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Normobaric hypoxia

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https://www.readbyqxmd.com/read/28923140/working-memory-capacity-and-surgical-performance-while-exposed-to-mild-hypoxic-hypoxemia
#1
Paul J Parker, Andrew J Manley, Ross Shand, John P O'Hara, Adrian Mellor
INTRODUCTION: Medical Emergency Response Team (MERT) helicopters fly at altitudes of 3000 m in Afghanistan (9843 ft). Civilian hospitals and disaster-relief surgical teams may have to operate at such altitudes or even higher. Mild hypoxia has been seen to affect the performance of novel tasks at flight levels as low as 5000 ft. Aeromedical teams frequently work in unpressurized environments; it is important to understand the implications of this mild hypoxia and investigate whether supplementary oxygen systems are required for some or all of the team members...
October 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28923139/cerebral-hemodynamics-and-executive-function-during-exercise-and-recovery-in-normobaric-hypoxia
#2
Jon Stavres, Hayden D Gerhart, Jung-Hyun Kim, Ellen L Glickman, Yongsuk Seo
BACKGROUND: Hypoxia and exercise each exhibit opposing effects on executive function, and the mechanisms for this are not entirely clear. This study examined the influence of cerebral oxygenation and perfusion on executive function during exercise and recovery in normobaric hypoxia (NH) and normoxia (N). METHODS: There were 18 subjects who completed cycling trials in NH (12.5% FIo2) and N (20.93% FIo2). Right prefrontal cortex (PFC) oxyhemoglobin (O2Hb) and middle cerebral artery blood velocity (MCAbv) were collected during executive function challenges [mathematical processing and running memory continuous performance task (RMCPT)] at baseline, following 30 min of acclimation, during 20 min of cycling (60% Vo2max), and at 1, 15, 30, and 45 min following exercise...
October 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28914359/changes-in-acid-base-and-ion-balance-during-exercise-in-normoxia-and-normobaric-hypoxia
#3
Olaf Lühker, Marc Moritz Berger, Alexander Pohlmann, Lorenz Hotz, Tilmann Gruhlke, Marcel Hochreiter
PURPOSE: Both exercise and hypoxia cause complex changes in acid-base homeostasis. The aim of the present study was to investigate whether during intense physical exercise in normoxia and hypoxia, the modified physicochemical approach offers a better understanding of the changes in acid-base homeostasis than the traditional Henderson-Hasselbalch approach. METHODS: In this prospective, randomized, crossover trial, 19 healthy males completed an exercise test until voluntary fatigue on a bicycle ergometer on two different study days, once during normoxia and once during normobaric hypoxia (12% oxygen, equivalent to an altitude of 4500 m)...
September 15, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28912649/does-live-high-train-low-and-high-hypoxic-training-alter-running-mechanics-in-elite-team-sport-players
#4
Olivier Girard, Grégoire P Millet, Jean-Benoit Morin, Franck Brocherie
This study aimed to investigate if "Live High-Train Low (and High)" hypoxic training alters constant-velocity running mechanics. While residing under normobaric hypoxia (≥14 h·d(-1); FiO2 14.5-14.2%) for 14 days, twenty field hockey players performed, in addition to their usual training in normoxia, six sessions (4 × 5 × 5-s maximal sprints; 25 s passive recovery; 5 min rest) under either normobaric hypoxia (FiO2 ~14.5%, n = 9) or normoxia (FiO2 20.9%, n = 11). Before and immediately after the intervention, their running pattern was assessed at 10 and 15 km·h(-1) as well as during six 30-s runs at ~20 km·h(-1) with 30-s passive recovery on an instrumented motorised treadmill...
September 2017: Journal of Sports Science & Medicine
https://www.readbyqxmd.com/read/28901662/acute-hypoxemia-and-vascular-function-in-healthy-humans
#5
N C S Lewis, A R Bain, K W Wildfong, D J Green, P N Ainslie
Endothelium-dependent flow mediated dilation (FMD) and endothelium-independent dilation (GTN) are impaired at high altitude (5050 m), and FMD is impaired following acute exposure (<60-minutes) to normobaric hypoxia equivalent to ∼5050 m (∼FI O2  = 0.11). Whether glyceryl trinitrate (GTN)-induced dilation is impaired acutely, and whether FMD is impaired during milder hypoxia is unknown. Therefore, we assessed brachial FMD at baseline and following 30-minutes of mild (74 ± 2 mmHg PET O₂) and moderate (50 ± 3 mmHg PET O₂) normobaric hypoxia (n = 12) or normoxia (time-control trial; n = 10)...
September 13, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28879713/impact-of-moderate-altitude-on-pro-inflammatory-cytokines-in-healthy-volunteers
#6
Christoph Edlinger, Catharina Schreiber, Bjoern Goebel, Rudin Pistulli, Vera Paar, Christiana Schernthaner, Ilonka Rohm, Hans-Reiner Figulla, Uta C Hoppe, Marcus Franz, Christian Jung, Michael Lichtenauer
BACKGROUND: The induction of microvascular inflammation and the effects on cytokine production in blood due to hypoxia has been shown in the past. We have previously reported a statistically significant increase of the pro-inflammatory cytokine interleukin-8 (IL-8) in normobaric hypoxia in the setting of a hypoxia-chamber. In the present study, we sought to analyze plasma levels of inflammatory cytokines in a real-life stetting in order to foster our knowledge on hypoxia induced microvascular inflammation at moderate altitude...
September 1, 2017: Clinical Laboratory
https://www.readbyqxmd.com/read/28876128/influence-of-inhaled-amiloride-on-lung-fluid-clearance-in-response-to-normobaric-hypoxia-in-healthy-individuals
#7
Courtney M Wheatley, Sarah E Baker, Bryan J Taylor, Manda L Keller-Ross, Steven C Chase, Alex R Carlson, Robert J Wentz, Eric M Snyder, Bruce D Johnson
Wheatley, Courtney M., Sarah E. Baker, Bryan J. Taylor, Manda L. Keller-Ross, Steven C. Chase, Alex R. Carlson, Robert J. Wentz, Eric M. Snyder, and Bruce D. Johnson. Influence of inhaled amiloride on lung fluid clearance in response to normobaric hypoxia in healthy individuals. High Alt Med Biol 00:000-000, 2017. AIM: To investigate the role of epithelial sodium channels (ENaC) on lung fluid clearance in response to normobaric hypoxia, 20 healthy subjects were exposed to 15 hours of hypoxia (fraction of inspired oxygen [FiO2] = 12...
September 6, 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28873460/perfluorocarbon-emulsions-radiosensitise-brain-tumors-in-carbogen-breathing-mice-with-orthotopic-gl261-gliomas
#8
Lisa A Feldman, Marie-Sophie Fabre, Carole Grasso, Dana Reid, William C Broaddus, Gregory M Lanza, Bruce D Spiess, Joel R Garbow, Melanie J McConnell, Patries M Herst
BACKGROUND: Tumour hypoxia limits the effectiveness of radiation therapy. Delivering normobaric or hyperbaric oxygen therapy elevates pO2 in both tumour and normal brain tissue. However, pO2 levels return to baseline within 15 minutes of stopping therapy. AIM: To investigate the effect of perfluorocarbon (PFC) emulsions on hypoxia in subcutaneous and intracranial mouse gliomas and their radiosensitising effect in orthotopic gliomas in mice breathing carbogen (95%O2 and 5%CO2)...
2017: PloS One
https://www.readbyqxmd.com/read/28852828/exercise-related-sensations-contribute-to-decrease-power-during-repeated-cycle-sprints-with-limited-influence-on-neural-drive
#9
Olivier Girard, François Billaut, Ryan J Christian, Paul S Bradley, David J Bishop
PURPOSES: We manipulated the inspired oxygen fraction (FiO2) to examine the effects of physiological perturbations on exercise-related sensations and the neural drive of the quadriceps during repeated, brief, maximal cycle sprints. METHODS: Nine active males completed a repeated sprint cycle protocol (10 × 4-s maximal sprints with 30 s of passive recovery) in normoxia (NM; FiO2 0.21) and severe normobaric hypoxia (HY; FiO2 0.13). Peak power, quadriceps Root Mean Squared electromyography (RMS EMG), physiological (heart rate, arterial oxygen saturation, blood lactate concentration) and perceptual responses were recorded...
August 29, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28846046/the-use-of-simulated-altitude-techniques-for-beneficial-cardiovascular-health-outcomes-in-nonathletic-sedentary-and-clinical-populations-a-literature-review
#10
Catherine A Lizamore, Michael J Hamlin
Lizamore, Catherine A., and Michael J. Hamlin. The use of simulated altitude techniques for beneficial cardiovascular health outcomes in nonathletic, sedentary, and clinical populations: A literature review. High Alt Med Biol 00:000-000, 2017. BACKGROUND: The reportedly beneficial improvements in an athlete's physical performance following altitude training may have merit for individuals struggling to meet physical activity guidelines. AIM: To review the effectiveness of simulated altitude training methodologies at improving cardiovascular health in sedentary and clinical cohorts...
August 28, 2017: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/28818999/short-term-arrival-strategies-for-endurance-exercise-performance-at-moderate-altitude
#11
Joshua L Foss, Keren Constantini, Timothy D Mickleborough, Robert F Chapman
For sea level-based endurance athletes who compete at moderate and high altitudes, many are not logistically able to arrive at altitude weeks prior to the event to fully acclimatize. For those who can only arrive at altitude the night before competition, we asked if there is a physiological and performance advantage in reducing altitude exposure time to two hours prior to competition. On three separate visits, ten cyclists completed overnight laboratory exposures of: 1) a 14-hour exposure to normobaric hypoxia (16...
August 17, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28782598/physiological-and-performance-effects-of-nitrate-supplementation-during-roller-skiing-in-normoxia-and-normobaric-hypoxia
#12
Linn Nybäck, Caroline Glännerud, Gustav Larsson, Eddie Weitzberg, Oliver Michael Shannon, Kerry McGawley
The present study examined the effects of acute nitrate (NO3(-)) supplementation ingested in the form of concentrated beetroot juice on cross-country roller-ski performance in normoxia (N) and normobaric hypoxia (H). Eight competitive cross-country skiers (five males: age 22 ± 3 years, V·O2max 71.5 ± 4.7 mL kg(-1)·min(-1); three females: age 21 ± 1 years, V·O2max 58.4 ± 2.5 mL kg(-1)·min(-1)) were supplemented with a single dose of NO3(-)-rich beetroot juice (BRJ, ∼13 mmol NO3(-)) or a NO3(-)-depleted placebo (PL, ∼0 mmol NO3(-)) and performed 2 x 6-min submaximal exercise bouts and a 1000-m time-trial (TT) on a treadmill in N (20...
August 4, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28775065/effect-of-hypoxia-and-hyperoxia-on-exercise-performance-in-healthy-individuals-and-in-patients-with-pulmonary-hypertension-a-systematic-review
#13
Silvia Ulrich, Simon Raphael Schneider, Konrad E Bloch
Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension, exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange and, presumably, these limitations are more pronounced at altitude...
August 3, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28774953/cerebrovascular-and-ventilatory-responses-to-acute-normobaric-hypoxia-in-girls-and-women
#14
Laura E Morris, Daniela Flück, Philip N Ainslie, Ali M McManus
Physiological responses to hypoxia in children are incompletely understood. We aimed to characterize cerebrovascular and ventilatory responses to normobaric hypoxia in girls and women. Ten healthy girls (9.9 ± 1.7 years; mean ± SD; Tanner stage 1 and 2) and their mothers (43.9 ± 3.5 years) participated. Internal carotid (ICA) and vertebral artery (VA) velocity, diameter and flow (Duplex ultrasound) was recorded pre- and post-1 h of hypoxic exposure (FIO2 = 0.126;~4000 m) in a normobaric chamber...
August 2017: Physiological Reports
https://www.readbyqxmd.com/read/28765942/protein-kinase-c-isozyme-expression-in-right-ventricular-hypertrophy-induced-by-pulmonary-hypertension-in-chronically-hypoxic-rats
#15
Chao Zeng, Bin Liang, Rui Jiang, Yiwei Shi, Yongcheng Du
In chronic hypoxia, pulmonary hypertension (PH) induces right ventricular hypertrophy (RVH). Evidence indicates that protein kinase C (PKC) serves a crucial role in hypoxia‑induced RVH. The present study investigated PKC isoform-specific expression and its involvement in RVH. Rats were exposed to normobaric hypoxia for a number of days to induce PH. PKC isoform‑specific membrane translocation and protein expression in the myocardium were evaluated by western blotting and immunostaining. A total of six isoforms of conventional PKC (cPKC; α, βI and βII) and of novel PKC (nPKC; δ, ε and η), were detected in the rat myocardium...
October 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28763443/intermittent-hypoxic-training-improves-anaerobic-performance-in-competitive-swimmers-when-implemented-into-a-direct-competition-mesocycle
#16
Miłosz Czuba, Robert Wilk, Jakub Karpiński, Małgorzata Chalimoniuk, Adam Zajac, Józef Langfort
The main objective of this research was to evaluate the efficacy of intermittent hypoxic training (IHT) on anaerobic and aerobic capacity and swimming performance in well-trained swimmers. Sixteen male swimmers were randomly divided into a hypoxia (H) group (n = 8), which trained in a normobaric hypoxia environment, and a control (C) group (n = 8), which exercised under normoxic conditions. However, one participant left the study without explanation. During the experiment group H trained on land twice per week in simulated hypoxia (FiO2 = 15...
2017: PloS One
https://www.readbyqxmd.com/read/28757365/assessing-chemoreflexes-and-oxygenation-in-the-context-of-acute-hypoxia-implications-for-field-studies
#17
Jamie R Pfoh, Craig D Steinback, Emily R Vanden Berg, Christina D Bruce, Trevor A Day
Carotid chemoreceptors detect changes in PO2 and elicit a peripheral respiratory chemoreflex (PCR). The PCR can be tested through a transient hypoxic ventilatory response test (TT-HVR), which may not be safe nor feasible at altitude. We characterized a transient hyperoxic ventilatory withdrawal test in the setting of steady-state normobaric hypoxia (13.5-14% FIO2) and compared it to a TT-HVR and a steady-state poikilocapnic hypoxia test, within-individuals. No PCR test magnitude was correlated with any other test, nor was any test magnitude correlated with oxygenation while in steady-state hypoxia...
July 27, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28752154/epidemiology-pathophysiology-clinical-evaluation-and-treatment-of-carbon-monoxide-poisoning-in-child-infant-and-fetus
#18
REVIEW
Atilla Alp Gozubuyuk, Huseyin Dag, Alper Kacar, Yakup Karakurt, Vefik Arica
Carbon monoxide (CO) poisoning is one of the most common types of poisoning causing death worldwide. In our country, it occurs particularly during winter as a result of leak from stove or water heater, or as result of inhalation during a fire. Although most poisonings occur accidentally, some cases are suicide attempt. As CO is a substance that is not visible and has no taste or smell and is therefore difficult to detect, the gas can be a "silent killer" that is not noticed until effects develop. CO reacts with oxygen, creating carboxy hemoglobin (COHb), which leads to tissue hypoxia...
2017: Northern Clinics of Istanbul
https://www.readbyqxmd.com/read/28744647/antioxidant-and-antiamnestic-effects-of-potassium-comenate-and-comenic-acid-under-conditions-of-normobaric-hypoxia-with-hypercapnia
#19
L V Shurygina, E I Zlishcheva, A N Kravtsova, A A Kravtsov
Potassium comenate and comenic acid exhibit manifest and virtually identical antioxidant activity under conditions of hypoxia with hypercapnia. The effects of these drugs on conditioned reflex training with positive reinforcement differ significantly. Potassium comenate promotes retention of the learning capacity and memory in hypoxic rats at the level of intact control, that is, exhibits a pronounced protective antiamnestic effect, while comenic acid only facilitates training of the conditioned reflex with positive reinforcement...
July 26, 2017: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28721516/motor-cognitive-dual-tasking-under-hypoxia
#20
Dennis Hamacher, Marie Brennicke, Tom Behrendt, Prisca Alt, Alexander Törpel, Lutz Schega
Hypoxic conditions diminish motor performance and cognitive functions, especially when the motor task and the cognitive task are conducted simultaneously. Hypoxia does further increase prefrontal cortex activity which provokes a reduced capability of efficient resource utilisation. This, again, might evoke that the capacity of the limited mental resources of a dual task will be reached at an earlier stage of task complexity. The purpose of our study was to examine whether a cognitive task would increase gait variability to a higher extent under hypoxic as compared to normoxic conditions...
July 18, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
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