Intrapulmonary gas mixing and dead space in artificially ventilated dogs

A. C. M. Schrikker; H. Wesenhagen; S. C. M. Luijendijk

doi:10.1007/bf00386187

Gas transport in a model derived from Hansen-Ampaya anatomical data of the human lung

Journal of Applied Physiology ◽

10.1152/jappl.1976.41.1.115 ◽

1976 ◽

Vol 41 (1) ◽

pp. 115-119 ◽

Cited By ~ 30

Author(s):

M. Paiva ◽

L. M. Lacquet ◽

L. P. van der Linden

Keyword(s):

Experimental Data ◽

Transport Equation ◽

Satisfactory Agreement ◽

Dead Space ◽

Empirical Formula ◽

Molecular Diffusion ◽

Human Lung ◽

Gas Transport ◽

Gas Mixing ◽

Anatomical Data

The anatomical data of the human lung published by Hansen and Ampaya are used in a model of gas transport in the lung. The Bohr dead space is calculated from solutions of a transport equation where diffusivity is given by an empirical formula obtained by Sherer et al. A satisfactory agreement is found with experimental data obtained from simultaneous washouts of H2 and SF6 for respiratory frequencies ranging between 15 and 60 min-1 and tidal volumes between 200 and 1,800 ml. The results support the idea that molecular diffusion is the main but not the only physical phenomenom which intervenes in gas mixing during breathing.

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Uneven gas mixing during rebreathing assessed by simultaneously measuring dead space

Journal of Applied Physiology ◽

10.1152/jappl.1982.53.4.930 ◽

1982 ◽

Vol 53 (4) ◽

pp. 930-939 ◽

Cited By ~ 11

Author(s):

M. F. Petrini ◽

B. T. Peterson ◽

R. W. Hyde ◽

V. Lam ◽

M. J. Utell ◽

...

Keyword(s):

Dead Space ◽

Sulfur Hexafluoride ◽

Breath Holding ◽

Gas Mixing ◽

Pulmonary Tissue ◽

Pulmonary Capillary Blood Flow ◽

Pulmonary Capillary Blood ◽

Anatomical Dead Space ◽

The Difference ◽

Uneven Ventilation

To evaluate the rate of gas mixing in human lungs during rebreathing maneuvers used to measure pulmonary tissue volume (Vt) and pulmonary capillary blood flow (Qc), we devised a method to determine the dead space during rebreathing (VRD). Required measurements are initial concentration of a foreign inert insoluble gas in the rebreathing bag, first mixed expired concentration, equilibrated concentration, volume inspired, and volume of the first expired breath. In subjects breathing rapidly at 30 breaths/min with inspired volumes in excess of 2 liters, VRD had values three or more times greater than the predicted anatomical dead space (VD). Breath holding after the first inspiration progressively diminished VRD so that after 10–15 s, it approximately equaled predicted VD. VRD measured with helium was smaller than VRD measured with sulfur hexafluoride. The reported degree of uneven ventilation from gravitational forces in normal humans can account for only about one-third of the difference between VRD and VD. These findings support the concept that mixing by diffusion between peripheral parallel airways is incomplete at normal breathing rates in humans and can result in errors as high as 25% in Vt and Qc.

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Water-sealed spirometer for measurements in newborns and infants

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.1.470 ◽

1993 ◽

Vol 74 (1) ◽

pp. 470-475 ◽

Cited By ~ 4

Author(s):

I. T. Merth ◽

G. J. Verschragen ◽

I. C. Olievier ◽

P. J. De Winter ◽

P. H. Quanjer

Keyword(s):

Frequency Response ◽

Dead Space ◽

Gas Mixing ◽

Maximum Volume ◽

Volume Changes ◽

Minimum Volumes ◽

Neonates And Infants

Details are given of two spirometers for use in neonates and infants < 12 mo old. The minimum volumes are 520 and 670 ml, respectively. The maximum volume changes that can be recorded are 250 and 450 ml, respectively. The minimal detectable volume changes are 0.4 and 0.6 ml, respectively. Rebreathing of dead space gas is prevented by a fan producing a flow of 6.2 and 10.2 l/min, respectively; 100% gas mixing after injecting a gas bolus in the two spirometers is achieved in 5.7 and 6.6 s, respectively. Resistance to airflow is 0.2 kPa.l-1.s (2 cmH2O.l-1.s) at 150 ml/s in both spirometers. The frequency response of both instruments is flat to 6 cycles/s. The instruments can be easily cleaned and are suitable for bedside measurements.

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Gas-Mixing Dead Space Measurement with Paired Tracers1

Gas Exchange Function of Normal and Diseased Lungs - Progress in Respiratory Research ◽

10.1159/000395114 ◽

2015 ◽

pp. 31-32

Author(s):

N. B. Kindig ◽

M. E. Perry ◽

G. F. Filley

Keyword(s):

Dead Space ◽

Gas Mixing ◽

Space Measurement

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Effect of Atropine on Alveolar Gas Mixing in Man

Clinical Science ◽

10.1042/cs0620549 ◽

1982 ◽

Vol 62 (5) ◽

pp. 549-551 ◽

Cited By ~ 5

Author(s):

W. Kox ◽

F. Langley ◽

K. Horsfield ◽

G. Cumming

Keyword(s):

Tidal Volume ◽

Dead Space ◽

Normal Subjects ◽

Acute Effect ◽

Tidal Mixing ◽

Mixing Efficiency ◽

Normal Male ◽

Gas Mixing ◽

Nitrogen Washout ◽

In Series

1. Atropine is known to diminish broncho-motor tone. In order to investigate the acute effect of atropine on respiration and alveolar gas mixing, a dose of 2.4 mg was given intravenously. 2. Ten normal male volunteers were each studied three times with a nitrogen washout method, once before administration of atropine and then 20 min and 60 min thereafter. 3. After the administration of atropine there was a reduction in tidal volume, a slight increase in frequency of respiration and an increase in series dead space. The tidal mixing volume showed a fall of 25%. In spite of the reduced alveolar dead space the effective mixing volume fell by 29%. Multi-breath alveolar mixing efficiency fell by 3.5%. 4. Multi-breath alveolar mixing efficiency was found to be less with smaller tidal mixing volumes, a fall of 518 ml in the latter causing a reduction of 17.2% in mixing efficiency. 5. A reduction of 100 ml in tidal volume in normal subjects was associated with a decrease of 6.9% in alveolar mixing efficiency. In the subjects receiving atropine tidal volume reduced by 96 ml, but the observed fall in alveolar mixing efficiency was only 3.5%, This suggests an improvement in alveolar mixing of 3.4% due to the administration of atropine. Despite this small improvement, the mixing efficiency is still only 66%. The residual inefficiency of 34% cannot therefore be explained on the basis of broncho-motor tone.

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Alveolar Gas Mixing Efficiency in the Human Lung

Clinical Science ◽

10.1042/cs0620541 ◽

1982 ◽

Vol 62 (5) ◽

pp. 541-547 ◽

Cited By ~ 34

Author(s):

G. Cumming ◽

A. R. Guyatt

Keyword(s):

Dead Space ◽

Breath Test ◽

Polynomial Regression ◽

Nitrogen Concentration ◽

Chronic Respiratory Disease ◽

Mixing Efficiency ◽

Gas Mixing ◽

Mean Values ◽

Single Breath ◽

Single Breath Test

1. The lung nitrogen from ten normal nonsmoking subjects and ten patients with chronic respiratory disease was washed out by inspiration of 21% oxygen and 79% argon, whilst expired nitrogen concentration was measured with a mass spectrometer and flow with a box-bag system, and the quantity of nitrogen in each expirate calculated with a Varian 73 digital computer and plotted against expired volume. 2. The resulting curve from each breath was handled either as a linear or a polynomial regression, the intercept on the abscissa being designated the series dead space volume (VDS). This dead space has also been measured by the Fowler method and by the mathematical differentiation of phase II. 3. The nitrogen recovered from the first breath varied between 190 ml and 584 ml and this has been expressed as a percentage of that volume predicted assuming perfect alveolar mixing; this has been called the alveolar gas mixing efficiency for nitrogen. The mean values for alveolar mixing efficiency computed from the four different series dead space volumes were 89.8%, 90.8%, 89.0% and 85.7%. This suggests that the value of series dead space used in computing mixing efficiency is not of great importance, and any of the four methods gives satisfactory results. 4. The data from multi-breath washout were also similarly expressed as a percentage efficiency, making the results from the two methods directly comparable. The median value for alveolar gas mixing efficiency by the single breath test was 89%, and for the multi-breath test about 76%. The latter was apparently more discriminating for ventilatory defect. In patients the values were respectively 73% and 40%.

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