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  • 1. Amon, M
    et al.
    Keramidas, Michail E.
    Kounalakis, S
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Simpson, L
    MacDonald, I
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, IB
    Effect of hypoxia on postprandial blood glucose and insulin response2011Conference paper (Refereed)
  • 2. Bense, L
    et al.
    Eklund, G
    Jorulf, H
    Farkas, A
    Balashazy, I
    Hedenstierna, G
    Krebsz, A
    Balazs, G
    Eden Strindberg, J
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Douglas, J
    Perforation of the right main bronchus, detected by HRCT 3D technique2011Conference paper (Refereed)
  • 3. Berg, Ulf
    et al.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Fysiska tester i samband med Grundläggande militär utbildning (GMU)2012Report (Other academic)
  • 4.
    Bergh, Ulf
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Danielsson, Ulf
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Värmehandbok för markstridssoldaten2011Report (Other academic)
  • 5. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Direct comparison of audio Doppler ultrasound scores and 2D ultrasound images of venous gas emboli.2010Conference paper (Refereed)
  • 6. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Near maximal venous bubble scores and arterial bubbles with no signs or symptoms of DCS - a case study.2011Conference paper (Refereed)
  • 7. Blogg, S. Lesley
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    The need for optimisation of post-dive ultrasound monitoring to properly evaluate the evolution of venous gas emboli2011In: Diving and hyperbaric medicine : the journal of the South Pacific Underwater Medicine Society, ISSN 1833-3516, Vol. 41, no 3, p. 139-146Article in journal (Refereed)
    Abstract [en]

    Audio Doppler ultrasound and echocardiographic techniques are useful tools for investigating the formation of inert gas bubbles after hyperbaric exposure and can help to assess the risk of occurrence of decompression sickness. However, techniques, measurement period and regularity of measurements must be standardised for results to be comparable across research groups and to be of any benefit. There now appears to be a trend for fewer measurements to be made than recommended, which means that the onset, peak and cessation of bubbling may be overlooked and misreported. This review summarises comprehensive Doppler data collected over 15 years across many dive profiles and then assesses the effectiveness of measurements made between 30 and 60 minutes (min) post-dive (commonly measured time points made in recent studies) in characterising the evolution and peak of venous gas emboli (VGE). VGE evolution in this dive series varied enormously both intra- and inter-individually and across dive profiles. Median, rather than mean values are best reported when describing data which have a non-linear relation to the underlying number of bubbles, as are median peak grades, rather than maximum, which may reflect only one individual's data. With regard to monitoring, it is apparent that the evolution of VGE cannot be described across multiple dive profiles using measurements made at only 30 to 60 min, or even 90 min post-dive. Earlier and more prolonged measurement is recommended, while the frequency of measurements should also be increased; in doing so, the accuracy and value of studies dependent on bubble evolution will be improved.

  • 8. Ciuha, U
    et al.
    Grönkvist, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, I
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Pavlinič, D
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Thermal strain in soldiers performing patrol missions in a desert climate: effect of two different cooling strategies2011Conference paper (Refereed)
  • 9. Debevec, T
    et al.
    Amon, M
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Kounalakis, S.N.
    Mekjavic, I.B.
    Hematological responses to two different intermittent hypoxic training regimens2009Conference paper (Refereed)
    Abstract [en]

    "Hypoxic training has been reported to enhance athletes’ altitude and sea-level performance by augmenting oxygen carrying capacity of the blood, as a consequence of increases in hematocrit and hemoglobin concentrations. However the effect of intermittent hypoxic training on hematological responses remains unresolved."

    This study investigated the effect of two intermittent hypoxic training regimens on the response of hematological indices. Healthy male Ss (N = 27) were equally assigned to a control group, a live low-train high (LL-TH) group, or a intermittent hypoxic exposure group. Ss performed a one-hour submaximal endurance exercise on a cycle ergometer, five days per week for four weeks, at an intensity corresponding to 50% of normoxic peak power output for the control and intermittent hypoxic exposure groups, and to 50% of hypoxic peak power output for the LL-TH group. Thus, all groups trained at the same relative work rate. The absolute work rate during training was 18-20 W lower for the LL-TH group compared to the other two groups. All groups lived at an altitude of ~300 m above sea level. The control and intermittent hypoxic exposure groups also trained at this altitude, whereas the LL-TH group trained in a hypoxic chamber, breathing a hypoxic mixture (FIO2=12%). In addition to the daily exercise training, the intermittent hypoxic exposure group also inspired a hypoxic gas mixture at rest, and prior to the cycle ergometry. The intermittent hypoxic training comprised breathing a hypoxic mixture during seven phases. Each phase consisted of five minutes of breathing a hypoxic mixture, followed by three minutes of breathing a normoxic gas mixture. Prior to, during, at the end, and 10 days after the training period, blood samples were taken from all Ss in order to measure hemoglobin, hematocrit, erythrocytes, ferritin, and transferrin concentrations.

    No significant differences were observed between groups in any measured hematological variables. Similarly, no significant differences were found within groups at the different testing periods.

    Implication. Although it has been reported that both LL-TH and intermittent hypoxic exposure protocols provide hematological benefits, that was not confirmed by this study. The tested protocols did not induce any changes in the measured hematological variables; therefore no improvements of the oxygen carrying capacity of the blood should be expected following this type of hypoxic training.

  • 10. Debevec, T
    et al.
    Amon, M
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Kounalakis, S.N.
    Mekjavic, I.B.
    The use of live low – train high protocol for the enhancement of endurance performance and aerobic capacity.2009Conference paper (Other academic)
  • 11. Debevec, T.
    et al.
    Amon, M.
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Simunic, B.
    Pisot, R.
    Kounalakis, S.N.
    Eiken, O.
    Mekjavic, I.B.
    “Sleep high – train low” altitude training2008Conference paper (Other academic)
  • 12. Debevec, T
    et al.
    Keramidas, Michail E.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Amon, M
    Kounalakis, S.N.
    Mekjavic, I.B.
    Evaluation of training protocols for the improvement of altitude and sea level performance2009Conference paper (Other academic)
  • 13. Debevec, T.
    et al.
    Keramidas, Michail E.
    Norman, B
    Gustafsson, T
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, I
    No evidence for the “normobaric oxygen paradox”2011In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, Vol. 43, no S5, p. 151-151Article in journal (Other academic)
  • 14. Debevec, Tadej
    et al.
    Keramidas, Michail E.
    Norman, Barbara
    Gustafsson, Thomas
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, Igor B.
    Acute short-term hyperoxia followed by mild hypoxia does not increase EPO production: resolving the "normobaric oxygen paradox''2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 3, p. 1059-1065Article in journal (Refereed)
    Abstract [en]

    Recent findings suggest that besides renal tissue hypoxia, relative decrements in tissue oxygenation, using a transition of the breathing mixture from hyperoxic to normoxic, can also stimulate erythropoietin (EPO) production. To further clarify the importance of the relative change in tissue oxygenation on plasma EPO concentration [EPO], we investigated the effect of a consecutive hyperoxic and hypoxic breathing intervention. Eighteen healthy male subjects were assigned to either IHH (N = 10) or CON (N = 8) group. The IHH group breathed pure oxygen (F(i)O(2) ~ 1.0) for 1 h, followed by a 1-h period of breathing a hypoxic gas mixture (F(i)O(2) ~ 0.15). The CON group breathed a normoxic gas mixture (F(i)O(2) ~ 0.21) for the same duration (2 h). Blood samples were taken just before, after 60 min, and immediately after the 2-h exposure period. Thereafter, samples were taken at 3, 5, 8, 24, 32, and 48 h after the exposure. During the breathing interventions, subjects remained in supine position. There were significant increases in absolute [EPO] within groups at 8 and 32 h in the CON and at 32 h only in the IHH group. No significant differences in absolute [EPO] were observed between groups following the intervention. Relative (∆[EPO]) levels were significantly lower in the IHH than in the CON group, 5 and 8 h following exposure. The tested protocol of consecutive hyperoxic-hypoxic gas mixture breathing did not induce [EPO] synthesis stimulation. Moreover, the transient attenuation in ∆[EPO] in the IHH group was most likely due to a hyperoxic suppression. Hence, our findings provide further evidence against the "normobaric O(2) paradox" theory.

  • 15.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Militär verksamhet på höga höjder2011Report (Other academic)
  • 16.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Bergsten, Eddie
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Grönkvist, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    G-protection mechanisms afforded by the anti-G suit abdominal bladder with and without pressure breathing.2011In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 82, no 10, p. 972-7Article in journal (Refereed)
    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.

  • 17.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Danielsson, Ulf
    Hallberg, M.
    Mekjavic, I.
    Kounalakis, S.N.
    Energiomsättning vid simulerad patrullering i mörker2010Report (Other academic)
  • 18.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Danielsson, Ulf
    Hallberg, M
    Mekjavic, IB
    Babic, J
    Kounalakis, S
    Energy expenditure during simulated patrol in darkness2011Conference paper (Refereed)
  • 19.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Grönkvist, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Signs and symptoms during supra-tolerance +Gz exposures, with reference to G-garment failure.2013In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 84, no 3, p. 196-205Article in journal (Refereed)
    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.

  • 20.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Grönkvist, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Danielsson, Ulf
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Zavec, D.
    Kounalakis, S.N.
    Mekjavic, I.
    Termisk belastning hos soldater som bär svensk stridsutrustning2010Report (Other academic)
  • 21.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Grönkvist, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    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 nedkylning2011Report (Other academic)
  • 22.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Repeated exposures to moderately increased intravascular pressure increases stiffness in human arteries and arterioles2011In: Journal of Hypertension, ISSN 0263-6352, E-ISSN 1473-5598, Vol. 29, no 10, p. 1963-1971Article in journal (Refereed)
    Abstract [en]

    The aim was to investigate whether repeated exposures to moderate pressure elevations in the blood vessels of the arms (pressure training; PT) affect pressure distension in arteries/arterioles of healthy subjects (n=11). PT and vascular pressure-distension determinations were conducted with the subject seated in a pressure chamber with one arm slipped through a hole in the chamber door. Increased intravascular pressure was accomplished by increasing chamber pressure. Before PT, one arm was investigated (control arm) during stepwise increases in chamber pressure to 180 mmHg. Artery diameter and flow were measured in the brachial artery using ultrasonography/Doppler techniques. Thereafter, the contralateral arm underwent a PT regimen consisting of three 40 min sessions/ week during 5 weeks. Chamber pressure was increased during PT from 65 mmHg during the first week to 105 mmHg during the last week. After PT, pressure-distension relationships were examined in both the trained arm and the control arm. Prior to and following PT, endothelium-dependent and endothelium-independent dilatations of the brachial artery were studied. PT reduced (p<0.01) arterial pressure distension by 46 ± 18%. Likewise, the pressure-induced increase in arterial flow was less pronounced after (350 ± 249%) compared with before (685 ± 216 %) PT. The PT-induced reductions in arterial/arteriolar pressure distension were reversed 5 weeks post-PT. Neither endothelium-dependent nor endothelium-independent arterial dilatation were affected by PT. It thus appears that the in vivo wall stiffness in arteries and arterioles increases markedly in response to intermittent, moderate increments of transmural pressure during 5 weeks. The increases in arterial/arteriolar stiffness are reversible and do not reflect a reduced capacity to dilate the vessels. The findings are compatible with the notion that local load serves as “ a prime mover” in the development of vascular changes in hypertension.

  • 23.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, I.
    Sundblad, Patrik
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    G tolerance vis-à-vis pressure-distension and pressure-flow relationships of leg arteries2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 10, p. 3619-3627Article in journal (Refereed)
    Abstract [en]

    During increased gravitoinertial (G) load in the head-to-foot direction, pressures in dependent vascular beds are commonly raised to levels capable of distending precapillary vessels, which, in turn, may reduce arterial pressure, and hence compromise the capacity to withstand G load (G tolerance). We hypothesized that distensibility in precapillary leg vessels would be lower in a group of subjects possessing high G tolerance (H; n = 7; relaxed G tolerance = 6.6 ± 0.8 G) than in a group with low G tolerance (L; n = 8; G tolerance = 3.9 ± 0.3 G). The groups were matched with regard to gender, age, weight, height, and resting arterial pressure. Arterial pressure-distension and pressure-flow experiments were performed with the subject supine in a pressure chamber with a lower leg protruding to the outside. Increased intravascular pressure in the blood vessels of the outside leg was accomplished by stepwise increasing chamber pressure to 240 mmHg. Diameter and flow in the posterior tibial artery were measured by ultrasonographic/Doppler techniques. Pressure-induced increments in arterial diameter and flow were more pronounced (p < 0.03) in the L (14.1 ± 4.2% and 32 ± 21 ml/min respectively) than in the H (1.7 ± 5.0% and 1.6 ± 25 ml/min) group, and the pressure thresholds at which these increments commenced were lower (by 52 and 48 mmHg, respectively) in the L than in the H group (p < 0.04). Negative correlations were observed between G tolerance and the increments in diameter and flow (p < 0.02). Thus, the wall stiffness of precapillary leg vessels is greater in individuals with high relaxed G tolerance; whether a causal relationship exists remains to be established.

  • 24.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, IB
    Kounalakis, S
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Stiffness in leg arteries/arterioles is reduced by prolonged bedrest.2011Conference paper (Refereed)
  • 25.
    Eiken, Ola
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, Igor B.
    Kolegard, Roger
    Local Intravascular Pressure Habituation in Relation to G-Induced Arm Pain2012In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 83, no 7, p. 667-672Article in journal (Refereed)
    Abstract [en]

    EIKEN O, MEKJAVIC IB, KOLEGARD R. Local intravascular pressure habituation in relation to G-induced arm pain. Aviat Space Environ Med 2012; 83:667-72. Background: During high +G(z) loads, pilots may experience arm pain. It is commonly assumed that such pain is caused by distension of blood vessels and that vascular distensibility adapts to the prevailing transmural pressure. The aim was to investigate whether vascular pressure habituation (PH) is as efficient in alleviating G-induced arm pain as using counterpressure/support garments. Methods: In Series I, 7 subjects underwent a 5-wk PH regimen, consisting of 15 40-min sessions, during which intravascular pressures in one arm were elevated by 65-105 mmHg. Before and after PH, arm pain was determined during incremental +G(z)-exposures in a centrifuge. In Series II, the effect on G-induced arm pain of wearing protective garments around the lower part of the upper arm was investigated in 10 subjects in 4 conditions: 1) counterpressure; 2) rigid support; 3) sham support; and 4) no support (control). Pain was rated using a 10-point graded scale. Results: PH reduced arm pain at 7.5 G from [median (range)] 4 (2-9) to 2 (0-5) in the pressure-habituated arm. The sham support did not affect pain compared to in the control condition (5.2; 3.0-10.0), whereas pain was reduced by both the rigid support (3.7; 1.0-8.0) and the counterpressure (2.5; 0.0-5.5). PH was as efficient in alleviating pain as the counterpressure and more efficient than the rigid support. Discussion: The results support the notion that G-induced arm pain is caused by vascular overdistension. Repeated moderate elevations of local intravascular pressure reduce G-induced arm pain, presumably because such PH reduces vascular distensibility.

  • 26.
    Frånberg, Oskar
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Ericsson, M.
    Larsson, Å.
    Lindholm, P.
    Investigation of a Halcyon RB80 semiclosed rebreather in connection with a diving accident2010Conference paper (Refereed)
  • 27.
    Frånberg, Oskar
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Ericsson, Mikael
    Larsson, Agneta
    Lindholm, Peter
    Investigation of a demand-controlled rebreather in connection with a diving accident2011In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 38, no 1, p. 61-72Article in journal (Refereed)
    Abstract [en]

    This paper describes the examination of a Halcyon RB80 semi-closed underwater breathing apparatus used in a diving accident in 2007. The apparatus was supplied with trimix (oxygen, nitrogen and helium) containing 31% oxygen. The duration of the dive was 105 minutes at 28 meters' average depth in fresh water, with a 19-minute oxygen decompression stop at 6 meters. Upon surfacing the diver experienced seizures and signs of severe neurological deficits. The apparatus was tested with regard to the oxygen fraction drop from the supply gas to the breathing loop - i.e., the oxygen fraction inhaled by the diver (FiO2) was investigated. The FiO2 was measured and found to be lower than the value stated on the manufacturer's web page at the time of the accident. This investigation suggests that during the dive, the actual FiO2% was 17.9-25.3%, which is considerably lower than the FiO2% used for decompression calculations (30%). The underestimation of FiO2 resulted in too short and/or too few decompression stops during ascent. The low FiO2 would also put a diver at risk of hypoxia at shallow depths. It is concluded that inadequate information on the performance of the rebreather was a major contributing factor to this accident.

  • 28.
    Frånberg, Oskar
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Oxygenandningsapparat med nitroxväxlingsmöjlighet.2010Report (Other academic)
  • 29.
    Frånberg, Oskar
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Linden, J.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Evaluating a simplified purge procedure for oxygen/nitrox switch rebreathers2011Conference paper (Refereed)
  • 30.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Jämförelse mellan två olika slussystem för djup FU från ubåt2011Report (Other academic)
  • 31.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Kolmonoxidnivåer i ubåtsatmosfär2011Report (Other academic)
  • 32.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Luftkvalitet för BIBS- och HIS-gas2011Report (Other academic)
  • 33.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    PM angående Trimixdyk med IS-Mix vid Søværnets dykerskole, maj 20112011Report (Other academic)
  • 34.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Bergh, Ulf
    Metoder för effektivare utprovning av dekompressionstabeller för dykning2011Conference paper (Refereed)
  • 35.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Blogg, L.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, I.
    Comparison between mild dehydration and body temperature on decompression bubble formation2010Conference paper (Refereed)
  • 36.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Blogg, L.
    Frånberg, Oskar
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Bubble recordings after nitrox dives with a semi-closed demand controlled rebreather2011Conference paper (Refereed)
  • 37.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Blogg, Samantha L.
    Venous Gas Emboli in Goats After Simulated Submarine Escape from 290 msw Breathing Air or Hyperoxic Gas2009In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 80, no 11, p. 927-932Article in journal (Refereed)
    Abstract [en]

    GENNSER M, BLOGG. SL. Venous gas emboli in goats after simulated submarine escape from 290 msw breathing air or hyperoxic gas. Aviat Space Environ Med 2009; 80:927-32. Introduction: Escape from a disabled submarine has many inherent risks. Including the development of venous gas emboli (VGE) Breathing hyperoxic gas during rapid ascent from 2500 kPa (240 msw) reduces VGE, we Investigated whether it would also be beneficial during all escape from 3000 kPa (290 msw), thought to be at the limit of escape from a sunk sub Methods: Adult castrated male or female goats (45-85 kg, N = 35) Underwent dry chamber compression to 3000 kPa in 28 s, then decompressed at a rate of 2 75 m . s(-1) while breathing either air or hyperoxic gas (60/40%. O-2/N-2) Postsurfacing, precordial Doppler measurements were made using the Kisman Masurel (KM) scoring system, the animals were observed for signs of decompression illness (DCI) and/or oxygen toxicity Results: Six animals in the air group (N = 19) and two in the hyperoxic group (N = 10) suffered from severe I)pulmonary barotrauma on surfacing and were euthanized No cases of DO arose later than 5 min postsurfacing. Oxygen toxicity was not observed Although initial bobble Scores (median KM score 4) were the same in both groups, the time taken for the median KM score to reach 3 or less was significantly faster in the hyperoxic group (20 min vs 120 min) Disappearance of VGE was faster in the hyperoxic group Conclusion: Breathing hyperoxic gas during escape from 3000 kPa reduces the overall time. With circulating VGE and, despite exposure to a maximum inspired partial pressure, of oxygen of 1 8 MPa, symptoms of oxygen toxicity were not observed

  • 38.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Blogg, S.L.
    Jurd, K.
    Pre-dive exercise and post-dive evolution of gas emboli2011In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448Article in journal (Other academic)
  • 39.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Effekter av exponering för måttlig hypoxi vid vistelse i brandsäkrat arbetsutrymme.2011Report (Other academic)
  • 40.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Frånberg, Oskar
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Maximala dyktider för direktuppstigning med FM återandningssystem2012Report (Other academic)
  • 41.
    Gennser, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Jurd, Karen M.
    Blogg, S. Lesley
    Pre-Dive Exercise and Post-Dive Evolution of Venous Gas Emboli2012In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 83, no 1, p. 30-34Article in journal (Refereed)
    Abstract [en]

    Background: Recent studies have indicated that exercise before diving significantly reduces the number of circulating bubbles and the risk of decompression sickness. However, the most effective time delay between exercise and dive is not clear; the present aim was to resolve this. Methods: In a hyperbaric chamber, 10 men were compressed to 18 m for 100 min, then decompressed as per Royal Navy Table 11. Each subject performed three dives: a control dive and two after exercise performed either 24 h or 2 h before diving. Exercise consisted of 40 min submaximal work on a cycle ergometer. Venous gas emboli (VGE) were evaluated using precordial Doppler ultrasound immediately on surfacing, with measurements made at 5-min intervals for 30 min, and at 15-min intervals for at least 2.5 h total using the Kisman Masurel (KM) scale. Results: Exercise either 24 or 2 h prior to a dive did not reduce the median number of circulating VGE (median maximum KM grade: control, 2+; for both exercise dives, 3). Bubbles disappeared from the circulation faster after the control dive than the exercise dives. Time to median KM Doppler scores of zero were: control:120 min; 2-h group: 225 min; 24-h group: 165 min. Conclusion: Cycling exercise prior to diving did not reduce the number of circulating VGE in comparison to control, in contrast to recent studies. A number of factors may be responsible for these findings, including type of exercise performed, wet diving experience, and disparity in Doppler measurement techniques.

  • 42. Groselj, L. Dolenc
    et al.
    Rojc, B.
    Jeran, J.
    Pangerc, A.
    Morrison, S. A.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, I. B.
    Effect of bed rest and hypoxia on sleep macrostructure and respiration during sleep2012In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 21, p. 63-63Article in journal (Other academic)
  • 43.
    Grönkvist, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Bergsten, Eddie
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Effekter av tryckbortfall i G-skyddssystemet i JAS 39 Gripen2009Report (Other academic)
  • 44.
    Grönkvist, Mikael
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Bergsten, Eddie
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Loss of pressure in the anti-G system at high G-loads2011Conference paper (Refereed)
  • 45. Gustafsson, T.
    et al.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Sundblad, Patrik
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Norman, B.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Elevations of local intravascular pressures release vasoactive substances in humans2013In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 33, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    The wall stiffness of arteries and arterioles adapts to the long-term demands imposed by local intravascular pressure. We investigated whether substances capable of inducing acute and long-term effects on arterial wall stiffness are released locally into the bloodstream in response to an acute marked increase in local intravascular pressure in the blood vessels of the human arm. Experiments were performed on ten subjects positioned in a pressure chamber with one arm extended through a hole in the chamber door and kept at normal atmospheric pressure. Intravascular pressure was increased in the arm, by a stepwise increase in chamber pressure up to +150 mmHg. Diameter and flow were measured in the brachial artery by Doppler ultrasonography. Blood samples were drawn simultaneously from both arms before, during, immediately after and 2 h after the release of the chamber pressure. Plasma levels of endothelin-1 (ET-1), vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2) and angiotensin II (Ang-II) were measured. Elevation of chamber pressure by 150 mmHg increased local arterial distending pressure to about 220260 mmHg, resulting in an increase in brachial artery diameter of 9% and flow of 246%. The pressure stimulus increased the plasma levels of ET-1 and Ang-II, but not of VEGF-A or FGF-2 in the test arm. The local release of the vasoconstrictors ET-1 and Ang-II in response to markedly increased distending pressure may reflect one mechanism behind adaptation to acute and long-term changes in intravascular pressure.

  • 46. Jurd, Karen M.
    et al.
    Thacker, Julian C.
    Seddon, Fiona M.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Loveman, Geoffrey A. M.
    The effect of pre-dive exercise timing, intensity and mode on post-decompression venous gas emboli2011In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 41, no 4, p. 183-188Article in journal (Refereed)
    Abstract [en]

     Introduction: The effect of pre-dive exercise on post-decompression venous gas emboli (VGE) remains contentious. The aim of our study was to investigate the effect of timing, intensity and mode of exercise before diving on post-decompression VGE production. Methods: Fifteen male volunteers performed three identical 100 min chamber dives to 18 metres' sea water. Two of the three dives were conducted with prior exercise at 24 or 2 h; a dive without prior exercise formed the control. Moderate-intensity impact exercise consisted of jogging on the spot for one minute followed by ten star jumps, repeated for a total of 40 min at 70% of maximum heart rate. Post-dive Doppler monitoring began within 2 mm of surfacing and was carried out for at least 180 min VGE were assessed using the Kisman-Masurel (KM) code and the Kisman Integrated Severity Score (KISS). Results: The median peak KM grade for each condition following the dives was not significantly different. Pre-dive exercise at 2 h resulted in a significant reduction in the mean KISS compared to the control (11.3 versus 17.2, P < 0.04, Wilcoxon sign-ranked test). Moderate-intensity jogging/star jump exercise used in this series of dives resulted in significantly lower mean KISS (11.3 versus 21.8, P < 0.04) and median KM grade over 180 min (P < 0.006, Mann Whitney U test) compared to high-intensity cycling exercise used in our previous study. Conclusions: This study suggests that moderate-intensity impact exercise reduces VGE production when conducted 2 h prior to diving.

  • 47.
    Keramidas, Michail E.
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Mekjavic, Igor B.
    Prevailing evidence contradicts the notion of a "normobaric oxygen paradox"2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 12, p. 4177-4178Article in journal (Refereed)
  • 48.
    Keramidas, Michail E.
    et al.
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Geladas, Nickos D.
    Mekjavic, Igor B.
    Kounalakis, Stylianos N.
    Forearm-finger skin temperature gradient as an index of cutaneous perfusion during steady-state exercise2013In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 33, no 5, p. 400-404Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to examine whether the forearm-finger skin temperature gradient (Tforearm-finger), an index of vasomotor tone during resting conditions, can also be used during steady-state exercise. Twelve healthy men performed three cycling trials at an intensity of similar to 60% of their maximal oxygen uptake for 75min separated by at least 48h. During exercise, forearm skin blood flow (BFF) was measured with a laser-Doppler flowmeter, and finger skin blood flow (PPG) was recorded from the left index fingertip using a pulse plethysmogram. Tforearm-finger of the left arm was calculated from the values derived by two thermistors placed on the radial side of the forearm and on the tip of the middle finger. During exercise, PPG and BFF increased (P<0.001), and Tforearm-finger decreased (P<0.001) from their resting values, indicating a peripheral vasodilatation. There was a significant correlation between Tforearm-finger and both PPG (r=-0.68; P<0.001) and BFF (r=-0.50; P<0.001). It is concluded that Tforearm-finger is a valid qualitative index of cutaneous vasomotor tone during steady-state exercise.

  • 49. Keramidas, Michail E.
    et al.
    Kounalakis, S.
    Debevec, T.
    Norman, B.
    Gustafsson, T.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, I.
    The effect of acute normobaric hyperoxia on EPO concentration in healthy males2010Conference paper (Refereed)
  • 50. Keramidas, Michail E.
    et al.
    Kounalakis, S.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).
    Mekjavic, I.
    The effect of 10-days of hypoxia on muscle and cerebral oxygenation during a submaximal performance test2010In: High Altitude Medicine & Biology, ISSN 1527-0297, E-ISSN 1557-8682, Vol. 11, no 3, p. 269-269Article in journal (Refereed)
123 1 - 50 of 101
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