What is cold water immersion injury?
Cold water immersion injury is a hand or foot injury that’s caused by exposing a part of your body to cold (but not freezing) and wet conditions for a long period of time.
It’s also known as trench foot, trench hand or a non-freezing cold injury.
Cold immersion injuries happen because being exposed to the cold or wet for a long time can affect blood flow and nerve function.
These injuries most commonly happen in temperatures of -1C to 15C.
What are the symptoms of cold water immersion injury?
Cold water immersion injuries usually progress in 4 stages. The symptoms you’ll have will depend on the stage of the injury, but can include:
- numbness of your hand or foot
- a change in foot or hand colour – it can turn pale, blue, red or black
- blotchy skin
- blisters on your skin
- feeling cold
The stages of cold immersion injuries are:
- During cold exposure – while your foot or hand is in cold water, the first thing you’ll notice is numbness and your hand or foot may feel like a block or wood. You may feel clumsy and have problems walking. At first your foot or hand will look bright red, but it can then turn pale or white as blood starts to flow away from your skin.
- After cold exposure – as soon as you’ve taken your hand or foot away from the cold water, your hand or foot will usually start turning blue as it warms up and blood starts flowing in your hand or foot. It’ll still feel cold and numb and you may also have some swelling. This stage can continue for hours or days.
- Redness (hyperaemia) – in this stage, your foot or hand suddenly turns red and becomes swollen. You may find that the affected hand or foot becomes very painful while your fingers or toes stay numb. Occasionally, if the injury is really bad, blisters may also form on your skin. This stage can continue for days or weeks.
- After hyperaemia – in the last stage of a cold immersion injury, your hand or foot will usually look normal. But it will typically feel cold and be very sensitive to cold temperatures. Your hand or foot may also be painful and numb in places for a long time afterwards. This stage can last a few weeks, years or forever.
In very serious cases, cold water immersion injury can cause gangrene.
How is cold water immersion injury treated?
If you have a cold immersion injury, you should:
- get out of the cold, wet environment as soon as possible
- avoid putting weight on the affected hand or foot
- take off any wet socks or clothes
- clean and dry your hand or foot thoroughly
You should also see a doctor as soon as possible if the injury is mild, and call an ambulance or go to an emergency department if the injury is bad or not improving.
Treatment in hospital may involve:
- gradual rewarming of your body
- fluids given through a vein in your arm
- bedrest with your legs and arms raised
- painkillers – if you’re in pain
- other medications to help with nerve pain
- surgery if you have any dead tissue
- a vaccine to prevent tetanus
You may later be referred to a foot specialist for footwear advice and/or to a pain specialist if you have ongoing pain.