An assessment of overall "gain" of the O2-feedback control system with and without external dead space breathing.

Masuyama, Hidenori; Hayashi, Fumiaki; Honda, Yoshiyuki

doi:10.2170/jjphysiol.33.699

Cited by 2 publications

(3 citation statements)

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“…The experimental setup and procedures as well as the method of data analysis were almost the same as those in the investigation previously reported MASUYAMA et al, 1983). The external dead spaces (DS) used were plastic tubings of 250, 500, and 750 ml in capacity.…”

Section: Methodsmentioning

confidence: 99%

“…In the present study, we defined the overall open-loop gain as GHco2 (defined as overall gain in our previous study) by dividing the slope of the CO2-ventilation response line (S) by the slope of the metabolic hyperbola (SL) at a given end-tidal Pco2 (PETco2). When a disturbance is introduced into the system in order to change PETco2 by 4PETco2, the final change in PETC02 will be reduced to 4PETc o 2/(l + GHc o 2).In the previous communication (MASUYAMA et al, 1983), overall open-loop gain of the 02-ventilation feedback control system was evaluated and compared with that of the C02-ventilation feedback control system in normoxia. The latter was found to exceed the former, suggesting the predominant role of CO2 in the control of ventilation.…”

mentioning

confidence: 99%

“…In the previous communication (MASUYAMA et al, 1983), overall open-loop gain of the 02-ventilation feedback control system was evaluated and compared with that of the C02-ventilation feedback control system in normoxia. The latter was found to exceed the former, suggesting the predominant role of CO2 in the control of ventilation.…”

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confidence: 99%

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An assessment of overall open-loop "gain" of CO2-ventilation feedback control system in hypoxia.

1985

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Overall open-loop gain of the CO2-ventilation feedback control system in hypoxia (GHco2) was determined on 8 male and one female healthy subjects. They breathed in a closed circuit, and were subjected to the progressive hypoxia test. This procedure was first conducted without dead space (DS), then with 250, 500, and finally 750 ml DS, consecutively. GHC02 was calculated by dividing the slope of the CO2 response curve (S) by that of the metabolic hyperbola (SL). GHco2 was considerably larger than the overall open-loop gain of the 02-ventilation feedback control system (Go2) previously obtained. This was ascribed to the facts that S was larger than the slope of the hypoxia response curve, and that the absolute value of SL in GHco 2 was smaller than that in G02. SEVERINGHAUS (1972) was the first to present the concept of the overall gain of the C02-feedback control system. The same idea was also proposed as the open-loop gain by MILHORN (1966). The concept of overall gain corresponds to that of open-loop gain. In the present study, we defined the overall open-loop gain as GHco2 (defined as overall gain in our previous study) by dividing the slope of the CO2-ventilation response line (S) by the slope of the metabolic hyperbola (SL) at a given end-tidal Pco2 (PETco2). When a disturbance is introduced into the system in order to change PETco2 by 4PETco2, the final change in PETC02 will be reduced to 4PETc o 2/(l + GHc o 2).In the previous communication (MASUYAMA et al., 1983), overall open-loop gain of the 02-ventilation feedback control system was evaluated and compared with that of the C02-ventilation feedback control system in normoxia. The latter was found to exceed the former, suggesting the predominant role of CO2 in the control of ventilation. However, it is known that CO2 sensitivity in regulation of respiration is affected by the presence of hypoxia (NIELSEN and SMITH, 1951).To assess the actual significance in the feedback control system in hypoxia, both

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An assessment of overall open-loop "gain" of CO2-ventilation feedback control system in hypoxia.

1985

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Limitations of the open loop gain concept in studies of respiratory control

Bennett

1990

Annals of Biomedical Engineering

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A steady state mathematical model was used to study the limitations of applying the open loop gain concept to the ventilatory control system. Open loop gain is a term used in the study of linear control systems and is an indicator of how well the controlled variable is regulated. The model contained descriptions of the O2 and CO2 control systems as well as their interactions. Disturbances to the system were modelled as occurring via inspired air, metabolic rate and ventilation. The ventilatory response to hypoxia was simulated for (a) hypocapnic hypoxia, (b) normocapnic hypoxia (PaCO2 = 40 torr) and (c) hypercapnic hypoxia (PaCO2 = 45 torr). The open loop gains of the O2 and CO2 loops were calculated at each operating point. In addition, the sensitivity of the controlled variable to disturbances to the loop were also compared. It was observed that open loop gain did not completely describe the characteristics of the ventilatory control system. This was due to the fact that the ventilatory system is nonlinear and the regulatory ability of the ventilatory system depends on the route of the disturbance, and (2) open loop gain ignores the interactions of the CO2 and O2 loops, which can be substantial.

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An assessment of overall "gain" of the O2-feedback control system with and without external dead space breathing.

Cited by 2 publications

References 9 publications

An assessment of overall open-loop "gain" of CO2-ventilation feedback control system in hypoxia.

An assessment of overall open-loop "gain" of CO2-ventilation feedback control system in hypoxia.

Limitations of the open loop gain concept in studies of respiratory control

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