Effect of acceleration on the distribution of pulmonary blood flow

1965 ◽  
Vol 20 (6) ◽  
pp. 1129-1132 ◽  
Author(s):  
A. C. Bryan ◽  
W. D. Macnamara ◽  
J. Simpson ◽  
H. N. Wagner
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Pulmonary Blood Flow ◽  
Lung Perfusion ◽  
Centrifugal Acceleration ◽  
Vascular Bed ◽  
Macroaggregated Albumin ◽  
Iodine 131 ◽  
Pulmonary Vascular Bed

The distribution of pulmonary blood flow has been measured during increased positive (+Gz) acceleration. Macroaggregated albumin labeled with iodine 131 was injected intravenously during centrifugal acceleration, by the method described by Wagner and co-workers. The particles embolize the pulmonary vascular bed in proportion to flow and can be subsequently detected by scintillation scanning of the lung. One study was done in one subject in one of the five following conditions: supine, seated, +2 Gz, +3 Gz, and +4 Gz. The results show a progressively smaller reduction in upper zone perfusion with increasing acceleration agreeing with hydrostatic principles. Flow increased in the base up to +2 Gz but thereafter becomes fixed, suggesting that the vessels were then maximally dilated. The gas exchange consequences of these changes of perfusion are discussed indicating that there must also be ventilatory changes. lung; perfusion; iodine 131; acceleration Submitted on January 18, 1965

Pressure-Flow Relationships in the Dog Lung During Acute, Subtotal Pulmonary Vascular Occlusion

1958 ◽  
Vol 192 (3) ◽  
pp. 613-619 ◽  
Author(s):  
Michael T. Lategola
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Pulmonary Blood Flow ◽  
Vascular Occlusion ◽  
Percentage Change ◽  
Artery Pressure ◽  
Vascular Bed ◽  
Change In Mean ◽  
Pulmonary Vascular Bed

The relationship of pulmonary artery pressure to pulmonary blood flow was studied in the dog by means of occlusive shifting of blood flow within the pulmonary vascular bed. All experiments were performed using the closed-chest preparation. The range of blood flow increases studied was 25–388%. A graphical plot of the percentage change in blood flow versus the percentage change in mean pulmonary artery pressure is presented. A visually estimated curve of this latter data is presented, discussed and compared to four other curves from previous pulmonary vascular studies. A comparison of these curves suggests that the relative maximum capacity of the pulmonary vascular bed of man and dog are similar. These curves plus certain assumptions allow the speculative delineation of a graphical area representing the ‘active’ vasomotor component of exercise at different levels of pulmonary blood flow increase.

scholarly journals The Effect of Increased Pulmonary Blood Flow on the Pulmonary Vascular Bed in Pigs

1975 ◽  
Vol 9 (6) ◽  
pp. 547-553 ◽  
Author(s):  
Beat Friedli ◽  
Geraldine Kent ◽  
B S Langford Kidd ◽  
M Luide ◽  
F Hamilton
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Vascular Bed ◽  
Pulmonary Vascular Bed

Lower limb exercise generates pulsatile flow into the pulmonary vascular bed in the setting of the Fontan circulation

2018 ◽  
Vol 28 (5) ◽  
pp. 732-733 ◽  
Author(s):  
Rachael Cordina ◽  
David S. Celermajer ◽  
Yves d’Udekem
Keyword(s):  
Blood Flow ◽  
Pulsatile Flow ◽  
Lower Limb ◽  
Pulmonary Blood Flow ◽  
Fontan Circulation ◽  
Vascular Bed ◽  
Lower Limb Exercise ◽  
Limb Exercise ◽  
Pulmonary Vascular Bed

AbstractThe absence of a subpulmonary ventricle in the Fontan circulation results in non-pulsatile pulmonary blood flow. Lower limb exercise in this setting can generate pulsatile pulmonary blood flow.

Pulmonary response of normal human subjects to inhaled vasodilator substances

1998 ◽  
Vol 95 (5) ◽  
pp. 621-627 ◽  
Author(s):  
S. J. BRETT ◽  
J. CHAMBERS ◽  
A. BUSH ◽  
M. ROSENTHAL ◽  
T. W. EVANS
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Pulmonary Hypertension ◽  
Pulmonary Blood Flow ◽  
Inhaled Nitric Oxide ◽  
Prostaglandin I2 ◽  
Vascular Bed ◽  
Normal Individuals ◽  
Chronic Pulmonary Hypertension ◽  
Pulmonary Vascular Bed

1.Inhaled vasodilators such as nitric oxide and epoprostenol (prostaglandin I2) are now widely employed as supportive therapies to improve oxygenation and reduce pulmonary vascular resistance in patients with acute and chronic pulmonary hypertension. However, few data exist concerning their effects in normal individuals. The aim of this study was to characterize the response of the pulmonary circulation in normal individuals to inhaled nitric oxide and nebulized prostaglandin I2. 2.Eight healthy volunteers were exposed to inhaled nitric oxide (0, 20 and 40 ;p.p.m.) and nebulized prostaglandin I2 (10 ;μg/ml). Changes in effective pulmonary blood flow and diffusing capacity of the lung for carbon monoxide (TLCO) were measured using respiratory mass spectrometry. Bicycle ergometry was used to increase effective pulmonary blood flow as a positive control. 3.Exercise produced significant increases in both effective pulmonary blood flow and TLCO, but neither nitric oxide nor prostaglandin I2 produced significant changes in either parameter. 4.No significant change in pulmonary haemodynamics was demonstrated in response to inhaled nitric oxide or nebulized prostaglandin I2, using doses known to be effective in patients with acute and chronic pulmonary hypertension. These data suggest that the normal pulmonary vascular bed is not amenable to vasodilatation by inhaled drugs. The study further suggests that the normal pulmonary vasodilatation seen on exercise is not mediated pharmacologically, but is a secondary consequence to the mechanical effects of a rise in pulmonary blood flow. This study thus supports the view that there is no resting vasoconstrictor tone in the pulmonary vascular bed.

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.

Effects of Vaporized Perfluorocarbon on Pulmonary Blood Flow and Ventilation/Perfusion Distribution in a Model of Acute Respiratory Distress Syndrome

2001 ◽  
Vol 95 (6) ◽  
pp. 1414-1421 ◽  
Author(s):  
Matthias Hübler ◽  
Jennifer E. Souders ◽  
Erin D. Shade ◽  
Nayak L. Polissar ◽  
Carmel Schimmel ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oleic Acid ◽  
Gas Exchange ◽  
Lung Injury ◽  
Repeated Measures ◽  
Pulmonary Blood Flow ◽  
Analysis Of Covariance ◽  
Inert Gas ◽  
Low Flow ◽  
Repeated Measures Analysis

Background Perfluorocarbon (PFC) liquids are known to improve gas exchange and pulmonary function in various models of acute respiratory failure. Vaporization has been recently reported as a new method of delivering PFC to the lung. Our aim was to study the effect of PFC vapor on the ventilation/perfusion (VA/Q) matching and relative pulmonary blood flow (Qrel) distribution. Methods In nine sheep, lung injury was induced using oleic acid. Four sheep were treated with vaporized perfluorohexane (PFX) for 30 min, whereas the remaining sheep served as control animals. Vaporization was achieved using a modified isoflurane vaporizer. The animals were studied for 90 min after vaporization. VA/Q distributions were estimated using the multiple inert gas elimination technique. Change in Qrel distribution was assessed using fluorescent-labeled microspheres. Results Treatment with PFX vapor improved oxygenation significantly and led to significantly lower shunt values (P &lt; 0.05, repeated-measures analysis of covariance). Analysis of the multiple inert gas elimination technique data showed that animals treated with PFX vapor demonstrated a higher VA/Q heterogeneity than the control animals (P &lt; 0.05, repeated-measures analysis of covariance). Microsphere data showed a redistribution of Qrel attributable to oleic acid injury. Qrel shifted from areas that were initially high-flow to areas that were initially low-flow, with no difference in redistribution between the groups. After established injury, Qrel was redistributed to the nondependent lung areas in control animals, whereas Qrel distribution did not change in treatment animals. Conclusion In oleic acid lung injury, treatment with PFX vapor improves gas exchange by increasing VA/Q heterogeneity in the whole lung without a significant change in gravitational gradient.

PULMONARY FUNCTION, DEDUCED FROM URINARY NITROGEN TENSIONS

PEDIATRICS ◽  
1967 ◽  
Vol 40 (6) ◽  
pp. 937-938
Author(s):  
M. E. A.
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Pulmonary Function ◽  
Partial Pressure ◽  
Urine Sample ◽  
Pulmonary Blood Flow ◽  
Lung Perfusion ◽  
Alveolar Ventilation ◽  
Arterial Oxygen ◽  
Urinary Nitrogen

THE elegant studies reported by Led-better, Homma, and Farhi in this issue are entitled `'Readjustment in Distribution of Alveolar Ventilation and Lung Perfusion in the Newborn." It must come as a great surprise to the reader to discover that the only measurement actually made was the partial pressure of nitrogen in the infants' urine. How could one conclude that there were significant imbalances between the distribution of alveolar ventilation and pulmonary blood flow (VA/Q) in the first days of life in normal infants from a urine sample? It is all the more astounding in the light of previous (and seemingly more direct) studies of alveolar-arterial oxygen and carbon dioxide differences which led others to consider the differences largely explained by anatomical right-to-left shunts.

Gas exchange in dogs in the prone and supine positions

1992 ◽  
Vol 72 (6) ◽  
pp. 2292-2297 ◽  
Author(s):  
K. C. Beck ◽  
J. Vettermann ◽  
K. Rehder
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Prone Position ◽  
Pulmonary Blood Flow ◽  
Random Order ◽  
Arterial Pco2 ◽  
Supine Posture ◽  
Pulmonary Shunting ◽  
The Difference ◽  
Arterial Po2

To determine the cause of the difference in gas exchange between the prone and supine postures in dogs, gas exchange was assessed by the multiple inert gas elimination technique (MIGET) and distribution of pulmonary blood flow was determined using radioactively labeled microspheres in seven anesthetized paralyzed dogs. Each animal was studied in the prone and supine positions in random order while tidal volume and respiratory frequency were kept constant with mechanical ventilation. Mean arterial PO2 was significantly lower (P less than 0.01) in the supine [96 +/- 10 (SD) Torr] than in the prone (107 +/- 6 Torr) position, whereas arterial PCO2 was constant (38 Torr). The distribution of blood flow (Q) vs. ventilation-to-perfusion ratio obtained from MIGET was significantly wider (P less than 0.01) in the supine [ln SD(Q) = 0.75 +/- 0.26] than in the prone position [ln SD (Q) = 0.34 +/- 0.05]. Right-to-left pulmonary shunting was not significantly altered. The distribution of microspheres was more heterogeneous in the supine than in the prone position. The larger heterogeneity was due in part to dorsal-to-ventral gradients in Q in the supine position that were not present in the prone position (P less than 0.01). The decreased efficiency of oxygenation in the supine posture is caused by an increased ventilation-to-perfusion mismatch that accompanies an increase in the heterogeneity of Q distribution.

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