scholarly journals Effects of inertial load and countermeasures on the distribution of pulmonary blood flow

2000 ◽  
Vol 89 (2) ◽  
pp. 445-457 ◽  
Author(s):  
Myron A. Chornuk ◽  
Susan L. Bernard ◽  
John W. Burns ◽  
Robb W. Glenny ◽  
Don D. Sheriff ◽  
...  
Keyword(s):  
Blood Flow ◽  
Air Force ◽  
Pulmonary Blood Flow ◽  
Inertial Force ◽  
Flow Distribution ◽  
Pulmonary Vasculature ◽  
Positive Pressure ◽  
Anatomic Structure ◽  
Air Force Base ◽  
Air Force Research Laboratory

We assessed the influence of cranial-to-caudal inertial force (+G z ) and the countermeasures of anti-G suit and positive pressure breathing during G (PBG), specifically during +G z , on regional pulmonary blood flow distribution. Unanesthetized swine were exposed randomly to 0 G z (resting), +3 G z , +6 G z , and +9 G z , with and without anti-G suit and PBG with the use of the Air Force Research Laboratory centrifuge at Brooks Air Force Base (the gravitational force of the Earth, that is, the dorsal-to-ventral inertial force, was present for all runs). Fluorescent microspheres were injected into the pulmonary vasculature as a marker of regional pulmonary blood flow. Lungs were excised, dried, and diced into ∼2-cm3 pieces, and the fluorescence of each piece was measured. As +G z was increased from 0 to +3 G z , blood flow shifted from cranial and hilar regions toward caudal and peripheral regions of the lung. This redistribution shifted back toward cranial and hilar regions as anti-G suit inflation pressure increased at +6 and +9 G z . Perfusion heterogeneity increased with +G z stress and decreased at the higher anti-G suit pressures. The distribution of pulmonary blood flow was not affected by PBG. ANOVA indicated anatomic structure as the major determinant of pulmonary blood flow.

Pulmonary blood flow redistribution by increased gravitational force

1998 ◽  
Vol 84 (4) ◽  
pp. 1278-1288 ◽  
Author(s):  
Michael P. Hlastala ◽  
Myron A. Chornuk ◽  
David A. Self ◽  
Harry J. Kallas ◽  
John W. Burns ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coefficient Of Variation ◽  
Pulmonary Blood Flow ◽  
Inertial Force ◽  
Blood Gases ◽  
Zone Model ◽  
Arterial Blood ◽  
Entire Experiment ◽  
Air Force Base ◽  
Laboratory Centrifuge

This study was undertaken to assess the influence of gravity on the distribution of pulmonary blood flow (PBF) using increased inertial force as a perturbation. PBF was studied in unanesthetized swine exposed to −G x (dorsal-to-ventral direction, prone position), where G is the magnitude of the force of gravity at the surface of the Earth, on the Armstrong Laboratory Centrifuge at Brooks Air Force Base. PBF was measured using 15-μm fluorescent microspheres, a method with markedly enhanced spatial resolution. Each animal was exposed randomly to −1, −2, and −3 G x . Pulmonary vascular pressures, cardiac output, heart rate, arterial blood gases, and PBF distribution were measured at each G level. Heterogeneity of PBF distribution as measured by the coefficient of variation of PBF distribution increased from 0.38 ± 0.05 to 0.55 ± 0.11 to 0.72 ± 0.16 at −1, −2, and −3 G x , respectively. At −1 G x , PBF was greatest in the ventral and cranial and lowest in the dorsal and caudal regions of the lung. With increased −G x , this gradient was augmented in both directions. Extrapolation of these values to 0 G predicts a slight dorsal (nondependent) region dominance of PBF and a coefficient of variation of 0.22 in microgravity. Analysis of variance revealed that a fixed component (vascular structure) accounted for 81% and nonstructure components (including gravity) accounted for the remaining 19% of the PBF variance across the entire experiment (all 3 gravitational levels). The results are inconsistent with the predictions of the zone model.

Mechanisms of improvement in pulmonary gas exchange during isovolemic hemodilution

1999 ◽  
Vol 87 (1) ◽  
pp. 132-141 ◽  
Author(s):  
Steven Deem ◽  
Richard G. Hedges ◽  
Steven McKinney ◽  
Nayak L. Polissar ◽  
Michael K. Alberts ◽  
...  
Keyword(s):  
Blood Flow ◽  
Fractal Dimension ◽  
Gas Exchange ◽  
Spatial Correlation ◽  
Pulmonary Blood Flow ◽  
Minute Ventilation ◽  
Flow Distribution ◽  
Pulmonary Gas Exchange ◽  
Normal Lung ◽  
Blood Flow Distribution

Severe anemia is associated with remarkable stability of pulmonary gas exchange (S. Deem, M. K. Alberts, M. J. Bishop, A. Bidani, and E. R. Swenson. J. Appl. Physiol. 83: 240–246, 1997), although the factors that contribute to this stability have not been studied in detail. In the present study, 10 Flemish Giant rabbits were anesthetized, paralyzed, and mechanically ventilated at a fixed minute ventilation. Serial hemodilution was performed in five rabbits by simultaneous withdrawal of blood and infusion of an equal volume of 6% hetastarch; five rabbits were followed over a comparable time. Ventilation-perfusion (V˙a/Q˙) relationships were studied by using the multiple inert-gas-elimination technique, and pulmonary blood flow distribution was assessed by using fluorescent microspheres. Expired nitric oxide (NO) was measured by chemiluminescence. Hemodilution resulted in a linear fall in hematocrit over time, from 30 ± 1.6 to 11 ± 1%. Anemia was associated with an increase in arterial [Formula: see text] in comparison with controls ( P < 0.01 between groups). The improvement in O2 exchange was associated with reducedV˙a/Q˙heterogeneity, a reduction in the fractal dimension of pulmonary blood flow ( P = 0.04), and a relative increase in the spatial correlation of pulmonary blood flow ( P = 0.04). Expired NO increased with anemia, whereas it remained stable in control animals ( P < 0.0001 between groups). Anemia results in improved gas exchange in the normal lung as a result of an improvement in overallV˙a/Q˙matching. In turn, this may be a result of favorable changes in pulmonary blood flow distribution, as assessed by the fractal dimension and spatial correlation of blood flow and as a result of increased NO availability.

Pulmonary blood flow distribution after the total cavopulmonary connection for complex cardiac anomalies

1999 ◽  
Vol 14 (3) ◽  
pp. 154-160 ◽  
Author(s):  
Masao Tayama ◽  
Nobuaki Hirata ◽  
Tohru Matsushita ◽  
Tetsuya Sano ◽  
Norihide Fukushima ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Total Cavopulmonary Connection ◽  
Blood Flow Distribution ◽  
Cardiac Anomalies ◽  
Cavopulmonary Connection

The pulmonary vasculature in a neonatal porcine model with increased pulmonary blood flow and pressure

2001 ◽  
Vol 11 (4) ◽  
pp. 420-430 ◽  
Author(s):  
Elisabeth V. Stenbøg ◽  
Daniel A. Steinbrüchel ◽  
Anne Bloch Thomsen ◽  
Ulrik Baandrup ◽  
Lene Heickendorff ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Vascular Disease ◽  
Pulmonary Blood Flow ◽  
Left Pulmonary Artery ◽  
Pulmonary Vasculature ◽  
Pulmonary Vascular Disease ◽  
Systolic Pulmonary Arterial Pressure ◽  
Pulmonary Arterial ◽  
Circulating Levels

Introduction: Hypertension and hyperperfusion of the pulmonary vascular bed in the setting of congenital cardiac malformations may lead to progressive pulmonary vascular disease. To improve the understanding of the basic mechanisms of this disease, there is a need for clinically relevant animal models which reflect the disease process. Material and Results: We randomly allocated 45 newborn pigs, at the age of 48 hrs, to groups in which there was either construction of a 3 mm central aorto-pulmonary shunt, undertaken in 9, or ligation of the left pulmonary artery, achieved in 13. Controls included sham operations in 13, or no operations in 10 pigs. Follow-up was continued for three months. The interventions were compatible with survival in most pigs. The shunts resulted in an acute 85% increase in systolic pulmonary arterial pressure, and a more than twofold increase in pulmonary blood flow. By three months of age, nearly all shunts had closed spontaneously, and haemodynamics were normal. Ligation of the left pulmonary artery resulted in a normal total pulmonary blood flow, despite only the right lung being perfused, and a 33% increase in systolic pulmonary arterial pressure. These haemodynamic changes were maintained throughout the period of study. In both groups, histomorphometry revealed markedly increased muscularity of the intra-acinar pulmonary arteries. Circulating levels of endothelin were normal in the shunted animals, and elevated in those with ligation of the left pulmonary artery. Conclusion: In neonatal porcine models of pulmonary vascular disease, created by construction of 3 mm central aorto-pulmonary shunts and ligation of one pulmonary artery, we observed histopathological changes of the pulmonary vasculature similar to early hypertensive pulmonary vascular disease in humans. Elevated circulating levels of endothelin were associated with abnormal haemodynamics rather than abnormal pathology. These findings could be valuable for future studies on the pathogenesis of hypertensive pulmonary vascular disease associated with congenital cardiac malformations.

scholarly journals Pulmonary NO synthase inhibition and inspired CO2: effects on V ′/Q ′ and pulmonary blood flow distribution

2000 ◽  
Vol 16 (2) ◽  
pp. 288 ◽  
Author(s):  
T.V. Brogan ◽  
R.G. Hedges ◽  
S. McKinney ◽  
H.T. Robertson ◽  
M.P. Hlastala ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
No Synthase ◽  
Blood Flow Distribution ◽  
Co2 Effects

Pulmonary Blood Flow Distribution during Normal Ambulation

Respiration ◽  
1974 ◽  
Vol 31 (4) ◽  
pp. 289-295
Author(s):  
M. Arborelius, jr. ◽  
V. Lopéz-Majano ◽  
R.C. Reba ◽  
T.K. Natarajan
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution

scholarly journals Headed in the Wrong Direction: Chronic and Acute Derangements in Pulmonary Blood Flow Distribution in a Patient with Severe Pulmonary Vein Stenosis

2019 ◽  
Vol 16 (10) ◽  
pp. 1321-1326 ◽  
Author(s):  
Luisa Morales-Nebreda ◽  
Christopher S. Chung ◽  
Rishi Agrawal ◽  
Anjana V. Yeldandi ◽  
Benjamin D. Singer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Vein ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Pulmonary Vein Stenosis ◽  
Blood Flow Distribution ◽  
Wrong Direction ◽  
Vein Stenosis

Effects of pulmonary edema on regional pulmonary perfusion in the intact dog lung

1980 ◽  
Vol 49 (5) ◽  
pp. 834-840 ◽  
Author(s):  
A. B. Malik ◽  
H. van der Zee ◽  
P. H. Neumann ◽  
N. B. Gertzberg
Keyword(s):  
Blood Flow ◽  
Pulmonary Edema ◽  
Pulmonary Blood Flow ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Weight Ratio ◽  
Flow Distribution ◽  
Base Line ◽  
Dependent Lung ◽  
Lung Water ◽  
Pulmonary Hemodynamics

Regional pulmonary blood flow was determined in dogs during varying degrees of pulmonary edema induced by infusing 179.2-659.4 ml/kg normal saline over 2-3 h. Pulmonary hemodynamics and regional blood flows were measured during the base-line period and at 30 min postinfusion. The degree of pulmonary edema was determined by the final extravascular lung water-to-bloodless dry lung weight ratio (W/D). In dogs developing gross alveolar edema (W/D of 10.70 +/- 0.88 vs. 3.10 +/- 0.30 in controls), the blood flow was shifted to either upper or dependent lung regions. The shift to the upper regions was associated with an increased (P < 0.05) pulmonary arterial pressure (Ppa), whereas the shift to the dependent lung was not associated with a significant change in Ppa. Breathing 100% O2 did not prevent these shifts, suggesting that they were not due to localized hypoxic pulmonary vasoconstriction. The flow distribution patterns were also not related to regional differences in edema. In contrast to the changes during fulminant edema, blood flow distribution did not change after moderate levels of pulmonary edema (W/D of 6.03 0.69), suggesting that gross alveolar flooding is required for a redistribution of pulmonary blood flow. Flow redistribution to the upper lung during airway flooding may be due to increase in Ppa, whereas the increased flow in the dependent lung during the same degree of edema may be due to "bulging" of alveolar vessels into the air spaces, secondary to a decrease in surface activity.

Effect of furosemide on pulmonary blood flow distribution in resting and exercising horses

1999 ◽  
Vol 86 (6) ◽  
pp. 2034-2043 ◽  
Author(s):  
Howard H. Erickson ◽  
Susan L. Bernard ◽  
Robb W. Glenny ◽  
M. Roger Fedde ◽  
Nayak L. Polissar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Thoroughbred Horses ◽  
Dorsal Portion ◽  
Primary Finding ◽  
Pulmonary Arterial ◽  
Relationship Of ◽  
The Relationship ◽  
Rest And Exercise

We determined the spatial distribution of pulmonary blood flow (PBF) with 15-μm fluorescent-labeled microspheres during rest and exercise in five Thoroughbred horses before and 4 h after furosemide administration (0.5 mg/kg iv). The primary finding of this study was that PBF redistribution occurred from rest to exercise, both with and without furosemide. However, there was less blood flow to the dorsal portion of the lung during exercise postfurosemide compared with prefurosemide. Furosemide did alter the resting perfusion distribution by increasing the flow to the ventral regions of the lung; however, that increase in flow was abated with exercise. Other findings included 1) unchanged gas exchange and cardiac output during rest and exercise after vs. before furosemide, 2) a decrease in pulmonary arterial pressure after furosemide, 3) an increase in the slope of the relationship of PBF vs. vertical height up the lung during exercise, both with and without furosemide, and 4) a decrease in blood flow to the dorsal region of the lung at rest after furosemide. Pulmonary perfusion variability within the lung may be a function of the anatomy of the pulmonary vessels that results in a predominantly fixed spatial pattern of flow distribution.

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