Positive pressure ventilation improves oxygen saturation at altitude during recreational aviation: A pilot study

Physiological Reports, Journal Year: 2025, Volume and Issue: 13(3)

Published: Feb. 1, 2025

We investigated whether a commercial bi-level positive airway pressure (BPAP) device, would improve peripheral oxygen saturation (SpO2) during recreational aviation up to 12,500 feet without supplemental oxygen. Ten adults with flight experience (age:47 ± 14; female = 5) completed standardized profile in an unpressurised aircraft, involving randomized crossover design at 8,000 and BPAP or control. SpO2, middle cerebral artery velocity (MCAv), heart rate (HR), respiratory (RR), relative tidal volume (TV) index were measured continuously. Psychomotor vigilance test (3-min) assessed reaction time halfway through taxi altitude stages. Altitude significantly (p < 0.05) decreased mean MCAv, RR, increased TV HR. There was no effect of > on time. SpO2 [Control: 92 1%; BPAP: 94 2%; difference (MD) 2 p 0.002] 86 4%; 89 MD 3%; 0.013]. lowered MCAv 53 10 cm/s; 50 9 -3 0.001] 52 8 -2 3 0.041]. (Control: 6.6 1.3; BPAP:8.1 1.8; 1.9 0.8; 0.001) but not feet, RR This study provides preliminary results that may for aviators

Language: Английский

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Neurovascular coupling is optimized to compensate for the increase in proton production from nonoxidative glycolysis and glycogenolysis during brain activation and maintain homeostasis of pH, pCO₂, and pO₂

Journal of Neurochemistry, Journal Year: 2023, Volume and Issue: 168(5), P. 632 - 662

Published: May 8, 2023

Abstract During transient brain activation cerebral blood flow (CBF) increases substantially more than metabolic rate of oxygen consumption (CMRO 2 ) resulting in hyperoxygenation, the basis BOLD‐fMRI contrast. Explanations for high CBF versus CMRO slope, termed neurovascular coupling (NVC) constant, focused on maintenance tissue oxygenation to support mitochondrial ATP production. However, paradoxically has a 3‐fold lower extraction fraction (OEF) other organs with energy requirements, like heart and muscle during exercise. Here, we hypothesize that NVC constant capillary mass transfer coefficient (which combination determine OEF) are co‐regulated maintain simultaneous homeostasis pH partial pressure CO O ( p ). To test our hypothesis, developed an arteriovenous flux balance model calculating pH, , as function baseline OEF (OEF 0 ), CBF, proton production by nonoxidative metabolism coupled hydrolysis. Our was validated against published difference studies then used calculate activated human cortex from calibrated fMRI PET measurements. In agreement calculated remained close independently correspondence experimental measurements . We also found optimum values ensure were remarkably similar their values. Thus, is overall determined removal due glycolysis glycogenolysis. These findings resolve paradox brain's yet low activation, may contribute explaining vulnerability reductions density aging disease. image

Language: Английский

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Integrating physiological monitoring systems in military aviation: a brief narrative review of its importance, opportunities, and risks

Ergonomics, Journal Year: 2023, Volume and Issue: 66(12), P. 2242 - 2254

Published: March 22, 2023

Military pilots risk their lives during training and operations. Advancements in aerospace engineering, flight profiles, mission demands may require the pilot to test safe limits of physiology. Monitoring physiology (e.g. heart rate, oximetry, respiration) inflight is consideration by several nations inform reduced performance capacity guide future developments aircraft life-support system design. Numerous challenges, however, prevent immediate operationalisation physiological monitoring sensors, particularly unreliability environment incompatibility with clothing protective equipment. Human behaviour are also highly variable measuring these controlled laboratory settings do not mirror real-world conditions must endure. Misleading or erroneous predictive models unacceptable as could compromise success lose operator trust. This narrative review provides an overview considerations for integrating systems within military aviation environment.Practitioner summary: technology can conflictingly enhance safety performance. We summarise some opportunities, limitations, risks aviation. Our intent catalyse further research technological development.Abbreviations: AGS: anti-gravity suit; AGSM: straining manoeuvre; A-LOC: almost loss consciousness; CBF: cerebral blood flow; ECG: electrocardiogram; EEG: electroencephalogram; fNIRS: functional near-infrared spectroscopy; G-forces: gravitational forces; G-LOC: gravity-induced HR: rate; HRV: rate variability; LSS: system; NATO: North Atlantic Treaty Organisation; PE: Physiological Episode; PCO2: partial pressure carbon dioxide; PO2: oxygen; OBOGS: on board oxygen generating systems; SpO2: peripheral haemoglobin-oxygen saturation; STANAG: Organisation Standardisation Agreement; UPE: Unexplained WBV: whole body vibration

Language: Английский

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Acute high‐altitude hypoxia exposure causes neurological deficits via formaldehyde accumulation

CNS Neuroscience & Therapeutics, Journal Year: 2022, Volume and Issue: 28(8), P. 1183 - 1194

Published: May 18, 2022

Abstract Introduction Acute high‐altitude hypoxia exposure causes multiple adverse neurological consequences. However, the exact mechanisms are still unclear, and there is no targeted treatment with few side effects. Excessive cerebral formaldehyde (FA) impairs numerous functions, can be eliminated by nano‐packed coenzyme Q10 (CoQ10). Aims In this study, we aimed to investigate whether FA was accumulated after hypobaric exposure, further explored preventative effect of CoQ10 through elimination. Results Accumulated found in C57BL/6 mice acute which resulted metabolic disturbance elevation semicarbazide‐sensitive amine oxidase, declination aldehyde dehydrogenase‐2. also induce neuronal ferroptosis vivo. Excitingly, administration for 3 days before reduced accumulation, alleviated subsequent ferroptosis, preserved functions. Conclusion Cerebral accumulation mediates deficits under hypoxia, supplementation may a promising strategy visitors sojourners at plateau.

Language: Английский

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Hypoxia Protocols in a Normobaric Environment for Aviators: a Scoping Review

Revista de Gestão Social e Ambiental, Journal Year: 2025, Volume and Issue: 19(1), P. e010458 - e010458

Published: Jan. 23, 2025

Objective: Identify the protocols used in normobaric hypoxia and main symptoms that context. Theoretical Framework: Hypoxia, particularly hypoxic hypoxia, is a critical challenge aviation, caused by reduced atmospheric pressure at high altitudes. Controlled training allows aviators to recognize symptoms, assess time of useful consciousness, practice emergency responses. This study synthesizes key parameters training, addressing gaps oxygen concentrations, exposure times, symptom monitoring. Method: Systematic electronic searches were conducted MEDLINE Embase databases. Inclusion criteria required original studies involving aircraft crews, descriptions gas mixtures for altitude simulation, details simulated altitudes during training. Results Discussion: From 295 identified articles, eight met inclusion criteria. Sample sizes ranged from 8 89 participants, predominantly male. Protocols varied widely, with O₂ concentrations 6%, 7%, 8% frequently simulate 25,919 feet (7,900 m) 20,341 (6,200 m). Considerable heterogeneity was found same altitude, likely due differences equipment calibration. Continuous periods three five minutes common, diverse reported, emphasizing importance recognition operational safety. Research Implications: offers practical insights standardizing protocols, enhancing safety procedures, developing guidelines environments. Originality/Value: By synthesizing parameters, this research highlights need protocol standardization ensure aviator efficiency.

Language: Английский

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Specific Activity of Lactate Dehydrogenase in Muscle and Liver Tissues of Rats Exposed to Intermittent Hypobaric Hypoxia

BIO Integration, Journal Year: 2025, Volume and Issue: 6(1)

Published: Jan. 1, 2025

Abstract As the altitude increases, partial pressure of oxygen will decrease and cause hypobaric hypoxia conditions. During hypoxia, anaerobic glycolysis be activated, which is facilitated by lactate dehydrogenase (LDH) enzyme. This study aimed to analyze LDH-specific activity in rat muscle liver tissue, as well glucose levels blood plasma after intermittent exposure. Twenty-five Wistar rats were divided into five groups: one control group four (HH) exposure groups consisting 1 (1× HH), 2 (2× 3 (3× 4 (4× HH) with a range 7 days between found that increased tissues 1, but then decreased (groups 2–4). The change was similar levels. Interestingly, tissues, there slight increase it started significantly kept increasing 4. level. We conclude LDH tissue contributes levels, maintaining exposures. finding could implemented individuals who experience exposures or various diseases hypoxic conditions their pathogenesis

Language: Английский

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Oxidative Stress Reaction to Hypobaric–Hyperoxic Civilian Flight Conditions

Biomolecules, Journal Year: 2024, Volume and Issue: 14(4), P. 481 - 481

Published: April 15, 2024

Background: In military flight operations, during flights, fighter pilots constantly work under hyperoxic breathing conditions with supplemental oxygen in varying hypobaric environments. These are suspected to cause oxidative stress neuronal organ tissues. For civilian the Federal Aviation Administration (FAA) also recommends for flying equivalent higher than 3048 m altitude, and has made it mandatory more 3657 altitude. Aim: We hypothesized that hypobaric–hyperoxic commercial private a simulation chamber at 2500 4500 altitude would significant 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 larger cohort were selected perform 3 h increasing levels (35%, 50%, 60%, 100% fraction inspired oxygen, FiO2, via venturi valve-equipped face mask), switching back forth between simulated altitudes m. Arterial blood pressure saturation measured radial catheter samples gases taken each level. Additional arterial baseline 60% both centrifuged inside serum was frozen instantly −21 °C later analysis markers malondialdehyde low-density lipoprotein (M-LDL) glutathione-peroxidase 1 (GPX1) ELISA test. Results: Eleven finished without adverse events. Whereas partial (PO2) increased 96.2 mm mercury (mmHg) 160.9 mmHg FiO2 113.2 there no increase these altitudes. Some individuals had slight increase, whereas some showed all or even decrease. A moderate correlation (Pearson coefficient 0.55) existed subject glutathione peroxidase Conclusion: Supplemental simulation, compared cabin m–4500 does not lead decrease M-LDL GPX1 blood.

Language: Английский

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CircRNA-miRNA-mRNA regulatory network in high-altitude hypobaric hypoxia-induced hearing impairment and hearing acclimatization

Brazilian Journal of Otorhinolaryngology, Journal Year: 2025, Volume and Issue: 91(2), P. 101557 - 101557

Published: Jan. 27, 2025

Language: Английский

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Improved oxygen saturation and acclimatization with bacteriotherapy at high altitude

iScience, Journal Year: 2025, Volume and Issue: 28(4), P. 112053 - 112053

Published: Feb. 17, 2025

Language: Английский

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Reduced removal of waste products from energy metabolism takes center stage in human brain aging

Scientific Reports, Journal Year: 2025, Volume and Issue: 15(1)

Published: March 8, 2025

Despite extensive research on neuroimaging correlates of human brain aging, there is little mechanistic insight into how they are linked to loss function. Previous studies the role cerebral blood flow (CBF) in supporting function have focused delivery nutrients, namely oxygen and glucose. However, CBF required also clear byproducts energy metabolism, CO2 protons. With goal determining whether age-associated reduction regional may lead abnormal partial pressure carbon dioxide (pCO2) pH levels that sufficient alter activity cognitive function, we applied a recently introduced homeostatic modeling nutrients waste products PET data acquired young older adults (Goyal et al. Cell Metab 26(2):353–360, 2017). Our results demonstrate reductions CBF, presence virtually unaltered consumption rates, show concurrent increases pCO2 associated acid-shifts possible functional relevance. We conclude implications altered vascular health needs be revisited light its central removing from metabolism at resting state and, future studies, during external stimulations.

Language: Английский

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