scholarly journals Two steps forward in bedside monitoring of lung mechanics: transpulmonary pressure and lung volume

Critical Care ◽  
2013 ◽  
Vol 17 (2) ◽  
pp. 219 ◽  
Author(s):  
Gustavo A Cortes ◽  
John J Marini
Keyword(s):  
Lung Volume ◽  
Transpulmonary Pressure ◽  
Lung Mechanics ◽  
Bedside Monitoring

scholarly journals Lung tissue behavior in the mouse during constriction induced by methacholine and endothelin-1

1996 ◽  
Vol 81 (6) ◽  
pp. 2373-2378 ◽  
Author(s):  
Takahide Nagase ◽  
Hirotoshi Matsui ◽  
Tomoko Aoki ◽  
Yasuyoshi Ouchi ◽  
Yoshinosuke Fukuchi
Keyword(s):  
Lung Tissue ◽  
Lung Volume ◽  
Mammalian Species ◽  
Transpulmonary Pressure ◽  
Lung Mechanics ◽  
Similar Degree ◽  
Dependent Manner ◽  
Endothelin 1 ◽  
Tissue Resistance ◽  
Volume Challenge

Nagase, Takahide, Hirotoshi Matsui, Tomoko Aoki, Yasuyoshi Ouchi, and Yoshinosuke Fukuchi. Lung tissue behavior in the mouse during constriction induced by methacholine and endothelin-1. J. Appl. Physiol. 81(6): 2373–2378, 1996.—Recently, mice have been extensively used to investigate the pathogenesis of pulmonary disease because appropriate murine models, including transgenic mice, are being increasingly developed. However, little information about the lung mechanics of mice is currently available. We questioned whether lung tissue behavior and the coupling between dissipative and elastic processes, hysteresivity (η), in mice would be different from those in the other species. To address this question, we investigated whether tissue resistance (Rti) and η in mice would be affected by varying lung volume, constriction induced by methacholine (MCh) and endothelin-1 (ET-1), and high-lung-volume challenge during induced constriction. From measured tracheal flow and tracheal and alveolar pressures in open-chest ICR mice during mechanical ventilation [tidal volume = 8 ml/kg, frequency (f) = 2.5 Hz], we calculated lung resistance (Rl), Rti, airway resistance (Raw), lung elastance (El), and η (= 2πfRti/El). Under baseline conditions, increasing levels of end-expiratory transpulmonary pressure decreased Raw and increased Rti. The administration of aerosolized MCh and intravenous ET-1 increased Rl, Rti, Raw, and El in a dose-dependent manner. Rti increased from 0.207 ± 0.010 to 0.570 ± 0.058 cmH2O ⋅ ml−1 ⋅ s after 10−7 mol/kg ET-1 ( P < 0.01). After induced constriction, increasing end-expiratory transpulmonary pressure decreased Raw. However, η was not affected by changing lung volume, constriction induced by MCh and ET-1, or high-lung-volume challenge during induced constriction. These observations suggest that 1) η is stable in mice regardless of various conditions, 2) Rti is an important fraction of Rl and increases after induced constriction, and 3) mechanical interdependence may affect airway smooth muscle shortening in this species. In mammalian species, including mice, analysis of η may indicate that both Rti and El essentially respond to a similar degree.

Static lung mechanics of intact and excised rhesus monkey lungs and lobes

1978 ◽  
Vol 44 (4) ◽  
pp. 547-552 ◽  
Author(s):  
P. D. Pare ◽  
R. Boucher ◽  
M. C. Michoud ◽  
J. C. Hogg
Keyword(s):  
Lung Volume ◽  
Transpulmonary Pressure ◽  
Lung Mechanics ◽  
Unit Weight ◽  
Water Displacement ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Boyle’S Law

Subdivisions of lung volume and pressure-volume (PV) curves of the lung and chest wall (CW) were measured in 12 rhesus monkeys (Macacca mulatta) under pentobarbital anesthesia. In addition, volumes and PV curves were obtained on the excised lungs and lobes of 12 cynomolgus monkeys (M. fasicularis). Boyle's law was used to determine functional residual capacity (FRC) in the intact animals and water displacement to determine minimal volume (MV) in the excised lungs. Total lung capacity (TLC = lung volume at a transpulmonary pressure of 30 cmH2O) was similar in vivo and in vitro (90 + 83 ml/kg) but residual volume (RV = volume at airway pressure of -50 cmH2O) and MV differed markedly (16.5 + 5.9 ml/kg). In the intact animals a very stiff CW appeared to determine RV, whereas airway closure determined MV in excised lungs. PV curves of upper and lower lobes were not different when expressed as %TLC but when expressed as milliliters of gas per gram of lung, the upper lobes contained significantly more gas per unit weight.

Breathing at low lung volumes and chest strapping: a comparison of lung mechanics

1981 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
N. J. Douglas ◽  
G. B. Drummond ◽  
M. F. Sudlow
Keyword(s):  
Lung Volume ◽  
Maximum Flow ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Lung Volumes ◽  
Flow Rates ◽  
Recoil Pressure ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

In six normal subjects forced expiratory flow rates increased progressively with increasing degrees of chest strapping. In nine normal subjects forced expiratory flow rates increased with the time spent breathing with expiratory reserve volume 0.5 liters above residual volume, the increase being significant by 30 s (P less than 0.01), and flow rates were still increasing at 2 min, the longest time the subjects could breathe at this lung volume. The increase in flow after low lung volume breathing (LLVB) was similar to that produced by strapping. The effect of LLVB was diminished by the inhalation of the atropinelike drug ipratropium. Quasistatic recoil pressures were higher following strapping and LLVB than on partial or maximal expiration, but the rise in recoil pressure was insufficient to account for all the observed increased in maximum flow. We suggest that the effects of chest strapping are due to LLVB and that both cause bronchodilatation.

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.

Rib cage and abdominal restrictions have different effects on lung mechanics

1980 ◽  
Vol 49 (6) ◽  
pp. 946-952 ◽  
Author(s):  
C. A. Bradley ◽  
N. R. Anthonisen
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Lung Mechanics ◽  
Elastic Recoil ◽  
Rib Cage ◽  
Lung Capacity ◽  
Single Breath ◽  
Restrictive Procedures ◽  
Maximum Expiratory Flow ◽  
Per Se

The effects of a variety of restrictive procedures on lung mechanics were studied in eight healthy subjects. Rib cage restriction decreased total lung capacity (TLC) by 43% and significantly increased elastic recoil and maximum expiratory flow (MEF). Subsequent immersion of four subjects with rib cage restriction resulted in no further change in either parameter; shifts of blood volume did not reverse recoil changes during rib cage restriction. Abdominal restriction decreased TLC by 40% and increased MEF and elastic recoil, but recoil was increased significantly less than was the case with rib cage restriction. Further, at a given recoil pressure, MEF was less during rib cage restriction than during either abdominal restriction or no restriction. Measurements of the unevenness of inspired gas distribution by the single-breath nitrogen technique showed increased unevenness during rib cage restriction, which was significantly greater than that during abdominal restriction. We conclude that lung volume restriction induces changes in lung function, but the nature of these changes depends on how the restriction is applied and therefore cannot be ascribed to low lung volume breathing per se.

Effect of parenchymal shear modulus and lung volume on bronchial pressure-diameter behavior

1978 ◽  
Vol 44 (6) ◽  
pp. 859-868 ◽  
Author(s):  
S. J. Lai-Fook ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Shear Modulus ◽  
Lung Volume ◽  
Pressure Difference ◽  
Transpulmonary Pressure ◽  
Pleural Pressure ◽  
Air Trapping ◽  
Control State ◽  
General Method

A method that interrelates lung pressure-volume behavior, bronchial pressure-diameter behavior, and parenchymal shear modulus is presented. The method was used to predict changes in intraparenchymal bronchial diameter that occurred when lobe pressure-volume behavior and parenchymal shear modulus were markedly changed by inducing air trapping in isolated dog lobes. Predictions agreed with measurements, thereby supporting the general method. Measured values for the shear modulus were approximately 0.7 times the transpulmonary pressure for the control state. Estimated values for the peribronchial pressure difference from pleural pressure during a deflation pressure-volume maneuver for transpulmonary pressures below 12 cmH2O were small, approximately +/- 1 cmH2O, its sign being positive or negative, depending on whether the bronchus was dilated or contricted.

High lung volume increases stress failure in pulmonary capillaries

1992 ◽  
Vol 73 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Z. Fu ◽  
M. L. Costello ◽  
K. Tsukimoto ◽  
R. Prediletto ◽  
A. R. Elliott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lung Volume ◽  
Autologous Blood ◽  
Physiological Mechanism ◽  
Transpulmonary Pressure ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Pulmonary Capillaries ◽  
Scanning Electron

We previously showed that when pulmonary capillaries in anesthetized rabbits are exposed to a transmural pressure (Ptm) of approximately 40 mmHg, stress failure of the walls occurs with disruption of the capillary endothelium, alveolar epithelium, or sometimes all layers. The present study was designed to test whether stress failure occurred more frequently at high than at low lung volumes for the same Ptm. Lungs of anesthetized rabbits were inflated to a transpulmonary pressure of 20 cmH2O, perfused with autologous blood at 32.5 or 2.5 cmH2O Ptm, and fixed by intravascular perfusion. Samples were examined by both transmission and scanning electron microscopy. The results were compared with those of a previous study in which the lung was inflated to a transpulmonary pressure of 5 cmH2O. There was a large increase in the frequency of stress failure of the capillary walls at the higher lung volume. For example, at 32.5 cmH2O Ptm, the number of endothelial breaks per millimeter cell lining was 7.1 +/- 2.2 at the high lung volume compared with 0.7 +/- 0.4 at the low lung volume. The corresponding values for epithelium were 8.5 +/- 1.6 and 0.9 +/- 0.6. Both differences were significant (P less than 0.05). At 52.5 cmH2O Ptm, the results for endothelium were 20.7 +/- 7.6 (high volume) and 7.1 +/- 2.1 (low volume), and the corresponding results for epithelium were 32.8 +/- 11.9 and 11.4 +/- 3.7. At 32.5 cmH2O Ptm, the thickness of the blood-gas barrier was greater at the higher lung volume, consistent with the development of more interstitial edema. Ballooning of the epithelium caused by accumulation of edema fluid between the epithelial cell and its basement membrane was seen at 32.5 and 52.5 cmH2O Ptm. At high lung volume, the breaks tended to be narrower and fewer were oriented perpendicular to the axis of the pulmonary capillaries than at low lung volumes. Transmission and scanning electron microscopy measurements agreed well. Our findings provide a physiological mechanism for other studies showing increased capillary permeability at high states of lung inflation.

Effect of volume and volume history of the lungs on pulmonary shunt flow

1964 ◽  
Vol 207 (1) ◽  
pp. 235-238 ◽  
Author(s):  
Nicholas R. Anthonisen
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Full Range ◽  
Transpulmonary Pressure ◽  
Pulmonary Shunt ◽  
Shunt Flow ◽  
Lung Capacity ◽  
Surface Active Properties ◽  
History Of ◽  
Surface Active

Relative pulmonary shunt flow (Qs/Qt), was measured in denitrogenated open-chested cats during apnea over the full range of lung volumes. The particular lung volume and transpulmonary pressure were also measured. When completely collapsed lungs were inflated, Qs/Qt decreased sharply to 3% at total lung capacity (TLC). During deflation from TLC Qs/Qt was insensitive to changes in lung volume. Qs/Qt remained low during reinflation after deflation from TLC. These changes in shunt flow can be interpreted as due to either recruitment or collapse of gas exchange units during lung volume change. It appears that completely collapsed lungs inflate very unevenly but that deflation from TLC proceeds remarkably evenly. Reinflation after deflation from TLC also seems to proceed evenly, and the manifest pressure-volume hysteresis is most likely due to hysteresis of the surface-active properties of the alveolar lining material.

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