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  • 1. Andersson, Jan
    et al.
    Berggren, Peter
    Grönkvist, Mikael
    Swedish Defence Research Agency.
    Magnusson, Staffan
    Svensson, Erland
    Oxygen saturation and cognitive performance.2002Inngår i: Psychopharmacology, ISSN 0033-3158, E-ISSN 1432-2072, Vol. 162, nr 2, s. 119-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of the experiments was to investigate how inhalation of 100% oxygen affected cognitive performance. A test battery was developed that was designed to capture different aspects of cognitive processes, i.e., perception, attention, working memory, long-term memory and prospective memory. All tests were verbally based, thus reducing cognitive spatial processes to a minimum. In experiment 1, 48 participants volunteered in a complete factorial within-participant design. Two different conditions for type of gas were used, inhalation of 100% oxygen and inhalation of breathing air (approximately 21% oxygen balanced with nitrogen). The inhalation was performed during the 1 min prior to starting each separate test. The instructions for each test were given during the inhalation period. All participants inhaled oxygen or breathing air through a Swedish military pilot mask. Physiological (heartbeats per minute and blood oxygen saturation level) reactions were recorded continuously throughout the session. Participants also completed a mood-state questionnaire before and after the test battery. The results revealed that cognitive performance were not affected by inhalation. Hence, this experiment does not replicate previous findings that suggest that inhalation of 100% oxygen could increase cognitive performance. Another experiment was performed to control for methodological issues. Experiment 2 revealed exactly the same pattern, i.e., inhalation of oxygen did not affect cognitive functioning.

  • 2. Ciuha, U
    et al.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Mekjavic, I.B.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Strategies for increasing evaporative cooling during simulated desert patrol missions2014Inngår i: Proceedings from 3rd International Congress on Soldiers Physical Performance, 2014Konferansepaper (Annet vitenskapelig)
  • 3. Ciuha, U
    et al.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Mekjavic, B.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Strategies for increasing evaporative cooling during simulated desert patrol mission.2016Inngår i: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 59, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study evaluated the efficiency of two heat dissipation strategies under simulated desert patrol missions. Ten men participated in four trials, during which they walked on a treadmill (45°C, 20% relative humidity), carrying a load of 35 kg; two 50-min walks were separated by a 20-min rest. Cooling strategies, provided by an ambient air-ventilated vest (active cooling condition, AC), or water spraying of the skin during the rest (passive cooling condition, PC), in addition to reduced clothing and open zippers, were compared to conditions with full protective (FP) clothing and naked condition (NC). Skin temperature was higher during NC (37.9 ± 0.4°C; p < 0.001), and rectal temperature and heart rate were higher during FP (38.6 ± 0.4°C, p < 0.001 and 145 ± 12, p < 0.001, respectively), compared to other conditions. Four subjects terminated the trial prematurely due to signs of heat exhaustion in FP. Both cooling strategies substantially improved evaporative cooling.

  • 4. Ciuha, U
    et al.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Mekjavic, I
    Kölegård, Roger
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Pavlinič, D
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Thermal strain in soldiers performing patrol missions in a desert climate: effect of two different cooling strategies2011Konferansepaper (Fagfellevurdert)
  • 5.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Bergsten, Eddie
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    G-protection mechanisms afforded by the anti-G suit abdominal bladder with and without pressure breathing.2011Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 82, nr 10, s. 972-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: G protection afforded by the abdominal bladder of a pneumatic anti-G suit is usually attributed to counteraction of G-induced caudad displacement of the heart and pooling of blood in the abdominal veins. The study examined whether the abdominal bladder might provide G protection also via other mechanisms.

    METHODS: Each subject was exposed to +Gz loads while sitting relaxed, wearing a full-coverage anti-G suit modified to permit separate pressurization of the abdominal and leg bladders. In two experimental series (N = 8, N = 14), subjects were breathing at positive airway pressure (PPB); in a third series, five subjects were breathing at atmospheric airway pressure. Intrathoracic pressures were estimated by use of esophageal catheters.

    RESULTS: During PPB at high G loads, intrathoracic pressure was higher with than without the pressurized abdominal bladder. In 7 of the 14 subjects, basilar intrathoracic pressure exceeded airway pressure during PPB when the abdominal bladder was pressurized. The mean arterial pressure response at high G loads was higher in this subset of subjects (55 +/- 23 mmHg) than in the subjects in whom airway pressure exceeded intrathoracic pressure (41 +/- 27 mmHg). Without PPB at increased G load, the intrathoracic pressure gradient was higher with than without the pressurized abdominal bladder.

    DISCUSSION: During PPB, the abdominal bladder acts as an airway counterpressure, thereby facilitating pressure transmission from the airways to the thorax and hence improving G protection. It also appears that in several individuals, pressure may be transmitted from the abdominal bladder to the thorax and heart.

  • 6.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi (Stängd 20130701).
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi (Stängd 20130701).
    Signs and symptoms during supra-tolerance +Gz exposures, with reference to G-garment failure.2013Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 84, nr 3, s. 196-205Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction: +Gz 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 +Gz-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. Simulated target-chase flights during which AGG pressure was released were performed by seven pilots; the pilot was instructed to behave as during real flight. Results: Latent time to symptoms was shorter at +2 G than at +1 G, and shorter in AGG_10 and AGG_120 than in NoAGG. In AGG_120, 43 and 64% of the subjects experienced serious symptoms (black out, Almost LOC, G-LOC) at +1 and +2 G, respectively, compared to 21 and 54% in AGG_10 and 7 and 29% in NoAGG. The incidence of A-LOC/G-LOC was higher in AGG_10 and especially in AGG_120 than in NoAGG. During the target chase, one pilot did not notice the pressure loss, one experienced G-LOC, and two A-LOC. Discussion: The risk of serious consequences of G exposure exceeding the tolerance level appears to be greater when G-garment failure occurs after a prolonged than after a brief exposure.

  • 7.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Gennser, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Kabintryck och risk för barotrauma vid explosiv decompression I fpl 392015Rapport (Annet vitenskapelig)
  • 8.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Kölegård, Roger
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Danielsson, Ulf
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Zavec, D.
    Kounalakis, S.N.
    Mekjavic, I.
    Termisk belastning hos soldater som bär svensk stridsutrustning2010Rapport (Annet vitenskapelig)
  • 9.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Kölegård, Roger
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Zavec, D.
    Ciuha, U.
    Mekjavic, I.
    Termisk belastning hos markstridssoldater vid patrullering i ökenklimat: effekter av två olika ballistiska kroppsskydd samt av två olika strategier för nedkylning2011Rapport (Annet vitenskapelig)
  • 10.
    Eiken, Ola
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Keramidas, Michail E.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Taylor, Nigel A S
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Intraocular pressure and cerebral oxygenation during prolonged headward acceleration2017Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 117, nr 1, s. 61-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supra-tolerance head-to-foot directed gravitoinertial load (+Gz) typically induces a sequence of symptoms/signs, including loss of: peripheral vision-central vision-consciousness. The risk of unconsciousness is greater when anti-G-garment failure occurs after prolonged rather than brief exposures, presumably because, in the former condition, mental signs are not consistently preceded by impaired vision. The aims were to investigate if prolonged exposure to moderately elevated +Gz reduces intraocular pressure (IOP; i.e., improves provisions for retinal perfusion), or the cerebral anoxia reserve. Subjects were exposed to 4-min +Gz plateaux either at 2 and 3 G (n = 10), or at 4 and 5 G (n = 12). Measurements included eye-level mean arterial pressure (MAP), oxygenation of the cerebral frontal cortex, and at 2 and 3 G, IOP. IOP was similar at 1 (14.1 +/- 1.6 mmHg), 2 (14.0 +/- 1.6 mmHg), and 3 G (14.0 +/- 1.6 mmHg). During the G exposures, MAP exhibited an initial prompt drop followed by a partial recovery, end-exposure values being reduced by ae<currency>30 mmHg. Cerebral oxygenation showed a similar initial drop, but without recovery, and was followed by either a plateau or a further slight decrement to a minimum of about -14 mu M. Gz loading did not affect IOP. That cerebral oxygenation remained suppressed throughout these G exposures, despite a concomitant partial recovery of MAP, suggests that the increased risk of unconsciousness upon G-garment failure after prolonged +Gz exposure is due to reduced cerebral anoxia reserve.

  • 11.
    Eiken, Ola
    et al.
    Swedish Defence Research Agency.
    Kölegärd, Roger
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Grönkvist, Mikael
    Swedish Defence Research Agency.
    G protection: interaction of straining maneuvers and positive pressure breathing2007Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 78, nr 4, s. 392-398Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    INTRODUCTION: G protection in the 39 Gripen aircraft is provided by a full coverage anti-G suit, a pressure-breathing system, and anti-G straining maneuvers (AGSM). The purpose was to study (1) the interaction of pressure breathing and AGSM while wearing an anti-G suit; and (2) the G-protective properties of the anti-G suit alone and in combination with the pressure-breathing system.

    METHODS: During rapid onset rate G-time profiles (< or =9 G), 10 subjects were investigated in 5 conditions: (I) sitting relaxed, without any G-protective garment; (II) sitting relaxed and wearing an anti-G suit; (III) sitting relaxed, wearing an anti-G suit, and pressure breathing; IV) wearing an anti-G suit and performing AGSM; and V) wearing an anti-G suit, pressure breathing, and performing AGSM. In supplementary experiments (n=9), the share of the anti-G suit protection afforded by the abdominal bladder was investigated.

    RESULTS: G tolerance was 3.4 Gz (range: 2.8-4.3) in condition I, > or = 6.5 Gz (4.5-9.0) in II, > or = 8.0 Gz (6.5-9.0) in III, > or = 8.9 Gz (8.5-9.0) in IV and > or = 9.0 Gz (8.5-9.0) in V. In the supplementary experiments, the anti-G suit afforded a 2.8-G protection, a third of which was contributed by the abdominal bladder. In the relaxed state, pressure applied to the airways was transmitted undistorted to the intrathoracic space. During AGSM, intrathoracic pressure rose to 10-14 kPa, regardless of whether AGSM was performed with or without pressure breathing.

    DISCUSSION AND CONCLUSIONS: The anti-G suit and the pressure breathing system provide G protection of > or = 4.6 G, of which the anti-G suit contributes about 3.0 G. The C-protective properties of the anti-G suit and those of pressure breathing appears to be additive, whereas the G protection afforded by pressure breathing does not add to that provided by AGSM.

  • 12.
    Gennser, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    No changes in pulmonary function indices after nitrox saturation dives.2017Konferansepaper (Fagfellevurdert)
  • 13.
    Gennser, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Norrbrand, Lena
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Sundblad, Patrik
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Mekjavic, I.B.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Effekt av gasdensitet på ventilation och arteriell oxygenmättnad vid normobar och hypobar hypoxi2016Konferansepaper (Fagfellevurdert)
  • 14.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Bergsten, Eddie
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Effekter av tryckbortfall i G-skyddssystemet i JAS 39 Gripen2009Rapport (Annet vitenskapelig)
  • 15.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Bergsten, Eddie
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Loss of pressure in the anti-G system at high G-loads2011Konferansepaper (Fagfellevurdert)
  • 16.
    Grönkvist, Mikael
    et al.
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Eiken, Ola
    Swedish Defence Research Agency.
    Lung mechanics and transpulmonary pressures during unassisted pressure breathing at high Gz loads2008Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 79, nr 11, s. 1041-1046Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Positive pressure breathing (PPB) is commonly used in modern fighter aircraft as part of the anti-G ensemble. PPB is combined with a chest counterpressure bladder which is pressurized to the same magnitude as the breathing mask (balanced PPB). The chest counterpressure is expected to reduce the expiratory work of breathing, reduce the risk for lung rupture, and increase G tolerance. In a previous study we did not find any effect from chest counterpressure on G tolerance or G endurance. The aim of this study was to investigate the effects of chest counterpressure on the work of breathing and the risk for lung rupture.

    METHODS: Eight male test subjects were exposed to 20-s periods of PPB at +1.0, 5.0, 6.0, 7.0, and 8.0 Gz. Each Gz level was accomplished twice, with and without pressurization of the chest bladder. Inspiratory and expiratory flows were measured and esophageal pressures were measured in the lower and upper third of the thorax. Subsequently, work and power of breathing and apical transpulmonary pressure were estimated.

    RESULTS: The apical transpulmonary pressure was slightly larger without than with chest counterpressure at 1.0 Gz, while chest counterpressure did not affect apical transpulmonary pressure at increased Gz load. Nor did the chest counterpressure affect work or power of breathing at any Gz load.

    CONCLUSION: Inflation of the chest bladder does not seem to have any effects on work or power of breathing or risk for lung rupture during PPB at high Gz loads.

  • 17.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Bergsten, Eddie
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Skyddsdräkter för ytbärgare; Utvärdering under 2 timmars immersion i 6-gradigt vatten2015Rapport (Annet vitenskapelig)
  • 18.
    Grönkvist, Mikael
    et al.
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Eiken, Ola
    Swedish Defence Research Agency.
    Gustafsson, Per M
    Inter- and intraregional ventilation inhomogeneity in hypergravity and after pressurization of an anti-G suit2003Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 94, nr 4, s. 1353-1364Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study assessed the effects of increased gravity in the head-to-foot direction (+G(z)) and anti-G suit (AGS) pressurization on functional residual capacity (FRC), the volume of trapped gas (V(TG)), and ventilation distribution by using inert- gas washout. Normalized phase III slope (Sn(III)) analysis was used to determine the effects on inter- and intraregional ventilation inhomogeneity. Twelve men performed multiple-breath washouts of SF(6) and He in a human centrifuge at +1 to +3 G(z) wearing an AGS pressurized to 0, 6, or 12 kPa. Hypergravity produced moderately increased FRC, V(TG), and overall and inter- and intraregional inhomogeneities. In normogravity, AGS pressurization resulted in reduced FRC and increased V(TG), overall, and inter- and intraregional inhomogeneities. Inflation of the AGS to 12 kPa at +3 G(z) reduced FRC markedly and caused marked gas trapping and intraregional inhomogeneity, whereas interregional inhomogeneity decreased. In conclusion, increased +G(z) impairs ventilation distribution not only between widely separated lung regions, but also within small lung units. Pressurizing an AGS in hypergravity causes extensive gas trapping accompanied by reduced interregional inhomogeneity and, apparently, results in greater intraregional inhomogeneity.

  • 19.
    Grönkvist, Mikael
    et al.
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Gustafsson, Per M.
    Effects of body posture and tidal volume on inter- and intraregional ventilation distribution in healthy men2002Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 92, nr 2, s. 634-642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influences of body posture and tidal volume (VT) on inter- and intraregional ventilation inhomogeneity were assessed by normalized phase III slope (Sn(III)) analysis of multiple-breath washout recordings of SF(6) and He in 11 healthy men. Washouts with target VT of 750, 1,000, and 1,250 ml were performed standing and supine. A linear-fit method was used to establish the contributions of convection-dependent (interregional) (cdi) and diffusion-convection interaction-dependent (intraregional) inhomogeneity (dcdi). Overall inhomogeneity was defined as the sum of cdi and dcdi. The difference in first-breath Sn(III) for SF(6) vs. He, the (SF(6) - He)Sn(III), served as an index of intra-acinar inhomogeneity. Multiple-regression analysis revealed greater cdi supine vs. standing (P < 0.001) but no significant effects of posture on dcdi or overall inhomogeneity. Larger VT were associated with greater cdi (P < 0.001), particularly when supine, but reduced dcdi (P < 0.001), overall inhomogeneity (P < 0.001), and (SF(6) - He)Sn(III) (P = 0.031). In conclusion, during resting breathing overall and intraregional ventilation inhomogeneities remain unchanged when the supine posture is assumed and improve with larger VT, but supine posture and larger breaths result in greater interregional inhomogeneities.

  • 20.
    Grönkvist, Mikael
    et al.
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Kölegård, Roger
    Swedish Defence Research Agency.
    Linder, Jan
    Eiken, Ola
    Swedish Defence Research Agency.
    G tolerance and pulmonary effects of removing chest counterpressure during pressure breathing2005Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 76, nr 9, s. 833-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: In agile fighter aircraft positive pressure breathing is commonly used as part of the anti-G ensemble. To optimize G protection and prevent over-distention of the lungs, increased airway pressure is balanced by applying a counterpressure to the chest. The aim was to investigate the efficacy of chest counterpressure.

    METHODS: Three series of experiments were performed using the anti-G ensemble of the 39 Gripen aircraft (AGE-39) and exposing the subjects to 20-s G time profiles; in the first (n = 12) up to +8.0 Gz, in the second (n = 9) up to + 9.0 Gz, and also to simulated aerial combat maneuvers (SACM). Central and peripheral vision, arterial and airway pressures, pressure in the lower portion of the esophagus, and chest wall distension were measured. In the third series, six subjects were exposed to up to +7.0 Gz and esophageal pressure was measured in the upper thorax. In all series, two conditions were compared: with and without pressurized chest bladder.

    RESULTS: During the 20-s profiles arterial and esophageal pressures, chest wall distension, and visual impairment were similar with and without pressurized chest bladder. Upper esophageal pressure was slightly higher by 10-24% with than without chest bladder (p = 0.03). During SACM, time to exhaustion and the level of perceived exertion were similar with and without pressurized chest bladder.

    SUMMARY: The results suggest that the chest counterpressure can be removed from the AGE-39 without diminishing G tolerance or G endurance or significantly increasing the risk of lung parenchyma disruption.

  • 21.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Cihua, U
    Mekjavic, I.B.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Heat strain in a helicopter during a simulated desert mission2016Konferansepaper (Fagfellevurdert)
  • 22.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Ciuha, U
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Mekjavic, I.B.
    The effect of ambient humidity on performance during simulated desert patrols2014Konferansepaper (Fagfellevurdert)
  • 23.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Ciuha, U
    Mekjavic, IB
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Värmebelastning i helikopter vid simulerat ökenuppdrag2015Konferansepaper (Fagfellevurdert)
  • 24.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Effects of loss of pressure in the anti-G system during a simulated target chase2013Konferansepaper (Fagfellevurdert)
  • 25.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Gustafsson, Per
    Centralsjukhuset, Skövde.
    Eiken, Ola
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Ventilationsfördelning i lungorna med och utan övertrycksandning vid ökad Gz-belastning med trycksatt anti-G-dräkt2018Inngår i: Proceedings from Swedish Aeronautical Medical Association, Annual Scientific Meeting, 2018 / [ed] Claes Bothin, 2018Konferansepaper (Fagfellevurdert)
  • 26.
    Grönkvist, Mikael J
    et al.
    Swedish Defence Research Agency.
    Bergsten, Eddie
    Swedish Defence Research Agency.
    Eiken, Ola
    Swedish Defence Research Agency.
    Gustafsson, Per M
    Contributions of lower limb and abdominal compression to ventilation inhomogeneity in hypergravity2005Inngår i: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 148, nr 1-2, s. 113-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gravito-inertial load in the head-to-foot direction (Gz) and compression of the lower body half by an anti-G suit (AGS) are both known to influence ventilation distribution in the lungs. To study the interaction of Gz and AGS and to asses the separate contributions from lower limbs and abdominal compressions to large and small-scale ventilation inhomogeneities nine males performed SF6/He vital capacity (VC) single-breath washouts at 1, 2, and 3 Gz in a centrifuge, with abdominal and/or lower limbs compressions. SF6/He and (SF6-He) phase III slopes were used for determination of overall and small-scale ventilation inhomogeneity. Closing volume and phase IV height were used as measures of large-scale inhomogeneity. VC decreased marginally with G-load but markedly with lower limbs compression. Small-scale ventilation inhomogeneity increased slightly with G-load, but substantially with AGS pressurization. Small-scale ventilation inhomogeneity increased with AGS pressurization. Large-scale inhomogeneity increased markedly with G-load. Translocation of blood to the lungs might be the key determinant for changes in small-scale ventilation inhomogeneity when pressurizing an AGS.

  • 27.
    Grönkvist, Mikael J
    et al.
    Swedish Defence Research Agency.
    Emery, Michael J.
    Gustafsson, Per M.
    Mechanisms of ventilation inhomogeneity during vital capacity breaths standing and supine2002Inngår i: Respiration Physiology, ISSN 0034-5687, E-ISSN 1872-7611, Vol. 129, nr 3, s. 345-355Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Overall inhomogeneity of ventilation distribution, as measured by single-breath vital capacity (VC) washout (SBW) is known to be greater supine vs. standing. To establish the underlying mechanisms 13 healthy males performed VC SBW of 4% SF(6) and He, standing and supine, with or without a 10 sec breathhold (BH). Overall inhomogeneity, as indicated by normalized phase III slopes, was >50% greater supine (SF(6) 13.1 x 10(-3); He 10.7 x 10(-3) L(-1)) than standing (SF(6) 8.6 x 10(-3); He 6.4 x 10(-3) L(-1); P<0.001). The (SF(6)-He) slope, an index of intraacinar inhomogeneity, did not change with posture. Breathholding, assumed to eliminate convective dependent inhomogeneity within and/or between small lung units, produced twice as great reduction of inhomogeneity when supine vs. standing. After BH inhomogeneity remained significantly greater supine vs. standing. In conclusion, at least two events seem to underlie the increased inhomogeneity when supine: (1) a substantially increased convection dependent non-uniformity between well-separated lung regions; and (2) a somewhat increased convection dependent non-uniformity within and/or between peripherally located lung units.

  • 28.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Johannesson, Björn
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    KTH test report of CBRN equipment in the centrifuge2013Rapport (Annet vitenskapelig)
  • 29.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Keramidas, Michail E.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Intraokulärt tryck och oxygenering av hjärnans frontallob under långvarig, måttlig G-belastning i huvud-fot-riktning2013Inngår i: Hygiea, 2013Konferansepaper (Fagfellevurdert)
    Abstract [sv]

    Bakgrund: Under G-belastning i huvud-fot-riktning (+Gz) faller pilotens artärtryck mellan hjärt- och huvudnivå. Trots att avståndet - och därmed artärtrycksfallet - är större mellan hjärta och hjärnbark än mellan hjärta och ögon, är näthinnan vanligen det organ som tidigast drabbas av kritiskt ischemi vid +Gz-belastning, vilket huvudsakligen anses bero på att artärtrycket måste övervinna ögonbulbens övertryck om ca 10-15 mmHg för att genomblödning av näthinnan skall kunna ske. I en tidigare undersökning fann vi att den symptomsekvens som normalt uppträder efter 3-10 sekunders latensperiod vid förhöjning av G-belastningen från låg till övertrösklig nivå (d.v.s. perifer synfältsinskränkning - central synfältsinskränkning - grumlat medvetande - medvetandeförlust) ofta uteblir om exponeringen för övertrösklig G-nivå föregås av långvarig exponering för måttligt, men tolererbart, förhöjd belastning. Således, då trycket i G-dräkten fjärmades efter 2 minuter vid +Gz-belastning om 5-6 G var risken att drabbas av medvetslöshet mångfalt högre än då G-belastningen höjdes till motsvarande nivå utan trycksättning av G-dräkt. Föreliggande experimentserier genomfördes för att undersöka om den ändrade symptomsekvensen beror på successivt minskande syrereserver i frontalcortex eller på ökande genomblödning av retina (d.v.s. på minskande intraokulärt tryck (IOP)). Metoder: Friska försökspersoner (fp) exponerades för +Gz-belastning om 2 respektive 3 G, under det att IOP mättes (n= 10), samt för 2, 3, 4 och 5 G, under det att förändringar av frontalcortex syreinnehåll (total oxygen index; TOI) mättes (n=13). Under alla betingelser registrerades mättnadsgraden för oxyhemoglobin i kapillärblodet (SpO2). Samtliga mätningar genomfördes då fp använde G-dräkt och de vid 2 och 3 G även utan att fp använde G-dräkt Resultat: IOP påverkades ej nämnvärt av +Gz-belastning. Såväl SpO2 som TOI sjönk successivt under G-exponeringarna, i synnerhet vid 4- och 5-G-nivåerna, då fp bar G-dräkt. Slutsatser: Den successiva minskningen av TOI vid given belastning antas bero på en pulmonell höger-till-vänster shuntning av blod. Resultaten talar för att den ökade incidens G-betingade medvetslöshet då tryck i G-dräkt fjärmas efter långvarig, måttlig belastning beror på successivt minskande cerebral syrereserv, ledande till att medvetslöshet kan uppträda utan att föregås av varningssymtom i form av synfältsbortfall.

  • 30.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Keramidas, Michail E.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Sundgren, Carl Johan
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Interaction of anti-G suit and airway pressures on cerebral oxygenation during prolonged headward acceleration.2015Konferansepaper (Fagfellevurdert)
  • 31.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Keramidas, Michail E.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Taylor, Nigel A.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Intraocular pressure and cerebral oxygenation during prolonged headward acceleration2014Konferansepaper (Fagfellevurdert)
  • 32.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Keramidas, Michail
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi. KTH, Skolan för teknik och hälsa (STH), Centra, Centrum för flyg- och rymdfysiologi, SAPC.
    Samverkan mellan anti-G-dräkt och övertryck i luftvägarna på cerebral syresättning vid långvarig G-belastning i huvud-fot riktning2015Konferansepaper (Fagfellevurdert)
  • 33.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    LaPelusa, M.
    Univ Texas Rio Grande Valley, Sch Med, Edinburg, TX USA..
    Gennser, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi. Royal Inst Technol, Environm Physiol, Stockholm, Sweden..
    Machado-Moreira, Christiano Antonio
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Postural and Daily Variations in the Single-Breath Diffusion Capacity of the Lungs for Carbon Monoxide2018Inngår i: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 197Artikkel i tidsskrift (Annet vitenskapelig)
  • 34.
    Grönkvist, Mikael
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Levin, Britta
    Eiken, Ola
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    G Tolerance During Open- vs. Closed-Loop G-Time Control.2018Inngår i: Aerospace Medicine and Human Performance, ISSN 2375-6314, E-ISSN 2375-6322, Vol. 89, nr 9, s. 798-804Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: +Gz tolerance is traditionally determined in centrifuges with open-loop G control, i.e., the centrifuge is under operator control (open loop), and thus the test subject is unable to influence the Gz load. In modern centrifuges, however, the subject is commonly able to continuously control the Gz load (closed loop). It is a widespread opinion among fighter pilots that +Gz tolerance is higher under closed- than open-loop G control. The aims were to investigate whether +Gz tolerance is higher in closed- than open-loop G control, and whether it is possible to use closed-loop G control during precise determination of +Gz tolerance.

    METHODS: Relaxed +Gz tolerance was determined in eight men during rapid Gz-onset rate (ROR) under three conditions: 1) OL-VFB, open loop with visual feedback; 2) OL-NFB, open loop with no visual feedback; and 3) CL, closed loop. Straining +Gz tolerance was determined in 10 men during ROR in OL and CL conditions.

    RESULTS: Relaxed +Gz tolerance did not differ between CL (3.66 Gz), OL-VFB (3.70 Gz) and OL-NFB (3.64 Gz). Straining +Gz tolerance was similar in the CL (8.5 Gz) and OL (8.6 Gz) conditions. In the CL condition, the Gz load varied substantially and was on average lower than in the OL conditions, at any stipulated G-time profile.

    DISCUSSION: There is no systematic difference in relaxed or straining +Gz tolerance as determined in closed- vs. open-loop G-controlled systems. During closed-loop control, precision and reproducibility are too low to recommend it for accurate determination of relaxed G tolerance.Grönkvist M, Levin B, Eiken O. G tolerance during open- vs. closed-loop G-time control. Aerosp Med Hum Perform. 2018; 89(9):798-804.

  • 35. Gustafsson, P M
    et al.
    Eiken, Ola
    Swedish Defence Research Agency.
    Grönkvist, Mikael
    Swedish Defence Research Agency.
    Effects of hypergravity and anti-G suit pressure on intraregional ventilation distribution during VC breaths2001Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 91, nr 2, s. 637-644Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of increased gravity in the head-to-foot direction (+G(z)) and pressurization of an anti-G suit (AGS) on total and intraregional intra-acinar ventilation inhomogeneity were explored in 10 healthy male subjects. They performed vital capacity (VC) single-breath washin/washouts of SF(6) and He in +1, +2, or +3 G(z) in a human centrifuge, with an AGS pressurized to 0, 6, or 12 kPa. The phase III slopes for SF(6) and He over 25-75% of the expired VC were used as markers of total ventilation inhomogeneity, and the (SF(6) -- He) slopes were used as indicators of intraregional intra-acinar inhomogeneity. SF(6) and He phase III slopes increased proportionally with increasing gravity, but the (SF(6) -- He) slopes remained unchanged. AGS pressurization did not change SF(6) or He slopes significantly but resulted in increased (SF(6) -- He) slope differences at 12 kPa. In conclusion, hypergravity increases overall but not intraregional intra-acinar inhomogeneity during VC breaths. AGS pressurization provokes increased intraregional intra-acinar ventilation inhomogeneity, presumably reflecting the consequences of basilar pulmonary vessel engorgement in combination with compression of the basilar lung regions.

  • 36.
    Kölegård, Roger
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Sundblad, Patrik
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Är det möjligt att uppskatta Gz-tolerans medelst ortostatisk prov?2015Konferansepaper (Fagfellevurdert)
  • 37.
    Machado-Moreira, Christiano
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Norrbrand, Lena
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Omgivningsfysiologi.
    Thermoregulation upon transition from exercise in a warm environment to exposure to a markedly cold environment; effects of a ventilated vest2018Inngår i: Proceedings from Physiology and Pharmacology Annual Scientific Meeting, 2018, 2018Konferansepaper (Fagfellevurdert)
  • 38. Mekjavic, I.B.
    et al.
    Ciuha, U
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    The physiological strain index does not predict heat exhaustion2014Konferansepaper (Fagfellevurdert)
  • 39. Mekjavic, Igor B.
    et al.
    Ciuha, Ursa
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    The Effect of Low Ambient Relative Humidity on Physical Performance and Perceptual Responses during Load Carriage2017Inngår i: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 8, nr July, artikkel-id 451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction: The study evaluated the effect of low ambient relative humidity on physical performance and perceptual responses during load carriage in a hot environment. Methods: Ten heat-unacclimatized male subjects participated in three 130-min trials, during which they walked on a treadmill, carrying a load of similar to 35 kg, at a speed of 3.2 km.h(-1), with an incident wind at the same velocity and ambient temperature at 45 degrees C. Each trial commenced with a 10-min baseline at 20 degrees C and 50% relative humidity (RH), the subjects transferred to a climatic chamber and commenced their simulated hike, comprising two 50-min walks separated by a 20-min rest period. In two, full protective equipment (FP) trials, RH was 10% (partial pressure of water vapor, p(H20) = 7.2 mmHg) in one (FP10), and 20% (p(H20) = 14.4 mmHg; FP20) in the other. In the control trial, subjects were semi-nude (SN) and carried the equipment in their backpacks; RH was 20%. Measurements included oxygen uptake, ventilation, heart rate, rectal and skin temperatures, heat flux, temperature perception, and thermal comfort. Results: In FP20, four subjects terminated the trial prematurely due to signs of heat exhaustion; there were no such signs in FP10 or SN. Upon completion of the trials, pulmonary ventilation, heart rate, and rectal temperature were lower in FP10 (33 5 I/min; 128 +/- 21 bpm; 38.2 +/- 0.4 degrees C) and SN (34 4 I/min; 113 +/- 18 bpm; 38.1 +/- 0.4 degrees C than in FP20 (39 +/- 8 l/min; 145 +/- 12 bpm; 38.6 +/- 0.42 degrees C). Evaporation was significantly greater in the SN compared to FPI and FP20 trials. FP10 was rated thermally more comfortable than FP20. Conclusion: A lower ambient partial pressure of water vapor, reflected in a lower ambient relative humidity, improved cardiorespiratory, thermoregulatory, and perceptual responses during load carriage.

  • 40.
    Norrbrand, Lena
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Johannesson, Björn
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Extensive increase of metabolic demand while walking wearing night vision goggles in hilly terrain2017Inngår i: Journal of Science and Medicine in Sport, ISSN 1440-2440, E-ISSN 1878-1861, Vol. 20, artikkel-id S77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Introduction: The motivation for the foot-borne soldiers to carry out nighttime operations may be to reduce heat strain. We have previously found elevated metabolic demand (+7 %), and hence endogenous heat production, during walking on a flat gravel road in darkness wearing Night Vision Goggles (NVG) compared with wearing a headlamp. The aim of the present study was to evaluate the effect of wearing NVG while walking in a hilly forest terrain, and compare results between skilled and unskilled NVG users.

    Methods: A group of cadets, i.e. unskilled (5 men, 6 women, age: 23±3 yrs, height: 172±10 cm, weight: 75±12 kg) and skilled NVG users (9 men, age: 26±2 yrs, height: 184±6 cm, weight: 84±5 kg) participated. At night time, subjects walked 1.1 km at a self-selected comfortable pace in a hilly forest, following a trail in the uphill part, and walking on the under bush in the downhill part. Walks were performed wearing either a headlamp (Light), monocular NVG (MNVG), binocular NVG (BNVG), or MNVG and 25 kg extra weight (backpack and body armor). Oxygen uptake, heart rate, rate of perceived exertion and walking speed were measured. To evaluate walking economy, oxygen uptake was expressed in relation to body mass and distance covered (VO2 mL·kg-1·km-1). 

    Results: In both groups, VO2 (mL·kg-1·km-1) was higher in all three conditions with limited vision (MNVG; BNVG; Backpack) than in the Light condition, both during the Uphill (MNVG/BNVG; skilled: +25/+24%, unskilled: +35/+28%) and Downhill part (MNVG/BNVG; skilled: +42/+44%, unskilled: +67/+51%). In the Backpack condition, the inter-group difference in mechanical efficiency was maintained or exaggerated: Uphill (skilled: +46%, unskilled: +80%), Downhill (skilled: +70%, unskilled: +115%). The skilled NVG users walked faster, but there was no difference in heart rate between groups. In the unskilled, heart rate was higher in the MNVG and BNVG than in the Light condition during the Downhill part. Likewise, in the unskilled, the rate of perceived exertion was higher in the MNVG and BNVG than in the Light condition. 

    Conclusions: Despite that in darkness foveal vision is markedly improved by NVG, it appears that the mechanical efficiency during walking in hilly terrain is markedly lower whilst wearing NVG than with full vision, regardless of whether the soldier is a skilled or unskilled NVG user.

  • 41.
    Norrbrand, Lena
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Johannesson, Björn
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Rappe, A
    Sjölin, J
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Metabolic demand during walking with night vision goggles2014Konferansepaper (Fagfellevurdert)
  • 42.
    Norrbrand, Lena
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Johannesson, Björn
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Rappe, Annika
    Sjölin, Johan
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Walking with night vision goggles increases metabolic demand2014Konferansepaper (Fagfellevurdert)
  • 43. Strömberg, N O
    et al.
    Grönkvist, Mikael J.
    Swedish Defence Research Agency.
    Improved accuracy and extended flow range for a Fleisch pneumotachograph1999Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 37, nr 4, s. 456-460Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A large linear flow range and a small instrumental dead space volume are incompatible properties for a pneumotachometer (PTM). The linearity of a Fleisch number 2 PTM is studied for flows up to 6 litre s-1 (nominal range 0-2 litre s-1) with various up- and downstream geometries. It is hypothesised that using an array of calibration factors (conductance; flow/pressure), instead of a single calibration factor over the entire flow range, could improve accuracy and also extend the applicable flow range. The conductance against pressure characteristics are calculated with a previously described weighted averaging technique based on multiple strokes from a precision syringe. A single conductance value gives stroke volume errors in the range of -5 to 3% (0-2 litre s-1) and -6 to 11% (0-6 litre s-1) for validation using the same geometry as for calibration. The pressure dependent conductance improves accuracy to within -3% and 1% independent of flow range. However, for validation using a different geometry than for calibration, errors range from -5% to +8%. The degree of non-linearity varies between the geometries (range 3-15%) and is highest when using a one-directional valve upstream of the PTM and a Y-shaped connector. In conclusion, a pressure-dependent conductance improves accuracy and can also be used to extend the applicable flow range up to at least three times the nominal flow range.

  • 44.
    Tribukait, Arne
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Betydelsen av flygerfarenhet för förmågan att uppfatta förändringar i pitch–position i gondolcentrifug/DFS2011Inngår i: Svenska Läkaresällskapets handlingar. Hygiea, 2011Konferansepaper (Fagfellevurdert)
  • 45.
    Tribukait, Arne
    et al.
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Omgivningsfysiologi.
    The perception of roll tilt in pilots during a simulated coordinated turn in a gondola centrifuge.2011Inngår i: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 82, nr 5, s. 523-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: It has previously been reported that nonpilots underestimate the roll tilt angle after acceleration in a gondola centrifuge. The aim of the present work was to elucidate the significance of flight experience for roll tilt perception based on vestibular information.

    METHODS: The subjective visual horizontal (SVH) was measured by means of an adjustable luminous line in darkness. Eight nonpilots (N), nine fighter pilots (F), and eight helicopter pilots (H) underwent two centrifuge runs (2 G, 5 min) heading forward and backward, respectively. The roll position of the gondola (60 degrees at 2 G) was controlled so that the subject was always upright with respect to the gravitoinertial force.

    RESULTS: Upon acceleration of the centrifuge there was a tilt of the SVH in a direction compensatory to the inclination of the gondola. This tilt was larger in the forward position [N: 17.2 +/- 6.4 degrees, F: 31.2 +/- 16.4 degrees, H: 33.6 +/- 18.2 degrees (means +/- SD)] than in the backward position (N: -5.0 +/- 6.8 degrees, F: -12.2 +/- 17.4 degrees, H: -10.4 +/- 15.4 degrees). In N the tilt declined with time, approaching zero by the end of the 2-G plateau. In the pilots it was significantly larger and did not decline.

    CONCLUSION: Flight experience results in an increased ability to perceive the roll tilt during movement along a curved path. That this can be revealed in a centrifuge might suggest that acceleration of the centrifuge constitutes a movement pattern which is similar, from a vestibular point of view, to that of an airplane entering a coordinated turn.

  • 46.
    Ånell, Rickard
    et al.
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Eiken, Ola
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Grönkvist, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Sundblad, Patrik
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Gennser, Mikael
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Omgivningsfysiologi.
    Vaskulära gasbubblor hos jaktplanspiloter under olika flygprofiler2016Konferansepaper (Fagfellevurdert)
1 - 46 of 46
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