxygen to tumors for better ROS-based therapeutic outcomes. Among the various strategies, NP-mediated supplemental tumor oxygenation is especially encouraging due to its physio-chemical, tumor targeting, and theranostic properties. Here, we focus on NP-based tumor oxygenation, which includes NP as oxygen carriers and oxygen-generating strategies to alleviate hypoxia monitored by PAI. The information obtained from quantitative tumor oxygenation by PAI not only supports optimal therapeutic design but also serves as a highly effective tool to predict therapeutic outcomes.

Derivation and Validation of a Score for Predicting Poor Neurocognitive Outcomes in Acute Carbon Monoxide Poisoning

IMPORTANCE

Preventing neurocognitive sequelae is a major goal of treating acute carbon monoxide (co) poisoning. There is a lack of reliable score systems exist for assessing the probability of these sequelae.

OBJECTIVE

To develop and validate a novel clinical scoring system for predicting poor neurocognitive outcomes after acute co poisoning.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study included derivation and validation cohorts based on consecutive patient data prospectively collected at university hospitals from January 2006 to July 2021 in Wonju, Republic of Korea, and from August 2016 to June 2020 in Incheon, Republic of Korea. Participants included individuals aged 16 years or older admitted with co poisoning. Data were analyzed from October 2021 to January 2022.

EXPOSURES

Clinical and laboratory variables.

MAIN OUTCOMES AND MEASURES

The outcome of interest was neurocognitive sequelae at 4 weeks after co poisoning. Logistic regression models were used to identify predictors of poor neurocognitive outcomes in the derivation cohort. Outcomes were assessed using the Global Deterioration Scale [GDS] at 1-month after co exposure and classified as good (1-3 points) or poor (4-7 points).

RESULTS

A total of 1282 patients (median [IQR] age, 47.0 [35.0-59.0] years; 810 [63.2%] men) were assessed, including 1016 patients in the derivation cohort and 266 patients in the validation cohort. The derivation cohort included 126 patients (12.4%) with poor GDS scores. Among 879 patients in the derivation cohort with 1-year follow-up data, 757 (86.1%) had unchanged GDS scores, 102 (11.6%) had improved GDS scores, and 20 (2.3%) had worsened GDS scores. In the final prediction model, age older than 50 years (1 point), Glasgow Coma Scale score of 12 or less (1 point), shock (1 point), serum creatine kinase level greater than 320 U/L at emergency department presentation (1 point), and no use of hyperbaric oxygen therapy (1 point) remained factors significantly associated with worse outcome; therefore, this scoring system was called COGAS (creatine kinase, hyperbaric oxygen therapy, Glasgow Coma Scale, age, shock). Area under the receiver operating characteristic curve for COGAS score was 0.862 (95% CI, 0.828-0.895) for the derivation cohort and 0.870 (95% CI, 0.779-0.961) for the validation cohort.

CONCLUSIONS AND RELEVANCE

These findings suggest that assessing the COGAS score during the early phase of co poisoning may help identify patients at risk of poor neurocognitive sequelae.

Hyperbaric oxygen therapy after mid-cervical spinal contusion injury

Hyperbaric oxygen (HBO) therapy is frequently used to treat peripheral wounds or decompression sickness. Evidence suggests that HBO therapy can provide neuroprotection and has an anti-inflammatory impact after neurological injury, including spinal cord injury (SCI). Our primary purpose was to conduct a genome-wide screening of mRNA expression changes in the injured spinal cord after HBO therapy. An mRNA gene array was used to evaluate samples taken from the contused region of the spinal cord following a lateralized mid-cervical contusion injury in adult female rats. HBO therapy consisted of daily, 1-h sessions (3.0 ATA, 100% O₂) initiated on the day of SCI and continued for 10 days. Gene set enrichment analyses indicated that HBO upregulated genes in pathways associated with electron transport, mitochondrial function, and oxidative phosphorylation, and downregulated genes in pathways associated with inflammation (including cytokines and nuclear factor kappa B [NF-κB]) and apoptotic signaling. In a separate cohort, spinal cord histology was performed to verify whether the HBO treatment impacted neuronal cell counts or inflammatory markers. Compared with untreated rats, there were increased NeuN positive cells in the spinal cord of HBO-treated rats (p = 0.004). We conclude that HBO therapy, initiated shortly after SCI and continued for 10 days, can alter the molecular signature of the lesioned spinal cord in a manner consistent with a neuroprotective impact.

Non-Surgical Strategies for Assisting Closure of Pharyngocutaneous Fistula after Total Laryngectomy: A Systematic Review of the Literature

Background: Pharyngocutaneous fistula (PCF) is a frequent complication after total laryngectomy, with an incidence of up to 65%. Many conservative or invasive approaches are available and the choice among them is usually made on a case-by-case basis. The aim of the present review is to critically summarize the available evidence of the effectiveness of the non-surgical management of PCF. Methods: A systematic review and a meta-analysis of the literature were conducted, according to the PRISMA guidelines. Studies investigating botulinum toxin therapy, scopolamine transdermal patch, hyperbaric oxygen therapy (HBOT), and negative pressure wound therapy (NPWT) were assessed. Complete fistula closure after the initiation of non-surgical treatment was the main outcome. Results: After the application of selection criteria, a total of seven articles and 27 patients were included in the present review. All the eligible studies were descriptive case series, while only one article used a standard group as a comparison. The mean age was 63.3 and 14 patients (51.9%) had previously received RT. The reported comorbidities were diabetes, ischemic heart disease, hypertension, dyslipidemia, COPD, and atrial fibrillation. With a mean healing time of 25.0 days, the overall success rate was 92.6%. Conclusions: Non-surgical treatment of PCF is only based on the experience of small series. Although success rates seem promising, the absence of properly designed comparative studies does not allow us, at present, to identify ideal candidates for these non-invasive management strategies for PCF.

Integrative Role of Hyperbaric Oxygen Therapy on Healthspan, Age-Related Vascular Cognitive Impairment, and Dementia

Growing life expectancy will contribute to the on-going shift towards a world population increasingly comprised of elderly individuals. This demographic shift is associated with a rising prevalence of age-related diseases, among all age-related pathologies it has become crucial to understand the age-associated cognitive changes that remain a major risk factor for the development of vascular cognitive impairment and dementia (VCID). Furthermore, age-related Alzheimer's disease and other neurogenerative diseases with vascular etiology are the most prominent contributing factors for the loss of cognitive function observed in aging. Hyperbaric Oxygen Therapy (HBOT) achieves physiologic effects by increasing oxygen tension (PO2), raising oxygen tissue levels, decreasing intracranial pressure and relieving cerebral edema. Many of the beneficial effects of HBOT exert their protective effects at the level of the microcirculation. Furthermore, the microcirculation's exquisite pervasive presence across every tissue in the body, renders it uniquely able to influence the local environment of most tissues and organs, including the brain. As such, treatments aimed at restoring aging-induced functional and structural alterations of the cerebral microcirculation may potentially contribute to the amelioration of a range of age-related pathologies including vascular cognitive impairment, Alzheimer's disease, and vascular dementias. Despite the presented evidence, the efficacy and safety of HBOT for the treatment of age-related vascular cognitive impairment and dementia remains understudied. The present review aims to examine the existing evidence indicative of a potential therapeutic role for HBOT-induced hyperoxia against age-related cerebromicrovascular pathologies contributing to cognitive impairment, dementia and decreased healthspan in the elderly.

Oxygen in Metabolic Dysfunction and Its Therapeutic Relevance

Significance: In recent years, a number of studies have shown altered oxygen partial pressure at a tissue level in metabolic disorders, and some researchers have considered oxygen to be a (macro) nutrient. Oxygen availability may be compromised in obesity and several other metabolism-related pathological conditions, including sleep apnea-hypopnea syndrome, the metabolic syndrome (which is a set of conditions), type 2 diabetes, cardiovascular disease, and cancer. Recent Advances: Strategies designed to reduce adiposity and its accompanying disorders have been mainly centered on nutritional interventions and physical activity programs. However, novel therapies are needed since these approaches have not been sufficient to counteract the worldwide increasing rates of metabolic disorders. In this regard, intermittent hypoxia training and hyperoxia could be potential treatments through oxygen-related adaptations. Moreover, living at a high altitude may have a protective effect against the development of abnormal metabolic conditions. In addition, oxygen delivery systems may be of therapeutic value for supplying the tissue-specific oxygen requirements. Critical Issues: Precise in vivo methods to measure oxygenation are vital to disentangle some of the controversies related to this research area. Further, it is evident that there is a growing need for novel in vitro models to study the potential pathways involved in metabolic dysfunction to find appropriate therapeutic targets. Future Directions: Based on the existing evidence, it is suggested that oxygen availability has a key role in obesity and its related comorbidities. Oxygen should be considered in relation to potential therapeutic strategies in the treatment and prevention of metabolic disorders. Antioxid. Redox Signal. 35, 642-687.

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

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

Hemodynamic response during hyperbaric treatment on skeletal muscle in a type 2 diabetes rat model

Mild hyperbaric treatment prevents type 2 diabetes progression due to increased oxygen concentration and blood flow in skeletal muscle. However, it remains unknown whether this treatment is effective during all stages of type 2 diabetes. This study aimed to investigate the influences of hyperbaric treatment at 1.3 atmospheres absolute (ATA) on hemodynamic response in various stages of type 2 diabetes. Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats were used as models of type 2 diabetes and healthy controls, respectively. Glucose levels were significantly higher in OLETF rats than in LETO rats at all ages. Glucose intolerance gradually increased with age in OLETF rats. Insulin levels in OLETF rats were significantly higher at 20-week-old, however, were significantly lower at 60-week-old than in LETO rats. Oxy-Hb, total Hb, and StO₂ in skeletal muscle were increased during hyperbaric treatment in both rats. The hemodynamic changes were significantly higher in OLETF rats than LETO rats, and those changes were also pronounced at 8-week-old compared with other age in OLETF rats. These results suggest that hyperbaric treatment at 1.3 ATA acts on pathophysiological factors and the efficacy could be found only in the early stage of type 2 diabetes.

Hyperbaric Oxygen Boosts PD-1 Antibody Delivery and T Cell Infiltration for Augmented Immune Responses Against Solid Tumors

Aberrant mechanical properties and immunosuppression are the two key factors that limit the antitumor efficacy of T cell immune checkpoint blockade inhibitors, e.g., programmed cell death-1 antibody (PD-1 Ab), against solid tumors in the clinic. This study leverages hyperbaric oxygen (HBO) for the first time to address these two issues and reports the PD-1-Ab-mediated immune responses against various stroma-rich solid malignancies. The results demonstrate that HBO promoted PD-1 Ab delivery and T cells infiltration into tumor parenchyma by depleting the extracellular matrix's main components, such as collagen and fibronectin. Furthermore, HBO disrupts hypoxia-mediated immunosuppression and helps PD-1 Ab trigger robust cytotoxic T lymphocytes and long-lasting immunological memory to inhibit tumor relapses. Such enhanced immune responses are effective in solid tumors from rodents and the cancer cells from hepatocellular carcinoma patients. The results illustrate that HBO bolsters antitumor efficacy of PD-1 Ab, and the HBO-PD-1 Ab combination is a promising stroma-rich solid tumors' treatment in the clinic.

To breathe or not to breathe: Understanding how oxygen sensing contributes to age-related phenotypes

Aging is characterized by a progressive loss of tissue integrity and functionality due to disrupted homeostasis. Molecular oxygen is pivotal to maintain tissue functions, and aerobic species have evolved a sophisticated sensing system to ensure proper oxygen supply and demand. It is not surprising that aberrations in oxygen and oxygen-associated pathways subvert health and promote different aspects of aging. In this review, we discuss emerging findings on how oxygen-sensing mechanisms regulate different cellular and molecular processes during normal physiology, and how dysregulation of oxygen availability lead to disease and aging. We describe various clinical manifestations associated with deregulation of oxygen balance, and how oxygen-modulating therapies and natural oxygen oscillations influence longevity. We conclude by discussing how a better understanding of oxygen-related mechanisms that orchestrate aging processes may lead to the development of new therapeutic strategies to extend healthy aging.

An Unusual Case of Compartment Syndrome of the Upper Extremity Caused by an iPad

Acute compartment syndrome develops when intracompartmental pressure increases either due to intrinsic or extrinsic causes. Increase in compartment pressure eventually can lead to impaired tissue perfusion followed by tissue death if no urgent intervention is performed. Patients with acute compartment syndrome usually present with pain out of proportion to apparent injury. It can cause rhabdomyolysis, myoglobinuria, and eventually acute renal failure. The definite treatment is fasciotomy in a timely manner. We here report a very interesting case of acute compartment syndrome in a young patient cause by pressure over his axilla by an iPad.

Hyperbaric oxygen treatment: Results in seven patients with severe bacterial postoperative central nervous system infections and refractory mucormycosis

INTRODUCTION

Resistant bacterial infections following brain and spine surgery and spontaneous mucormycosis with central nervous system (CNS) involvement represent a serious treatment challenge and more efficient therapeutic approaches ought to be considered. Hyperbaric oxygen treatment (HBOT) has shown promise as a complementary therapy. This case series evaluated whether HBOT contributed to infection resolution in seven patients with refractory CNS infectious conditions.

METHODS

Clinical results for seven patients referred for HBOT between 2010 to 2018 to treat refractory postoperative brain and spine infections or spontaneously developing mucormycosis were retrospectively analysed. The patients' clinical files and follow-up consultations were reviewed to assess evolution and outcome.

RESULTS

Seven patients were referred with a median age of 56 years. The median follow-up was 20 months. Four patients had postoperative infections and three had rhino-orbital-cerebral mucormycosis (ROCM). HBOT was used as an adjunctive treatment to antimicrobial therapy in all patients. Prior to HBOT, all patients had undergone an average of four operations due to infection refractoriness and had completed an average of five months of antimicrobial therapy. After HBOT, infection resolution was obtained in six patients without additional operations, while one patient with ROCM stopped HBOT after the third session due to intolerance. Three patients stopped antimicrobial therapy while four were maintained on prophylactic treatment.

CONCLUSIONS

Infection resolution was reached in the six patients that completed HBOT as prescribed. HBOT may serve as an effective complementary treatment in CNS refractory postoperative and spontaneous infections.