Anatomic distribution of pulmonary vascular compliance

1998 ◽  
Vol 84 (1) ◽  
pp. 303-310 ◽  
Author(s):  
Robert G. Presson ◽  
Said H. Audi ◽  
Christopher C. Hanger ◽  
Gerald M. Zenk ◽  
Richard A. Sidner ◽  
...  
Keyword(s):  
Arterial Compliance ◽  
Venous Occlusion ◽  
Longitudinal Distribution ◽  
Steady Flows ◽  
Flow Data ◽  
Venous Compliance ◽  
Vascular Compliance ◽  
Anatomic Distribution ◽  
Flow Changes ◽  
Pressure Changes

Presson, Robert G., Jr., Said H. Audi, Christopher C. Hanger, Gerald M. Zenk, Richard A. Sidner, John H. Linehan, Wiltz W. Wagner, Jr., and Christopher A. Dawson. Anatomic distribution of pulmonary vascular compliance. J. Appl. Physiol. 84(1): 303–310, 1998.—Previously, the pressure changes after arterial and venous occlusion have been used to characterize the longitudinal distribution of pulmonary vascular resistance with respect to vascular compliance using compartmental models. However, the compartments have not been defined anatomically. Using video microscopy of the subpleural microcirculation, we have measured the flow changes in ∼40-μm arterioles and venules after venous, arterial, and double occlusion maneuvers. The quasi-steady flows through these vessels after venous occlusion permitted an estimation of the compliance in three anatomic segments: arteries >40 μm, veins >40 μm, and vessels <40 μm in diameter. We found that ∼65% of the total pulmonary vascular compliance was in vessels <40 μm, presumably mostly capillaries. The transient portions of the pressure and flow data after venous, arterial, and double occlusion were consistent with most of the arterial compliance being upstream from most of the arterial resistance and most of the venous compliance being downstream from most of the venous resistance.

Changes in leg vein filling and emptying characteristics and leg volumes during long-term head-down bed rest

1997 ◽  
Vol 82 (6) ◽  
pp. 1726-1733 ◽  
Author(s):  
Francis Louisy ◽  
Philippe Schroiff ◽  
Antonio Güell
Keyword(s):  
Bed Rest ◽  
Venous Occlusion ◽  
Arterial Flow ◽  
Flow Index ◽  
Venous Compliance ◽  
Physiological Factors ◽  
Control Value ◽  
Flow Changes ◽  
Mercury Strain Gauge

Louisy, Francis, Philippe Schroiff, and Antonio Güell.Changes in leg vein filling and emptying characteristics and leg volumes during long-term head-down bed rest. J. Appl. Physiol. 82(6): 1726–1733, 1997.—Leg venous hemodynamics [venous distensibility index (VDI), arterial flow index (AFI), half-emptying time (T1/2)], and leg volumes (LV) were assessed by mercury strain-gauge plethysmography with venous occlusion and volometry, respectively, in seven men before, during, and after 42 days of 6° head-down bed rest. Results showed a high increase in VDI up to day 26 of bed rest (+50% vs. control at day 26, P < 0.05), which tended to subside thereafter (+20% increase vs. control value at day 41, P < 0.05). VDI changes were associated with parallel changes in T1/2 (+54% vs. control at day 26 of bed rest, P < 0.05, and +25% vs. control at day 41, P < 0.05) and with a decrease in AFI (−49% at day 41 vs. control, P < 0.05). LV continuously decreased throughout bed rest (−13% vs. control at day 41, P < 0.05) but was correlated with VDI only during the first month of bed rest. These results show that during long-term 6° head-down bed rest alterations of leg venous compliance are associated with impairment of venous emptying capacities and arterial flow. Changes in skeletal muscle mass and fluid shifts may account for venous changes during the first month of bed rest but, subsequently, other physiological factors, to be determined, may also be involved in leg venous hemodynamic alterations.

Functional diagrams of flow and volume for the dog's lung

1982 ◽  
Vol 52 (4) ◽  
pp. 1035-1042 ◽  
Author(s):  
D. S. Moffatt ◽  
A. C. Guyton ◽  
T. H. Adair
Keyword(s):  
Arterial Pressure ◽  
Blood Volume ◽  
Arterial Compliance ◽  
Venous Pressure ◽  
Flow Characteristics ◽  
Transpulmonary Pressure ◽  
Pulmonary Vasculature ◽  
Venous Compliance ◽  
Lung Weight ◽  
Pressure Changes

Quantitative diagrams have been constructed from data obtained in isolated perfused dog lungs for the multiple interrelationships among pressure, volume, and flow characteristics of the pulmonary vasculature. These characteristics are described in the form of functional diagrams for flows from 0.3 to 1.0 l . min-1 . 100 g wet lung weight-1 (WLW), for venous pressures from -8 to +14 Torr, and for arterial pressures from 16 to 30 Torr. The quantitative relationships were shown not to change significantly as the transpulmonary pressure changes within the range from 3 to 10 Torr. The change in blood volume with arterial pressure, called the “distributed arterial compliance,” averaged 1.5 g . Torr-1 . 100 g WLW-1. This compliance was nearly constant over the range of arterial pressure studied. On the other hand, the change in blood volume with venous pressure, called the 'distributed venous compliance” was different for different levels of venous pressures. Its maximum value was 1.04 g . Torr-1 . 100 g WLW-1 when the venous pressure was near 2 Torr. At venous pressures both above and below this pressure level this compliance decreased. These distributed compliances are described as resulting to a significant extent from changes in flow patterns through the pulmonary circulation rather than being direct indications of the true vascular compliances.

Hindlimb unweighting affects rat vascular capacitance function

2001 ◽  
Vol 281 (3) ◽  
pp. H1170-H1177 ◽  
Author(s):  
Stacey L. Dunbar ◽  
Laleh Tamhidi ◽  
Dan E. Berkowitz ◽  
Artin A. Shoukas
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Arterial Compliance ◽  
Filling Pressure ◽  
Right Atrial ◽  
Orthostatic Stress ◽  
Venous Compliance ◽  
Reservoir Volume ◽  
Venous Filling ◽  
And Control

Microgravity is associated with an impaired stroke volume and, therefore, cardiac output response to orthostatic stress. We hypothesized that a decreased venous filling pressure due to increased venous compliance may be an important contributing factor in this response. We used a constant flow, constant right atrial pressure cardiopulmonary bypass procedure to measure total systemic vascular compliance (CT), arterial compliance (CA), and venous compliance (CV) in seven control and seven 21-day hindlimb unweighted (HLU) rats. These compliance values were calculated under baseline conditions and during an infusion of 0.2 μg · kg−1 · min−1norepinephrine (NE). The change in reservoir volume, which reflects changes in unstressed vascular volume (ΔV0) that occurred upon infusion of NE, was also measured. CT and CV were larger in HLU rats both at baseline and during the NE infusion ( P < 0.05). Infusion of NE decreased CT and CV by ∼20% in both HLU and control rats ( P < 0.01). CA was also significantly decreased in both groups of rats by NE ( P < 0.01), but values of CA were similar between HLU and control rats both at baseline and during the NE infusion. Additionally, the NE-induced ΔV0 was attenuated by 53% in HLU rats compared with control rats ( P < 0.05). The larger CV and attenuated ΔV0 in HLU rats could contribute to a decreased filling pressure during orthostasis and thus may partially underlie the mechanism leading to the exaggerated fall in stroke volume and cardiac output seen in astronauts during an orthostatic stress after exposure to microgravity.

Effects of 18 days of bed rest on leg and arm venous properties

2004 ◽  
Vol 96 (3) ◽  
pp. 840-847 ◽  
Author(s):  
M. W. P. Bleeker ◽  
P. C. E. De Groot ◽  
J. A. Pawelczyk ◽  
M. T. E. Hopman ◽  
B. D. Levine
Keyword(s):  
Orthostatic Intolerance ◽  
Lower Body Negative Pressure ◽  
Bed Rest ◽  
Venous Occlusion ◽  
Stress Index ◽  
Orthostatic Tolerance ◽  
Venous Compliance ◽  
Venous Flow ◽  
Gravitational Gradients ◽  
Small Change

Venous function may be altered by bed rest deconditioning. Yet the contribution of altered venous compliance to the orthostatic intolerance observed after bed rest is uncertain. The purpose of this study was to assess the effect of 18 days of bed rest on leg and arm (respectively large and small change in gravitational gradients and use patterns) venous properties. We hypothesized that the magnitude of these venous changes would be related to orthostatic intolerance. Eleven healthy subjects (10 men, 1 woman) participated in the study. Before (pre) and after (post) 18 days of 6° head-down tilt bed rest, strain gauge venous occlusion plethysmography was used to assess limb venous vascular characteristics. Leg venous compliance was significantly decreased after bed rest (pre: 0.048 ± 0.007 ml·100 ml-1·mmHg-1, post: 0.033 ± 0.007 ml·100 ml-1·mmHg-1; P < 0.01), whereas arm compliance did not change. Leg venous flow resistance increased significantly after bed rest (pre: 1.73 ± 1.08 mmHg·ml-1·100 ml·min, post: 3.10 ± 1.00 mmHg·ml-1·100 ml·min; P < 0.05). Maximal lower body negative pressure tolerance, which was expressed as cumulative stress index (pressure·time), decreased in all subjects after bed rest (pre: 932 mmHg·min, post: 747 mmHg·min). The decrease in orthostatic tolerance was not related to changes in leg venous compliance. In conclusion, this study demonstrates that after bed rest, leg venous compliance is reduced and leg venous outflow resistance is enhanced. However, these changes are not related to measures of orthostatic tolerance; therefore, alterations in venous compliance do not to play a major role in orthostatic intolerance after 18 days of head-down tilt bed rest.

Peripheral circulatory control of preload-afterload mismatch with angiotensin in dogs

1987 ◽  
Vol 253 (1) ◽  
pp. H126-H132
Author(s):  
R. W. Lee ◽  
L. D. Lancaster ◽  
D. Buckley ◽  
S. Goldman
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Arterial Compliance ◽  
Peripheral Circulation ◽  
Aortic Pressure ◽  
Venous Compliance ◽  
Mean Aortic Pressure

To determine whether changes in the venous circulation were responsible for preload-afterload mismatch with angiotensin, we examined the changes in the heart and the peripheral circulation in six splenectomized dogs after ganglion blockade during an angiotensin infusion to increase mean aortic pressure 25 and then 50%. The peripheral circulation was evaluated by measuring mean circulatory filling pressure (MCFP), arterial compliance, and venous compliance. A 25% increase in mean aortic pressure increased MCFP from 6.2 +/- 0.3 to 7.6 +/- 0.3 mmHg (P less than 0.001) but did not change cardiac output, heart rate, or stroke volume. Systemic vascular resistance increased (P less than 0.01) from 0.50 +/- 0.02 to 0.59 +/- 0.03 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.03 to 0.06 +/- 0.03 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.6 +/- 0.1 ml X mmHg-1 X kg-1, respectively. A 50% elevation in mean aortic pressure increased MCFP from 7.1 +/- 0.4 to 9.5 +/- 0.9 mmHg (P less than 0.001) but did not change heart rate. At this level of aortic pressure, cardiac output and stroke volume decreased (P less than 0.01) 12 and 19%, respectively, whereas systemic vascular resistance increased (P less than 0.001) from 0.48 +/- 0.03 to 0.83 +/- 0.05 mmHg X min X kg X ml-1. Arterial and venous compliances decreased (P less than 0.01) from 0.08 +/- 0.01 to 0.05 +/- 0.01 ml X mmHg-1 X kg-1 and from 2.1 +/- 0.1 to 1.4 +/- 0.1 ml X mmHg-1 X kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Large venous compliance in carboxyhemoglobinemia and hemodilutional anemia

1986 ◽  
Vol 64 (5) ◽  
pp. 556-560 ◽  
Author(s):  
George P. Biro
Keyword(s):  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Venous Return ◽  
Vena Cava ◽  
Transverse Diameter ◽  
Venous Compliance ◽  
Reduced Viscosity ◽  
Anesthetized Dogs ◽  
Pressure Changes ◽  
Made In

Anesthetized dogs were prepared for the measurement of compliance of the inferior vena cava by placement of a catheter for pressure measurement and a pair of ultrasonic dimension transducers for the measurement of transverse diameter. Measurements of compliance were made in a control state, after the induction of carboxyhemoglobinemia or hemodilutional anemia, by measuring pressure changes and diameter changes during brief occlusions of the inferior vena cava downstream from the transducers. Carboxyhemoglobinemia cuased an upward shift of the averaged pressure–diameter curve while there was a negligible shift in the hemodiluted group. These results indicate that in carboxyhemoglobinemia a change in the compliance of the vena cava occurs, which favours augmented venous return by improved conductance rather than by a dislocation of blood by constriction of the large venous reservoir. In hemodilutional anemia the change in compliance is insignificant, but venous return is favoured by the reduced viscosity.

Cardiac homeostasis is independent of calf venous compliance in subjects with paraplegia

2003 ◽  
Vol 284 (6) ◽  
pp. H2393-H2399 ◽  
Author(s):  
Jill M. Wecht ◽  
Ronald E. De Meersman ◽  
Joseph P. Weir ◽  
Ann M. Spungen ◽  
William A. Bauman
Keyword(s):  
Cardiac Output ◽  
Vascular Function ◽  
Structural Changes ◽  
Random Order ◽  
Venous Occlusion ◽  
Control Group ◽  
Calf Circumference ◽  
Venous Compliance ◽  
Venous Capacitance ◽  
Cardiac Hemodynamics

The purpose of this study was to examine cardiac hemodynamics during acute head-up tilt (HUT) and calf venous function during acute head-down tilt (HDT) in subjects with paraplegia compared with sedentary nondisabled controls. Nineteen paraplegic males (below T6) and nine age-, height-, and weight-matched control subjects participated. Heart rate, stroke volume, and cardiac output were assessed using the noninvasive acetylene uptake method. Venous vascular function of the calf was assessed using venous occlusion plethysmography. After supine measurements were collected, the table was moved to 10° HDT followed by the three levels of HUT (10, 35, and 75°) in random order. Cardiac hemodynamics were similar between the groups at all positions. Calf circumference was significantly reduced in the paraplegic group compared with the control group ( P < 0.001). Venous capacitance and compliance were significantly reduced in the paraplegic compared with control group at supine and HDT. Neither venous capacitance ( P = 0.37) nor compliance ( P = 0.19) increased from supine with 10° HDT in the paraplegic group. A significant linear relationship was established between supine venous compliance and supine cardiac output in the control group ( r = 0.80, P < 0.02) but not in the paraplegic group. The findings of reduced calf circumference and similar venous capacitance at supine rest and 10° HDT in the paraplegic group imply that structural changes may have limited venous dispensability in individuals with chronic paraplegia. Furthermore, the lack of a relationship between supine venous compliance and supine cardiac output suggests that cardiac homeostasis does not rely on venous compliance in subjects with paraplegia.

scholarly journals Validation of the mean systemic filling pressure assessment with preserved arterial blood flow by comparing two methods of calculation 

2021 ◽  
Author(s):  
Roberto Alberto De Blasi ◽  
Stefano Finazzi
Keyword(s):  
Near Infrared ◽  
Venous Occlusion ◽  
Calculation Model ◽  
Arterial Blood Flow ◽  
Venous Compliance ◽  
Model Method ◽  
Arterial Blood ◽  
Methods Of Calculation ◽  
Multi Phase

Abstract Significance: We developed a method for measuring in vivo venular volumes and pressures in the limbs using near-infrared spectroscopy (NIRS).Aim: 36 We aimed to validate the NIRS methodology by comparing two independent methods of calculation based on different physiological approaches.Approach: Pressure-volumes curves were recorded following graded venous occlusion on the forearm. Values from a multi-phase model (method 1) were compared with data derived from a resistor-capacitance calculation model (method 2) based on arterial pressure and venous compliance. We tested these methods on 10 healthy participants at rest and during exercise and on 6 severely ill patients.Results: Pressure-volume curves measured by method 1 were comparable with those calculated by method 2. Venular volumes calculated using method 1 correlated linearly with those calculated using method 2 both in participants (R2 = 0.98, p < 0.001) and in patients (R2 = 0.94, p < 0.001). The Bland-Altman test showed a good agreement between methods with few values out of the range of ± 1.96 SD.Conclusions: Our findings showed that the NIRS methodology may be valid for the assessment of venular bed with no flow interruption. Further research will be required to confirm the relevance of methodology in the clinical setting.

Effects of arterial ligation and embolization on pulmonary vascular pressure distribution

1987 ◽  
Vol 63 (4) ◽  
pp. 1387-1395 ◽  
Author(s):  
M. L. Tod ◽  
M. L. McGeady ◽  
P. Rock ◽  
J. T. Sylvester
Keyword(s):  
Pressure Gradient ◽  
Pressure Distribution ◽  
Vascular Occlusion ◽  
Longitudinal Distribution ◽  
Middle Region ◽  
Arterial Ligation ◽  
Vasomotor Responses ◽  
Vascular Compliance ◽  
Occlusion Technique ◽  
Flow Through

The effects of embolization on the longitudinal distribution of pulmonary vascular pressures with respect to vascular compliance were determined by the vascular inflow and outflow occlusion technique in isolated blood-perfused pig lungs treated with papaverine to prevent vasomotor responses. Embolization with microspheres having mean diameters of 75, 200, and 550 microns and with barrier beads (2 X 3 X 3.5 mm) significantly increased the pressure gradient across the relatively compliant middle region (delta Pm) without increasing the gradients across the relatively noncompliant regions on the arterial (delta Pa) or venous (delta Pv) ends of the vasculature. In contrast ligation of several lobar arteries caused delta Pa to increase from 0.9 +/- 0.3 to 5.9 +/- 1.1 mmHg but did not change delta Pm or delta Pv. Assuming that delta Pa and delta Pv measured by vascular occlusion result from cessation of flow through resistances, these data suggest that in isolated pig lungs the vessels at the boundary between the arterial and middle regions defined by the occlusion technique are arteries greater than 2–3 mm diam and smaller than lobar arteries.

Localization of the sites of pulmonary vasomotion by use of arterial and venous occlusion

1991 ◽  
Vol 70 (5) ◽  
pp. 2126-2136 ◽  
Author(s):  
S. H. Audi ◽  
C. A. Dawson ◽  
D. A. Rickaby ◽  
J. H. Linehan
Keyword(s):  
Arterial Pressure ◽  
Venous Occlusion ◽  
Longitudinal Distribution ◽  
Pressure Curve ◽  
Equilibrium Pressure ◽  
Small Arteries ◽  
Arterial Resistance ◽  
Major Response ◽  
Sites Of Action ◽  
Arteries And Veins

In this study, we present a new approach for using the pressure vs. time data obtained after various vascular occlusion maneuvers in pump-perfused lungs to gain insight into the longitudinal distribution of vascular resistance with respect to vascular compliance. Occlusion data were obtained from isolated dog lung lobes under normal control conditions, during hypoxia, and during histamine or serotonin infusion. The data used in the analysis include the slope of the arterial pressure curve and the zero time intercept of the extrapolated venous pressure curve after venous occlusion, the equilibrium pressure after simultaneous occlusion of both the arterial inflow and venous outflow, and the area bounded by equilibrium pressure and the arterial pressure curve after arterial occlusion. We analyzed these data by use of a compartmental model in which the vascular bed is represented by three parallel compliances separated by two series resistances, and each of the three compliances and the two resistances can be identified. To interpret the model parameters, we view the large arteries and veins as mainly compliance vessels and the small arteries and veins as mainly resistance vessels. The capillary bed is viewed as having a high compliance, and any capillary resistance is included in the two series resistances. With this view in mind, the results are consistent with the major response to serotonin infusion being constriction of large and small arteries (a decrease in arterial compliance and an increase in arterial resistance), the major response to histamine infusion being constriction of small and large veins (an increase in venous resistance and a decrease in venous compliance), and the major response to hypoxia being constriction of the small arteries (an increase in arterial resistance). The results suggest that this approach may have utility for evaluation of the sites of action of pulmonary vasomotor stimuli.

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