How does an ice pack reduce swelling and promote healing in injured areas?

[pivoxa15]

It is common to see children when hurt while playing given ice packs to the injured area. Why is this coldness good? Does it numb the injured area so sensory signals less frequently reach the central nervous system?

Also dry ice such as CO2 is able to 'burn' skin because of its very low temperture, not through any chemical effect. It has been used in the past by doctors to remove warts and even small skin cancers. How does dry ice 'burn' skin? How does it remove what they claim is it the burning effect?

The article said that these days liquid nitrogen is used instead of CO2 as it is far colder and temporarily anaesthetises the skin - which goes back to my first question? It also burn warts and cancers more effectively.

 

[DaveC426913]

It is common to see children when hurt while playing given ice packs to the injured area. Why is this coldness good? Does it numb the injured area so sensory signals less frequently reach the central nervous system?

It does, but it also constricts blood vessels, staunching blood flow and inhibiting swelling.

Also dry ice such as CO2 is able to 'burn' skin because of its very low temperture, not through any chemical effect. It has been used in the past by doctors to remove warts and even small skin cancers. How does dry ice 'burn' skin? How does it remove what they claim is it the burning effect?

The cold freezes all the water in the cells, causing them to burst and die. Nitrogen is faster, meaning it's more effective and easier to "focus" the effect ( i.e. avoid collateral damage to surrounding tissues).

 

[Monique]

There is another application of cold: to prevent hair-loss during chemotherapy. A cold-cap is applied to the scalp, the cold constricts the bloodvessels so that the chemotherapeutic agent is unable to access that area and can thus not kill off the dividing cells of the hair follicle. A drawback is that metastases might escape treatment if they are located in the cold area, so it is not always used.

 

[pivoxa15]

It does, but it also constricts blood vessels, staunching blood flow and inhibiting swelling.

So the ice pack is more of a short term thing. To prevent the kids from cying too much.

The cold freezes all the water in the cells, causing them to burst and die. Nitrogen is faster, meaning it's more effective and easier to "focus" the effect ( i.e. avoid collateral damage to surrounding tissues).

Is that what causes the burning sensation - cells bursting due to expansion of liquid when frozen.

We usually talk about burning when putting our hand into the fire. Does the fire also burn our cells and when they burst we get the burning sensation? Its just that we are more use to being burned by hottness than coldness that we associate burn with hot.

 

[DaveC426913]

Why am I getting a sense of deja vu? Haven't we had this convo before?

So the ice pack is more of a short term thing. To prevent the kids from cying too much.

Partly, but it also prevents further damage.

Is that what causes the burning sensation - cells bursting due to expansion of liquid when frozen.

We usually talk about burning when putting our hand into the fire. Does the fire also burn our cells and when they burst we get the burning sensation? Its just that we are more use to being burned by hottness than coldness that we associate burn with hot.

Well, anything that stimulates the nerves will cause our brain to feel that sensation. Heat and cold are somehwat linked. I think one gets to the brain faster, masking the other one.

Note: our brains do not actually know what really happens, they can only know what the nerves tell them, and those messages can be fiddled with (which is why acupuncture works. You don't HAVE to stimalate the nerve at its end, say, in your finger. If you could isolate the nerve that runs to your finger, and stimulate it in your armpit, your brain thinks your finger has been poked.)

 

[Moonbear]

So the ice pack is more of a short term thing. To prevent the kids from cying too much.

The reduction in swelling also reduces the amount of injury to surrounding tissue so it will heal faster.

Is that what causes the burning sensation - cells bursting due to expansion of liquid when frozen.

We usually talk about burning when putting our hand into the fire. Does the fire also burn our cells and when they burst we get the burning sensation? Its just that we are more use to being burned by hottness than coldness that we associate burn with hot.

That "burning" sensation isn't associated with temperature sensation, but is a pain sensation. It doesn't matter if it's caused by hot or cold or a cut, it's all the same "stinging" feeling.

 

[pivoxa15]

The reduction in swelling also reduces the amount of injury to surrounding tissue so it will heal faster.

How does the ice pack reduce swelling?

That "burning" sensation isn't associated with temperature sensation, but is a pain sensation. It doesn't matter if it's caused by hot or cold or a cut, it's all the same "stinging" feeling.

Ok. And the pain sensation is due to the bursting or damage of cells?

 

[Monique]

How does the ice pack reduce swelling?

When you injure yourself, you get a local dilation of the bloodvessels as a response to the injury. This will lead to an increased bloodflow to the area, causing redness and warmth.
At the same time the bloodvessels locally permeabilize so that the increased number of passing leukocytes can pass the bloodvessel wall and enter the injured tissue to start the healing process. The white blood cells will release cytokines, that will attracts additional cells. The permeabilization increases the passage of plasma into the tissue, causing swelling. Pain results from the swelling and probably other factors.

So, an icepack will cause the contraction the dilating bloodcells, thereby the circulation in the area is reduced, there won't be enough circulating white bloodcells to start an inflammation reaction -> reduced swelling.