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Cureus Apr 2024Introduction In 2016, the European Committee for Hyperbaric Medicine strongly recommended hyperbaric oxygen therapy (HBOT) adjunctive to surgery in post-traumatic crush...
Introduction In 2016, the European Committee for Hyperbaric Medicine strongly recommended hyperbaric oxygen therapy (HBOT) adjunctive to surgery in post-traumatic crush injuries, initiating as rapidly as possible. For the last 30 years, HBOT has been used in crush injury, but in most cases as a last resort, after skin flaps necrosis or wound bed infection, diminishing its potential benefits as a complementary treatment. It is, therefore, essential to understand how HBOT modulates the outcome of crush injury, and when to use it, since this can be a significant and underused therapeutic weapon that may alter the natural course of these patients. Methods Nineteen (n=19) adult patients with upper limb crush injuries underwent adjunctive HBOT, after the initial surgical approach. The measured outcomes included trauma-related acute complications (tissue necrosis and local infection), and late complications (pseudarthrosis and late deep infection). Results Only six (n=6) patients started HBOT in the first 24 hours. Four (n=4) patients presented acute complications; in half of those cases (n=2), HBOT was initiated more than 24 hours post-injury. Late complications were observed in three patients, none of which had initiated HBOT in the first 24 hours post-injury. Conclusions Either lack of awareness or logistic difficulties, preclude initiating timely HBOT, limiting its potential benefits. It is important to alert all practitioners to the right timing to initiate HBOT in order to improve these patients' outcomes.
PubMed: 38803792
DOI: 10.7759/cureus.59146 -
Immunobiology May 2024This study investigated the effect of oxidative stress and the TLR4/NF-κB/NLRP3 pathway on the pathogenesis of acute lung injury (ALI) induced by high-altitude hypoxia.
OBJECTIVE
This study investigated the effect of oxidative stress and the TLR4/NF-κB/NLRP3 pathway on the pathogenesis of acute lung injury (ALI) induced by high-altitude hypoxia.
METHODS
Rats were placed in an animal hyperbaric oxygen chamber to establish a rat model of ALI induced by high-altitude hypoxia after treatment with N-acetylcysteine (NAC; a reactive oxygen species [ROS] inhibitor) or/and MCC950 (an NLPR3 inflammasome inhibitor). After modeling, the wet-to-dry weight ratio (W/D) of rat lung tissues was calculated. In lung tissues, ROS levels were detected with immunofluorescence, the enzyme activity was tested with the kit, and the expression of TLR4/NF-κB/NLRP3 pathway-related genes and proteins was measured with western blotting and qRT-PCR. The levels of inflammatory factors in the serum were quantified with ELISA.
RESULTS
After modeling, rats showed significantly increased W/D, ROS levels, and Malondialdehyde (MDA) concentrations and markedly diminished Superoxide dismutase (SOD) and Glutathione (GSH) concentrations in lung tissues (all P < 0.01), accompanied by substantially enhanced serum levels of TNF-α, IL-6, and IL-1β, significantly reduced serum levels of IL-10, and remarkably augmented TLR4, NLRP3, p-NF-κB p65, NF-κB p65 mRNA, and Caspase-1 expression in lung tissues (all P < 0.01). Furthermore, treatment with NAC or MCC950 alone or in combination prominently lowered the W/D of lung tissues (P < 0.01), serum levels of TNF-α (P < 0.05), IL-6 (P < 0.05), and IL-1β (P < 0.01), and NF-κB p65 expression and phosphorylation (P < 0.05, P < 0.01) while significantly increasing SOD and GSH concentrations (P < 0.05, P < 0.01) and serum levels of IL-10 (P < 0.01) in modeled rats. Meanwhile, treatment of NAC alone or combined with MCC950 significantly reduced MDA concentration and ROS levels (P < 0.05, P < 0.01) in modeled rats, and treatment of MCC950 alone or combined with NAC considerably declined TLR4, NLRP3, and Caspase-1 expression in modeled rats (P < 0.05, P < 0.01).
CONCLUSION
Inhibition of oxidative stress and the TLR4/NF-κB/NLRP3 pathway can ameliorate ALI in rats exposed to high-altitude hypoxia.
PubMed: 38788361
DOI: 10.1016/j.imbio.2024.152809 -
Archives of Medical Science : AMS 2024Hyperbaric oxygen (HBO) therapy involves the inhalation of pure oxygen in a pressure chamber under increased ambient pressure. Recent research indicates that circulating...
INTRODUCTION
Hyperbaric oxygen (HBO) therapy involves the inhalation of pure oxygen in a pressure chamber under increased ambient pressure. Recent research indicates that circulating small extracellular vesicles (sEVs) play important roles in human physiology and pathology. Therefore, the objective of this pilot study was to monitor the impact of HBO therapy on the levels of circulating sEVs in the serum of patients with necrotizing soft-tissue infections (NSTI), aseptic bone necrosis (ABN) or idiopathic sudden sensory neural hearing loss (ISSNHL).
MATERIAL AND METHODS
Serum-derived sEVs were isolated and quantified in 80 patients before and after HBO therapy applied for NSTI, ISSNHL and ABN patients as well as in normal controls who received neither HBO therapy nor steroids.
RESULTS
We observed a significant increase of circulating sEVs in patients with ISSNHL after HBO therapy ( < 0.05), as well as significantly elevated levels of sEVs after HBO therapy compared to patients with NSTI ( < 0.05) and ABN ( < 0.01).
CONCLUSIONS
The increase in the levels of sEVs in ISSNHL may be evidence for both the intended reduction of inflammation as a result of steroid therapy and the inhibitory effect of oxidative stress induced by HBO therapy. Thus, sEVs released during HBO therapy might play an important biological role in mediating the response to therapy and might be a promising approach to gain further insights into the therapeutic efficacy of HBO therapy.
PubMed: 38757025
DOI: 10.5114/aoms/169382 -
Fluids and Barriers of the CNS May 2024Hyperbaric oxygen has been used as a medical treatment tool in hyperbaric chambers and is an integral part of professional and combat divers' activity. In extreme cases,...
INTRODUCTION
Hyperbaric oxygen has been used as a medical treatment tool in hyperbaric chambers and is an integral part of professional and combat divers' activity. In extreme cases, exposure to hyperbaric oxygen can develop central nervous system oxygen toxicity (CNS-OT), which leads to seizures and eventually death. CNS-OT is caused by neuronal hyperactivity due to high oxygen levels, potentially damaging brain cells including the blood-brain barrier (BBB). However, the effect of hyperbaric oxygen levels on the healthy BBB has not been characterized directly yet.
METHODS
Six or three different groups of ~ eight rats or mice, respectively, were exposed to increasing levels of partial pressure of oxygen (0.21 to 5 ATA) in a hyperbaric chamber, followed by MRI scanning with gadolinium. Statistical significance (adjusted p-value ≤ 0.05) was assessed using linear regression and ordinary one-way (rats) or two-way (mice) ANOVA with correction of multiple comparison tests. In rats, the effect of 100% oxygen at 5 ATA was independently validated using FITC-Dextran (5 kDa). Statistical significance (p-value ≤ 0.05) was assessed using Welch's t-test and effect size was calculated by Cohen's D.
RESULTS
In rats, analyzed MRI scans showed a significant trend of increase in the % gadolinium in brain tissues as a result of hyperbaric oxygen pressures (p-value = 0.0079). The most significant increase was measured at 4 ATA compared to air (adjusted p-value = 0.0461). Significant increased FITC-Dextran levels were measured in the rats' brains under 100% oxygen at 5 ATA versus air (p-value = 0.0327; Effect size = 2.0). In mice, a significant increase in gadolinium penetration into the hippocampus and frontal cortex was measured over time (adjusted p-value < 0.05) under 100% oxygen at 3 and 5 ATA versus air, and between the treatments (adjusted p-value < 0.0001).
CONCLUSIONS
The BBB is increasingly disrupted due to higher levels of hyperbaric oxygen in rodents, indicating a direct relation between hyperbaric oxygen and BBB dysregulation for the first time. We suggest considering this risk in different diving activities, and protocols using a hyperbaric chamber. On the other hand, this study highlights the potential therapeutic usage of hyperbaric oxygen for controlled drug delivery through the BBB into brain tissues in different brain-related diseases.
Topics: Animals; Hyperbaric Oxygenation; Blood-Brain Barrier; Rats; Male; Mice; Magnetic Resonance Imaging; Oxygen; Rats, Sprague-Dawley; Mice, Inbred C57BL
PubMed: 38755589
DOI: 10.1186/s12987-024-00543-7 -
Biomolecules Apr 2024In military flight operations, during flights, fighter pilots constantly work under hyperoxic breathing conditions with supplemental oxygen in varying hypobaric...
BACKGROUND
In military flight operations, during flights, fighter pilots constantly work under hyperoxic breathing conditions with supplemental oxygen in varying hypobaric environments. These conditions are suspected to cause oxidative stress to neuronal organ tissues. For civilian flight operations, the Federal Aviation Administration (FAA) also recommends supplemental oxygen for flying under hypobaric conditions equivalent to higher than 3048 m altitude, and has made it mandatory for conditions equivalent to more than 3657 m altitude.
AIM
We hypothesized that hypobaric-hyperoxic civilian commercial and private flight conditions with supplemental oxygen in a flight simulation in a hypobaric chamber at 2500 m and 4500 m equivalent altitude would cause significant oxidative stress in healthy individuals.
METHODS
Twelve healthy, COVID-19-vaccinated (third portion of vaccination 15 months before study onset) subjects (six male, six female, mean age 35.7 years) from a larger cohort were selected to perform a 3 h flight simulation in a hypobaric chamber with increasing supplemental oxygen levels (35%, 50%, 60%, and 100% fraction of inspired oxygen, FiO, via venturi valve-equipped face mask), switching back and forth between simulated altitudes of 2500 m and 4500 m. Arterial blood pressure and oxygen saturation were constantly measured via radial catheter and blood samples for blood gases taken from the catheter at each altitude and oxygen level. Additional blood samples from the arterial catheter at baseline and 60% oxygen at both altitudes were centrifuged inside the chamber and the serum was frozen instantly at -21 °C for later analysis of the oxidative stress markers malondialdehyde low-density lipoprotein (M-LDL) and glutathione-peroxidase 1 (GPX1) via the ELISA test.
RESULTS
Eleven subjects finished the study without adverse events. Whereas the partial pressure of oxygen (PO) levels increased in the mean with increasing oxygen levels from baseline 96.2 mm mercury (mmHg) to 160.9 mmHg at 2500 m altitude and 60% FiO and 113.2 mmHg at 4500 m altitude and 60% FiO, there was no significant increase in both oxidative markers from baseline to 60% FiO at these simulated altitudes. Some individuals had a slight increase, whereas some showed no increase at all or even a slight decrease. A moderate correlation (Pearson correlation coefficient 0.55) existed between subject age and glutathione peroxidase levels at 60% FiO at 4500 m altitude.
CONCLUSION
Supplemental oxygen of 60% FiO in a flight simulation, compared to flying in cabin pressure levels equivalent to 2500 m-4500 m altitude, does not lead to a significant increase or decrease in the oxidative stress markers M-LDL and GPX1 in the serum of arterial blood.
Topics: Humans; Male; Oxidative Stress; Female; Adult; Altitude; Oxygen; COVID-19; Hyperoxia; Aircraft; Hyperbaric Oxygenation
PubMed: 38672497
DOI: 10.3390/biom14040481 -
Frontiers in Medicine 2024SCUBA diving exposes participants to a unique hyperbaric environment, but few studies have examined the effects of such an environment on intraocular pressure (IOP) and...
PURPOSE
SCUBA diving exposes participants to a unique hyperbaric environment, but few studies have examined the effects of such an environment on intraocular pressure (IOP) and glaucoma. This systematic review aims to consolidate recent literature findings regarding the impact of increased atmospheric pressure on IOP and glaucoma.
METHODS
Three online databases were searched to identify publications encompassing the subjects of diving or increased atmospheric pressure in conjunction with IOP or glaucoma. Three reviewers independently screened the publications and identified eligible articles. Relevant data was extracted from each article. The heterogeneity of the data precluded the conduct of a meta-analysis.
RESULTS
Nine studies met the inclusion criteria. Six experimental studies employed hyperbaric chambers to measure IOP under simulated diving conditions. Among these, IOP exhibited a reduction with increased atmospheric pressures in four studies, while the findings of two studies were inconclusive. One study measured IOP pre- and post-dive and another measured IOP with and without a diving mask. Post-dive, a decrease in IOP was observed, and a statistically significant reduction was noted when subjects wore a diving mask. A retrospective study examining the incidence of acute angle closure glaucoma attack found no association with weather or atmospheric pressure.
CONCLUSION
The majority of studies found IOP to decrease with increased atmospheric pressure and after diving. The mechanisms underlying this reduction remain incompletely understood, with potential contributors including changes in ocular blood flow, sympathetic responses, and increased oxygenation. Hyperbaric chambers may have potential in future glaucoma treatments, but more studies are required to draw reliable conclusions regarding the safety of diving for glaucoma patients.
PubMed: 38633303
DOI: 10.3389/fmed.2024.1365259 -
Cureus Mar 2024Introduction Hyperbaric oxygen therapy (HBOT) has been influential in treating many physical and psychological ailments, including the symptoms of autism. This current...
Introduction Hyperbaric oxygen therapy (HBOT) has been influential in treating many physical and psychological ailments, including the symptoms of autism. This current study aims to evaluate HBOT parents' goals and exit interviews describing the positive, negative, or no impacts experienced from the HBOT dives, asking the question, "Are your child's symptoms improving?" Methods Between January 2020 and July 2023, a Class B monoplace hyperbaric chamber (Sechrist 3300H, Sechrist Industries, Inc., Anaheim, California, United States) was used to administer HBOT sessions to patients with autism. Medical-grade oxygen was pressurized to 1.5-2.0 atmospheres absolute at a rate of 1-2 psi/min, with an average oxygen percentage of 100%, for up to five sessions per week. Retrospective descriptive data and patient information through parent testimonials were collected through a chart review of 30 children and one adult with autism who experienced HBOT sessions. Data were presented through exit interviews describing how parents felt about their child's progress toward goals. Four raters rated parent testimonies on a 5-point Likert scale (1 = Much worse, 2 = Somewhat worse, 3 = Stayed the same, 4 = Somewhat improved, and 5 = Much improved), and an inter-rater reliability estimate using interclass correlation (2) (r = 0.831) was derived, indicating excellent agreement between raters. Results Parents/caregivers provided testimony in an exit interview with a registered nurse after the individual with autism received an entire course of HBOT dives. Descriptive statistics resulted in Rater #1 (M = 4.19, median = 4, SD = 0.654): 87.1% of Rater #1 ratings were Somewhat improved and Much improved; Rater #2 (M = 4.23, median = 4, SD = 0.717): 83.9% of Rater #2 ratings were Somewhat improved and Much improved; Rater #3 (M = 4.23, median = 4, SD = 0.560): 93.5% of Rater #3 ratings were Somewhat improved and Much improved; and Rater #4 (M = 4.26, median = 4, SD = 0.631): 90.3% of Rater #4 ratings were Somewhat improved and Much improved. One-way ANOVA resulted in F (3,123) = 0.052, p = 0.984, which indicated a nonstatistically significant mean difference between rater groups. Conclusions The current study assessed HBOT parents'/caregivers' goals and exit interviews, describing the effects experienced from the complete course of HBOT dives on their children/individuals. A majority of parents/caregivers declared that their condition had "Much improved" or "Somewhat improved," based on the 5-point Likert scale. Based on parents'/caregivers' testimonies, HBOT was demonstrated as a safe and effective intervention, and side effects were primarily mild and did not lead to treatment discontinuation. As a result of this analysis, we recommend continued use of HBOT for treatment.
PubMed: 38586763
DOI: 10.7759/cureus.55648 -
Membranes Mar 2024Extracorporeal gas exchange therapies evolved considerably within the first three-four decades of their appearance, and have since reached a mature stage, where minor...
Extracorporeal gas exchange therapies evolved considerably within the first three-four decades of their appearance, and have since reached a mature stage, where minor alterations and discrete fine-tuning might offer some incremental improvement. A different approach is introduced here, making use of modern, purely diffusive membrane materials, and taking advantage of the elevated concentration gradient ensuing from gas pressure buildup in the gas chamber of the oxygenator. An assortment of silicone membrane gas exchangers were tested in vitro as per a modified protocol in pursuance of assessing their gas exchange efficiency under both regular and high-pressure aeration conditions. The findings point to a stark performance gain when pressurization of the gas compartment is involved; a 40% rise above atmospheric pressure elevates oxygen transfer rate (OTR) by nearly 30%. Carbon dioxide transfer rate (CTR) does not benefit as much from this principle, yet it retains a competitive edge when higher gas flow/blood flow ratios are employed. Moreover, implementation of purely diffusive membranes warrants a bubble-free circulation. Further optimization of the introduced method ought to pave the way for in vivo animal trials, which in turn may potentially unveil new realms of gas exchange performance for therapies associated with extracorporeal circulation.
PubMed: 38535287
DOI: 10.3390/membranes14030068 -
Diving and Hyperbaric Medicine Mar 2024This is a review of commercial heliox saturation decompression procedures. The scope does not include compression, storage depth or bell excursion dive procedures. The... (Review)
Review
INTRODUCTION
This is a review of commercial heliox saturation decompression procedures. The scope does not include compression, storage depth or bell excursion dive procedures. The objectives are to: identify the sources of the procedures; trace their evolution; describe the current practice; and detect relevant trends.
METHODS
Eleven international commercial diving companies provided their diving manuals for review under a confidentiality agreement.
RESULTS
Modern commercial diving saturation procedures are derived from a small number of original procedures (United States Navy, Comex, and NORSOK). In the absence of relevant scientific studies since the late 80's, the companies have empirically adapted these procedures according to their needs and experience. Such adaptation has caused differences in decompression rates shallower than 60 msw, decompression rest stops and the decision to decompress linearly or stepwise. Nevertheless, the decompression procedures present a remarkable homogeneity in chamber PO and daily decompression rates when deeper than 60 msw. The companies have also developed common rules of good practice; no final decompression should start with an initial ascending excursion; a minimum hold is required before starting a final decompression after an excursion dive. Recommendation is made for the divers to exercise during decompression.
CONCLUSIONS
We observed a trend towards harmonisation within the companies that enforce international procedures, and, between companies through cooperation inside the committees of the industry associations.
Topics: Humans; Diving; Decompression; Oxygen; Helium; Decompression Sickness
PubMed: 38507907
DOI: 10.28920/dhm54.1.23-38