Dynamics of the ventilatory response to hypoxia in humans.
Dynamic responses of the ventilatory system to rapid variations in isocapnic hypoxia were studied in five subjects. Sawtooth-shaped inputs were presented at constant amplitude with periods of 120, 90, 60, 45 and 30 sec, and square-wave inputs at different amplitudes with periods of 120, 60 and 30 se...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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1993
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| _version_ | 1826270470920470528 |
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| author | Clement, I Robbins, P |
| author_facet | Clement, I Robbins, P |
| author_sort | Clement, I |
| collection | OXFORD |
| description | Dynamic responses of the ventilatory system to rapid variations in isocapnic hypoxia were studied in five subjects. Sawtooth-shaped inputs were presented at constant amplitude with periods of 120, 90, 60, 45 and 30 sec, and square-wave inputs at different amplitudes with periods of 120, 60 and 30 sec. A breath-by-breath model fitting technique was used to assess whether any of a number of first order models of hypoxic ventilatory dynamics could fit the data adequately. The following was found: 1) An equation for the desaturation of haemoglobin provided a better expression for hypoxia in the model than did a hyperbolic function of PO2. 2) The gain and/or offset model parameters varied significantly between experiments, but the time constant and pure delay terms did not. 3) The time constants, and to a lesser extent the pure delays, were found to vary significantly between sawtooth experiments of different frequencies. The failure of a single set of dynamic parameters to describe all the responses suggests that the model is incomplete. 4) There was significant asymmetry in the hypoxic response with the on-transient dynamics faster than the off-transient dynamics. The results of the model fitting study suggest that a first order model cannot fully describe the hypoxic ventilatory dynamics. |
| first_indexed | 2024-03-06T21:41:21Z |
| format | Journal article |
| id | oxford-uuid:480c82af-63f6-4ded-96b2-01287006a854 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:41:21Z |
| publishDate | 1993 |
| record_format | dspace |
| spelling | oxford-uuid:480c82af-63f6-4ded-96b2-01287006a8542022-03-26T15:23:21ZDynamics of the ventilatory response to hypoxia in humans.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:480c82af-63f6-4ded-96b2-01287006a854EnglishSymplectic Elements at Oxford1993Clement, IRobbins, PDynamic responses of the ventilatory system to rapid variations in isocapnic hypoxia were studied in five subjects. Sawtooth-shaped inputs were presented at constant amplitude with periods of 120, 90, 60, 45 and 30 sec, and square-wave inputs at different amplitudes with periods of 120, 60 and 30 sec. A breath-by-breath model fitting technique was used to assess whether any of a number of first order models of hypoxic ventilatory dynamics could fit the data adequately. The following was found: 1) An equation for the desaturation of haemoglobin provided a better expression for hypoxia in the model than did a hyperbolic function of PO2. 2) The gain and/or offset model parameters varied significantly between experiments, but the time constant and pure delay terms did not. 3) The time constants, and to a lesser extent the pure delays, were found to vary significantly between sawtooth experiments of different frequencies. The failure of a single set of dynamic parameters to describe all the responses suggests that the model is incomplete. 4) There was significant asymmetry in the hypoxic response with the on-transient dynamics faster than the off-transient dynamics. The results of the model fitting study suggest that a first order model cannot fully describe the hypoxic ventilatory dynamics. |
| spellingShingle | Clement, I Robbins, P Dynamics of the ventilatory response to hypoxia in humans. |
| title | Dynamics of the ventilatory response to hypoxia in humans. |
| title_full | Dynamics of the ventilatory response to hypoxia in humans. |
| title_fullStr | Dynamics of the ventilatory response to hypoxia in humans. |
| title_full_unstemmed | Dynamics of the ventilatory response to hypoxia in humans. |
| title_short | Dynamics of the ventilatory response to hypoxia in humans. |
| title_sort | dynamics of the ventilatory response to hypoxia in humans |
| work_keys_str_mv | AT clementi dynamicsoftheventilatoryresponsetohypoxiainhumans AT robbinsp dynamicsoftheventilatoryresponsetohypoxiainhumans |