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.

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.

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.

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.

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.

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)

Mechanism of the Increased Venous Return and Cardiac Output Caused by Epinephrine

1957 ◽  
Vol 192 (1) ◽  
pp. 126-130 ◽  
Author(s):  
Arthur C. Guyton ◽  
Arthur W. Lindsey ◽  
Berry Abernathy ◽  
Jimmy B. Langston
Keyword(s):  
Cardiac Output ◽  
Pressure Gradient ◽  
Spinal Anesthesia ◽  
Right Atrium ◽  
Venous Return ◽  
Operating Conditions ◽  
Total Spinal Anesthesia ◽  
Vascular Walls ◽  
The Mean ◽  
The Right

The effect of epinephrine on venous return has been measured in 11 dogs under total spinal anesthesia. The mechanism by which epinephrine increases venous return seems to be to increase the tone of the vascular walls thereby increasing the mean circulatory pressure. This in turn increases the pressure gradient forcing blood from the systemic vessels toward the right atrium. By equating the recorded venous return curves with curves that depict the effect of epinephrine on the heart's ability to pump blood, it is shown that under normal operating conditions cardiac output is determined far more by the tendency for blood to return to the heart than by the heart's ability to pump blood.

Pleural liquid pressure measured with rib capsules in anesthetized ponies

1988 ◽  
Vol 64 (1) ◽  
pp. 102-107 ◽  
Author(s):  
L. E. Olson ◽  
S. J. Lai-Fook
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Body Position ◽  
Transpulmonary Pressure ◽  
Vertical Gradient ◽  
Liquid Pressure ◽  
Minimal Distortion ◽  
Poor Ventilation ◽  
Spontaneously Breathing ◽  
Pleural Liquid Pressure

Pleural liquid pressure was measured at end expiration in 11 spontaneously breathing anesthetized ponies in the prone and supine positions. A liquid-filled capsule was implanted into a rib to measure pleural liquid pressure with minimal distortion of the pleural space (Wiener-Kronish et al., J. Appl. Physiol. 59: 597-602, 1985). Capsule position relative to lung height was measured from thoracic radiographs taken in each position. In each body position, pleural liquid pressure was most negative in the superior lung regions and least negative in the inferior lung regions. In the supine position, the magnitude of the vertical gradient in pleural liquid pressure was 0.67 cmH2O/cm ht and was not significantly different from 1 cmH2O/cm ht. In the inferior lung regions (less than 50% lung ht), pleural liquid pressure averaged -1.3 cmH2O, indicating a low transpulmonary pressure over the region of the chest where most of the lung mass is located. When animals were in the prone position, the magnitude of the vertical gradient in pleural liquid pressure was 0.14 cmH2O/cm ht and was not statistically different from 0 cmH2O/cm ht. In each body position, mean transpulmonary pressure, measured postmortem, was similar to the estimated magnitude of pleural liquid pressure at 50% lung ht. This suggests that pleural liquid pressure is closely related to pleural surface pressure. These results are consistent with the poor ventilation distribution and reduced lung volumes measured in anesthetized horses in the supine position compared with values measured in horses in the prone position.

Direct measurement of interstitial pulmonary pressure in in situ lung with intact pleural space

1990 ◽  
Vol 69 (6) ◽  
pp. 2168-2174 ◽  
Author(s):  
G. Miserocchi ◽  
D. Negrini ◽  
C. Gonano
Keyword(s):  
Lateral Position ◽  
Pleural Space ◽  
Measuring System ◽  
Parietal Pleura ◽  
Interstitial Pressure ◽  
Liquid Pressure ◽  
Space Experiments ◽  
Report Data ◽  
Pleural Liquid Pressure

We developed an experimental approach to measure the pulmonary interstitial pressure with the micropuncture technique in in situ lungs with an intact pleural space. Experiments were done in anesthetized paralyzed rabbits that were oxygenated via an endotracheal tube with 50% humidified oxygen and kept in either the supine or the lateral position. A small area of an intercostal space was cleared of the intercostal muscles down to the endothoracic fascia. Subsequently a "pleural window" was opened by stripping the endothoracic fascia over a 0.2-cm2 surface and leaving the parietal pleura (approximately 10 microns thick). Direct micropuncture through the pleural window was performed with 2- to 3-microns-tip pipettes connected to a servo-null pressure-measuring system. We recorded pleural liquid pressure and, after inserting the pipette tip into the lung, we recorded interstitial pressure from subpleural lung tissue. Depth of recording for interstitial pressure averaged 263 +/- 122 (SD) microns. We report data gathered at 26, 53, and 84% lung height (relative to the most dependent portion of the lung). For the three heights, interstitial pressure was -9.8 +/- 3, -10.1 +/- 1.6, and -12.5 +/- 3.7 cmH2O, respectively, whereas the corresponding pleural liquid pressure was -3.4 +/- 0.5, -4.4 +/- 1, and -5.2 +/- 0.3 cmH2O, respectively.

Pleural liquid pressure

1991 ◽  
Vol 71 (2) ◽  
pp. 393-403 ◽  
Author(s):  
E. Agostoni ◽  
E. D'Angelo
Keyword(s):  
Complete Removal ◽  
Vertical Gradient ◽  
Lymphatic Drainage ◽  
Pleural Space ◽  
Parietal Pleura ◽  
Liquid Pressure ◽  
Mechanical Coupling ◽  
The Third ◽  
New Ideas ◽  
Pleural Liquid Pressure

The knowledge of pleural liquid pressure (Pliq) is essential for understanding the mechanical coupling between lung and chest wall and the liquid exchanges of the pleural space. In the last decade, research in this field contributed new ideas and stimulating controversies but also caused some confusion. These aspects, along with the older contributions, are considered in this review, which is divided into three sections. The topics of the first section are 1) measurements of Pliq with different techniques in various mammals and various regions of the pleural space, 2) comparison of Pliq with the pressure exerted by the lung recoil (Ppl), and 3) vertical gradient of Pliq and downward flow of pleural liquid. In the second section the mechanisms absorbing liquid from the pleural space are analyzed: 1) Starling forces of the visceral pleura, 2) lymphatic drainage through the stomata of the parietal pleura, and 3) active transport of solutes. The third section deals with 1) measurements of pleural liquid thickness with two approaches in the costal region of various mammals and 2) mechanisms preventing a complete removal of pleural liquid and, thus, ensuring the lubrication.

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