Arterial Pulsatility; Cardiac Aspiration; General Information Of Venous Dynamics - Fscaresystems Viridex Rf Bedienungsanleitung

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3.4.6. Arterial Pulsatility

The rhythm of the venous flow is controlled by the satellite artery that exercises pressure on it.
This pressure propels the venous blood in the opposite direction to the arterial blood. However,
it only makes a modest contribution.

3.4.7. Cardiac Aspiration

A moderate intra-auricular systolic suction effect is produced by the downward traction of the
tricuspid and mitral valves. This mechanism is particularly reduced in the case of arrhythmia.
3.5.

General information of Venous Dynamics

The anti-reflux role of the valves is dependent on the integrity of the flaps (2 or 3) that float in
the lumen of the vein. They tolerate pressure in excess of 200 mm Hg. The closing speed of
the valves is less than 0.5 seconds in the event of rapid reflux.
Parietal Distensibility
The peripheral vein walls contain little smooth muscle tissue and are fine. They are easily
distended.
They become larger with age. This distensibility of the vein wall depends on the level of
progesterone serum.
Venous capacity
The lumen diameter of the vein is 20 µm for venules, 5 mm for average peripheral veins, and
3 cm for the vena cava
Venous compliance is 24 times greater than for the corresponding artery.
The veins are capacious vessels; 64% of the blood volume flows through the veins, 1/3 of it in
the major veins and the blood reservoirs (spleen - liver).
Veinous Pressure
In decubitus: the hydrostatic venous pressure is 20 mm Hg. In the case of existing varicosity,
it varies between 40 and 70 mm hg, and in the case of a post-thrombotic syndrome it oscillates
between 50 and 85. Venous blood return in the supine position is characterised by a low-
pressure peripheral and a shallow pressure gradient: pressure at the ankle of 12 to 18 mm Hg
and filling pressure of the right auricle -2 to 10 mm Hg. Hence the moderate suction effect
created by the heart.
In the sitting position: venous pressure at the ankle is 56 mm Hg.
In orthostatism: in an immobile standing position the pressure is 85 mm Hg for an average-
sized adult. It increases by 0.8 mm Hg per additional centimetre of height. When taking up a
standing position, the blood volume in the inferior members increases by 300 ml, which is
responsible for a transient diminution of the cardio-respiratory blood volume and the systolic
volume.
Date 27/03/2014
THERMOCOAGULATION – Viridex
Page 22 de 49 N° de révision : 05