Browsing by Autor "Walter Schmidt"

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Hemoglobin Mass and Blood Volume in Patients With Altitude-Related Polycythemia
(Frontiers Media, 2022) Walter Schmidt; Nadine Wachsmuth; Jesús Jiménez; Rudy Soria
In CMS patients, the decrease in PV only partially compensated for the substantial increase in Hbmass, but it did not prevent an increase in BV; the decrease in PV contributed to an excessively high [Hb].
Modification of the CO‐rebreathing method to determine haemoglobin mass and blood volume in patients suffering from chronic mountain sickness
(Wiley, 2019) Nadine Wachsmuth; Rudy Soria; Jesús Jiménez; Walter Schmidt
Patients suffering from chronic mountain sickness (CMS) exhibit extremely high haemoglobin concentrations. Their haemoglobin mass (Hbmass), however, has rarely been investigated. The CO-rebreathing protocol for Hbmass determination in those patients might need to be modified because of restricted peripheral perfusion. The aim of this study was to evaluate the CO uptake and carboxyhaemoglobin-mixing time in the blood of CMS patients and to adapt the CO-rebreathing method for this group. Twenty-five male CMS patients living at elevations between 3600 and 4100 m above sea level were compared with ethnically matched healthy control subjects from identical elevations (n = 11) and near sea level (n = 9) and with a Caucasian group from sea level (n = 6). CO rebreathing was performed for 2 min, and blood samples were taken for the subsequent 30 min. After the method was modified, its reliability was evaluated in test-retest experiments (n = 28), and validity was investigated by measuring the Hbmass before and after the phlebotomy of 500 ml (n = 4). CO uptake was not affected by CMS. The carboxyhaemoglobin mixing was completed after 8 min in the Caucasian group but after 14 min in the groups living at altitude. When blood was sampled 14-20 min after inhalation, the typical error of the method was 1.6% (confidence limits 1.2-2.5%). After phlebotomy, Hbmass decreased from 1779 ± 123 to 1650 ± 129 g, and no difference was found between the measured and calculated Hbmass (1666 ± 122 g). When the time of blood sampling was adapted to accommodate a prolonged carboxyhaemoglobin-mixing time, the CO-rebreathing method became a reliable and valid tool to determine Hbmass in CMS patients.
Possible strategies to reduce altitude-related excessive polycythemia
(American Physiological Society, 2023) Walter Schmidt; Nadine Wachsmuth; Maria Catarina Romero Pozo; Martha Teresa Aguilar Valerio; Ivonee Clorinda Contreras Tapia; Marina Vater; Julia Kaufmann; Jesus Carlos Jimenez-Claros; Rudy Soria
We sought to determine the effects of three treatments on hemoglobin (Hb) levels in patients with chronic mountain sickness (CMS): 1) descent to lower altitude, 2) nocturnal O2 supply, 3) administration of acetazolamide. Nineteen patients with CMS living at an altitude of 3,940 ± 130 m participated in the study, which consisted of a 3-wk intervention phase and a 4-wk postintervention phase. Six patients spent 3 wk at an altitude of 1,050 m (low altitude group, LAG), six received supplemental oxygen for 12 h overnight (oxygen group, OXG), and seven received 250 mg of acetazolamide daily (acetazolamide group, ACZG). Hemoglobin mass (Hbmass) was determined using an adapted carbon monoxide (CO) rebreathing method before, weekly during, and 4 wk postintervention. Hbmass decreased by 245 ± 116 g (P < 0.01) in the LAG and by 100 ± 38 g in OXG, and 99 ± 64 g in ACZG (P < 0.05, each), respectively. In LAG, hemoglobin concentration ([Hb]) decreased by 2.1 ± 0.8 g/dL and hematocrit by 7.4 ± 2.9% (both P < 0.01), whereas OXG and ACZG only trended toward lower values. Erythropoietin concentration ([EPO]) decreased between 81 ± 12% and 73 ± 21% in LAG at low altitude (P < 0.01) and increased by 161 ± 118% 5 days after return (P < 0.01). In OXG and ACZG, the [EPO] decrease was ∼75% and ∼50%, respectively, during the intervention (P < 0.01). Descent to low altitude (from 3,940 m to 1,050 m) is a fast-acting measure for the treatment of excessive erythrocytosis in patients with CMS, reducing Hbmass by 16% within 3 wk. Nighttime oxygen supplementation and daily acetazolamide administration are also effective, but reduce Hbmass by only 6%.NEW & NOTEWORTHY To our knowledge, this is the first study examining the effect of three different treatments [descending to lower altitude (from 3,900 m to 1,050 m), nocturnal oxygen supply, and administration of acetazolamide] on changes in hemoglobin mass in patients experiencing chronic mountain sickness (CMS). We report that descent to low altitude is a fast-acting measure for the treatment of excessive erythrocytosis in patients with CMS, reducing Hbmass by 16% within 3 wk. Nighttime oxygen supplementation and daily acetazolamide administration are also effective, but reduce Hbmass by only 6%. In all three treatments, the underlying mechanism is a reduction in plasma erythropoietin concentration due to higher oxygen availability.
Predicting sickness during a 2-week soccer camp at 3600 m (ISA3600)
(BMJ, 2013) Martin Buchheit; Ben Simpson; Walter Schmidt; Robert J. Aughey; Rudy Soria; Robert Hunt; Laura A. Garvican‐Lewis; David B. Pyne; Christopher J. Gore; Pitre C. Bourdon
A >4% increased heart rate during submaximal exercise in response to a moderate increase in perceived training load the previous day may be an indicator of sickness the next day. All other variables, that is, resting heart rate, heart rate variability and psychometric questionnaires may be less powerful at predicting sickness.
Soccer activity profile of altitude versus sea-level natives during acclimatisation to 3600 m (ISA3600)
(BMJ, 2013) Robert J. Aughey; Kristal Hammond; Matthew C. Varley; Walter Schmidt; Pitre C. Bourdon; Martin Buchheit; Ben Simpson; Laura A. Garvican‐Lewis; Marlen Kley; Rudy Soria
High altitude reduces the distance covered by elite youth soccer players during matches. Neither 13 days of acclimatisation nor lifelong residence at high altitude protects against detrimental effects of altitude on match activity profile.
The impact of altitude on the sleep of young elite soccer players (ISA3600)
(BMJ, 2013) Charli Sargent; Walter Schmidt; Robert J. Aughey; Pitre C. Bourdon; Rudy Soria; Jesus C Jimenez Claros; Laura A. Garvican‐Lewis; Martin Buchheit; Ben Simpson; Kristal Hammond
The immediate effects of terrestrial altitude of 3600 m are to reduce the amount of REM sleep obtained by young elite athletes, and to cause 50% of them to have impaired breathing during sleep. REM sleep returns to normal after 2 weeks at altitude, but impaired breathing does not improve.
The sleep of elite athletes at sea level and high altitude: a comparison of sea-level natives and high-altitude natives (ISA3600)
(BMJ, 2013) Gregory D. Roach; Walter Schmidt; Robert J. Aughey; Pitre C. Bourdon; Rudy Soria; Jesus C Jimenez Claros; Laura A. Garvican‐Lewis; Martin Buchheit; Ben Simpson; Kristal Hammond
Exposure to high altitude causes acute and chronic disruption to the sleep of elite athletes who are sea-level natives, but it does not affect the sleep of elite athletes who are high-altitude natives.
Wellness, fatigue and physical performance acclimatisation to a 2-week soccer camp at 3600 m (ISA3600)
(BMJ, 2013) Martin Buchheit; Ben Simpson; Laura A. Garvican‐Lewis; Kristal Hammond; Marlen Kley; Walter Schmidt; Robert J. Aughey; Rudy Soria; Charli Sargent; Gregory D. Roach
Despite partial physiological and perceptual acclimatisation, 2 weeks is insufficient for restoration of physical performance in young sea-level native soccer players. Because of the possible decrement in 20 m sprint time, a greater emphasis on speed training may be required during and after altitude training. The specific time course of restoration for each variable suggests that they measure different aspects of acclimatisation to 3600 m; they should therefore be used in combination to assess adaptation to altitude.