Acoustic evidence of airway opening during recruitment in excised dog lungs

2004 ◽  
Vol 97 (2) ◽  
pp. 592-598 ◽  
Author(s):  
Z. Hantos ◽  
J. Tolnai ◽  
T. Asztalos ◽  
F. Peták ◽  
Á. Adamicza ◽  
...  
Keyword(s):  
Power Law ◽  
Energy Levels ◽  
Normal Lung ◽  
Cumulative Energy ◽  
Sound Recordings ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Airway Opening ◽  
Normal Lungs ◽  
Lung Lobes

The aim of this study was to test the hypothesis that the mechanism of recruitment and the lower knee of the pressure-volume curve in the normal lung are primarily determined by airway reopenings via avalanches rather than simple alveolar recruitments. In isolated dog lung lobes, the pressure-volume loops were measured, and crackle sounds were recorded intrabronchially during both the first inflation from the collapsed state to total lobe capacity and a second inflation without prior degassing. The inflation flow contained transients that were accompanied by a series of crackles. Discrete volume increments were estimated from the flow transients, and the energy levels of the corresponding crackles were calculated from the sound recordings. Crackles were concentrated in the early phase of inflation, with the cumulative energy exceeding 90% of its final value by the lower knee of the pressure-volume curve. The values of volume increments were correlated with crackle energy during the flow transient for both the first and the second inflations ( r2 = 0.29–0.73 and 0.68–0.82, respectively). Because the distribution of volume increments followed a power law, the correlation between crackle energy and discrete volume increments suggests that an avalanche-like airway opening process governs the recruitment of collapsed normal lungs.

scholarly journals Heliox administration in anesthetized rabbits with spontaneous inspiratory flow limitation

2021 ◽  
Author(s):  
Edgardo Giacomo D'Angelo ◽  
Matteo M. Pecchiari ◽  
François Bellemare ◽  
Gabriele Cevenini ◽  
Paolo Barbini
Keyword(s):  
Inspiratory Flow ◽  
Flow Limitation ◽  
Upper Airways ◽  
Relative Contribution ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Tracheal Pressure ◽  
Airway Opening ◽  
Laminar And Turbulent Flow ◽  
Geometrical Factors

We investigated the effects of heliox administration (80% Helium in O2) on tidal inspiratory flow limitation (tIFL) occurring in supine anesthetized spontaneously breathing rabbits, regarded as an animal model of obstructive apnea-hypopnea syndrome. 22 rabbits were instrumented to record oro-nasal mask flow, airway opening, tracheal and esophageal pressures and diaphragm and genioglossus electromyographic activities while breathing either room air or heliox, and, in 12 rabbits, also during the application of continuous positive airway pressure (CPAP; 6 cmH2O). For the group, heliox increased peak inspiratory flow, ventilation (18±11%), peak inspiratory tracheal and dynamic transpulmonary pressures, but in no animal eliminated tIFL, as instead CPAP did in all. Muscle activities were unaffected by heliox. In the presence of IFL the increase in flow with heliox (ΔV̇IFL) varied markedly among rabbits (2 to 49%), allowing the distinction between responders and non-responders. None of the baseline variables discriminated responders and non-responders. However, fitting the Rohrer equation (R=K1+K2V̇) to the tracheal pressure-flow relationship over the first 0.1s of inspiration while breathing air allowed such discrimination on the basis of larger K2 in responders (0.005±.002 vs 0.002±.001 cmH2O·s2·ml-2; p<0.001), suggesting a corresponding difference in the relative contribution of laminar and turbulent flow. The differences in ΔV̇IFL between responders and non-responders were simulated by modeling the collapsible segment of the upper airways as a non-linear resistor and varying its pressure-volume curve, length and diameter, thus showing the importance of mechanical and geometrical factors in determining the response to heliox in the presence of tIFL.

Distortion of submerged dog lung lobes

1985 ◽  
Vol 59 (2) ◽  
pp. 521-527 ◽  
Author(s):  
L. E. Olson ◽  
T. A. Wilson ◽  
J. R. Rodarte
Keyword(s):  
Buoyancy Force ◽  
Transpulmonary Pressure ◽  
Vertical Position ◽  
Pressure Curve ◽  
Engineering Analysis ◽  
Vertical Strain ◽  
Analytical Results ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Lung Lobes

The conically shaped caudal lobes of dog lungs were submerged, tip downward in saline, and the lateral surfaces of the lobes were thereby exposed to a hydrostatic gradient in transpulmonary pressure. The force that was required to balance the buoyancy was applied through a clip attached to the tip of the lobe. The locations of metal markers implanted in the parenchyma and attached to the surface were tracked, and regional volume and the horizontal and vertical components of strain were obtained as functions of vertical position. An engineering analysis of the deformation is qualitatively consistent with the data, but the predicted strains are larger than the observed strains. From the experimental and analytical results, we conclude that, for this deformation, the regional volume-local transpulmonary pressure curve closely follows the pressure-volume curve because negative horizontal strains nearly balance the positive vertical strain caused by the buoyancy force.

Pressure-volume studies on lung lobes in man

1964 ◽  
Vol 19 (4) ◽  
pp. 823-826 ◽  
Author(s):  
Koh Ishikawa ◽  
C. J. Martin ◽  
A. C. Young
Keyword(s):  
Mechanical Properties ◽  
Vital Capacity ◽  
Esophageal Pressure ◽  
Chest Cavity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Mean Pressure ◽  
Lower Magnitude ◽  
Balloon System ◽  
Lung Lobes

This study has sought to measure pressure differences occurring within the chest cavity and some of the mechanical properties of lung lobes. One lobe in the hemithorax has been used as an intrapleural pressure capsule by blocking it with a catheter and balloon system. After insertion of an esophageal, a bronchospirometric, and a lobar pressure-measuring catheter, the interrupted vital capacity maneuver has been used to compare pressures within the lungs and esophagus. Pressure differences, which increased as lung volumes increased, were found between lobes, and between lobes and esophagus. Esophageal pressure swings were of lower magnitude than lobar pressure swings. Esophageal pressure was neither linearly related to lobe pressure nor a mean pressure for the hemithorax. Thus, lung volume is not a function of a single pressure within the chest, and the concept of the commonly used pressure-volume curve is oversimplified. mechanical properties; pressure capsules Submitted on October 18, 1963

Behavior of artificially produced holes in lung parenchyma

1977 ◽  
Vol 43 (4) ◽  
pp. 648-655 ◽  
Author(s):  
S. J. Lai-Fook ◽  
R. E. Hyatt ◽  
J. R. Rodarte ◽  
T. A. Wilson
Keyword(s):  
Shear Modulus ◽  
Continuum Mechanics ◽  
Transpulmonary Pressure ◽  
Lung Parenchyma ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Mechanics Analysis ◽  
Cylindrical Holes ◽  
Hole Boundary ◽  
Lung Lobes

Spherical and cylindrical holes were cut in the parenchyma of isolated dog lung lobes. The holes were insufflated with tantalum dust and the hole diameters were measured along the deflation limb of the lobe pressure-volume curve from transpulmonary pressures of 20 to 0 cmH2O. Hole volume as a fraction of lobe volume was found to be independent of transpulmonary pressure. The hole volume relative to the amount of tissue removed was used to determine the displacement at the hole boundary. A comparison of this displacement with the displacement predicted by a continuum mechanics analysis provides evidence for the applicability of the methods of continuum mechanics and further evidence that the shear modulus of the parenchyma is relatively small.

Derivation of recruitment function from the pressure–volume curve in an acute lung injury model

2015 ◽  
Vol 205 ◽  
pp. 16-20 ◽  
Author(s):  
Yoshihiro Uzawa ◽  
Mikiya Otsuji ◽  
Koichi Nakazawa ◽  
Wei Fan ◽  
Yoshitsugu Yamada
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Injury Model ◽  
Lung Injury Model

Elastic constants of inflated lobes of dog lungs

1976 ◽  
Vol 40 (4) ◽  
pp. 508-513 ◽  
Author(s):  
S. J. Lai-Fook ◽  
T. A. Wilson ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Inflation Pressure ◽  
Initial State ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Indentation Tests

The elastic constants of dog lungs were determined at various degrees of inflation. In one set of experiments, the lobes were subjected to deformations that approximated the conditions of uniaxial loading. These data, together with the bulk modulus data obtained from the local slope of the pressure-volume curve, were used to determine the two elastic moduli that are needed to describe small nonuniform deformations about an initial state of uniform inflation. The bulk modulus was approximately 4 times the inflation pressure, and Young's modulus was approximately 1.5 times the inflation pressure. In a second set of experiments, lobes were subjected to indentation tests using cylindric punches 1–3 cm in diameter. The value for Young's modulus obtained from these data was slightly higher, approximately twice the inflation pressure. These experiments indicate that the lung is much more easily deformable in shear than in dilatation and that the Poisson ratio for the lung is high, approximately 0.43.

Lung volumes and alveolar expansion pattern in immature rabbits treated with serum-diluted surfactant

2004 ◽  
Vol 97 (4) ◽  
pp. 1408-1413 ◽  
Author(s):  
Yongmei Xu ◽  
Tsutomu Kobayashi ◽  
Xiaoguang Cui ◽  
Keisuke Ohta ◽  
Chiharu Kabata ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Ringer Solution ◽  
Natural Surfactant ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Expansion Pattern

In acute respiratory distress syndrome, mechanical ventilation often induces alveolar overdistension aggravating the primary insult. To examine the mechanism of overdistension, surfactant-deficient immature rabbits were anesthetized with pentobarbital sodium, and their lungs were treated with serum-diluted modified natural surfactant (porcine lung extract; 2 mg/ml, 10 ml/kg). By mechanical ventilation with a peak inspiration pressure of 22.5 cmH2O, the animals had a tidal volume of 14.7 ml/kg (mean), when 2.5 cmH2O positive end-expiratory pressure was added. This volume was similar to that in animals treated with nondiluted modified natural surfactant (24 mg/ml in Ringer solution, 10 ml/kg). However, the lungs fixed at 10 cmH2O on the deflation limbs of the pressure-volume curve had the largest alveolar/alveolar duct profiles (≥48,000 μm2), accounting for 38% of the terminal air spaces, and the smallest (<6,000 μm2), accounting for 31%. These values were higher than those in animals treated with nondiluted modified natural surfactant ( P < 0.05). We conclude that administration of serum-diluted surfactant to immature neonatal lungs leads to patchy overdistension of terminal air spaces, similar to the expansion pattern that may be seen after dilution of endogenous surfactant with proteinaceous edema fluid in acute respiratory distress syndrome.

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