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Gravity induced loss of consciousness

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https://www.readbyqxmd.com/read/26812597/physical-condition-does-not-affect-gravity-induced-loss-of-consciousness-during-human-centrifuge-training-in-well-experienced-young-aviators
#1
Jinhee Park, Chul Yun, Seungcheol Kang
BACKGROUND: Consensus on whether physical condition affects the risk of gravity-induced loss of consciousness (G-LOC) has not been reached, and most previous studies about the issue did not include well-experienced aviators. We compared the physical conditions of well-experienced young aviators according to the occurrence of G-LOC during human centrifuge training. METHODS: Among 361 young male aviators on active flight duty with experience in high performance aircrafts for at least 2 years, 350 had full data available and were reviewed in this study...
2016: PloS One
https://www.readbyqxmd.com/read/23513280/signs-and-symptoms-during-supra-tolerance-g-z-exposures-with-reference-to-g-garment-failure
#2
Ola Eiken, Mikael Grönkvist
INTRODUCTION: +G(z) exposure above the tolerance threshold typically induces a sequence of symptoms/signs, with loss of: peripheral vision, central vision (black out), and consciousness (G-LOC). The aims of this study were to investigate: 1) whether G history influences latent time to, or sequence of, symptoms/signs upon G exposures exceeding the tolerance threshold; and 2) how pilots respond to a sudden loss of pressure in the anti-G garment (AGG) in flight-like scenarios. METHODS: There were 14 subjects who were exposed to rapid onset rate +G(z)-time profiles, with plateaus 1 and 2 G above the relaxed tolerance level, without initial pressurization of the AGG (NoAGG) and when losing AGG pressure after 10 (AGG_10) and 120 (AGG_120) s at the plateau...
March 2013: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/22980474/-mild-traumatic-brain-injury-and-postconcussive-syndrome-a-re-emergent-questioning
#3
REVIEW
Y Auxéméry
INTRODUCTION: Blast injuries are psychologically and physically devastating. Notably, primary blast injury occurs as a direct effect of changes in atmospheric pressure caused by a blast wave. The combat-related traumatic brain injuries (TBI) resulting from exposure to explosions is highly prevalent among military personnel who have served in current wars. Traumatic brain injury is a common cause of neurological damage and disability among civilians and servicemen. Most patients with TBI suffer a mild traumatic brain injury with transient loss of consciousness...
September 2012: L'Encéphale
https://www.readbyqxmd.com/read/22097637/severe-hypotension-during-the-decreasing-phase-of-gz-stress-in-anesthetized-rats-wearing-an-anti-g-suit
#4
Satoshi Maruyama, Takehito Kemuriyama, Tomoko Manabe, Tomofumi Takahata, Ichiro Shoji, Yasuhiro Nishida
INTRODUCTION: Physiological responses to +Gz stress have been reported in several studies. However, no reports exist on differences in arterial pressure responses between increasing and decreasing G phases. We hypothesized that +Gz stress and/or an anti-G support might disturb the circulation system and cause potential brain hypoperfusion, even if the anti-G support protects against G-induced loss of consciousness. METHODS: Dependency of +Gz magnitude, hemodynamic changes, renal sympathetic nerve activity (RSNA), and aortic blood flow (AoBF) were estimated in anesthetized rats to analyze the effects of +Gz stress and/or an anti-G support on arterial pressure at a level of the brain (APLB)...
November 2011: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/21097262/assessment-of-gravitational-stress-on-heart-rate-variability-during-maneuvers-on-high-performance-jet-flights
#5
Marco Di Rienzo, Paolo Castiglioni, Paolo Meriggi, Francesco Rizzo, Pierandrea Trivelloni, Salvatore Cacopardo, Anton Giulio Guadagno
The Push-Pull Effect (PPE) is a physiological phenomenon defined as a reduction of +Gz tolerance induced by a previous exposure to a -Gz acceleration, that may lead to loss of consciousness. Aim of this study was to evaluate, for the first time, the cardiac rhythm changes associated with PPE during real flights. Data were collected in 3 pilots during flights on the Aermacchi MB- 339-CD aircraft. In each flight, lasting about 60 minutes, ECG, respiration and 3D accelerations were recorded by a new smart garment (the MagIC System)...
2010: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/20415154/on-tracking-the-course-of-cerebral-oxygen-saturation-and-pilot-performance-during-gravity-induced-loss-of-consciousness
#6
Lloyd D Tripp, Joel S Warm, Gerald Matthews, Peter Y Chiu, R Bruce Bracken
OBJECTIVE: The aim of this study was to track the course of cerebral tissue oxygen saturation (rSO2) and pilot performance during an episode of gravity-induced loss of consciousness (GLOC). BACKGROUND: GLOC, a major problem facing pilots of high-performance aircraft, is brought about by a sudden reduction in rSO2 as a result of increased +Gz force. It consists of 24 s of complete functional impairment followed by a prolonged period of performance recovery. This study tested the hypothesis that delayed recovery in GLOC is caused by a slow return of rSO2 following removal of the g-force that induced the episode...
December 2009: Human Factors
https://www.readbyqxmd.com/read/20186423/ultrasonographic-finding-of-internal-jugular-vein-during-anti-g-straining-maneuver-is-it-associated-with-gravity-induced-loss-of-consciousness
#7
Hyun Seok Choi, Jin Gon Sul, Kyung Sik Yi, Jeong-Min Seo, Ki Young Chung
Gravity-induced loss of consciousness (G-LOC) is caused by loss of cerebral blood flow during high +Gz (head-to-foot inertial forces). The resistance of the jugular vein is a significant factor in decrease in cerebral blood flow. Ultrasonography of thoracic inlet veins, including internal jugular vein, is feasible to visualize the internal jugular vein and hemodynamic information. Anti-gravity straining maneuver (AGSM) was widely recognized as one of the important factors in preventing G-LOC. The purpose of this study was to evaluate the relationship between the ultrasonographic shape and size of internal jugular vein during AGSM and G-LOC...
July 2010: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/19750875/mathematical-modeling-of-the-push-pull-effect-for-various-acceleration-profiles-and-countermeasures
#8
Yang Liu, Li-Fan Zhang, Hong-Bing Lu, Guo-Peng Zhang, Huang-Sheng Pu
BACKGROUND: The push-pull maneuver (PPM) can lead to loss of consciousness in pilots of high-performance aircraft. Modeling of the physical and physiological aspects of this phenomenon should allow improved countermeasures. METHODS: A structurally based mechanistic computer model was developed to incorporate dynamic carotid baroreflex responses and detailed modeling of vessel segments for different anatomic regions. The model was used to predict the effect of the PPM on cardiovascular responses and the protection afforded by extended coverage anti-G suits (ECGS) and neck pressure...
September 2009: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/19504770/you-re-the-flight-surgeon-gravity-induced-loss-of-consciousness-and-psoriasis
#9
Lisa R Michels
No abstract text is available yet for this article.
May 2009: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/18238360/non-invasive-sensing-systems-for-acceleration-induced-physiologic-changes
#10
W B Albery, R E Van Patten
The status of a system under development for detection of gravity-induced loss of consciousness (G-LOC) and subsequent recovery is presented. The physiological factors under investigation for use in the loss-of-consciousness monitoring system (LOCOMS) effort are eye blink rate, head slumping, head-level arterial pulsations, and spectral shift in EEG frequency. Also being studied for inclusion in the LOCOMS are a means of detecting the presence/quality of the anti-G straining maneuver and anti-G suit functions, and a system for voice-synthesized query for interrogating the pilot prior to intervention in aircraft control...
1991: IEEE Engineering in Medicine and Biology Magazine
https://www.readbyqxmd.com/read/17641211/frontal-cortical-oxygenation-changes-during-gravity-induced-loss-of-consciousness-in-humans-a-near-infrared-spatially-resolved-spectroscopic-study
#11
Koichi Kurihara, Azusa Kikukawa, Asao Kobayashi, Toshio Nakadate
Gravity (G)-induced loss of consciousness (G-LOC), which is presumably caused by a reduction of cerebral blood flow resulting in a decreased oxygen supply to the brain, is a major threat to pilots of high-performance fighter aircraft. The application of cerebral near-infrared spectroscopy (NIRS) to monitor gravity-induced cerebral oxygenation debt has generated concern over potential sources of extracranial contamination. The recently developed NIR spatially resolved spectroscopy (SRS-NIRS) has been confirmed to provide frontal cortical tissue hemoglobin saturation [tissue oxygenation index (TOI)]...
October 2007: Journal of Applied Physiology
https://www.readbyqxmd.com/read/17486177/cardiovascular-consequences-of-high-performance-aircraft-maneuvers-implications-for-effective-countermeasures-and-laboratory-based-simulations
#12
REVIEW
Jessica M Scott, Ben T A Esch, Len S Goodman, Shannon S D Bredin, Mark J Haykowsky, Darren E R Warburton
The gravitational stress encountered by pilots of high-performance aircraft can cause dramatic shifts in blood volume and circulatory pressure, thus placing the cardiovascular system under significant stress, sometimes resulting in loss of consciousness due to cerebral under-perfusion. Since pilots experience both increased and decreased gravitational stress in high-risk environments, it is important not only to examine the cardiovascular effects of altered gravitational exposure, but also to create effective countermeasures that will increase pilot safety...
April 2007: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/16780240/g-induced-loss-of-consciousness-retrospective-survey-results-from-2259-military-aircrew
#13
Nicholas D C Green, Steven A Ford
INTRODUCTION: Prevalence of G-induced loss of consciousness (G-LOC) in the United Kingdom Royal Air Force (RAF) was found to be 19.3% in 1987. With the introduction of the Typhoon, a fourth generation aircraft, the prevalence of G-LOC has been re-assessed to determine the effectiveness of current G tolerance training. METHOD: A survey was sent to 4018 RAF aircrew, irrespective of their current role. Information was requested on G-LOC, role and aircraft type, experience, and attitudes toward G-LOC prevention...
June 2006: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/16696261/-gz-acceleration-loss-of-consciousness-time-course-of-performance-deficits-with-repeated-experience
#14
Lloyd D Tripp, Joel S Warm, Gerald Matthews, Peter Chiu, Paul Werchan, John E Deaton
OBJECTIVES: We examine the time course of performance recovery from gravity-induced loss of consciousness (GLOC) and evaluate the utility of exposing participants to repeated bouts of GLOC in promoting recovery time. BACKGROUND: A substantial number of accidents among fighter pilots have resulted from episodes of GLOC. U.S. Air Force doctrine holds that when pilots experience GLOC, impairment lasts for 24 s, in which there are 12 s of complete unconsciousness and 12 s of confusion...
2006: Human Factors
https://www.readbyqxmd.com/read/15892551/g-induced-visual-and-cognitive-disturbances-in-a-survey-of-65-operational-fighter-pilots
#15
Caroline A Rickards, David G Newman
INTRODUCTION: Only one previous study has assessed almost loss of consciousness (A-LOC) in operational fighter pilots, reporting an incidence rate of 14%. Research also indicates that 8-13% of pilots have experienced G-induced loss of consciousness (G-LOC). A-LOC can be as insidious as G-LOC due to the associated altered state of awareness and relative incapacitation time, making it a significant risk factor in the high +Gz environment. Royal Australian Air Force (RAAF) pilots currently fly the F/A-18 and Hawk 127, producing +Gz accelerations up to +7...
May 2005: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/12565142/cerebral-hemodynamics-and-brain-oxygen-changes-related-to-gravity-induced-loss-of-consciousness-in-rhesus-monkeys
#16
Cong Chi Tran, Geneviève Florence, Eric Tinet, Didier Lagarde, Jean-Christophe Bouy, Pascal Van Beers, André Serra, Sigrid Avrillier, Jean-Pierre Ollivier
The aim of the present experiment was to study the influence of +Gz acceleration (head-to-foot inertial forces) onset on cerebral oxygenation changes (cerebral oxy- and deoxy-hemoglobin) and cerebral blood volume (CBV) in order to evaluate the role of cerebral hypoxemia and ischemia in the appearance of +Gz-induced loss of consciousness (G-LOC). We used five rhesus monkeys which were equipped with near infrared spectroscopy optodes fixed onto the parietooccipital cranial bone. G-LOC (isoelectric electrocorticogram) was detected with silver balls electrodes in contact with the dura matter...
February 20, 2003: Neuroscience Letters
https://www.readbyqxmd.com/read/12192666/g-induced-loss-of-consciousness-gloc-an-aviation-psychology-challenge
#17
G W McCarthy
No abstract text is available yet for this article.
November 1996: Human Performance in Extreme Environments
https://www.readbyqxmd.com/read/11538544/guidelines-for-a-research-and-development-r-d-program-for-high-sustained-g
#18
R R Burton
This article is a contribution to the workshop on "Operational Requirements in the Prevention of G-Induced Loss of Consciousness (G-LOC) in High Performance Aircraft"; it focuses on the "operational" side of the requirements to prevent G-LOC. There are two types of requirements for prevention of G-LOC; a) pre-G-LOC detection devices that monitor physiologic changes of the pilot before G-LOC occurs, and b) the more generic personal G protection systems that increase G tolerance. Recently there have been major advances in G-protection research and development (R&D) systems (soon to become operational) that significantly improve G-level and G-duration tolerances...
February 1993: Physiologist
https://www.readbyqxmd.com/read/11538504/physiological-considerations-concerning-positive-pressure-breathing-pbg-during-gz
#19
REVIEW
J M Clere, G Ossard, F Melchior
The ability to tolerate +Gz radial acceleration depends primarily on the maintenance of sufficient head level arterial pressure and cerebral blood flow to prevent the occurrence of blackout and G-induced loss of consciousness (G-LOC). Because of the hydrostatic effect on the heart-to-head blood column during +Gz acceleration, if exposures to higher +Gz levels are to be tolerated, either the column must be shortened or arterial pressure at heart level must be elevated. This paper is an overview of the effect and concomitant side effects of positive pressure breathing (PBG) as a means to increase arterial pressure at the heart, and, indirectly, at the cerebral level...
February 1993: Physiologist
https://www.readbyqxmd.com/read/9737757/female-exposure-to-high-g-performance-of-simulated-flight-after-24-hours-of-sleep-deprivation
#20
COMPARATIVE STUDY
T L Chelette, W B Albery, R L Esken, L D Tripp
BACKGROUND: Ground-based research has investigated the loss of cognitive function in the extreme conditions of G-induced loss of consciousness, however, little is known about pilots' abilities to maintain cognitive performance throughout prolonged conscious exposure in the high-G environment. The effects of fatigue and G layoff on performance during exposure to high G are mostly unknown for the female population. METHODS: This research was conducted on the centrifuge Dynamic Environment Simulator...
September 1998: Aviation, Space, and Environmental Medicine
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