Deposition and dispersion of 1-μm aerosol boluses in the human lung: effect of micro- and hypergravity

1998 ◽  
Vol 85 (4) ◽  
pp. 1252-1259 ◽  
Author(s):  
Chantal Darquenne ◽  
John B. West ◽  
G. Kim Prisk
Keyword(s):  
Flow Rate ◽  
Functional Residual Capacity ◽  
Human Lung ◽  
Aerosol Concentration ◽  
Residual Volume ◽  
Parabolic Flights ◽  
Residual Capacity ◽  
Expired Gas

We performed bolus inhalations of 1-μm particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (μG) and in ∼1.6 G. Boluses of ∼70 ml 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 200 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The deposition, dispersion, and position of the bolus in the expired gas were calculated from these data. For Vp ≥400 ml, both deposition and dispersion increased with Vp and were strongly gravity dependent, with the greatest deposition and dispersion occurring for the largest G level. At Vp = 800 ml, deposition and dispersion increased from 33.9% and 319 ml in μG to 56.9% and 573 ml at ∼1.6 G, respectively ( P < 0.05). At each G level, the bolus was expired at a smaller volume than Vp, and this volume became smaller with increasing Vp. Although dispersion was lower in μG than in 1 G and ∼1.6 G, it still increased steadily with increasing Vp, showing that nongravitational ventilatory inhomogeneity is partly responsible for dispersion in the human lung.

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.

Postinspiratory mixing in the lung and cardiogenic oscillations

1981 ◽  
Vol 51 (4) ◽  
pp. 922-928 ◽  
Author(s):  
R. Arieli ◽  
A. J. Olszowka ◽  
H. D. Van Liew
Keyword(s):  
Mechanical Properties ◽  
Functional Residual Capacity ◽  
Pressure Wave ◽  
Phase Iii ◽  
Breath Hold ◽  
Residual Volume ◽  
Residual Capacity ◽  
Expired Gas ◽  
Cardiogenic Oscillations ◽  
Phase Iv

Subjects inspired a 300-ml bolus of indicator gas cocktail (5% each of SF6, Ar, Ne, and He) form residual volume (RV), then inspired air to functional residual capacity (FRC). There was no evidence that a 10-s breath hold changed the relative concentrations or amounts of indicator gases in phases III and IV of expiration or allowed additional gas to mix into the RV, but the breath hold caused cardiogenic oscillations (CO) in expired gas to decrease in height. The units responsible for cardiogenic troughs and peaks are different from the units responsible for phases III and IV, respectively, in that the oscillation troughs had a lower He/SF6 ratio than the peaks whereas phase III had a higher He/SF6 than phase IV. We explain the CO as due to variation in mechanical properties, leading to variation in response to the pressure wave caused by the heart, in units that are relatively near to each other. We conclude that there is little or no postinspiratory mixing between distant lung units, but the dampening of CO suggests that units that are close to each other can mix if time is allowed.

Minimal air in dogs

1964 ◽  
Vol 19 (2) ◽  
pp. 204-206 ◽  
Author(s):  
Leonard I. Kleinman ◽  
Dennis A. Poulos ◽  
Arthur A. Siebens
Keyword(s):  
Correlation Coefficient ◽  
Functional Residual Capacity ◽  
Residual Volume ◽  
Lung Weight ◽  
Volume Functional ◽  
Residual Capacity

The “minimal air” of supine dogs was measured by subtracting from the functional residual capacity the volume expelled from the lungs when the sternum was widely split. Minimal air/functional residual capacity, minimal air/lung weight, and minimal air/animal weight were 57.0 ± 8.6%, 9.51 ± 2.92 ml/g, 21.8 ± 4.2 ml/kg, respectively. The correlation coefficient of minimal air with functional residual capacity was .79 (P < 1%), of minimal air with animal weight was 0.70 (P < 1%), and of minimal air with lung weight was .67 (P < 5%). The ratio minimal air/functional residual capacity of these dogs compared with the ratio residual volume/functional residual capacity of supine men. The airway component of the minimal air was approximately 36% and the alveolar component approximately 64%. The lungs contained the minimal air at a time when airways were patent rather than collapsed. functional residual capacity; residual volume Submitted on March 11, 1963

Effect of small flow reversals on aerosol mixing in the alveolar region of the human lung

2004 ◽  
Vol 97 (6) ◽  
pp. 2083-2089 ◽  
Author(s):  
Chantal Darquenne ◽  
G. Kim Prisk
Keyword(s):  
Human Lung ◽  
Sudden Increase ◽  
Residual Volume ◽  
Research Aircraft ◽  
Residual Capacity ◽  
Small Flow ◽  
The One ◽  
High Degree ◽  
Flow Reversals

It has been suggested that irreversibility of alveolar flow combined with a stretched and folded pattern of streamlines can lead to a sudden increase in mixing in the lung. To determine whether this phenomenon is operative in the human lung in vivo, we performed a series of bolus studies with a protocol designed to induce complex folding patterns. Boli of 0.5- and 1-μm-diameter particles were inhaled at penetration volumes (Vp) of 300 and 1,200 ml in eight subjects during short periods of microgravity aboard the National Aeronautics and Space Administration Microgravity Research Aircraft. Inspiration was from residual volume to 1 liter above 1 G functional residual capacity. This was followed by a 10-s breathhold, during which up to seven 100-ml flow reversals (FR) were imposed at Vp = 300 ml and up to four 500-ml FR at Vp = 1,200 ml, and by an expiration to residual volume. Bolus dispersion and deposition were calculated from aerosol concentration and flow rate continuously monitored at the mouth. There was no significant increase in dispersion and deposition with increasing FR except for dispersion between 0 and 7 FR at Vp = 300 ml with 0.5-μm-diameter particles, and this increase was small. This suggested that either the phenomenon of stretch and fold did not occur within the number of FR we performed or that it had already occurred during the one breathing cycle included in the basic maneuver. We speculate that the phenomenon occurred during the basic maneuver, which is consistent with the high degree of dispersion and deposition observed previously in microgravity.

Respiratory changes in diaphragmatic intramuscular pressure

1990 ◽  
Vol 68 (1) ◽  
pp. 35-43 ◽  
Author(s):  
M. Decramer ◽  
T. X. Jiang ◽  
M. B. Reid
Keyword(s):  
Functional Residual Capacity ◽  
Total Lung Capacity ◽  
Residual Volume ◽  
Intramuscular Pressure ◽  
Phrenic Nerve Stimulation ◽  
Direct Stimulation ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Stimulation Of

We attempted to measure diaphragmatic tension by measuring changes in diaphragmatic intramuscular pressure (Pim) in the costal and crural parts of the diaphragm in 10 supine anesthetized dogs with Gaeltec 12 CT minitransducers. During phrenic nerve stimulation or direct stimulation of the costal and crural parts of the diaphragm in an animal with the chest and abdomen open, Pim invariably increased and a linear relationship between Pim and the force exerted on the central tendon was found (r greater than or equal to 0.93). During quiet inspiration Pim in general decreased in the costal part (-3.9 +/- 3.3 cmH2O), whereas it either increased or slightly decreased in the crural part (+3.3 +/- 9.4 cmH2O, P less than 0.05). Similar differences were obtained during loaded and occluded inspiration. After bilateral phrenicotomy Pim invariably decreased during inspiration in both parts (costal -4.3 +/- 6.4 cmH2O, crural -3.1 +/- 0.6 cmH2O). Contrary to the expected changes in tension in the muscle, but in conformity with the pressure applied to the muscle, Pim invariably increased during passive inflation from functional residual capacity to total lung capacity (costal +30 +/- 23 cmH2O, crural +18 +/- 18 cmH2O). Similarly, during passive deflation from functional residual capacity to residual volume, Pim invariably decreased (costal -12 +/- 19 cmH2O, crural -12 +/- 14 cmH2O). In two experiments similar observations were made with saline-filled catheters. We conclude that although Pim increases during contraction as in other muscles, Pim during respiratory maneuvers is primarily determined by the pleural and abdominal pressures applied to the muscle rather than by the tension developed by it.

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.

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.

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