Influence of state of inflation of the lung on pulmonary vascular resistance

1960 ◽  
Vol 15 (5) ◽  
pp. 878-882 ◽  
Author(s):  
James L. Whittenberger ◽  
Maurice McGregor ◽  
Erik Berglund ◽  
Hans G. Borst
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Flow Resistance ◽  
Transpulmonary Pressure ◽  
Lung Inflation ◽  
Pulmonary Arterial ◽  
Low Levels ◽  
The Relationship ◽  
Complete Collapse

The relationship between the degree of pulmonary inflation and the pulmonary vascular resistance was studied in an open-chested dog preparation. It was possible to control the state of inflation and the blood flow to the lung under study. Vascular resistance could then be observed under controlled conditions. In most cases the resistance at complete collapse was very slightly higher than at moderate levels of inflation. In a few instances collapse was associated with a more marked elevation of resistance. Higher levels of inflation resulted in elevation of vascular resistance. At high levels of pulmonary blood flow and pulmonary arterial pressure, the flow resistance curve is lower than at low levels of blood flow. The resistance values obtained during deflation of the lung were consistently different at equal transpulmonary pressures from those obtained during inflation. The possible reasons for this hysteresis are discussed. Evidence is presented that the increased resistance at high levels of lung inflation is due to the effect of transpulmonary pressure on the vessels surrounding the alveoli. Submitted on January 11, 1960

Relationship between regional lung volume and regional pulmonary vascular resistance

1982 ◽  
Vol 52 (4) ◽  
pp. 914-920 ◽  
Author(s):  
E. M. Baile ◽  
P. D. Pare ◽  
L. A. Brooks ◽  
J. C. Hogg
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Lung Volume ◽  
Regional Blood Flow ◽  
Transpulmonary Pressure ◽  
Simple Relationship ◽  
Volume Curve ◽  
Regional Lung ◽  
Residual Capacity

We have examined the relationship between regional pulmonary vascular resistance (PVRr) and regional lung volume (VLr) to determine whether the decrease in blood flow in the dependent lung (zone 4) was related to lung volume. Regional blood flow (Qr) was measured with radiolabeled macroaggregates at functional residual capacity (FRC) and at transpulmonary pressure of 10 cmH2O (PL10) in 10 anesthetized supine dogs. VLr was determined at FRC by measuring lung density in frozen lung slices and was calculated at PL10 using each dog's pressure-volume curve. We found that when PVRr was expressed as a function of VLr there was not a single relationship between the two. Instead we found two separate U-shaped curves, one at FRC and one at PL10 indicating that the increased vascular resistance at the lung base remained when the lung volume was made uniform by inflation to PL10. This suggests that there is no simple relationship between VLr and PVRr.

Pulmonary vasodilator drugs decrease lung liquid production in fetal sheep

1995 ◽  
Vol 79 (4) ◽  
pp. 1212-1218 ◽  
Author(s):  
J. J. Cummings
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Blood Flow ◽  
Fetal Lung ◽  
Prostaglandin D2 ◽  
Fetal Sheep ◽  
Pulmonary Vasodilator ◽  
Pulmonary Arterial ◽  
Lung Liquid

To examine a potential relationship between pulmonary vasodilatation and fetal lung liquid production, I measured lung liquid production in 20 fetal sheep at 130 +/- 4 days gestation while using several agents known to increase pulmonary blood flow. Thirty-two studies were done in which left pulmonary arterial flow (Qlpa) was measured by an ultrasonic Doppler flow probe and net lung luminal liquid production (Jv) was measured by plotting the change in lung luminal liquid concentration of radiolabeled albumin, an impermeant tracer that was mixed into the lung liquid at the start of each study. Qlpa and Jv were measured during a 1- to 2-h baseline period and then during a 1- to 2-h infusion period in which the fetuses received either an intravenous infusion of acetylcholine (n = 8), prostaglandin D2 (n = 10), or the leukotriene blocker FPL-55712 (n = 7). These vasodilators work by different mechanisms, each mechanism having been implicated in the decrease in pulmonary vascular resistance seen at birth. Control (saline) infusions (n = 7) caused no change in either Qlpa or Jv over 4 h. All vasodilator agents significantly increased pulmonary blood flow and decreased Jv. Pulmonary arterial pressure did not change significantly in either the control, acetylcholine, prostaglandin, or leukotriene-blocker studies, indicating that pulmonary vascular resistance decreased. Thus agents that increase pulmonary blood flow by mechanisms that occur at birth also decrease lung liquid production in fetal lambs.

Pulmonary blood flow, pressure and resistance following tetraethylammonium and aminophylline

1961 ◽  
Vol 200 (2) ◽  
pp. 287-291 ◽  
Author(s):  
M. Harasawa ◽  
S. Rodbard
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Systemic Blood Pressure ◽  
Arterial Blood Flow ◽  
Tetraethylammonium Chloride ◽  
Blood Flows ◽  
Arterial Blood ◽  
Pulmonary Arterial ◽  
Flow Pressure

The effects of tetraethylammonium chloride (TEAC) and aminophylline on the pulmonary vascular resistance were studied in thoracotomized dogs. Pulmonary arterial blood flow and pressure, and systemic blood pressure were measured simultaneously. Both drugs showed marked hypotensive effects on the systemic vessels. In every instance pulmonary arterial pressures and blood flows were reduced by TEAC given via the pulmonary artery and increased by aminophylline. However, the calculated pulmonary vascular resistance remained essentially unchanged in all experiments. These data challenge the concept that the pulmonary vessels respond to these drugs by active vasodilatation

Effect of high intra-alveolar O2 tensions on pulmonary circulation in perfused lungs of dogs

1965 ◽  
Vol 208 (1) ◽  
pp. 130-138 ◽  
Author(s):  
G. J. A. Cropp
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Circulation ◽  
Time Course ◽  
Systemic Circulation ◽  
The Body ◽  
Arterial Blood ◽  
Pulmonary Parenchyma ◽  
Pulmonary Arterial

The resistance to blood flow in the pulmonary circulation of dogs (PVR) increased when their lungs were ventilated with 95–100% oxygen and were perfused with blood that recirculated only through the pulmonary circulation; the systemic circulation was perfused independently. This increase in PVR occurred even when nerves were cut or blocked but was abolished by inhaled isopropylarterenol aerosol. Elevation of intra-alveolar Po2 without increase in pulmonary arterial blood Po2 was sufficient to increase pulmonary vascular resistance. The pulmonary venules or veins were thought to be the likely site of the constriction. These reactions were qualitatively similar to those produced by injection of serotonin or histamine into the pulmonary circulation. The time course of the response and failure to obtain it when the blood was perfused through the remainder of the body before it re-entered the pulmonary circulation are compatible with a theory that high intra-alveolar O2 tension activates a vasoconstrictor material in the pulmonary parenchyma.

Effect of lung inflation and hypoxia on pulmonary arterial blood volume

1977 ◽  
Vol 43 (1) ◽  
pp. 8-13 ◽  
Author(s):  
E. J. Quebbeman ◽  
C. A. Dawson
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Arterial Pressure ◽  
Pressor Response ◽  
Transpulmonary Pressure ◽  
The Other ◽  
Lung Inflation ◽  
Arterial Blood ◽  
Pulmonary Arterial ◽  
Arterial Blood Volume

Isolated cat lungs were perfused with constant blood flow. During control conditions (Pa02, 100 Torr), pulmonary artery pressure increased as the lungs were inflated. Hypoxia (Pa02, 22 Torr) increased arterial pressure. However, as the lungs were inflated arterial pressure fell. Thus, the magnitude of the hypoxic pressor response was reduced by inflation. During control conditions, arterial volume (ether bolus method) increased with increasing transpulmonary pressure. Hypoxia decreased arterial volume, and the increase in arterial volume with inflation was somewhat less than that during control conditions. When the influences of vascular and transpulmonary pressures were examined independently by changing one while holding the other constant, increasing transpulmonary pressure increased arterial volume beyond that which could be accounted for by changes in the differences between arterial and pleural pressure. However, this influence of transpulmonary pressure did not appear to be altered by hypoxia. Thus, while hypoxia decreased arterial volume at all levels of lung inflation, it had relatively little effect on the influence of interdependence between the pulmonary arterial bed and the surrounding lung tissue.

scholarly journals Pulmonary vascular resistance and compliance relationship in pulmonary hypertension

2015 ◽  
Vol 46 (4) ◽  
pp. 1178-1189 ◽  
Author(s):  
Denis Chemla ◽  
Edmund M.T. Lau ◽  
Yves Papelier ◽  
Pierre Attal ◽  
Philippe Hervé
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Circulation ◽  
Arterial Compliance ◽  
Pulmonary Arteries ◽  
Transpulmonary Pressure ◽  
Total Arterial Compliance ◽  
Arterial Load ◽  
Pulmonary Arterial

Right ventricular adaptation to the increased pulmonary arterial load is a key determinant of outcomes in pulmonary hypertension (PH). Pulmonary vascular resistance (PVR) and total arterial compliance (C) quantify resistive and elastic properties of pulmonary arteries that modulate the steady and pulsatile components of pulmonary arterial load, respectively. PVR is commonly calculated as transpulmonary pressure gradient over pulmonary flow and total arterial compliance as stroke volume over pulmonary arterial pulse pressure (SV/PApp). Assuming that there is an inverse, hyperbolic relationship between PVR and C, recent studies have popularised the concept that their product (RC-time of the pulmonary circulation, in seconds) is “constant” in health and diseases. However, emerging evidence suggests that this concept should be challenged, with shortened RC-times documented in post-capillary PH and normotensive subjects. Furthermore, reported RC-times in the literature have consistently demonstrated significant scatter around the mean. In precapillary PH, the true PVR can be overestimated if one uses the standard PVR equation because the zero-flow pressure may be significantly higher than pulmonary arterial wedge pressure. Furthermore, SV/PApp may also overestimate true C. Further studies are needed to clarify some of the inconsistencies of pulmonary RC-time, as this has major implications for our understanding of the arterial load in diseases of the pulmonary circulation.

Persistent fetal pulmonary hypoperfusion after acute hypoxia

1987 ◽  
Vol 253 (4) ◽  
pp. H941-H948 ◽  
Author(s):  
S. H. Abman ◽  
F. J. Accurso ◽  
R. B. Wilkening ◽  
G. Meschia
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Blood Flow ◽  
Acute Hypoxia ◽  
Arterial Blood Flow ◽  
Adrenergic Blockade ◽  
Flow Transducer ◽  
Arterial Blood ◽  
Pulmonary Arterial

To determine the effects of duration of hypoxia on fetal pulmonary blood flow and vasoreactivity, we studied the response of the fetal pulmonary vascular bed before, during, and after prolonged (2-h) and more brief (30-min) exposures to acute hypoxia in 19 chronically instrumented unanesthetized fetal lambs. Left pulmonary arterial blood flow was measured by an electromagnetic flow transducer. Fetal PO2 was lowered by delivering 10-12% O2 to the ewe. During 2-h periods of hypoxia left pulmonary arterial blood flow decreased, and main pulmonary arterial and pulmonary vascular resistance increased. The increase in pulmonary vascular resistance was sustained throughout the 2-h period of hypoxia. After the return of the ewe to room air breathing, pulmonary vascular resistance remained elevated for at least 1 h despite the rapid correction of hypoxemia and in the absence of acidemia. In contrast, after 30 min of hypoxia, left pulmonary arterial blood flow, pulmonary arterial pressure, and pulmonary vascular resistance returned to base-line values rapidly with the termination of hypoxia. The persistent pulmonary hypoperfusion after 2 h of hypoxia was attenuated by alpha-adrenergic blockade and was characterized by a blunted vasodilatory response to increases in fetal PO2. When fetal PO2 was elevated during the posthypoxia period in the presence of alpha-blockade, pulmonary blood flow still remained unresponsive to increases in fetal PO2. We conclude that 2-h periods of acute hypoxia can decrease fetal pulmonary vasoreactivity, and we speculate that related mechanisms may contribute to the failure of the normal adaptation of the pulmonary circulation at birth.

Effect of Norepinephrine on Circulation of the Dog in Hemorrhagic Shock

1956 ◽  
Vol 186 (1) ◽  
pp. 74-78 ◽  
Author(s):  
E. D. Frank ◽  
H. A. Frank ◽  
S. Jacob ◽  
H. A. E. Weizel ◽  
H. Korman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Hemorrhagic Shock ◽  
Renal Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Norepinephrine Infusion ◽  
Pulmonary Arterial

Norepinephrine infusion did not prolong the survival or effect the recovery of dogs in hemorrhagic shock unresponsive to replacement transfusion. During its pressor action in shock, either before or after replacement transfusion, norepinephrine infusion increased coronary, cerebral and adrenal blood flow, reduced renal blood flow, and did not change hepatic blood flow. Cardiac output was increased in oligemic shock but not after blood replacement. Pulmonary arterial pressure and right and left auricular pressures were raised by norepinephrine infusion in all phases of hemorrhagic shock, and calculated pulmonary vascular resistance was reduced.

Effects of lung inflation on longitudinal distribution of pulmonary vascular resistance

1977 ◽  
Vol 43 (6) ◽  
pp. 1089-1092 ◽  
Author(s):  
C. A. Dawson ◽  
D. J. Grimm ◽  
J. H. Linehan
Keyword(s):  
Pulmonary Vascular Resistance ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Transpulmonary Pressure ◽  
Longitudinal Distribution ◽  
Total Blood Volume ◽  
Total Blood ◽  
Lung Inflation ◽  
Low Viscosity ◽  
Vascular Bed

A low-viscosity bolus technique was employed to determine the influence of lung inflation on the distribution of pulmonary vascular resistance in isolated cat lungs. When the lungs were collapsed, the longitudinal distribution of resistance was concentrated near the proximal (arterial) part of the vascular bed. As the lungs were inflated, the resistance became more evenly distributed with the maximum located close to the midpoint of the total blood volume. The fraction of total pressure drop across the lung which occurred proximal to the midpoint of the total lung blood volume decreased from 0.69 in the collapsed lung to 0.43 at a transpulmonary pressure of 16 cmH2O.

Physical factors affecting normal and serotonin-constricted pulmonary vessels

1960 ◽  
Vol 198 (4) ◽  
pp. 864-872 ◽  
Author(s):  
Abraham M. Rudolph ◽  
Peter A. M. Auld
Keyword(s):  
Blood Flow ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Blood Flow ◽  
Venous Pressure ◽  
Physical Factors ◽  
Factors Affecting ◽  
Pulmonary Vessels ◽  
High Flows ◽  
Pulmonary Arterial

The effects of changes of pulmonary blood flow, pulmonary venous and pulmonary arterial pressure on calculated pulmonary vascular resistance were evaluated in open-chest, intact dogs, in which the pulmonary and systemic circulations were separately perfused. Similar observations were made after constricting the pulmonary vessels by continuous infusion of serotonin. An increase in pulmonary blood flow produced a decrease in pulmonary vascular resistance. At high flows, the calculated resistance in the serotonin-constricted vessels could be reduced to levels considered normal at lower flows in normal vessels. An increase of pulmonary venous pressure resulted in a decrease of calculated resistance up to pulmonary venous pressure levels of 15–20 mm Hg in ‘normal’ vessels, but in serotonin-constricted vessels, resistance continued to be decreased by increase of pulmonary venous pressure up to 25–30 mm Hg. These findings confirm that the usual formula for calculating pulmonary vascular resistance assesses only resistance to flow, but does not provide information regarding vascular tone.

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