The Relation Between Alveolar Oxygen Pressure and the Respiratory Response to Carbon Dioxide in Man

Lloyd, B. B.; Jukes, M. G. M.; Cunningham, D. J.

doi:10.1113/expphysiol.1958.sp001319

Cited by 230 publications

(115 citation statements)

References 8 publications

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“…In our experiments, the increment of VE responding to CO2 increased as PETo 2 decreased (Table 2), as was reported by LLOYD et al (1958) and EDELMAN et al (1973). On the other hand, the respiratory rates were not significantly changed in the PETo2 range of 40 to 80 mmHg, so the increment in VT was seen as the main reason for the augmented VE (Table 2).…”

Section: Discussionsupporting

confidence: 68%

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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Section: Discussionsupporting

confidence: 68%

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

1985

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“…The work of Lloyd et al (1958) suggests that there is little change in slope of the V/Pco, line with rising Po, at levels of alveolar Po, above 150 mm Hg. On the other hand, pure oxygen may increase ventilation and was therefore avoided in the present study.…”

Section: Discussionmentioning

confidence: 99%

“…5. For this purpose it is not enough to replot all data on the same co-ordinates, because different subjects have control CO2-response lines with different intercepts on the Pco2 axis (the parameter B of Lloyd, Jukes & Cunningham, 1958, or The result is shown in Fig. 5 (1) Ethamivan data with 3 points excluded and saline data.…”

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confidence: 99%

Effect of Ethamivan (Vanillic Acid Diethylamide) on the Respiratory Response of Healthy Young Men to Carbon Dioxide, in the Absence of Hypoxia

Anderton

Cowie

Harris

et al. 1962

British Journal of Pharmacology and Chemotherapy

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The effect of ethamivan (vanillic acid diethylamide) on the ventilatory response to carbon dioxide has been investigated in healthy young adult males. Intravenous infusion of the drug at a rate of 9 mg/min causes respiratory stimulation depending in degree upon the prevailing alveolar CO2 tension. When the latter is low stimulation by the drug is most marked and may largely support respiration below the CO, threshold. As alveolar Pco2 increases, the effect of the drug disappears. These findings are discussed.

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“…The system LG is then equal to the vector summation of LG O 2 and LG CO 2 , with the contribution to LG of the central CO 2 controller during PB being neglected (25). A further important difference is that the human controller apparently has a relatively fixed apneic threshold for CO 2 (19,30), whereas the lamb and several other species do not (12,28). It seems likely that these fundamental differences are the reason hypoxia normally precipitates PB in sleeping humans (6,27), whereas it has never been reported to do so in the lamb.…”

Section: Discussionmentioning

confidence: 99%

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

Wilkinson¹,

Sia²,

Skuza³

et al. 2005

Journal of Applied Physiology

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. Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb. J Appl Physiol 98: 437-446, 2005. First published October 8, 2004 doi:10.1152/japplphysiol.00532.2004We examined the effect of hypoxia and hypercapnia administered during deliberately induced periodic breathing (PB) in seven lambs following posthyperventilation apnea. Based on our theoretical analysis, the sensitivity or loop gain (LG) of the respiratory control system of the lamb is directly proportional to the difference between alveolar PO2 and inspired PO2. This analysis indicates that during PB, when by necessity LG is Ͼ1, replacement of the inspired gas with one of reduced PO2 lowers LG; if we made inspired PO2 approximate alveolar PO2, we predict that LG would be approximately zero and breathing would promptly stabilize. In six lambs, we switched the inspired gas from an inspiratory oxygen fraction of 0.4 to one of 0.12 during an epoch of PB; PB was immediately suppressed, supporting the view that the peripheral chemoreceptors play a pivotal role in the genesis and control of unstable breathing in the lamb. In the six lambs in which we administered hypercapnic gas during PB, breathing instability was also suppressed, but only after a considerable time lag, indicating the CO2 effect is likely to have been mediated through the central chemoreceptors. When we simulated both interventions in a published model of the adult respiratory controller, PB was immediately suppressed by CO2 inhalation and exacerbated by inhalation of hypoxic gas. These fundamentally different responses in lambs and adult humans demonstrate that PB has differing underlying mechanisms in the two species.Cheyne-Stokes respiration; hypoxia; hypercapnia; sleep apnea syndromes; control of breathing; periodic breathing PERIODIC BREATHING (PB), or Cheyne-Stokes respiration, appears under a wide range of physiological and clinical conditions. It is particularly prevalent during sleep, occurring at sea level in apparently normal-term and preterm infants (22,43), at high altitude in normal adults (27), and after hypoxic exposure in experimental animals (11,21). It also occurs in patients with congestive heart failure (36), with idiopathic central sleep apnea (52), with bilateral brain stem lesions (40), and in periodic obstructive sleep apnea (41). A form of PB can also be found in hibernating animals (7,34).Although it is often assumed that the underlying mechanisms causing PB in infants and adults are similar, in each case involving instability of the chemical control system that regulates breathing, there are some marked differences in the pattern of PB and its responses to changes in inspired gas that remain largely unexplained. For example, in preterm infants, the waxing and waning pattern of PB that is characteristic of the adult is replaced by a more or less abrupt on-off pattern that shows little change in tidal volume during the breathing phase (42); this pattern resembles that seen in hibernating animals (34). Furthermore, although the re...

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The Relation Between Alveolar Oxygen Pressure and the Respiratory Response to Carbon Dioxide in Man

Cited by 230 publications

References 8 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.

Effect of Ethamivan (Vanillic Acid Diethylamide) on the Respiratory Response of Healthy Young Men to Carbon Dioxide, in the Absence of Hypoxia

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

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