Pleural and extrapleural interstitial liquid pressure measured by cannulas and micropipettes

1988 ◽  
Vol 65 (2) ◽  
pp. 555-562 ◽  
Author(s):  
G. Miserocchi ◽  
S. Kelly ◽  
D. Negrini
Keyword(s):  
Pleural Cavity ◽  
Pleural Space ◽  
Hydraulic Pressure ◽  
Pressure Data ◽  
Liquid Pressure ◽  
Interstitial Liquid ◽  
Dependent Part ◽  
Identity Line ◽  
Lateral Posture

In 15 anesthetized apneic, oxygenated rabbits we simultaneously measured pleural liquid and interstitial extrapleural parietal pressures by using catheters and/or cannulas and micropipettes connected to a servonull system. With the animal in lateral posture, at an average recording height of 4.4 +/- 0.9 (SD) cm from the most dependent part of the cavity, the extrapleural catheter and the pleural cannula yielded -2.5 +/- 0.6 and -5.5 +/- 0.2 cmH2O; the corresponding values for micropipette readings in the two compartments were -2.4 +/- 0.6 and -5.4 +/- 0.4 cmH2O, respectively (not significantly different from those measured with catheters and cannulas). In the supine animal, interstitial extrapleural catheter pressure data obtained at recording heights ranging from 15 to 80% of pleural cavity lay on the identity line when plotted vs. the micropipette pressure values simultaneously gathered from the same tissues. We conclude that 1) micropipettes and catheters-cannulas yield similar results when recording from the same compartment and 2) the hydraulic pressure in the parietal extrapleural interstitium is less negative than that in the pleural space.

Size-related differences in parietal extrapleural and pleural liquid pressure distribution

1989 ◽  
Vol 67 (5) ◽  
pp. 1967-1972 ◽  
Author(s):  
D. Negrini ◽  
G. Miserocchi
Keyword(s):  
Body Size ◽  
Pressure Gradient ◽  
Right Atrium ◽  
Pleural Space ◽  
Hydraulic Pressure ◽  
Liquid Pressure ◽  
Dependent Part ◽  
The Right ◽  
Spontaneously Breathing ◽  
Pleural Liquid Pressure

The hydraulic pressure in the extrapleural parietal interstitium (Pepl) and in the pleural space over the costal side (Pliq) was measured in anesthetized spontaneously breathing supine adult mammals of increasing size (rats, dogs, and sheep) using saline-filled catheters and cannulas, respectively. From the Pliq and Pepl vs. lung height regressions it appears that in all species Pliq was significantly more subatmospheric than Pepl simultaneously measured at the same lung height. The vertical pleural liquid pressure gradient increased with size, amounting to -1, -0.69, and -0.44 cmH2O/cm in rats, dogs, and sheep, respectively. The vertical extrapleural liquid pressure gradient also increased with size, being -0.6, -0.52, and -0.33 cmH2O/cm in rats, dogs, and sheep, respectively. With increasing body size, the transpleural hydraulic pressure gradient (Ptp = Pepl - Pliq) at the level of the right atrium increased from 1.45 to 5.6 cmH2O going from rats to sheep. In all species Ptp increased, with lung height being greatest in the less dependent part of the pleural space.

Reabsorption kinetics of albumin from pleural space of dogs

1988 ◽  
Vol 255 (2) ◽  
pp. H375-H385 ◽  
Author(s):  
M. Miniati ◽  
J. C. Parker ◽  
M. Pistolesi ◽  
J. T. Cartledge ◽  
D. J. Martin ◽  
...  
Keyword(s):  
Control Mechanism ◽  
Mean Transit Time ◽  
Input Function ◽  
Pleural Space ◽  
Frequency Function ◽  
Liquid Pressure ◽  
Physiological Conditions ◽  
Transit Times ◽  
The Mean ◽  
Kinetics Of

The reabsorption of albumin from the pleural space was measured in eight dogs receiving 0.5 ml intrapleural injection of 131I-labeled albumin and a simultaneous intravenous injection of 125I-labeled albumin. Plasma curves for both tracers were obtained over 24 h. The 125I-albumin curve served as input function of albumin for interstitial spaces, including pleura, whereas the 131I-albumin curve represented the output function from pleural space. The frequency function of albumin transit times from pleural space to plasma was obtained by deconvolution of input-output plasma curves. Plasma recovery of 131I-albumin was complete by 24 h, and the mean transit time from pleura to plasma averaged 7.95 +/- 1.57 (SD) h. Albumin reabsorption occurred mainly via lymphatics as indicated by experiments in 16 additional dogs in which their right lymph ducts or thoracic ducts were ligated before intrapleural injection. A pleural lymph flow of 0.020 +/- 0.003 (SD) ml.kg-1.h-1 was estimated, which is balanced by a comparable filtration of fluid into the pleural space. This suggests that, under physiological conditions, the subpleural lymphatics represent an important control mechanism of pleural liquid pressure.

Intrapleural fluid movements described by a porous flow model

1992 ◽  
Vol 73 (6) ◽  
pp. 2511-2516 ◽  
Author(s):  
G. Miserocchi ◽  
D. Venturoli ◽  
D. Negrini ◽  
M. C. Gilardi ◽  
R. Bellina
Keyword(s):  
Porous Medium ◽  
Gamma Camera ◽  
Flow Model ◽  
Pleural Space ◽  
Interstitial Tissue ◽  
Hydraulic Pressure ◽  
Pressure Gradients ◽  
Hydraulic Radius ◽  
Porous Flow ◽  
Anesthetized Dogs

We injected technetium-labeled albumin (at a concentration similar to that of the pleural fluid) in the costal region of anesthetized dogs (n = 13) either breathing spontaneously or apneic. The decay rate of labeled activity at the injection site was studied with a gamma camera placed either in the anteroposterior (AP) or laterolateral (LL) projection. In breathing animals (respiratory frequency approximately 10 cycles/min), 10 min after the injection the activity decreased by approximately 50% on AP and approximately 20% on LL imaging; in apneic animals the corresponding decrease in activity was reduced to approximately 15 and approximately 3%, respectively. We considered label translocation from AP and LL imaging as a result of bulk flows of liquid along the costomediastinal and gravity-dependent direction, respectively. We related intrapleural flows to the hydraulic pressure gradients existing along these two directions and to the geometry of the pleural space. The pleural space was considered as a porous medium partially occupied by the mesh of microvilli protruding from mesothelial cells. Solution of the Kozeny-Carman equation for the observed flow velocities and pressure gradients yielded a mean hydraulic radius of the pathways followed by the liquid ranging from 2 to 4 microns. The hydraulic resistivity of the pleural space was estimated at approximately 8.5 x 10(5) dyn.s.cm-4, five orders of magnitude lower than that of interstitial tissue.

Gravity-dependent distribution of parietal subpleural interstitial pressure

1987 ◽  
Vol 63 (5) ◽  
pp. 1912-1918 ◽  
Author(s):  
D. Negrini ◽  
C. Capelli ◽  
M. Morini ◽  
G. Miserocchi
Keyword(s):  
Parietal Pleura ◽  
Hydraulic Pressure ◽  
Interstitial Pressure ◽  
Liquid Pressure ◽  
Exposed Area ◽  
Muscular Layer ◽  
Simultaneous Measurements ◽  
Pleural Surface ◽  
Tidal Change ◽  
Spontaneously Breathing

Using liquid-filled catheters, we recorded, in 30 anesthetized, spontaneously breathing supine rabbits, the hydraulic pressure from the parietal subpleural interstitial space (Pspl). Through a small exposed area of parietal pleura a plastic catheter (1 mm ED), with a closed and smooth tip and several holes on the last centimeter, was carefully advanced between the muscular layer and the parietal pleura, tangentially to the pleural surface to reach the submesothelial layer. Simultaneous measurements of pleural liquid pressure (Pliq) were obtained from intrapleurally placed cannulas. End-expiratory Pspl decreased (became more negative) with increasing height (LH) according to the following: Pspl (cmH2O) = -1 - 0.4 LH (cm), the corresponding equation for Pliq being Pliq (cmH2O) = -1.5 – 0.7 LH (cm). Thus at end expiration a transpleural hydraulic pressure difference (Pliq-Pspl) developed at any height, increasing from the bottom to the top of the cavity as Pliq - Pspl (cmH2O) = -0.5 – 0.3 LH (cm). The Pliq-Pspl difference increased during inspiration due to the much smaller tidal change in Pspl than in Pliq. By considering the gravity-dependent distribution of the functional hydrostatic pressure in the systemic capillaries of the pleura (Pc) and the Pspl and Pliq values integrated over the respiratory cycle we estimated that on the average, the Pc-Pspl difference is sevenfold larger than the Pspl-Pliq difference.

Pleural liquid pressure in dogs measured using a rib capsule

1985 ◽  
Vol 59 (2) ◽  
pp. 597-602 ◽  
Author(s):  
J. P. Wiener-Kronish ◽  
M. A. Gropper ◽  
S. J. Lai-Fook
Keyword(s):  
Pleural Space ◽  
Pleural Pressure ◽  
Parietal Pleura ◽  
Liquid Pressure ◽  
Strain Gauge Transducer ◽  
Invasive Method ◽  
The Mean ◽  
Spontaneously Breathing ◽  
Vertical Gradients ◽  
Pleural Liquid Pressure

We have developed a minimally invasive method for measuring the hydrostatic pressure in the pleural space liquid. A liquid-filled capsule is bonded into a rib and a small hole is cut in the parietal pleura to allow direct communication between the liquid in the capsule and the pleural space. The pressure can be measured continuously by a strain gauge transducer connected to the capsule. The rib capsule does not distort the pleural space or require removal of intercostal muscle. Pneumothoraces are easily detected when they occur inadvertently on puncturing the parietal pleura. We examined the effect of height on pleural pressure in 15 anesthetized spontaneously breathing dogs. The vertical gradients in pleural pressure were 0.53, 0.42, 0.46, and 0.23 cmH2O/cm height for the head-up, head-down, supine, and prone body positions, respectively. These vertical gradients were much less than the hydrostatic value (1 cmH2O/cm), indicating that the pleural liquid is not in hydrostatic equilibrium. In most body positions the magnitudes of pleural liquid pressure interpolated to midchest level were similar to the mean transpulmonary (surface) pressure determined postmortem. This suggests that pleural liquid pressure is closely related to the lung static recoil.

Regional protein absorption rates from the pleural cavity in dogs

1985 ◽  
Vol 58 (6) ◽  
pp. 2062-2067 ◽  
Author(s):  
D. Negrini ◽  
M. Pistolesi ◽  
M. Miniati ◽  
R. Bellina ◽  
C. Giuntini ◽  
...  
Keyword(s):  
Gamma Camera ◽  
Time Course ◽  
Saline Solution ◽  
Pleural Cavity ◽  
Pleural Space ◽  
Regions Of Interest ◽  
Functional Interaction ◽  
Unit Surface ◽  
Anesthetized Dogs ◽  
Spontaneously Breathing

In five supine spontaneously breathing anesthetized dogs we injected into the pleural space 0.5–1 ml of saline solution containing 2 mg/ml albumin labeled with technetium-99m. By use of a gamma camera placed horizontally over the chest, we followed, up to 120 min, the activity over the whole lung and over the preferential accumulation areas of the label (regions of interest, ROI) that corresponded to the apical, mediastinal, and laterodiaphragmatic regions. Activities were corrected for the decay rate of the isotope used. On the average, the activity over the whole lung decreased by 27% up to 120 min. The overall activity over the ROI amounted to 44.3% after the injection and decreased to 24% of total at 120 min, thus accounting for 75% of the total decrease in activity. At 10 min, the activity per unit surface of the gamma camera image (As) was from 2.2- to 5.7-fold higher over the ROI than for the rest of the lung image. The decrease of As at 120 min was 18-, 13-, and 5-fold greater for mediastinal, diaphragmatic, and apical regions, respectively, compared with the rest of the lung image. The time course of the changes in As are discussed in terms of regional albumin egress rate based on the functional interaction between the Starling and the lymphatic mechanisms.

scholarly journals Pleural Mechanics and Fluid Exchange

2004 ◽  
Vol 84 (2) ◽  
pp. 385-410 ◽  
Author(s):  
STEPHEN J. LAI-FOOK
Keyword(s):  
Chest Wall ◽  
Conceptual Understanding ◽  
Surface Pressure ◽  
Vertical Gradient ◽  
Pleural Space ◽  
Liquid Volume ◽  
Liquid Pressure ◽  
Fluid Exchange ◽  
Pleural Surface ◽  
The One

Lai-Fook, Stephen J. Pleural Mechanics and Fluid Exchange. Physiol Rev 84: 385–410, 2004; 10.1152/physrev.00026.2003.—The pleural space separating the lung and chest wall of mammals contains a small amount of liquid that lubricates the pleural surfaces during breathing. Recent studies have pointed to a conceptual understanding of the pleural space that is different from the one advocated some 30 years ago in this journal (Agostoni E. Physiol Rev 52: 57–128, 1972). The fundamental concept is that pleural surface pressure, the result of the opposing recoils of the lung and chest wall, is the major determinant of the pressure in the pleural liquid. Pleural liquid is not in hydrostatic equilibrium because the vertical gradient in pleural liquid pressure, determined by the vertical gradient in pleural surface pressure, does not equal the hydrostatic gradient. As a result, a viscous flow of pleural liquid occurs in the pleural space. Ventilatory and cardiogenic motions serve to redistribute pleural liquid and minimize contact between the pleural surfaces. Pleural liquid is a microvascular filtrate from parietal pleural capillaries in the chest wall. Homeostasis in pleural liquid volume is achieved by an adjustment of the pleural liquid thickness to the filtration rate that is matched by an outflow via lymphatic stomata.

Double-Acting Pneumatic-Hydraulic Pressure Amplifier Having Two-Step Liquid Pressure Output Pressure Driven by Pneumatic Cylinder with Rodless Piston

2014 ◽  
Vol 607 ◽  
pp. 467-471 ◽  
Author(s):  
Ming Di Wang ◽  
Li Ning Sun ◽  
Kang Min Zhong
Keyword(s):  
High Pressure ◽  
Green Manufacturing ◽  
Pneumatic Cylinder ◽  
Hydraulic Pressure ◽  
Liquid Pressure ◽  
Output Pressure ◽  
Working Principle ◽  
Working Efficiency ◽  
Pressure Output ◽  
Pressure Driven

The working principle of a new kind of double-acting pneumatic-hydraulic pressure amplifier having two-step output pressure driven by the pneumatic cylinder with rodless piston is introduced. The output flux and the output pressure calculating formulae are also given out. Compared with the known single-acting pressure amplifier,the innovative pressure-amplifier is simple in structure and has much higher working efficiency. It can also output adaptive two-step liquid pressure, which is similar with the hydraulic differential connection, thus it is easy to realize move quickly in low pressure and move slowly at high pressure. This system also fits a trend of green manufacturing for using green air as transmission medium and with closed oil without leak to output pressure liquid.

Pleural pressure as a function of body position in rabbits

1990 ◽  
Vol 69 (1) ◽  
pp. 336-344 ◽  
Author(s):  
L. E. Olson ◽  
R. L. Wardle
Keyword(s):  
Body Position ◽  
Pleural Space ◽  
Pleural Pressure ◽  
Liquid Pressure ◽  
Left Chest ◽  
Minimal Distortion ◽  
Space Capsule ◽  
The Right ◽  
Spontaneously Breathing ◽  
Nondependent Lung

Pleural pressure was measured at end expiration in spontaneously breathing anesthetized rabbits. A liquid-filled capsule was implanted into a rib to measure pleural liquid pressure with minimal distortion of the pleural space. Capsule position relative to lung height was measured from thoracic radiographs. Measurements were made when the rabbits were in the prone, supine, right lateral, and left lateral positions. Average lung heights in the prone and supine positions were 4.21 +/- 0.58 and 4.42 +/- 0.51 (SD) cm, respectively (n = 7). Pleural pressure was -2.60 +/- 1.87 (SD) cmH2O at 50.2 +/- 7.75% lung height in the prone position and -3.10 +/- 1.22 cmH2O at 51.4 +/- 6.75% lung height in the supine position. There was no difference between the values recorded in the prone and supine positions. Placement of the capsule into the right or left chest had no effect on the magnitude of the pleural pressure recorded in rabbits in right and left lateral recumbency (n = 12). Measurements over the nondependent lung were repeatable when rabbits were turned between the right and left lateral positions. Lung height in laterally recumbent rabbits averaged 4.55 +/- 0.52 (SD) cm.

Liquid thickness vs. vertical pressure gradient in a model of the pleural space

1987 ◽  
Vol 62 (4) ◽  
pp. 1747-1754 ◽  
Author(s):  
S. J. Lai-Fook ◽  
D. C. Price ◽  
N. C. Staub
Keyword(s):  
Body Position ◽  
Vertical Gradient ◽  
Radioactive Tracer ◽  
Pleural Space ◽  
Pleural Pressure ◽  
Cylindrical Shape ◽  
Liquid Pressure ◽  
Rubber Balloon ◽  
Plastic Cylinder ◽  
Pleural Liquid Pressure

In recent studies using relatively noninvasive techniques, the vertical gradient in pleural liquid pressure was 0.2–0.5 cmH2O/cm ht, depending on body position, and pleural liquid pressure closely approximated lung recoil (J. Appl. Physiol. 59: 597–602, 1985). We built a model to discover why the vertical gradient in pleural pressure is less than hydrostatic (1 cmH2O/cm). A long rubber balloon of cylindrical shape was inflated in a plastic cylinder. The “pleural” space between the balloon and cylinder was filled with blue-dyed water. With the cylinder vertical, we measured pleural pressure by a transducer through side taps at 2-cm intervals up the cylinder. The pressure was measured with different amounts of water in the pleural space. With a clear separation between the balloon and the container, the vertical gradient in pleural liquid pressure was hydrostatic. As water was withdrawn from the pleural space, the balloon approached the wall of the container. Over an 8-cm-long midregion of the model where the balloon diameter matched the cylinder diameter, the vertical gradient was not hydrostatic and was virtually absent. In this region, the pleural liquid pressure was uniform and equal to the recoil of the balloon. In this section we could not see any pleural space. By scintillation imaging using 99mTc-diethylenetriamine pentaacetic acid in the water, we estimated the thickness of this flat “costal” pleural space to be approximately 20 microns. Radioactive tracer injected at the top of the pleural space appeared by 24 h at the bottom, which indicated a slow drainage of liquid by gravity.(ABSTRACT TRUNCATED AT 250 WORDS)

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