normal venous characteristics

The normal venous wave form characterised by the following:

1-Spontaneous flow:
Continuous flow of phasic wave form.

2-Phasic flow:
The amplitude of the wave formed controlled by respiration
during inspiration,the intra-abdominal pressure is increased by descending of diaphragm resulting in cessation of blood flow inside the vein.
while in expiration,the intra abdominal pressure is decreased resulting in accentuation of the peak of the wave form.
If the examiner for example is situating the probe in the groin lesion and he found that the doppler wave form of the common femoral vein is monophasic,this will indicate a lesion situated between the site of examination and pelvic veins.
3-Distal augmentation:
squeesing or compression distal to the site of examination result in augmentation of doppler venous wave form.this indicate patency of the segment of the vein between the distal site of compression and the site where the probe is situated.

4-Non pulsatility:
-Normally veins are non pulsatile.
-It could be pulsatile in the following situations
a) cardiac diseases.
b) severe brady-cardia.
c) over-transfusion.

5-Compressability (the most important sign )
-Normal veins are thin walled and easly compressible.
-This is one of the most criteria for venous examination.
-When an external compression is applied to a vein using ultrasoud probe
a) if the vein is healthy
walls of the vein will be collapsed completely resulting in opposed walls.
b) partially occluded vein will be partially collapsed while
c) Total occluded vein will not collapse at all.
Demonstration of non collapsed vein indicate presence of venous thrombi.

6-Competency of valves.
-Can be demonstrated by one of the following
a) application of valsalva maneuver. or
b) compression maneuver proximal to the site of probe application.
-After application of one of these maneuvers,venous flow should be stopped untill this maneuver is discontinued.
-There should be no reversal of flow.

In case of competent vein:
-you will found only one sound.
-spectral doppler wave form will be in one direction.
-color doppler image will show one color.

In case of incompetent vein:
-there is two sounds ,forward and reverse as blood flow in two directions.
-spectral wave form will shows two direction of flow
-color doppler image will shows two color.


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