Alveolar liquid pressure measured by micropipettes in isolated dog lung

1982 ◽  
Vol 53 (3) ◽  
pp. 737-743 ◽  
Author(s):  
S. J. Lai-Fook ◽  
K. C. Beck
Keyword(s):  
Interstitial Fluid ◽  
Total Lung Capacity ◽  
Fluid Pressure ◽  
Transpulmonary Pressure ◽  
Initial Weight ◽  
Liquid Pressure ◽  
Lung Inflation ◽  
Main Determinant ◽  
Lung Capacity ◽  
Alveolar Surface

Micropipettes (2–5 microns), in conjunction with a servo-nulling system, were used to measure liquid pressure (Pliq) in subpleural alveoli of lobes of dog lungs made edematous by perfusing with plasma to a constant extravascular weight gain (W). Pliq was measured at fixed transpulmonary pressure (Ptp) in lungs whose W was more than 0.5 that of the initial weight (Wi). In six lobes at W/Wi = 0.6, Pliq, relative to alveolar pressure (Palv), was -2.6 +/- 0.4 cmH2O (mean +/- SE), -11.8 +/- 0.6, and -17.5 +/- 1.7 at deflation Ptp values of 5, 15, and 25 cmH2O, respectively. The Pliq increased to -2, -7, and -13.7, respectively, at W/Wi = 2.8. Based on a mean alveolar radius of 50 micron at Ptp at 25 cmH2O and values of Palv - Pliq, values for alveolar surface tension (tau) at W/Wi = 0.6 were 6, 30, and 44 dyn/cm at Ptp of 5, 15, and 25 cmH2O, respectively. In five other lobes at W/Wi = 0.5 and at 65 and 84% total lung capacity, tau was much higher on lung inflation than on deflation. If pericapillary interstitial fluid pressure (Pi) and Pliq were identical under edematous conditions, tau would be the main determinant of Pi.

Alveolar surface tension, lung inflation, and hydration affect interstitial pressure [Px(f)]

1984 ◽  
Vol 57 (1) ◽  
pp. 262-270 ◽  
Author(s):  
W. Hida ◽  
J. Hildebrandt
Keyword(s):  
Interstitial Fluid ◽  
Total Lung Capacity ◽  
Fluid Pressure ◽  
Transpulmonary Pressure ◽  
Mineral Oil ◽  
Interstitial Pressure ◽  
Alveolar Pressure ◽  
Lung Inflation ◽  
Lung Capacity ◽  
Alveolar Surface

Peribronchoarterial interstitial fluid pressure [Px(f)] was measured by wicks inserted between bronchus and artery of dog lobes filled with air, saline, 6% dextran in saline, or mineral oil. Five inflations were made to total lung capacity, with one min stops at eight selected volume levels in each cycle. Deflation recoil (measured as transpulmonary pressure, Ptp) was largest for air and least for saline and dextran, and it fell between these extremes for mineral oil. Correspondingly, Px(f) was most negative for air, slightly less negative for mineral oil, and least for saline and dextran. On the first cycle, the Px(f) for saline and dextran were nearly equal, but in later cycles Px(f) with saline drifted fairly rapidly toward alveolar pressure. By plotting Px(f) vs. Ptp, all first-cycle curves were brought toward a single line. During later cycles, Ptp and Px(f) always changed together along this line, except for saline. We conclude that 1) at fixed vascular pressure, Px(f) depends mainly on Ptp and less on lung volume; 2) large changes in Px(f) with saline suggest that at least some fluid can enter this interstitial space quite rapidly; and 3) peripheral tissue swelling with saline causes some reduction in Ptp, and both swelling and lower recoil contribute to increased trapping of saline.

Perivascular interstitial fluid pressure measured by micropipettes in isolated dog lung

1982 ◽  
Vol 52 (1) ◽  
pp. 9-15 ◽  
Author(s):  
S. J. Lai-Fook
Keyword(s):  
Interstitial Fluid ◽  
Fluid Pressure ◽  
Transpulmonary Pressure ◽  
Alveolar Pressure ◽  
Lung Weight ◽  
Lung Inflation ◽  
Water Accumulation ◽  
The Right ◽  
Alveolar Surface ◽  
Lung Lobes

Micropipettes in conjunction with a servo-nulling system were used to measure fluid pressure (Pf) in the interstitium around the partially exposed vein near the hilus of the right upper lung lobes of the dog. Lobes were studied at constant transpulmonary pressure (Ptp). In the absence of extravascular water accumulation, Pf was -1.5 cmH2O relative to pleural pressure at Ptp of 6 cmH2O and vascular pressure (Pv) of 0 cmH2O and was more negative in lobes tested at higher Ptp values. In five lobes made edematous with plasma at Ptp of 6 cmH2O and Pv of 15 cmH2O, mean Pf increased from -1 to 4.4 cmH2O as lung weight increased up to 400% of the initial excised weight. In four other lobes, at Ptp of 15 cmH2O and Pv of 20 cmH2O, Pf increased from -2.4 to 8.8 for a similar increase in weight. In lobes degassed and filled with saline or plasma, Pf always equilibrated to alveolar pressure (PA). Results suggest that alveolar surface tension (tau) in air-filled lobes with gross edema prevented Pf from reaching PA. Reduction in Pf below PA was larger at higher Ptp, consistent with increased tau with lung inflation.

Pressure-volume behavior of perivascular interstitium measured in isolated dog lung

1980 ◽  
Vol 48 (6) ◽  
pp. 939-946 ◽  
Author(s):  
S. J. Lai-Fook ◽  
B. Toporoff
Keyword(s):  
Interstitial Fluid ◽  
Venous Pressure ◽  
Fluid Pressure ◽  
Transpulmonary Pressure ◽  
Interstitial Fluid Pressure ◽  
Alveolar Pressure ◽  
Lung Weight ◽  
Lung Volumes ◽  
Water Accumulation ◽  
Alveolar Surface

Pulmonary perivascular interstitial fluid pressure (Px) was measured as a function of extravascular water accumulation (W). Px was measured directly by wick catheters and open-ended needles inserted in the interstitium near the hilus of isolated perfused dog lobes. Lobes were studied at constant transpulmonary pressure (Ptp) and vascular pressure (Pv, arterial equal to venous pressure). Px-W behavior had two distinct phases: an initial low compliance phase interpreted as perivascular filling, followed sometimes by an abrupt transition to a high compliance phase interpreted as alveolar flooding. W at transition was between 20 and 50% of the initial lung weight. Perivascular compliance during filling at a Ptp of 6 cmH2O was 0.1 g.g wet lobe wt-1.cmH2O-1, which was one-sixth that during alveolar flooding and 2.5 times that at a Ptp of 25 cmH2O. At the start of alveolar flooding, estimated alveolar interstitial fluid pressure was slightly (2 cmH2O) below alveolar pressure (PAlv) at a Ptp of 6 cmH2O but considerably belov PAlv at high lung volumes. These findings support the concept that alveolar surface tension reduces the interstitial fluid pressure below PAlv.

Effect of lung inflation in vivo on airways with smooth muscle tone or edema

1997 ◽  
Vol 82 (2) ◽  
pp. 491-499 ◽  
Author(s):  
Robert H. Brown ◽  
Wayne Mitzner ◽  
Yonca Bulut ◽  
Elizabeth M. Wagner
Keyword(s):  
Smooth Muscle ◽  
Total Lung Capacity ◽  
Muscle Tone ◽  
Transpulmonary Pressure ◽  
Airway Wall ◽  
Lung Inflation ◽  
Airway Narrowing ◽  
Lung Capacity ◽  
Luminal Area

Brown, Robert H., Wayne Mitzner, Yonca Bulut, and Elizabeth M. Wagner. Effect of lung inflation in vivo on airways with smooth muscle tone or edema. J. Appl. Physiol. 82(2): 491–499, 1997.—Fibrous attachments to the airway wall and a subpleural surrounding pressure can create an external load against which airway smooth muscle must contract. A decrease in this load has been proposed as a possible cause of increased airway narrowing in asthmatic individuals. To study the interaction between the airways and the surrounding lung parenchyma, we investigated the effect of lung inflation on relaxed airways, airways contracted with methacholine, and airways made edematous by infusion of bradykinin into the bronchial artery. Measurements were made in anesthetized sheep by using high-resolution computed tomography to visualize changes in individual airways. During methacholine infusion, airway area was decreased but increased minimally with increases in transpulmonary pressure. Bradykinin infusion caused a 50% increase in airway wall area and a small decrease in airway luminal area. In contrast to airways contracted with methacholine, the luminal area after bradykinin increased substantially with increases in transpulmonary pressure, reaching 99% of the relaxed area at total lung capacity. Thus airway edema by itself did not prevent full distension of the airway at lung volumes approaching total lung capacity. Therefore, we speculate that if a deep inspiration fails to relieve airway narrowing in vivo, this must be a manifestation of airway smooth muscle contraction and not airway wall edema.

Effects of surfactant on the in vivo alveolar surface-to-volume ratio

1996 ◽  
Vol 80 (1) ◽  
pp. 86-90 ◽  
Author(s):  
N. Miyazawa ◽  
S. Suzuki ◽  
T. Akahori ◽  
T. Okubo
Keyword(s):  
Surface Tension ◽  
Pulmonary Surfactant ◽  
Total Lung Capacity ◽  
Volume Ratio ◽  
Transpulmonary Pressure ◽  
Mean Free Path ◽  
Lung Capacity ◽  
Alveolar Surface ◽  
Saline Lavage

To investigate how pulmonary surfactant influences alveolar structure in vivo, we examined the alveolar surface area-to-lung volume (S/V) ratio of the lung parenchyma of a live dog by light-scattering stereology before and after saline lavage. We measured the backscattered light pattern produced by applying a laser beam to the pleural surface of a ventilated animal and obtained the S/V [equivalent to the inverse of the optical mean free path (lambda)]. After saline lavage, V at transpulmonary pressure (P) of 30 cmH2O (defined as total lung capacity) decreased by 11.1 +/- 3.1% (SD) and the P-V curve shifted to a lower V. The lambda-V curve was shifted to a higher lambda and to a lower V after saline lavage. S/V decreased after saline lavage (lambda increased by 38 +/- 27% on the deflation limb at a V of 80% of control total lung capacity). The alveolar surface tension increased after saline lavage, and the increase in surface tension was greater on inflation than on deflation. We conclude that depletion of pulmonary surfactant increases the alveolar surface tension in vivo, resulting in a decrease in S/V.

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.

Factors determining degree of inflation in intratracheally fixed rat lungs

1980 ◽  
Vol 48 (2) ◽  
pp. 389-393 ◽  
Author(s):  
G. Hayatdavoudi ◽  
J. D. Crapo ◽  
F. J. Miller ◽  
J. J. O'Neil
Keyword(s):  
Slow Rate ◽  
Total Lung Capacity ◽  
Formaldehyde Solution ◽  
Initial Flow ◽  
Lung Inflation ◽  
Lung Capacity ◽  
Final Degree ◽  
Low Rate

The total lung capacity (TLC) of rats was measured in vivo and was compared to the displacement volume of the lungs following intratracheal fixation with glutaraldehyde or formaldehyde solution. When glutaraldehyde was used the speed of infusion of the fixative was an important factor in the final degree of lung inflation achieved. With a low rate of fixative infusion and a final pressure of 20 cm of fixative the glutaraldehyde-fixed lungs inflated to 55% TLC. With a high initial flow of glutaraldehyde and a final pressure of 20 cm of fixative the lungs inflated to 84% TLC. Fixation of lungs inside the intact chest wall was found to result in a higher degree of inflation. With a reservoir height of 20 cm and a low rate of fixative infusion lungs fixed in situ reached 74% TLC, whereas lungs fixed in situ, but from animals that have been exsanguinated prior to fixation, inflated to only 58% TLC. This suggests that the volume of the blood in the lungs prior to infusion of glutaraldehyde influences the degree of inflation achieved. Formaldehyde-fixed lungs required 72 h to be completely fixed and they were inflated to 90% TLC when a reservoir height of 20 cm was used. Because of the slow rate of fixation using with formaldehyde solution the rate of infusion was found not to limit the degree of inflation that could be achieved.

Comparison of balloon and transducer catheters for estimating lung elasticity

1992 ◽  
Vol 72 (1) ◽  
pp. 231-235 ◽  
Author(s):  
J. A. Panizza ◽  
K. E. Finucane
Keyword(s):  
Elastic Properties ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Least Squares Method ◽  
Balloon Catheter ◽  
Transpulmonary Pressure ◽  
Repeatability Coefficient ◽  
Lung Capacity ◽  
Acceptable Alternative ◽  
Paired T Test

Pleural pressure is usually estimated with a balloon catheter (BC) positioned in the middle third of the esophagus. An alternate method, which avoids potential inaccuracies associated with changes in balloon volume, is a catheter-mounted transducer (CMT) system. To assess the accuracy of a CMT system in defining the elastic properties of the lungs, we compared the static pressure-volume (PV) properties of the lungs measured sequentially with CMT and BC systems in six healthy subjects each on two occasions, relating static transpulmonary pressure (Pst,L) to lung volume during interrupted exhalations from total lung capacity (TLC). PV data were fitted with an exponential function (least-squares method), and the exponent (k) was used to define the shape of the PV curve; position was defined by Pst,L at TLC and at 90 and 60% TLC. These data were examined for agreement (paired t test) and repeatability (coefficient of repeatability). No significant differences were demonstrated: k was 0.10 +/- 0.02 and 0.11 +/- 0.03 (SD) and Pst,L at 60% TLC was 8.27 +/- 2.09 and 8.37 +/- 1.63 cmH2O for the CMT and BC systems, respectively. The coefficient of repeatability for each parameter was not significantly different but was consistently less with the BC, suggesting better repeatability. We conclude that a CMT system is an acceptable alternative to a BC system for defining the elastic properties of lungs.

Effect of parenchyma and length changes on vessel pressure-diameter behavior in pig lungs

1979 ◽  
Vol 47 (4) ◽  
pp. 666-669 ◽  
Author(s):  
S. J. Lai-Fook ◽  
R. E. Hyatt
Keyword(s):  
Arterial Pressure ◽  
Interstitial Fluid ◽  
Fluid Pressure ◽  
Physiological Changes ◽  
Arterial Segment ◽  
Lung Inflation ◽  
Intact State ◽  
Direct Measurements ◽  
Residual Capacity ◽  
Length Changes

At several transpulmonary pressures (Ptp), the pressure-diameter (PD) behavior of the largest intraparenchymal arterial segment in the isolated pig lung was compared with the behavior of the segment after its excision from the parenchyma and its extension to lengths equivalent to those in the intact state. For physiological changes in length, as may occur with lung inflation during Ptp changes from 4 to 25 cmH2O, excised-vessel diameters did not change significantly at a constant transmural pressure. The excised-vessel PD behavior was not significantly different from the intact-vessel PD behavior at a Ptp of 4 cmH2O. At any constant arterial pressure, intact-vessel diameters became larger as Ptp increased. Estimates of the perivascular pressure (Px) obtained by directly comparing intact-vessel and excised-vessel PD curves were as follows: 1) Px was equal to pleural pressure at a Ptp approximating the functional residual capacity; 2) Px decreased almost linearly as Ptp increased; and 3) Px decreased with a fall in arterial pressure. These results are consistent with direct measurements of the perivascular interstitial fluid pressure.

Size distribution of recruited alveolar volumes in airway reopening

2000 ◽  
Vol 89 (5) ◽  
pp. 2030-2040 ◽  
Author(s):  
Béla Suki ◽  
Adriano M. Alencar ◽  
József Tolnai ◽  
Tibor Asztalos ◽  
Ferenc Peták ◽  
...  
Keyword(s):  
Size Distribution ◽  
Total Lung Capacity ◽  
Transpulmonary Pressure ◽  
Wave Tube ◽  
Pressure Oscillations ◽  
Lung Capacity ◽  
Impedance Data ◽  
Tissue Elastance ◽  
Good Agreement ◽  
Lung Lobes

In 11 isolated dog lung lobes, we studied the size distribution of recruited alveolar volumes that become available for gas exchange during inflation from the collapsed state. Three catheters were wedged into 2-mm-diameter airways at total lung capacity. Small-amplitude pseudorandom pressure oscillations between 1 and 47 Hz were led into the catheters, and the input impedances of the regions subtended by the catheters were continuously recorded using a wave tube technique during inflation from −5 cmH2O transpulmonary pressure to total lung capacity. The impedance data were fit with a model to obtain regional tissue elastance (Eti) as a function of inflation. First, Eti was high and decreased in discrete jumps as more groups of alveoli were recruited. By assuming that the number of opened alveoli is inversely proportional to Eti, we calculated from the jumps in Eti the distribution of the discrete increments in the number of opened alveoli. This distribution was in good agreement with model simulations in which airways open in cascade or avalanches. Implications for mechanical ventilation may be found in these results.

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