Veins

[Kevin]

I dive in the UK which is always cold (usually around 5 dgrees C). After diving I find that the veins on the backs of my hands look like they have lumps in them. Can anyone tell me why and what causes it.

 

[John Reinertson]

I can't be sure without seeing the lumps, but usually when the veins in the back of the hand have "lumps" what you're seeing is dilation of the veins from constriction closer to the heart, such as from a snug wetsuit or the seals of a drysuit.

You can probably reproduce these at home with a common blood pressure cuff (sphygmomanometer) inflated to 15 Torr for about fifteen minutes, especially if the hand is submerged in warm water.

The actual lumps are the sites of venous valves that prevent refluxing of blood into the hand.

Give it a try and see if that isn't the same thing.

John

 

[Kevin]

Thanks for the reply, but what is 'refluxing' and should I be taking any action to prevent it happening ?

 

[scubadoc]

Hi Kevin:

Blood is pumped around throught the arteries into the capillaries by a head of pressure from the heart. After the oxygen is extracted and CO2 added, the blood gets back to the heart through a system of blood vessels called veins. Since there is no 'pump' to push htis blood around, there is a system of flap valves (little swinging doors) that allow the blood to flow toward the heart but not back toward the tissues. "Reflux' means to flow backward.

Arm and leg muscles help this blood to flow toward the heart. Sitting too long in one place with pressure on the back of the legs can cause clotting of these vessels with destruction of the valves. This is thought by some to lead to varicose veins.

The little knots that you see on your hand are the slight dilations at the locations of the valves.