scholarly journals THE VESSELS INVOLVED IN HYDROSTATIC TRANSUDATION

1932 ◽  
Vol 55 (3) ◽  
pp. 417-430 ◽  
Author(s):  
Philip D. McMaster ◽  
Stephen Hudack

The gradient of permeability which exists along the cutaneous capillaries and venules is accentuated and broadened in scope by increasing the venous pressure moderately. Under such circumstances transudation leading to edema takes place most abundantly from the venules. The permeability of the portion of the capillary web that is near the arterioles increases only when the venous pressure rises so high as to approximate that in the arteries. Under such circumstances the gradient of permeability along the small vessels disappears, the capillaries and venules everywhere leaking fluid. The character of the vital staining developing under such circumstances indicates, like the evidence of previous work, that the cause for the gradient is to be sought in a structural differentiation.

1932 ◽  
Vol 55 (3) ◽  
pp. 431-439 ◽  
Author(s):  
Stephen Hudack ◽  
Philip D. McMaster

The mounting gradient of permeability along the small vessels of the corium is essentially unaltered by active hyperemia produced by heat, cold, or light. Only when the vascular walls are so damaged that rapid leakage ensues, as shown by the development of edema, does the permeability of the capillary web as a whole approximate that of the venules. It is plain that the normal gradient of vascular permeability depends upon the integrity of the vessel wall. The method of experiment described can be utilized for a study of the functional changes which result in the lesions due to burning and freezing.


1977 ◽  
Vol 233 (6) ◽  
pp. H660-H664
Author(s):  
G. G. Power ◽  
R. D. Gilbert

To explore the mechanical properties of umbilical vessels and to test for possible interactions between maternal and fetal circulations, we recorded pressure-volume curves from isolated in situ placentas of 17 sheep. We estimated static umbilical compliance by extrapolating to infinitely slow rates of volume change. We found that compliance averaged .231 +/- .014 SE ml/mmHg per kg fetal wt under control conditions, a value that increased 26.5% when maternal arterial pressure was lowered 85 mmHg (clamping the aorta), but did not change when venous pressure was raised 37 mmHg (clamping IVC). After replacing blood with kerosene which does not penetrate small vessels because of interfacial tension, we found arteries accounted for 22% and veins for 41% of total compliance, leaving 37% attributable to small placental vessels and surrounding tissue. We conclude that umbilical vessels are about one-half as compliant as adult vessels on a body-weight basis, but only slightly less compliant than vessels elsewhere in the fetal body. When maternal vessels expand they interact with surrounding placental tissue, displacing fetal blood and altering the apparent compliance of umbilical vessels.


1931 ◽  
Vol 53 (2) ◽  
pp. 219-242 ◽  
Author(s):  
Peyton Rous ◽  
Frederick Smith

A steeply mounting gradient of permeability is demonstrable along the meshwork of capillaries which connects the arterioles and venules of the skin of the frog. The venules incorporated in the meshwork are even more permeable than the capillary meshes giving into them. The presence of the gradient under such differing conditions as exist along frog and mammalian capillaries enables one to rule out certain factors which might be invoked to explain it; and it is not explainable in terms of those influences generally recognized as conditioning exchange between the blood and tissues. Not improbably it results from a structural differentiation along the capillary.


VASA ◽  
2006 ◽  
Vol 35 (3) ◽  
pp. 157-166 ◽  
Author(s):  
Hach-Wunderle ◽  
Hach

It is known from current pathophysiology that disease stages I and II of truncal varicosity of the great saphenous vein do not cause changes in venous pressure on dynamic phlebodynamometry. This is possibly also the case for mild cases of the disease in stage III. In pronounced cases of stage III and all cases of stage IV, however, venous hypertension occurs which triggers the symptoms of secondary deep venous insufficiency and all the complications of chronic venous insufficiency. From these facts the therapeutic consequence is inferred that in stages I and II and perhaps also in very mild cases of stage III disease, it is enough "merely" to remove varicose veins without expecting there to be any other serious complications in the patient’s further life caused by the varicosity. Recurrence rates are not included in this analysis. In marked cases of disease stages III and IV of the great saphenous vein, however, secondary deep venous insufficiency is to be expected sooner or later. The classical operation with saphenofemoral high ligation ("crossectomy") and stripping strictly adheres to the recognized pathophysiologic principles. It also takes into account in the greatest detail aspects of minimally invasive surgery and esthetics. In the past few years, developments have been advanced to further minimize surgical trauma and to replace the stripping maneuver using occlusion of the trunk vein which is left in place. Obliteration of the vessel is subsequently performed via transmission of energy through an inserted catheter. This includes the techniques of radiofrequency ablation and endovenous laser treatment. High ligation is not performed as a matter of principle. In a similar way, sclerotherapy using microfoam is minimally invasive in character. All these procedures may be indicated for disease stages I and II, and with reservations also in mild forms of stage III disease. Perhaps high ligation previously constituted overtreatment in some cases. Targeted studies are still needed to prove whether secondary deep venous insufficiency can be avoided in advanced stages of varicose vein disease without high ligation and thus without exclusion of the whole recirculation circuit.


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