<i>Alveolar CO<sub>2</sub> During the Respiratory Cycle</i>

DuBois, Arthur B.; Britt, Alec; Fenn, Wallace O.

doi:10.1152/jappl.1952.4.7.535

Cited by 195 publications

(78 citation statements)

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“…The breath-by-breath oscillations in pH recorded by the electrode are presumed to be due to fluctuations in Paco, for the amplitude of the pH oscillation is compatible with their arising from fluctuations of alveolar Pco2 (Dubois, Britt & Fenn, 1952). In addition Plaas-Link, Mueller, Luttman, Miickenhoff & Loeschcke (1977) have recorded simultaneously PaC0, and pH oscillations with appropriate electrodes and shown that breath-by-breath oscillations ofpH can be solely accounted for by changes in PaCo The assumption is made in this discussion, therefore, that the oscillations of pH are due to Pco, but that the mean level of the oscillations is determined by alveolar ventilation and the production of metabolic acids and carbon dioxide.…”

Section: Discussionmentioning

confidence: 98%

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

Cross¹,

Davey²,

Guz³

et al. 1982

The Journal of Physiology

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SUMMARY1. The effect of electrically induced 'exercise' on the respiratory oscillation of arterial pH was studied in chloralose-anaesthetized dogs with spinal cord transaction at T8/9 (dermatome level T6/7).2. Respiratory oscillations of arterial pH (presumed to be due to oscillations of arterial Pco2) were sensed with a fast-responding electrode in one carotid artery.Breath-by-breath estimates of the maximum rate of change of pH of the downstroke of the pH oscillation (dpH/dtjmax) were obtained by differentiating the pH signal.3. Consistent with the findings of the previous paper (Cross et al. 1982), the ventilatory response to exercise could not be explained on the basis of sensitivity to C02; the A T4/APaco, was significantly greater for 'exercise' than for CO2 inhalation.4. On average, the amplitude of the pH oscillations decreased during 'exercise'.The change in the phase relationship (0) between respiratory and pH cycles, although significant from the second breath onwards, was not thought to be responsible for the increased ventilation V,; the direction of the change was opposite to that previously found to increase VI. 14 and dpH/dtjmax were also linearly related during the on-transient, although the same relationship did not hold true throughout 'exercise'.6. The dpH/dtjmax was related to CO2 production (1rco,) lending support to the prediction that the slope of the downstroke of the pH oscillation is a function of TCo2.7. It was concluded that the dpH/dtimax (dpCO2/dttmax) is a potential humoral signal in 'exercise' and could account totally for the shortening of te. Since there was a late rise in VI (due to an increase in tidal volume VT) in the absence of a change in dpH/dtjmax, it was considered unlikely that the dpH/dtjmax was the only humoral signal present during 'exercise'.

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Section: Discussionmentioning

confidence: 98%

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

Cross¹,

Davey²,

Guz³

et al. 1982

The Journal of Physiology

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“…19 and Edwards et al 22. In essence, this is formulated from the assumption that the rate of change in oxygen concentration in the alveolar compartment is the algebraic sum of the rate at which it is added (or removed) by ventilation, and the rate of uptake by the pulmonary circulation.…”

Section: Observations Of Dynamic Oxygen Signals In the Normal And Injmentioning

confidence: 95%

Intravascular oxygen sensors with novel applications for bedside respiratory monitoring

Formenti

Farmery

2017

Anaesthesia

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SummaryMeasurement allows us to quantify various parameters and variables in natural systems. In addition, by measuring the effect by which a perturbation of one part of the system influences the system as a whole, insights into the functional mechanisms of the system can be inferred. Clinical monitoring has a different role to that of scientific measurement. Monitoring describes measurements whose prime purpose is not to give insights into underlying mechanisms, but to provide information to ‘warn’ of imminent events. What is often more important is the description of trends in measured variables. In this article, we give some examples ‐ focussed around oxygen sensors ‐ of how new sensors can make important measurements and might in the future contribute to improved clinical management.

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“…Previous experience with a valve assembly having a dead space of 65 ml., which was of irregular shape and therefore not easily flushed out, showed that with this valve assembly true end tidal samples may not be obtained even with a tidal volume of 1 liter. The concentration of CO2 in the alveolar gas at the end of a normal expiration lies between the maximum and minimum concentrations which are reached during the respiratory cycle (16). The end tidal sample of 60 will also lie between the maximum and minimum levels, rather closer to the minimum level, so that the value of FA0 will be too low and the resultant DL will tend to be too high.…”

Section: B Single Breath DL Measurementsmentioning

confidence: 98%

A Comparison of Methods of Measuring the Diffusing Capacity of the Lungs for Carbon Monoxide. Investigation by Fractional Analysis of the Alveolar Air

Marshall¹

1958

J. Clin. Invest.

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The diffusing capacity of the lungs for carbon monoxide is measured as the ml. of carbon monoxide (CO) that can be transferred from the alveoli to the blood per mm. Hg pressure difference of CO between the alveoli and the blood. This measurement can be made by steady state techniques or by the single breath method. Two steady state methods have been described recently, which differ in the methods by which the mean alveolar CO concentration is measured. In one method (1) the mean alveolar CO concentration is calculated by assuming that CO and CO2 have the same dead space and that the partial pressure of CO2 in the arterial blood is equal to the mean alveolar partial pressure of CO2. This method requires an arterial puncture and accurate estimation of the partial pressure of CO2 in the arterial blood so that its routine and repeated use in patients is limited. The sults have been obtained in this laboratory when comparing the single breath method with the steady state method of Bates and co-workers (2). By this latter method patients with emphysema give a uniformly low DL2 but many of these patients have a normal DL measured by the single breath method. Because of these findings it was decided to make further comparisons of the single breath and steady state methods of measuring DL by applying methods for fractional analysis of the alveolar air. METHODSThe single breath measurements of DL. These were made using the apparatus and methods described by Ogilvie and co-workers (5). The gas mixture inspired consisted of 14 per cent helium, 0.125 per cent CO, 20 per cent 02 and the remainder N2. Before and after each determination on the normal subj ects the alveolar air was equilibrated with the carboxyhemoglobin in the blood by breath holding for the maximum time at the functional residual capacity (F.R.C.) The patients equilibrated the blood and alveolar CO by rebreathing the expired air for 30 to 45 seconds (7). These two methods have been found to give the same result and the patients find rebreathing easier to do than breath holding. The back pressure of carbon monoxide before breath holding was calculated by correcting the equilibrated CO according to the following equation: Back pressure of CO in lungs during breath holding = equilibrated CO per cent X equi. 02 where B.H. 02 is the tension of 02 in the lungs during the test, and equil. 02 is the tension of 02 in the rebreathing bag at the end of the equilibration. This correction is only approximate since it assumes that the hemoglobin in the capillaries is fully saturated with oxygen, but in these subjects the equilibration CO tension was small (approximately 0.1 to 0.5 per cent of the tension of CO in the alveoli during breath holding) and the error introduced is small. This back pressure of CO was sub2The abbreviation DL is used to designate the apparent diffusing capacity of the lung for CO (5). 394

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Alveolar CO₂ During the Respiratory Cycle

Cited by 195 publications

References 0 publications

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

Intravascular oxygen sensors with novel applications for bedside respiratory monitoring

A Comparison of Methods of Measuring the Diffusing Capacity of the Lungs for Carbon Monoxide. Investigation by Fractional Analysis of the Alveolar Air

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Alveolar CO2 During the Respiratory Cycle

Cited by 195 publications

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The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

The pH oscillations in arterial blood during exercise; a potential signal for the ventilatory response in the dog

Intravascular oxygen sensors with novel applications for bedside respiratory monitoring

A Comparison of Methods of Measuring the Diffusing Capacity of the Lungs for Carbon Monoxide. Investigation by Fractional Analysis of the Alveolar Air

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Alveolar CO₂ During the Respiratory Cycle