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- Elia, Antonis, Dr, et al.
(författare)
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Inter- and Intra-Rater Level of Agreement in Ultrasonic Video Grading of Venous Gas Emboli
- 2022
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Ingår i: Aerospace Medicine and Human Performance. - : Aerospace Medical Association. - 2375-6314 .- 2375-6322. ; 93:1, s. 54-57
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: This study aimed to evaluate whether a short familiarization session is sufficient for individuals with no prior experience of sonography to both reliably and consistently evaluate the prevalence of venous gas emboli (VGE) from precordial ultrasonic videos.METHODS: A total of 10 adults with no prior experience of sonography were introduced to the Eftedal-Brubakk 6-grade scale and were shown 6 video sequences, each of a maximum of 10 heartbeats, representing each grading level. Thereafter, they independently evaluated the prevalence of VGE in 70 ultrasonic videos before and after a 14-d interval (test-retest; intra-rater), with these being compared to an experienced sonographer's grading (inter-rater).RESULTS: A significant inter-rater level of agreement was found between the naïve and experienced sonographers' bubble grading both during the first (W = 0.945) and second (W = 0.952) round of bubble evaluation. The naïve observers' evaluations were on average 79% (range: 61-95%) and 75% (range: 48-95%) in complete agreement with the experienced sonographer's gradings, while the level of agreement was 99% and 98% within 1 grade unit. There was a significant intra-rater level of agreement (κ = 0.845) during the test-retest series, with a mean percentage level of agreement of 87% (range: 72-93%).CONCLUSION: This study demonstrates that a short familiarization session enables individuals with no prior sonography experience to consistently evaluate VGE prevalence from precordial ultrasonic videos.Elia A, Ånell R, Eiken O, Grönkvist M, Gennser M. Inter- and intra-rater level of agreement in ultrasonic video grading of venous gas emboli. Aerosp Med Hum Perform. 2022; 93(1):54-57.
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| 3. |
- Elia, Antonis, et al.
(författare)
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Whole-body vibration preconditioning reduces the formation and delays the manifestation of high-altitude-induced venous gas emboli.
- 2021
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Ingår i: Experimental Physiology. - : Wiley. - 0958-0670 .- 1469-445X. ; 106:8, s. 1743-1751
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Tidskriftsartikel (refereegranskat)abstract
- NEW FINDINGS: What is the central question of this study? Is performing a 30-min whole-body vibration (WBV) prior to a continuous 90-min exposure at 24,000 ft sufficient to prevent venous gas emboli (VGE) formation? What is the main finding and its importance? WBV preconditioning significantly reduces the formation and delays the manifestation of high-altitude-induced VGE. This study suggests that WBV is an effective strategy in lowering decompression stress.ABSTRACT: Rapid decompression may give rise to formation of venous gas emboli (VGE) and resultantly, increase the risk of sustaining decompression sickness. Preconditioning aims at lowering the prevalence of VGE during decompression. The purpose of this study was to investigate the efficacy of whole-body vibration (WBV) preconditioning on high-altitude-induced VGE. Eight male subjects performed, on separate days in a randomised order, three preconditioning strategies: 40-min seated-rest (control), 30-min seated-rest followed by 150 knee-squats performed over a 10-min period (exercise) and 30-min WBV proceeded by a 10-min seated-rest. Thereafter, subjects were exposed to an altitude of 24,000 ft (7315 m) for 90 min whilst laying in a supine position and breathing 100% oxygen. VGE were assessed ultrasonically both during supine rest (5-min intervals) and after three fast, unloaded knee-bends (15-min intervals) and were scored using a 5-grade scale and evaluated using the Kisman Integrated Severity Score (KISS). There was a significant difference in VGE grade (P < 0.001), time to VGE manifestation (P = 0.014) and KISS score following knee-bends (P = 0.002) across protocols, with a trend in KISS score during supine rest (P = 0.070). WBV resulted in lower VGE grades (median (range), 1 (0-3)) and KISS score (2.69 ± 4.56 a.u.) compared with control (2 (1-3), P = 0.002; 12.86 ± 8.40 a.u., P = 0.011) and exercise (3 (2-4) , P < 0.001; 22.04 ± 13.45 a.u., P = 0.002). VGE were detected earlier during control (15 ± 14 min, P = 0.024) and exercise (17 ± 24 min, P = 0.032) than WBV (54 ± 38 min). Performing a 30-min WBV prior to a 90-min continuous exposure at 24,000 ft both delays the manifestation and reduces the formation of VGE compared with control and exercise preconditioning.
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| 7. |
- Ånell, Rickard, 1971-
(författare)
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Decompression strain during long-duration, high-altitude exposures : Effects of intermittent excursions to moderate altitude and inspired fractions of oxygen
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today´s tactical demands and new technical solutions in fighter aircraft entail longer exposure periods at higher altitudes than before. A low cabin pressure protects pilots from pulmonary barotrauma in case of a sudden loss of cabin pressure, however it can also generate a supersaturation of nitrogen (N2) in the tissues, increasing the risks of bubble formation and decompression sickness (DCS). To be able to perform long-duration missions at high altitude, in-air refuelling is required, often performed at lower cabin altitudes between 15000-20000 ft. Therefore, the aim of the thesis was to explore different mechanisms that could affect decompressive strain during long and intermittent high altitude-exposures. In our experiments, upon which this thesis is based, we examined how ambient pressure and different breathing gas-mixtures affected the N2 washout and presence of venous gas emboli (VGE) as markers of decompressive strain, in particular during long-duration exposures. The thesis is based on four different studies and a short communication. The first two studies measured N2-washout during normoxic exposures. In studies I- IV, VGE were measured during normoxic or hyperoxic conditions with different ambient pressures. The results show that a high enough pressure increase compressed the existing bubbles and decreased the number of VGE before returning to high altitude. Hyperoxia alone did not protect subjects from VGE formation and DCS, whereas a combination of an early recompression during high-altitude exposures while breathing 100% O2 decreased VGE, probably by changing the bubble content from N2 to O2, making the bubbles unstable, probably reducing the risk for DCS returning to high altitude.
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| 8. |
- Ånell, Rickard, et al.
(författare)
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Evolution and Preservation of Venous Gas Emboli at Alternating High and Moderate Altitude Exposures
- 2020
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Ingår i: Aerospace Medicine and Human Performance. - : Aerospace Medical Association. - 2375-6314 .- 2375-6322. ; 91:1, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The evolution and preservation of venous gas emboli (VGE), as markers of decompression stress, were investigated during alternating high- and moderate altitude exposures, thus, simulating a fighter aircraft high-altitude flight, interrupted by refueling excursions to lower altitudes. METHODS: Eight men served as subjects during three normoxic simulated altitude exposures: High = 90 min at 24,000 ft; High-Low = three x 30 min at 24,000 ft, interspersed by two 30-min intervals at 15,000 ft; Low = 90 min at 15,000 ft. VGE scores were assessed by cardiac ultrasound, using a 5-grade scale. Respiratory nitrogen exchange was measured continuously using a modified closed-circuit electronic rebreather. RESULTS: Both High and High-Low induced persistent VGE, with no inter-condition difference either at rest [median (range): High: 1 (0-3), High-Low: 2 (0-3)] or during unloaded knee-bends [High: 3 (1-4), High-Low: 3 (0-4)], whereas VGE was considerably less in Low, both at rest [0 (0-1)] and during knee-bends [0 (0-2)]. In High-Low, VGE decreased temporarily during the 15,000-ft excursions, but resumed pre-excursion values upon return to 24,000 ft. During the final descent to ground level, VGE were more persistent following High-Low than High. In both High and Low, nitrogen was continuously washed out at altitude, whereas in High-Low, the washout at 24,000 ft was interrupted by nitrogen uptake at 15,000 ft. DISCUSSION: In normoxic conditions, long-duration flying at a cabin altitude of 24,000 ft is associated with substantial VGE occurrence, which is not abolished by intermittent excursions to a cabin altitude of 15,000 ft.
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| 9. |
- Ånell, Rickard, et al.
(författare)
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High-Altitude Decompression Strain Can Be Reduced By An Early Excursion To Moderate Altitude While Breathing Oxygen
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Recent observations suggest that development of venous gas emboli (VGE) during high-altitude flying whilst breathing hyperoxic gas will be reduced by intermittent excursions to moderate altitude. The present study aimed to investigate if an early, single excursion from high to moderate altitude can be used as an in-flight means to reduce high-altitude decompression strain. Ten healthy men were investigated whilst breathing oxygen in a hypobaric chamber under two conditions, once during a 90-min continuous exposure to a simulated cabin altitude of 24000 ft (High; H) and once during 10 min at 24000 ft, followed by 30 min at 15000 ft and by 80 min at 24000 ft (High-Low-High; H-L-H). VGE scores were assessed by cardiac ultrasound, using a 6-graded scale. In H, VGE increased throughout the course of the sojourn at 24000 ft to attain peak value (median (range)) of 3 (2-4) at min 90, just prior to descent. In H-L-H, median VGE scores were 0 throughout the trial, except for at min 10, just prior to the excursion to 15000 ft, whence the VGE score was 1.5 (0-3). Thus, an early, single excursion from high to moderate cabin altitude holds promise as an in-flight means to reduce the risk of altitude decompression sickness during long-duration high-altitude flying in aircraft with limited cabin pressurization. Presumably, such excursion acts by facilitating the gas exchange in decompression bubbles from a predomination of nitrogen to that of oxygen.Key words: altitude decompression sickness, decompression sickness risk, fighter aircraft, gas bubble formation, repeated altitude decompression, VGE.
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| 10. |
- Ånell, Rickard, et al.
(författare)
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High-altitude decompression strain can be reduced by an early excursion to moderate altitude while breathing oxygen.
- 2021
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Ingår i: European Journal of Applied Physiology. - : Springer Nature. - 1439-6319 .- 1439-6327. ; 121:11, s. 3225-3232
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Tidskriftsartikel (refereegranskat)abstract
- Recent observations suggest that development of venous gas emboli (VGE) during high-altitude flying whilst breathing hyperoxic gas will be reduced by intermittent excursions to moderate altitude. The present study aimed to investigate if an early, single excursion from high to moderate altitude can be used as an in-flight means to reduce high-altitude decompression strain. Ten healthy men were investigated whilst breathing oxygen in a hypobaric chamber under two conditions, once during a 90-min continuous exposure to a simulated cabin altitude of 24,000 ft (High; H) and once during 10 min at 24,000 ft, followed by 30 min at 15,000 ft and by 80 min at 24,000 ft (high-low-high; H-L-H). VGE scores were assessed by cardiac ultrasound, using a 6-graded scale. In H, VGE increased throughout the course of the sojourn at 24,000 ft to attain peak value [median (range)] of 3 (2-4) at min 90, just prior to descent. In H-L-H, median VGE scores were 0 throughout the trial, except for at min 10, just prior to the excursion to 15,000 ft, whence the VGE score was 1.5 (0-3). Thus, an early, single excursion from high to moderate cabin altitude holds promise as an in-flight means to reduce the risk of altitude decompression sickness during long-duration high-altitude flying in aircraft with limited cabin pressurization. Presumably, such excursion acts by facilitating the gas exchange in decompression bubbles from a predomination of nitrogen to that of oxygen.
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