Airway closure during anesthesia: a comparison between resident-gas and argon-bolus techniques

1979 ◽  
Vol 47 (4) ◽  
pp. 874-881 ◽  
Author(s):  
G. Hedenstierna ◽  
J. Santesson
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Healthy Subjects ◽  
Abrupt Onset ◽  
Closing Volume ◽  
Residual Volume ◽  
Airway Closure ◽  
Venous Admixture ◽  
Residual Capacity ◽  
Nitrogen Concentrations

Airway closure was measured in awake and then anesthetized supine healthy subjects with the argon-bolus and the resident-gas (nitrogen) techniques simultaneously. The preinspiratory lung volume for the closing volume maneuver was varied from residual volume to closing capacity (CC). Comparative measurements were also performed in the upright and supine positions in awake subjects. Closing volume (CV) was consistently larger with the bolus technique in supine subjects both when awake and when anesthetized (difference between methods 0.1--0.2 l, P less than 0.01), whereas no difference between the methods was noted in upright subjects. The lower “nitrogen CV” in supine subjects may be due to a shorter vertical lung height with a smaller range of nitrogen concentrations, resulting in a less abrupt onset of phase IV (taken to indicate CV). CV was not significantly affected by the preinspiratory lung volume with either technique, and CC was unchanged when anesthesia was instituted. Functional residual capacity (FRC) was reduced with anesthesia (mean reduction: 0.6 l, P less than 0.01) and FRC-CC became negative in all subjects with either technique. This implies intermittent or continuous airway closure during anesthesia and the possibility of increased venous admixture.

Airway closure and closing volume

1979 ◽  
Vol 46 (1) ◽  
pp. 24-30 ◽  
Author(s):  
L. Forkert ◽  
S. Dhingra ◽  
N. R. Anthonisen
Keyword(s):  
Blood Flow ◽  
Lung Volume ◽  
Regional Perfusion ◽  
Phase Iii ◽  
Breath Hold ◽  
Closing Volume ◽  
Residual Volume ◽  
Airway Closure ◽  
Lung Volumes ◽  
Phase Iv

Using boluses of radioactive Xe we compared regional N2O uptake with regional perfusion distribution during open glottis breath hold in five seated men. Measurements were made near residual volume, at closing volume (CV), above CV and when possible, between CV and residual volume (RV). At low lung volumes basal N2O uptake was small whereas basal blood flow was not. This discrepancy was interpreted as evidence of airway closure and was quantitated. All subjects showed extensive basal closure near RV. At closing volume four of five subjects demonstrated closure and some closure was evident in these subjects at volumes in excess of CV. The increase in airway closure with decreasing lung volume was much greater below CV than above it. Conventional CV tracings were obtained using helium boluses; the height of phase IV was positively correlated with the change in airway closure between CV and RV as assessed by the N2O technique. The slope of phase III did not correlate with the amount of airway closure measured at CV. We concluded that the conventionally measured CV is not the volume at which airway closure begins but that the onset of phase IV reflects an increase in basal airway closure and the height of phase IV reflects the amount of basal closure between CV and RV.

Hydrostatic weighing at residual volume and functional residual capacity

1980 ◽  
Vol 49 (1) ◽  
pp. 157-159 ◽  
Author(s):  
T. R. Thomas ◽  
G. L. Etheridge
Keyword(s):  
Prone Position ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Residual Volume ◽  
Body Density ◽  
Residual Capacity ◽  
Hydrostatic Weighing ◽  
Helium Dilution ◽  
The Subject ◽  
The Difference

Hydrostatic weighing (HW) was performed at both residual volume (RV) and functional residual capacity (FRC) to determine if underwater weighing at different lung volumes affected the measurement of body density. Subjects were 43 males, 18-25 yr. Subjects were submerged in the prone position, and the lung volume was measured by helium dilution at the time of the underwater weighing. Underwater weight was first assessed at FRC followed by assessment at RV. Changes in lung volume were accurately reflected in the underwater weight. Body density (D) was not different with the use of the FRC (mean D = 1.0778) or RV (mean D = 1.0781) data. Percent fat values for the FRC and RV data were 9.3 ± 5.4 and 9.2 ± 5.1%, respectively, and were not statistically different. The results indicate that the difference between percent fat determinations by HW in the prone position at FRC and RV is negligible. Because measurement of underwater weight at FRC is more comfortable for the subject, this may be the method of choice when the lung volume can be measured during the underwater weighing.

A fundamental problem in determining functional residual capacity or residual volume

1986 ◽  
Vol 60 (5) ◽  
pp. 1810-1813 ◽  
Author(s):  
U. Boutellier ◽  
L. E. Farhi
Keyword(s):  
Experimental Data ◽  
Functional Residual Capacity ◽  
Volume Change ◽  
Lung Volume ◽  
General Equation ◽  
Fundamental Problem ◽  
Residual Volume ◽  
Volume Changes ◽  
Final Volume ◽  
Residual Capacity

To measure a lung volume that is not directly accessible, one often follows dilution of a single-gas tracer, present initially only in the lung or in a rebreathing bag. The final volume available to the tracer is assumed to be the sum of the two initial components. Since O2 is taken up and CO2 is eliminated during the few breaths required for mixing, the total volume changes. The error in lung volume due to this volume change can exceed 10%. In this paper we 1) present theoretical and experimental data to demonstrate the effect of CO2 and O2 exchange, 2) introduce a general equation, based on N2 and Ar, which allows one to circumvent the problems created by these fluxes, and 3) show the pitfall of the back-extrapolation approach for a single tracer.

Airway closure with high PEEP in vivo

2000 ◽  
Vol 89 (3) ◽  
pp. 956-960 ◽  
Author(s):  
Robert H. Brown ◽  
Wayne Mitzner
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Transpulmonary Pressure ◽  
High Peep ◽  
Airway Closure ◽  
Residual Capacity

When airway smooth muscle is contracted in vitro, the airway lumen continues to narrow with increasing concentrations of agonist until complete airway closure occurs. Although there remains some controversy regarding whether airways can close in vivo, recent work has clearly demonstrated that, if the airway is sufficiently stimulated with contractile agonists, complete closure of even large cartilaginous conducting airways can readily occur with the lung at functional residual capacity (Brown RH and Mitzner W. J Appl Physiol 85: 2012–2017, 1998). This result suggests that the tethering of airways in situ by parenchymal attachments is small at functional residual capacity. However, at lung volumes above functional residual capacity, the outward tethering of airways should increase, because both the parenchymal shear modulus and tethering forces increase in proportion to the transpulmonary pressure. In the present study, we tested whether we could prevent airway closure in vivo by increasing lung volume with positive end-expiratory pressure (PEEP). Airway smooth muscle was stimulated with increasing methacholine doses delivered directly to airway smooth muscle at three levels of PEEP (0, 6, and 10 cmH2O). Our results show that increased lung volume shifted the airway methacholine dose-response curve to the right, but, in many airways in most animals, airway closure still occurred even at the highest levels of PEEP.

Hysteresis in the relation between diffusing capacity of the lung and lung volume

1980 ◽  
Vol 49 (4) ◽  
pp. 566-570 ◽  
Author(s):  
S. S. Cassidy ◽  
M. Ramanathan ◽  
G. L. Rose ◽  
R. L. Johnson
Keyword(s):  
Carbon Monoxide ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Total Lung Capacity ◽  
Breath Holding ◽  
Residual Volume ◽  
Diffusing Capacity ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Residual Capacity

The diffusing capacity of the lung for carbon monoxide (DLCO) varies directly with lung volume (VA) when measured during a breath-holding interval. DLCO measured during a slow exhalation from total lung capacity (TLC) to functional residual capacity (FRC) does not vary as VA changes. Since VA is reached by inhaling during breath holding and by exhaling during the slow exhalation maneuver, we hypothesized that the variability in the relation between DLCO and VA was due to hysteresis. To test this hypothesis, breath-holding measurements of DLCO were made at three lung volumes, both when VA was reached by inhaling from residual volume (RV) and when Va was reached by exhaling from TLC. At 72% TLC, DLCO was 22% higher when VA was reached by exhalation compared to inhalation (P < 0.02). At 52% TLC, DLCO was 19% higher when VA was reached by exhalation compared to exhalation (P < 0.005). DCLO measured during a slow exhalation fell on the exhalation limb of the CLCO/VA curve. these data indicate that there is hysteresis in DLCO with respect to lung volume.

Dispersion of 0.5- to 2-μm aerosol in μG and hypergravity as a probe of convective inhomogeneity in the lung

1999 ◽  
Vol 86 (4) ◽  
pp. 1402-1409 ◽  
Author(s):  
Chantal Darquenne ◽  
John B. West ◽  
G. Kim Prisk
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Distal Part ◽  
Sedimentation Velocity ◽  
Residual Volume ◽  
Gas Mixing ◽  
Residual Capacity ◽  
Expired Gas

We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (μG) and hypergravity (∼1.6 G). Boluses of 0.5-, 1-, and 2-μm-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-μm-diameter particles for which sedimentation velocity is low, the differences between dispersion in μG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between μG and 1 G.

LUNG VOLUMES OF NORMAL AND ASTHMATIC CHILDREN

PEDIATRICS ◽  
1959 ◽  
Vol 23 (3) ◽  
pp. 507-519
Author(s):  
John F. Andrewes ◽  
Daniel H. Simmons
Keyword(s):  
Allergic Rhinitis ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Bronchial Obstruction ◽  
Residual Volume ◽  
Normal Children ◽  
Lung Volumes ◽  
Asthmatic Children ◽  
Residual Capacity ◽  
Time Required

Measurements of the various lung volumes were carried out with 27 normal children, 21 asthmatic children and 4 with allergic rhinitis. The asthmatic children had increases in functional residual capacity and residual volume. There was a significant increase in the time required for intrapulmonary mixing of gas in the asthmatic subjects. A biphasic character to the "wash-out" curves in both normal and asthmatic subjects was shown. It was considered, though not proved, that the increases in lung volume were due to the presence of bronchial obstruction.

Lung volume effects on pharyngeal swallowing physiology

2003 ◽  
Vol 95 (6) ◽  
pp. 2211-2217 ◽  
Author(s):  
Roxann Diez Gross ◽  
Charles W. Atwood ◽  
Judith P. Grayhack ◽  
Susan Shaiman
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Total Lung Capacity ◽  
Regulatory Function ◽  
Residual Volume ◽  
Bolus Transit ◽  
Repeated Measures Design ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Intramuscular Electromyography

The experiment was a prospective, repeated-measures design intended to determine how the variation of lung volume affects specific measures of swallowing physiology. Swallows were recorded in 28 healthy subjects, who ranged in age from 21 to 40 yr (mean age of 29 yr), by using simultaneous videofluoroscopy, bipolar intramuscular electromyography, and respiratory inductance plethysmography. Each subject swallowed three standardized pudding-like consistency boluses at three randomized lung volumes: total lung capacity, functional residual capacity, and residual volume. The results showed that pharyngeal activity duration of deglutition for swallows produced at residual volume was significantly longer than those occurring at total lung capacity or at functional residual capacity. No significant differences were found for bolus transit time or intramuscular electromyography of the superior constrictor. The results of this experiment lend support to the hypothesis that the respiratory system may have a regulatory function related to swallowing and that positive subglottic air pressure may be important for swallowing integrity. Eventually, new treatment paradigms for oropharyngeal dysphagia that are based on respiratory physiology may be developed.

Airway closure and reopening assessed by the alveolar capsule oscillation technique

1996 ◽  
Vol 80 (6) ◽  
pp. 2077-2084 ◽  
Author(s):  
D. R. Otis ◽  
F. Petak ◽  
Z. Hantos ◽  
J. J. Fredberg ◽  
R. D. Kamm
Keyword(s):  
Lung Volume ◽  
Input Impedance ◽  
Transpulmonary Pressure ◽  
Closing Volume ◽  
Airway Closure ◽  
Breathing Cycle ◽  
Abrupt Increase ◽  
Consistent Effect ◽  
Peripheral Airways

An alveolar capsule oscillation technique was used to determine 1) the lobe pressure and volume at which airways close and reopen, 2) the effect of expiration rate on closing volume and pressure, 3) the phase in the breathing cycle at which airway closure occurs, and 4) the site of airway closure. Experiments were conducted in excised dog lobes; closure was detected by an abrupt increase in the input impedance of surfacemounted alveolar capsules. Mean transpulmonary pressure (Ptp) at closure was slightly less than zero (Ptp = -2.3 cmH2O); the corresponding mean reopening pressure was Ptp = 14 cmH2O. The expiration rate varied between 1 and 20% of total lobe capacity per second and had no consistent effect on the closing volume and pressure. When lung volume was cycled up to frequencies of 0.2 Hz, closure generally occurred on expiration rather than inspiration. These observations support the conclusion that mechanical collapse, rather than meniscus formation, is the most likely mechanism producing airway closure in normal excised dog lungs. Analysis of measured acoustic impedances and reopening pressures suggests that closure occurs in the most peripheral airways. Reopening during inspiration was often observed to consist of a series of stepwise decreases in capsule impedance, indicating a sequence of opening events.

LUNG VOLUME IN THE NEWBORN INFANT

PEDIATRICS ◽  
1962 ◽  
Vol 30 (1) ◽  
pp. 111-116
Author(s):  
M. Klaus ◽  
W. H. Tooley ◽  
K. H. Weaver ◽  
J. A. Clements
Keyword(s):  
Newborn Infant ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Newborn Infants ◽  
Du Bois ◽  
Residual Capacity

The plethysmographic technique of Du-Bois and associates has been modified for use in newborn infants and found suitable for the measurement of lung volume. Of 37 normal infants studied with this method, most achieved full functional residual capacity during the first few minutes of life.

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