Effect of alveolar and pleural pressures on interstitial pressures in isolated dog lungs

1991 ◽  
Vol 70 (2) ◽  
pp. 914-918 ◽  
Author(s):  
M. R. Glucksberg ◽  
J. Bhattacharya
Keyword(s):  
Transpulmonary Pressure ◽  
Pleural Pressure ◽  
Alveolar Pressure ◽  
Lung Lobe ◽  
Direct Measurements ◽  
The Difference

We report the first direct measurements of perialveolar interstitial pressures in lungs inflated with negative pleural pressure. In eight experiments, we varied surrounding (pleural) pressure in a dog lung lobe to maintain constant inflation with either positive alveolar and ambient atmospheric pleural pressures (positive inflation) or ambient atmospheric alveolar and negative pleural pressures (negative inflation). Throughout, vascular pressure was approximately 4 cmH2O above pleural pressure. By the micropuncture servo-null technique we recorded interstitial pressures at alveolar junctions (Pjct) and in the perimicrovascular adventitia (Padv). At transpulmonary pressure of 7 cmH2O (n = 4), the difference of Pjct and Pady from pleural pressure of 0.9 +/- 0.4 and -1.1 +/- 0.2 cmH2O, respectively, during positive inflation did not significantly change (P less than 0.05) after negative inflation. After increase of transpulmonary pressure from 7 to 15 cmH2O (n = 4), the decrease of Pjct by 3.3 +/- 0.3 cmH2O and Pady by 2.0 +/- 0.4 cmH2O during positive inflation did not change during negative inflation. The Pjct-Pady gradient was not affected by the mode of inflation. Our measurements indicate that, in lung, when all pressures are referred to pleural or alveolar pressure, the mode of inflation does not affect perialveolar interstitial pressures.

Forces involved in lobar atelectasis in intact dogs

1980 ◽  
Vol 48 (1) ◽  
pp. 29-33 ◽  
Author(s):  
G. T. Ford ◽  
C. A. Bradley ◽  
N. R. Anthonisen
Keyword(s):  
Chest Wall ◽  
Lower Lobe ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Lateral Position ◽  
Relative Volume ◽  
Left Lower Lobe ◽  
Lung Lobe ◽  
Left Lateral Position ◽  
The Difference

When an excised lung lobe undergoes atelectasis, its shape differs from that observed when lobar atelectasis occurs in an intact animal: the chest wall deforms the collapsing lobe. In eight anesthetized dogs in the left lateral position we measured lung volume and transpulmonary pressure during the development of atelectasis. We then induced atelectasis of the left lower lobe with the rest of the lung maintained at FRC and measured lobar volume and "translobar" (lobar minus esophageal) pressure. Lung and lobar volumes were measured by prebreathing the animal with 88% O2-12% N2, occluding the airway and observing the increase in lung or lobar N2 concentration. When the left lower lobe alone collapsed, translobar pressures were more negative than transpulmonary pressure at the same relative volume when the whole lung collapsed. This pressure difference, which represents the deforming force applied to the lobe minus the pressure costs of deformation, averaged 3 cmH2O at 50% FRC. Infusion of 25 ml of normal saline into the pleural space sharply reduced the difference pulmonary pressure during lung collapse: this difference was abolished at 80% FRC and halved at 50% FRC. The large effect of the small volume of fluid suggested that deforming forces were largely generated in relatively local areas, such as regions of the chest wall with sharp angulation.

Effects of lung inflation and blood flow on capillary transit time in isolated rabbit lungs

1992 ◽  
Vol 72 (6) ◽  
pp. 2420-2427 ◽  
Author(s):  
P. M. Wang ◽  
C. D. Fike ◽  
M. R. Kaplowitz ◽  
L. V. Brown ◽  
I. Ayappa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Transpulmonary Pressure ◽  
Lung Inflation ◽  
Video Signals ◽  
Pulmonary Capillary ◽  
Direct Measurements ◽  
Video Microscope ◽  
The Difference ◽  
Group 2

In a previous study, direct measurements of pulmonary capillary transit time by fluorescence video microscopy in anesthetized rabbits showed that chest inflation increased capillary transit time and decreased cardiac output. In isolated perfused rabbit lungs we measured the effect of lung volume, left atrial pressure (Pla), and blood flow on capillary transit time. At constant blood flow and constant transpulmonary pressure, a bolus of fluorescent dye was injected into the pulmonary artery and the passage of the dye through the subpleural microcirculation was recorded via the video microscope on videotape. During playback of the video signals, the light emitted from an arteriole and adjacent venule was measured using a video photoanalyzer. Capillary transit time was the difference between the mean time values of the arteriolar and venular dye dilution curves. We measured capillary transit time in three groups of lungs. In group 1, with airway pressure (Paw) at 5 cmH2O, transit time was measured at blood flow of approximately 80, approximately 40, and approximately 20 ml.min-1.kg-1. At each blood flow level, Pla was varied from 0 (Pla less than Paw, zone 2) to 11 cmH2O (Pla greater than Paw, zone 3). In group 2, at constant Paw of 15 cmH2O, Pla was varied from 0 (zone 2) to 22 cmH2O (zone 3) at the same three blood flow levels. In group 3, at each of the three blood flow levels, Paw was varied from 5 to 15 cmH2O while Pla was maintained at 0 cmH2O (zone 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneity of mean alveolar pressure during high-frequency oscillations

1987 ◽  
Vol 62 (1) ◽  
pp. 223-228 ◽  
Author(s):  
J. L. Allen ◽  
I. D. Frantz ◽  
J. J. Fredberg
Keyword(s):  
High Frequency ◽  
Flow Distribution ◽  
Transpulmonary Pressure ◽  
Alveolar Pressure ◽  
Regional Heterogeneity ◽  
Regional Flow ◽  
High Frequency Oscillations ◽  
Dynamic Head ◽  
Mean Pressure ◽  
The Difference

Mean alveolar pressure may exceed mean airway pressure during high-frequency oscillations (HFO). To assess the magnitude of this effect and its regional heterogeneity, we studied six excised dog lungs during HFO [frequency (f) 2–32 Hz; tidal volume (VT) 5–80 ml] at transpulmonary pressures (PL) of 6, 10, and 25 cmH2O. We measured mean pressure at the airway opening (Pao), trachea (Ptr), and four alveolar locations (PA) using alveolar capsules. Pao was measured at the oscillator pump, wherein the peak dynamic head was less than 0.2 cmH2O. Since the dynamic head was negligible here, and since these were excised lungs, Pao thus represented true applied transpulmonary pressure. Ptr increasingly underestimated Pao as f and VT increased, with Pao - Ptr approaching 8 cmH2O. PA (averaged over all locations) and Pao were nearly equal at all PL's, f's, and VT's, except at PL of 6, f 32 Hz, and VT 80 ml, where (PA - Pao) was 3 cmH2O. Remarkably, mean pressure in the base exceeded that in the apex increasingly as f and VT increased, the difference approaching 3 cmH2O at high f and VT. We conclude that, although global alveolar overdistension assessed by PA - Pao is small during HFO under these conditions, larger regional heterogeneity in PA's exists that may be a consequence of airway branching angle asymmetry and/or regional flow distribution.

Regional differences in alveolar density in the human lung are related to lung height

2015 ◽  
Vol 118 (11) ◽  
pp. 1429-1434 ◽  
Author(s):  
John E. McDonough ◽  
Lars Knudsen ◽  
Alexander C. Wright ◽  
W. Mark Elliott ◽  
Matthias Ochs ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Regional Differences ◽  
Volume Fraction ◽  
Transpulmonary Pressure ◽  
Pleural Pressure ◽  
Lung Inflation ◽  
Residual Capacity ◽  
Alveolar Duct ◽  
The Difference

The gravity-dependent pleural pressure gradient within the thorax produces regional differences in lung inflation that have a profound effect on the distribution of ventilation within the lung. This study examines the hypothesis that gravitationally induced differences in stress within the thorax also influence alveolar density in terms of the number of alveoli contained per unit volume of lung. To test this hypothesis, we measured the number of alveoli within known volumes of lung located at regular intervals between the apex and base of four normal adult human lungs that were rapidly frozen at a constant transpulmonary pressure, and used microcomputed tomographic imaging to measure alveolar density (number alveoli/mm3) at regular intervals between the lung apex and base. These results show that at total lung capacity, alveolar density in the lung apex is 31.6 ± 3.4 alveoli/mm3, with 15 ± 6% of parenchymal tissue consisting of alveolar duct. The base of the lung had an alveolar density of 21.2 ± 1.6 alveoli/mm3 and alveolar duct volume fraction of 29 ± 6%. The difference in alveolar density can be negated by factoring in the effects of alveolar compression due to the pleural pressure gradient at the base of the lung in vivo and at functional residual capacity.

The Effect of Lobar Obstruction on Regional Perfusion in the Intact Dog

1975 ◽  
Vol 53 (5) ◽  
pp. 954-957 ◽  
Author(s):  
A. Zidulka ◽  
M. Desmeules ◽  
J. Harvey ◽  
N. R. Anthonisen
Keyword(s):  
Functional Residual Capacity ◽  
Transpulmonary Pressure ◽  
Acute Obstruction ◽  
Alveolar Pressure ◽  
Pressure Region ◽  
Residual Capacity ◽  
Xenon 133 ◽  
The Difference ◽  
The Right ◽  
Hypoxic Region

The effect of acute obstruction of the right lower lobes (RLL) on the relative perfusion of different lung regions was studied using Xenon-133 in anesthetized artificially ventilated supine dogs. When the RLL were obstructed at functional residual capacity (FRC) and the rest of the lung was inflated to a transpulmonary pressure of 10 or 20 cm H2O (1 cm H2O = 94.1 N/m2), relative perfusion increased within 10 s to the obstructed lobes by 59 and 92%, respectively. The increase was less marked but still present (17 and 42%, respectively) when obstruction was maintained for 15 min, at a time when arterial hypoxemia had occurred. Hence, there was increased perfusion to an obstructed hypoxic region. The perfusion distribution correlated with the difference in alveolar pressure between the obstructed lobes and the unobstructed lobes such that relative perfusion was always increased to the low alveolar pressure region.

Pleural pressure increases during inspiration in the zone of apposition of diaphragm to rib cage

1988 ◽  
Vol 65 (5) ◽  
pp. 2207-2212 ◽  
Author(s):  
W. F. Urmey ◽  
A. De Troyer ◽  
K. B. Kelly ◽  
S. H. Loring
Keyword(s):  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Direct Measurements ◽  
Anesthetized Dogs ◽  
Theoretical Mechanism ◽  
Phrenic Stimulation ◽  
Anatomic Region

The zone of apposition of diaphragm to rib cage provides a theoretical mechanism that may, in part, contribute to rib cage expansion during inspiration. Increases in intra-abdominal pressure (Pab) that are generated by diaphragmatic contraction are indirectly applied to the inner rib cage wall in the zone of apposition. We explored this mechanism, with the expectation that pleural pressure in this zone (Pap) would increase during inspiration and that local transdiaphragmatic pressure in this zone (Pdiap) must be different from conventionally determined transdiaphragmatic pressure (Pdi) during inspiration. Direct measurements of Pap, as well as measurements of pleural pressure (Ppl) cephalad to the zone of apposition, were made during tidal inspiration, during phrenic stimulation, and during inspiratory efforts in anesthetized dogs. Pab and esophageal pressure (Pes) were measured simultaneously. By measuring Ppl's with cannulas placed through ribs, we found that Pap consistently increased during both maneuvers, whereas Ppl and Pes decreased. Whereas changes in Pdi of up to -19 cmH2O were measured, Pdiap never departed from zero by greater than -4.5 cmH2O. We conclude that there can be marked regional differences in Ppl and Pdi between the zone of apposition and regions cephalad to the zone. Our results support the concept of the zone of apposition as an anatomic region where Pab is transmitted to the interior surface of the lower rib cage.

Dynamic lung compliance in newborn and adult cats

1986 ◽  
Vol 60 (3) ◽  
pp. 743-750 ◽  
Author(s):  
K. J. Sullivan ◽  
J. P. Mortola
Keyword(s):  
Stress Relaxation ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Theoretical Treatment ◽  
The Difference ◽  
Adult Cats ◽  
Isolated Lungs ◽  
Dynamic Lung Compliance ◽  
Volume History ◽  
Lung Stress

Static (Cstat) and dynamic (Cdyn) lung compliance and lung stress relaxation were examined in isolated lungs of newborn kittens and adult cats. Cstat was determined by increasing volume in increments and recording the corresponding change in pressure; Cdyn was calculated as the ratio of the changes in volume to transpulmonary pressure between points of zero flow at ventilation frequencies between 10 and 110 cycles/min. Lung volume history, end-inflation volume, and end-deflation pressure were maintained constant. At the lowest frequency of ventilation, Cdyn was less than Cstat, the difference being greater in newborns. Between 20 and 100 cycles/min, Cdyn of the newborn lung remained constant, whereas Cdyn of the adult lung decreased after 60 cycles/min. At all frequencies, the rate of stress relaxation, measured as the decay in transpulmonary pressure during maintained inflation, was greater in newborns than in adults. The frequency response of Cdyn in kittens, together with the relatively greater rate of stress relaxation, suggests that viscoelasticity contributes more to the dynamic stiffening of the lung in newborns than in adults. A theoretical treatment of the data based on a linear model of viscoelasticity supports this conclusion.

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.

Alveolar pressure-airflow characteristics in humans breathing air, He-O2, and SF6-O2

1981 ◽  
Vol 51 (4) ◽  
pp. 1033-1037 ◽  
Author(s):  
A. S. Slutsky ◽  
J. M. Drazen ◽  
C. F. O'Cain ◽  
R. H. Ingram
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Coefficient Of Friction ◽  
Transpulmonary Pressure ◽  
Normal Subjects ◽  
Sectional Area ◽  
Alveolar Pressure ◽  
Flow Conditions ◽  
Cross Sectional ◽  
The Coefficient Of Friction

In a system of rigid tubes under steady flow conditions, the coefficient of friction [CF = 2 delta P/(rho V2/A2)] (where delta P is pressure drop, rho is density, V is flow, and A is cross-sectional area) should be a unique function of Reynolds' number (Re). Recently it has been shown that at any given Re, the value of CF using transpulmonary pressure (PL) was lower when breathing He-O2 compared with air (Lisboa et al., J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 48: 878–885, 1980). One explanation for this discontinuity is that PL includes the pressure drop due to tissue viscance, which is independent of V, and thus would lead to an overestimate of CF on air compared with He-O2 at any Re. We tested this hypothesis by measuring V related to alveolar pressure, rather than PL, in normal subjects breathing air, He-O2, and SF6-O2. In each subject, for a given Re, CF was greatest breathing SF6-O2 and lowest breathing He-O2, similar to results using PL. Thus tissue viscance is not the sole cause of the discontinuous plot of CF vs. Re, and this phenomenon must be due to other factors, such as changing geometry or nonsteady behavior.

Determinants of transvascular fluid shifts in zone I lungs

1980 ◽  
Vol 48 (2) ◽  
pp. 256-264 ◽  
Author(s):  
G. Nicolaysen ◽  
A. Hauge
Keyword(s):  
Lung Volume ◽  
Transmural Pressure ◽  
Pleural Pressure ◽  
Alveolar Pressure ◽  
Fluid Filtration ◽  
Fluid Shifts ◽  
Transvascular Fluid Shifts

We studied the fluid shifts in isolated, plasma-perfused rabbit lungs kept completely within zone I. The rate of fluid filtration or reabsorption was determined gravimetrically. A rise in alveolar pressure at constant pleural and vascular pressures reduced th rate of filtration or increased the rate of reabsorption in seven of eight lungs. In seven of seven lungs a reduction in pleural pressure at constant alveolar and vascular pressures increased the rate of filtration or decreased the rate of reabsorption. Thus, a given rise in lung volume had opposite effects depending on whether this rise was caused by an increased alveolar or reduced pleural pressure. Therefore, the exchange vessels studied cannot be true extra-alveolar vessels, which always expand (reflecting a rise in transmural pressure) with a rise in lung volume. When alveolar and pleural pressures were equally increased at constant vascular pressure, the rate of filtration was reduced in four of four lungs. The results can be explained through the existence of exchange vessels situated neither in the alveolar septae proper nor among the true extra-alveolar vessels. The vessels in the alveolar junctions are the most likely candidates.

Sign in / Sign up

Export Citation Format

Share Document