Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1) to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2) to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase "AP"--breathing into the snow with a one-liter air pocket, and phase "NP"--breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume), but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO2 and EtCO2) and peripheral oxygen saturation (SpO2) between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for FIO2) or never (for FICO2). The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing.
- MeSH
- asfyxie patofyziologie prevence a kontrola MeSH
- dechová práce fyziologie MeSH
- dechový objem fyziologie MeSH
- dospělí MeSH
- dvojitá slepá metoda MeSH
- hyperkapnie patofyziologie MeSH
- hypoxie patofyziologie MeSH
- inspirační rezervní objem fyziologie MeSH
- katastrofy * MeSH
- klinické křížové studie MeSH
- kyslík fyziologie MeSH
- laviny * MeSH
- lidé MeSH
- monitorování fyziologických funkcí MeSH
- oxid uhličitý fyziologie MeSH
- sníh MeSH
- zdraví dobrovolníci pro lékařské studie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- randomizované kontrolované studie MeSH
- Klíčová slova
- přednemocniční, KPR, ventilace,
- MeSH
- ambulantní monitorování metody MeSH
- diferenciální diagnóza MeSH
- kapnografie * přístrojové vybavení využití MeSH
- lidé MeSH
- oxid uhličitý diagnostické užití fyziologie terapeutické užití MeSH
- urgentní zdravotnické služby metody MeSH
- Check Tag
- lidé MeSH
The purpose of this study was to examine how oxygen uptake (V . o2) in decrement-load exercise (DLE) is affected by changing rate of decrease in power output. DLE was performed at three different rates of decrease in power output (10, 20 and 30 watts·min-1: DLE10, DLE20 and DLE30, respectively) from power output corresponding to 90 % of peak V . o2. V . o2 exponentially increased and then decreased, and the rate of its decrease was reduced at low power output. The values of V . o2 in the three DLE tests were not different for the first 2 min despite the difference in power output. The relationship between V . o2 and power output below 50 watts was obtained as a slope to estimate excessive V . o2 (ex-V . o2) above 50 watts. The slopes were 10.0±0.9 for DLE10, 9.9±0.7 for DLE20 and 10.2±1.0 ml·min-1·watt-1 for DLE30. The difference between V . o2 estimated from the slope and measured V . o2 was defined as ex-V . o2. The peak value of ex-V . o2 for DLE10 (189±116 ml·min-1) was significantly greater than those for DLE20 and for DLE30 (93±97 and 88±34 ml·min-1). The difference between V . o2 in DLE and that in incremental-load exercise (ILE) below 50 watts (?V . o2) was greater in DLE30 and smallest in DLE10. There were significant differences in ?V . o2 among the three DLE tests. The values of ?V . o2 at 30 watts were 283±152 for DLE10, 413±136 for DLE20 and 483±187 ml·min-1 for DLE30. Thus, a faster rate of decrease in power output resulted in no change of V . o2 at the onset of DLE, smaller ex-V . o2 and greater ?V . o2. These results suggest that V . o2 is disposed in parallel in each motor unit released from power output or recruited in DLE.
- MeSH
- finanční podpora výzkumu jako téma MeSH
- kapnografie metody přístrojové vybavení statistika a číselné údaje MeSH
- kardiopulmonální resuscitace metody využití MeSH
- lidé MeSH
- oxid uhličitý fyziologie MeSH
- plicní oběh fyziologie MeSH
- rozšířená kardiopulmonální recuscitace metody přístrojové vybavení MeSH
- srdeční zástava terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- kazuistiky MeSH
- MeSH
- bronchiální astma krev MeSH
- dítě MeSH
- lidé MeSH
- oxid dusnatý analýza fyziologie krev MeSH
- oxid uhličitý analýza fyziologie krev MeSH
- vzduch analýza MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- MeSH
- finanční podpora výzkumu jako téma MeSH
- insuflace metody trendy využití MeSH
- králíci MeSH
- oxid uhličitý fyziologie škodlivé účinky MeSH
- parciální tlak MeSH
- ventilace umělá s přerušovaným přetlakem škodlivé účinky trendy využití MeSH
- vysokofrekvenční ventilace škodlivé účinky trendy využití MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
