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Träfflista för sökning "AMNE:(MEDICIN OCH HÄLSOVETENSKAP Medicinska grundvetenskaper Fysiologi) ;pers:(Schagatay Erika)"

Sökning: AMNE:(MEDICIN OCH HÄLSOVETENSKAP Medicinska grundvetenskaper Fysiologi) > Schagatay Erika

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1.
  • de Asis Fernandez, Fran, et al. (författare)
  • Hook Breathing Facilitates SaO(2) Recovery After Deep Dives in Freedivers With Slow Recovery
  • 2019
  • Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • (SaO2)To facilitate recovery from hypoxia, many freedivers use a breathing method called "hook breathing" (HB) after diving, involving an interrupted exhale to build up intrapulmonary pressure. Some divers experience a delay in recovery of arterial oxygen saturation (SaO2) after diving, interpreted as symptoms of mild pulmonary edema, and facilitated recovery may be especially important in this group to avoid hypoxic "blackout." We examined the influence of HB on recovery of (SaO2) in freedivers with slow recovery (SR) and fast recovery (FR) of (SaO2) after deep "free immersion" (FIM) apnea dives to 30 m depth. Twenty-two male freedivers, with a mean (SD) personal best in the discipline FIM of 57(26) m, performed two 30 m deep dives, one followed by HB and one using normal breathing (NB) during recovery, at different days and weighted order. (SaO2) and heart rate (HR) were measured via pulse oximetry during recovery. The SR group (n = 5) had a faster (SaO2) recovery using HB, while the FR group (n = 17) showed no difference between breathing techniques. At 105 s, the SR group reached a mean (SD) SaO(2) of 95(5)% using HB, while using NB, their (SaO2) was 87(5)% (p < 0.05), and 105-120 s after surfacing(SaO2) was higher with HB (p < 0.05). In SR subjects, the average time needed to reach 95% (SaO2) with HB was 60 s, while it was 120 s at NB (p < 0.05). HR was similar in the SR group, while it was initially elevated at HB in the FR group (p < 0.05). We conclude that HB efficiently increases (SaO2) recovery in SR individuals, but not in the FR group. The proposed mechanism is that increased pulmonary pressure with HB will reverse any pulmonary edema and facilitate oxygen uptake in divers with delayed recovery.
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2.
  • Holmström, Pontus, et al. (författare)
  • Test–retest reliability of splenic volume assessment by ultrasonography
  • 2022
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • While MRI and CT are the gold standards for assessments of splenic size in clinical settings, ultrasonography is particularly suited due to its portability, cost efficiency and easy utilization. However, ultrasonography is associated with subjective assessment, potentially resulting in increased variation. We used a test–retest design aiming to determine the reliability of splenic measurements assessed by ultrasonography during apnea. In addition, we compared reliability between different equations for volume calculations: Koga, Prolate ellipsoid and Pilström. Twelve healthy participants (6 women) performed two tests separated by 15 min, comprising a maximal voluntary apnea in a seated position. Splenic dimensions were measured via ultrasonography for 5 min before and immediately following apnea. Resting splenic volume displayed high test–retest reliability between tests (Pilström: 157 ± 39 mL vs 156 ± 34 mL, p = .651, ICC = .970, p < .001, CV = 2.98 ± 0.1%; Prolate ellipsoid: 154 ± 37 mL vs 144 ± 43 mL, p = .122, ICC = .942, p < .001, CV = 5.47 ± 0.3%; Koga: 142 ± 37 mL vs 140 ± 59 mL, p = .845, ICC = .859, p < .001, CV = 9.72 ± 1.4%). Apnea-induced volumes displayed similar reliability (127 ± 29 mL vs 129 ± 28 mL, p = .359, ICC = .967, p < .001, CV = 3.14 ± 3.1%). Reliability was also high between equations (Pilström vs Prolate ellipsoid: ICC = .818, p < .001, CV = 7.33 ± 0.3%, bias =  − 3.1 mL, LoA =  − 46.9 to 40.7 mL; Pilström vs Koga: ICC = .618, p < .01, CV = 11.83 ± 1.1%, bias =  − 14.8 mL, LoA =  − 76.9 to 47.3 mL). We conclude that splenic ultrasonographic measurements have practical applications during laboratory and field-based research as a reliable method detecting splenic volume change consistently between repeated tests. The Pilström equation displayed similar reliability compared to the prolate ellipsoid formula and slightly higher compared to the Koga formula and may be particularly useful to account for individual differences in splenic dimensions.
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4.
  • Andersson, Johan, et al. (författare)
  • Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans
  • 2004
  • Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 96:3, s. 1005-1010
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10degreesC) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.
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5.
  • Andersson, Johan, et al. (författare)
  • Cardiovascular responses to cold water immersions of the forearm and face, and their relationship to apnoea
  • 2000
  • Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 83:6, s. 566-572
  • Tidskriftsartikel (refereegranskat)abstract
    • Apnoea as well as cold stimulation of the face or the extremities elicits marked cardiovascular reflexes in humans. The purpose of this study was to investigate whether forearm immersion in cold water has any effect on the cardiovascular responses to face immersion and apnoea. We recorded cardiovascular responses to cold-water immersions of the forearm and face in 19 (part I) and 23 subjects (part II). The experimental protocol was divided in two parts, each part containing four tests: I1, forearm immersion during eupnoea; I2, face immersion during eupnoea; I3, forearm and face immersion during eupnoea; I4, face immersion during apnoea; II1, apnoea without immersion; II2, forearm immersion during apnoea; II3, face immersion during apnoea; and II4, forearm and face immersion during apnoea. The water temperature was 9–11 °C. Cold-water immersion of either the forearm or face was enough to elicit the most pronounced thermoregulatory vasoconstriction during both eupnoea and apnoea. During eupnoea, heart rate responses to forearm immersion (3% increase) and face immersion (9% decrease) were additive during concurrent stimulation (3% decrease). During apnoea, the heart rate responses were not affected by the forearm immersion. The oxygen-conserving diving response seems to dominate over thermoregulatory responses in the threat of asphyxia. During breathing, however, the diving response serves no purpose and does not set thermoregulatory adjustments aside
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6.
  • Andersson, Johan, et al. (författare)
  • Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers
  • 2002
  • Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 93:3, s. 882-886
  • Tidskriftsartikel (refereegranskat)abstract
    • This study addressed the effects of apnea in air and apnea with face immersion in cold water (10°C) on the diving response and arterial oxygen saturation during dynamic exercise. Eight trained breath-hold divers performed steady-state exercise on a cycle ergometer at 100 W. During exercise, each subject performed 30-s apneas in air and 30-s apneas with face immersion. The heart rate and arterial oxygen saturation decreased and blood pressure increased during the apneas. Compared with apneas in air, apneas with face immersion augmented the heart rate reduction from 21 to 33% (P < 0.001) and the blood pressure increase from 34 to 42% (P < 0.05). The reduction in arterial oxygen saturation from eupneic control was 6.8% during apneas in air and 5.2% during apneas with face immersion (P < 0.05). The results indicate that augmentation of the diving response slows down the depletion of the lung oxygen store, possibly associated with a larger reduction in peripheral venous oxygen stores and increased anaerobiosis. This mechanism delays the fall in alveolar and arterial Po2 and, thereby, the development of hypoxia in vital organs. Accordingly, we conclude that the human diving response has an oxygen-conserving effect during exercise.
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7.
  • Andersson, Johan, et al. (författare)
  • Pulmonary gas exchange is reduced by the cardiovascular diving response in resting humans
  • 2008
  • Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 160:3, s. 320-324
  • Tidskriftsartikel (refereegranskat)abstract
    • The diving response reduces the pulmonary O2 uptake in exercising humans, but it has been debated whether this effect is present at rest. Therefore, respiratory and cardiovascular responses were recorded in 16 resting subjects, performing apnea in air and apnea with face immersion in cold water (10 ◦C). Duration of apneas were predetermined to be identical in both conditions (average: 145 s) and based on individual maximal capacity (average: 184 s). Compared to apnea in air, an augmented diving response was elicited by apnea with face immersion. The O2 uptake from the lungs was reduced compared to the resting eupneic control (4.6 ml min−1 kg−1), during apnea in air (3.6 ml min−1 kg−1) and even more so during apnea with face immersion (3.4 ml min−1 kg -1). We conclude that the cardiovascular djustments of the diving response reduces pulmonary gas exchange in resting humans, allowing longer apneas by preserving the lungs’ O2 store for use by vital organs.
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8.
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9.
  • Andersson, Johan, et al. (författare)
  • Repeated apneas do not affect the hypercapnic ventilatory response in the short term
  • 2009
  • Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 105:4, s. 569-74
  • Tidskriftsartikel (refereegranskat)abstract
    • Long-term training of breath-hold diving reduces the hypercapnic ventilatory response (HCVR), an index of the CO(2) sensitivity. The aim of the present study was to elucidate whether also short-term apnea training (repeating apneas with short intervals) reduces the HCVR, thereby being one contributing factor explaining the progressively increasing breath-holding time (BHT) with repetition of apneas. Fourteen healthy volunteers performed a series of five maximal-duration apneas with face immersion and two measurements of the HCVR, using the Read rebreathing method. The BHT increased by 43% during the series of apneas (P < 0.001). However, the slope of the HCVR test was not affected by the series of apneas, being 2.52 (SD 1.27) and 2.24 (SD 1.14) l min(-1) mmHg(-1) in the control test and in the test performed within 2 min after the last apnea of the series, respectively (NS). Thus, a change in the HCVR cannot explain the observed short-term training effect on BHT.
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10.
  • de Bruijn, Robert, et al. (författare)
  • Erythropoietin production as a result of repeated apneas
  • 2004
  • Konferensbidrag (refereegranskat)abstract
    • Background: It has been known for decades that high altitude hypoxia will lead to increased erythropoiesis. Hypoxia in mainly the kidney results in an increased production of erythropoietin (EPO) stimulating erythropoiesis. High altitude natives display a higher haemoglobin concentration than sea level residents, which in turn increase their haemoglobin concentration as part of the adaptation to altitude. Another group of humans exposed to hypoxia is apneic divers, which may endure transient acute hypoxia, spaced by periods of normal breathing. We recently found higher haemoglobin levels in elite apneic divers, compared to groups of elite skiers and untrained subjects, suggesting that apnea training may induce erythropoiesis in humans. It is well known that diving mammals display high haemoglobin concentrations, and the beneficial effects are obvious: A larger oxygen store before diving prolongs the aerobic dive limit, and a higher haemoglobin concentration may speed up recovery after apneas and act as a buffer against acidosis during the dive. Although our group comparisons reveal a higher haemoglobin concentration in divers, it cannot be determined whether this is a training effect or genetically determined i.e. if individuals with higher concentrations of haemoglobin are more prone to take up apneic diving. Methods: To investigate if apnea training can induce EPO production, 5 previously untrained volunteers (3 men and 2 women, mean ageSD 28 5.5 years) performed 15 maximal apneas in a horizontal position in air. The apneas were grouped in 3 series of 5 apneas and spaced by 2 minutes of which 1 minute was spent slightly hyperventilating, to produce apneas sufficiently long to induce hypoxia. Series were spaced by 10 minutes resting periods. To determine EPO levels, venous blood samples were taken before apneas and directly after the last apnea series, followed by samples 1, 2, 3 and 5 hours after the apneas. Results: Mean baseline EPO before the apneas was 10.2 U/L. In all subjects EPO levels increased during the 5 hours period after the apneas. The time for EPO-peak values were different among individuals. The mean peak value occurred after 3 h, where the mean increase was 12 % of the pre apnea reference value. Conclusion: The results suggest that apnea induced intermittent hypoxia could lead to increased erythropoiesis. The evaluation of these findings in a larger group of subjects, including measurements of the individual circadian variations in EPO production, is in progress.
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