Effect of positive pressure breathing on lung lymph flow and water content in sheep.

Woolverton, William C.; Brigham, Kenneth L.; Staub, Norman C.

doi:10.1161/01.res.42.4.550

Cited by 52 publications

(19 citation statements)

References 36 publications

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“…However The association of mechanical ventilation and pulmonary edema was made in 1968 (15). It has been repeatedly described in both clinical and animal studies (16)(17)(18)(19). Webb and Tierney (19) have found that alveolar and perivascular edema resulted from ventilation with high inspiratory pressures at low end-expiratory volumes.…”

Section: Resultsmentioning

confidence: 99%

Increased surface tension favors pulmonary edema formation in anesthetized dogs' lungs.

Albert¹,

Lakshminarayan²,

Hildebrandt³

et al. 1979

J. Clin. Invest.

134

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A B S T R A C T The possibility that surface tension may affect the hydrostatic transmural pressure of pulmonary vessels and the development of pulmonary edema was studied in anesthetized, open-chested dogs.Isogravimetric pressure (the static intravascular pressure at which transmural osmotic and hydrostatic pressures are balanced such that net fluid flux is zero and lung weight is constant) was measured in nine animals under three conditions: (a) control, normal surface tension, at an alveolar pressure of 30 cm H20 with the apenic lung at room temperature; (b) after increasing surface tension by cooling and ventilating at a low functional residual capacity, at an alveolar pressure sufficient to produce the same lung volume present during control measurements; and (c) after restoring surface tension by rewarming while holding the lung at a high inflation volume, again at the control lung volume. Lung volumes were established from external dimensions and confirmed + 10% by deflation spirometry. The isogravimetric pressure (relative to alveolar pressure) was significantly less with increased surface tension than during either the initial control condition (P < 0.01), or when the surface tension has been restored (P < 0.01). Similar changes occurred in each ofthree additional studies performed with control alveolar pressures of 10 cm H20. Thus, increased surface tension favors fluid leakage presumably because it increases the microvascular transmural pressure.

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Section: Resultsmentioning

confidence: 99%

Increased surface tension favors pulmonary edema formation in anesthetized dogs' lungs.

Albert¹,

Lakshminarayan²,

Hildebrandt³

et al. 1979

J. Clin. Invest.

134

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“…Since, through most of our experiment, the entire lung was in zone III (West et al, 1964), the assumptions used in calculating pulmonary microvascular pressure are more likely valid than under normal hemodynamic conditions. Second, we assumed that interstitial hydrostatic pressure equalled alveolar pressure (Woolverton et al, 1978). It is certainly likely that as the fluid filtration rate increased, perimicrovascular pressure increased (Taylor et al, 1973).…”

Section: Discussionmentioning

confidence: 99%

“…It is certainly likely that as the fluid filtration rate increased, perimicrovascular pressure increased (Taylor et al, 1973). This local increase in interstitial pressure would aid fluid flux through the interstitial space resulting in formation of perivascular and peribronchial fluid cuffs (Staub, 1978). The extent to which fluid flux through the interstitium may modulate changes in interstitial pressure around exchanging vessels during formation of pulmonary edema is unknown.…”

Section: Discussionmentioning

confidence: 99%

“…We calculated the pulmonary microvascular pressure (Pmv) by assuming that 60% of the total pulmonary vascular resistance is precapillary (Gaar et al, 1967) and that the distribution of vascular resistance does not change. These data were used to estimate the net pulmonary microvascular fluid filtration pressure (£p) as follows: £ P = Pmv -(wp -TTL)-Since we did not have estimates of interstitial hydrostatic pressure in these experiments, we assumed that interstitial pressure for the fluid exchange vessels was equal to end-expiratory alveolar pressure (Woolverton et al, 1978). We also assumed that the reflection coefficients for albumin and globulin were unity and remained constant throughout the experiment.…”

Section: Analysis Of Samples and Datamentioning

confidence: 99%

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The dynamics of the lung fluid filtration system in dogs with edema.

Gee¹,

Spath²

1980

Circulation Research

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SUMMARY We studied the relationship between pulmonary microvasculature fluid filtration pressures and lung lymph flow rate (Q L ) as filtration pressures increased to determine why lungs with functional lymphatics become edematous and, as filtration pressures decreased, to determine the effect of edema formation on lymphatic function. Edema was induced by rapid intravenous infusion of neutralized Ringer's solution in a volume equivalent to 30% of body weight in seven anesthetized dogs. Pulmonary microvascular pressure (Pmv) and (JL increased to 58 cm H2O and 40 ml/hr, respectively, during the infusion. Initially, QL increased slowly and the estimated net fluid filtration pressure (£p) increased rapidly with infusion. Later in the 30-minute infusion period, small increases in £ P produced greater changes in Q L . Over a 3-hour postinfusion period, Pmv and Q L decreased, but they remained significantly greater than baseline levels. During the postinfusion period, Q L was a linear function of Pmv and a logarithmic function of £P. Extravascular lung water content, measured postmortem, was 70% greater than normal. The relationship between Q L and £P during and after the infusion demonstrated marked hysteresis. These results suggest that extravascular fluid accumulated in the lung in part because the lymphatics responded relatively slowly to rapid increases in £ P . Furthermore, the data suggest that, although the lymphatics may not be a quantitatively important route for removal of edema fluid, the pressure-volume characteristics of the pulmonary interstitium seem to have a major influence on lymphatic function. Circ Res 46: 796-801, 1980 DURING development of pulmonary edema, lymphatic function may determine in what manner and to what degree fluid accumulates in the extravascular space of the lung. Erdmann et al. (1975) measured lung lymph flow rates in unanesthetized sheep subjected to steady state elevations in left atrial pressure. They found that each cm H 2 O increase in pulmonary microvascular pressure resulted in an increase in lymph flow rate of about 0.5 ml/hr with no apparent maximum in lymph flow rate over the pressure range studied. However, their data suggest that the rapidity of the response of the lymphatics to a change in transvascular fluid dynamics is a factor that must be considered in studying the relationship between lymph formation and the accumulation of pulmonary extravascular fluid.After development of pulmonary edema, the lymphatics may continue the normal function of conservation of plasma filtrate. In addition, they may function as conduits for removing accumulated extravascular fluid (Pine et al., 1976). We designed experiments to study the dynamics of transvascular fluid flux and lymph flow during and after development of pulmonary edema. Our results suggest that extravascular fluid accumulated in the lung in part because the lymphatic system responded relatively slowly to a rapid increase in the net fluid filtration rate. Furthermore, the pressure-volume characteristics of the pulmo...

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“…Thus, the use of PEEP is limited in certain cases of ARDS. During ventilation with PEEP the transvascular flux of lung water has been found either to be increased (8) or to be unchanged (9)(10)(11)(12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

Continuous Negative External Chest Pressure Decreases Transvascular Lung Water Transport in Sheep after Pseudomonas Bacteremia

Krumpe¹,

Gorin²

1981

J. Clin. Invest.

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A B S T R A C T We studied the effects of continuous negative external chest pressure (CNECP) produced by a cuirass appliance on lung water and protein transport in sheep with chronic lung lymphatic fistulas. We compared data obtained during periods of mechanical ventilation (base line) to period of CNECP, using identical ventilatory support. Three groups were studied: six sheep were studied before and after application of CNECP for 1 h (control) and again after induction of a pulmonary vascular permeability defect (PVPD) by infusing live Pseudomonas bacteria (group I); another six sheep were studied under control conditions before and after prolonged application of CNECP for over 4 h (group II); 10 sheep were studied 24 h after a Pseudomonas infusion (PVPD), before and after 4 h of CNECP (group III).Compared to base-line data, CNECP produced significant increases in functional residual capacity and decreases in pulmonary blood volume, pulmonary artery pressure, and left atrial pressure in all groups. Lung lymph flow (QL) was unchanged during the 1st h of CNECP and therefore was not significantly different from base line in group I, but after prolonged CNECP a steady-state decrease in QL as well as a decrease in lung albumin transport was found in groups II and III (P < 0.05 by paired t test). We postulate that decreased pleural pressure during CNECP produces decreased hydrostatic filtration pressures, thereby decreasing QL. Reduction of both convective forces as well as microvascular surface area available for solute exchange account for decreases in lung albumin transport. Histologic examination and gravimetric studies on four sheep failed to demonstrate increase in lung water accumulation after 4 h of CNECP. We conclude that CNECP mechanically reversed the PVPD in our group III sheep. These physiologic effects of CNECP may be of benefit in the management of patients with adult respiratory distress syndrome.

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Effect of positive pressure breathing on lung lymph flow and water content in sheep.

Cited by 52 publications

References 36 publications

Increased surface tension favors pulmonary edema formation in anesthetized dogs' lungs.

Increased surface tension favors pulmonary edema formation in anesthetized dogs' lungs.

The dynamics of the lung fluid filtration system in dogs with edema.

Continuous Negative External Chest Pressure Decreases Transvascular Lung Water Transport in Sheep after Pseudomonas Bacteremia

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