Frostbite means that skin and underlying tissue actually freeze. This
condition rarely occurs in still air above -10°C but may do so at higher
temperatures in high winds due to the wind chill effect). It cannot be
emphasised strongly enough that frostbite need not happen even at
extremes of altitude, temperature and fatigue: frequently a degree of
carelessness is the chief cause.
Recognition
Below minus 10°C, any
tissue that feels numb for more than a few minutes may become
frostbitten. Although all climbers are well aware of having suffered
from numb cold feet or hands for hours at a time with no ill effects, it
is important to realise that while being frost-bitten the subject is
senses no more than this familiar numbness. It is wise therefore to have
some idea of the temperatures in unfamiliar terrain: many miniature
portable thermometers are available, so clip one on your sack or outer
jacket zipper tab. If you feel the numbness and the temperature is
particularly low it's time to act - flexing the fingers and toes,
stamping the feet, clapping your hands or placing them in the armpits or
groin should all bring back some sensation. If not, assume some degree
of frostbite (probably frostnip) and perform more specific re-warming
with warm water as below.
In early (superficial) frostbite in the
unthawed state, the skin is yellow-grey, painless, numb and leathery to
the touch - pain (lots of it!) occurs as re-warming takes place. In deep
frostbite, the tissue is hard, white and obviously frozen like a piece
of chicken from a freezer, and medical advice must be sought as soon as
possible.
Emergency treatment
For all but trivial frostbite (e.g. a
cheek, a fingertip) evacuation to a place of safety is essential. If
the feet are frostbitten the difficult decision has to be made about the
patient moving on foot. There are no absolute rules but in general, it
is better to move for six hours with frozen feet to a place of safety
than to thaw the feet at a high camp. Walking on vulnerable inflamed
unfrozen tissue can cause further injury.
Once safe, re-warming
should begin immediately. Avoid smoking (nicotine contracts blood
vessels), but alcohol may be helpful (it dilates blood vessels) -
however only provided hypothermia does not co-exist. If possible,
immerse the frostbitten area in a saucepan of hand hot water - 39-42°C
is optimal. If you have no thermometer heat the water until it is
"really quite hot" to the touch, about as hot as your elbow can stand:
take great care not to scald the patient! Immerse for periods of 20
minutes, moving fingers and toes if possible, but do not knock or rub
the frozen tissue.
Thawing may be extremely painful, but perseverance
is the key! After thawing, wrap gently in clean bandages, separating
fingers and toes. The victim must use thawed tissue as little as
possible - this may require them being nursed, fed and helped at the
lavatory by colleagues. If a hot water container is not available, warm
the affected parts in a warm sleeping bag (or on the abdomen, groin or
armpits) for several hours. Above 5500m, oxygen should be given if it is
available.
Further progress of frostbite
A few hours after
thawing the tissue swells and during the first two days giant blisters
form. Try not to break them, these blisters will settle during the first
week albeit to leave tissue hideously discoloured, and if gangrenous,
shrunken and black. This carapace, or shell separates in several weeks.
If the frostbite is superficial, pink new skin will appear beneath the
carapace, if deep, the end of a toe or finger will gradually separate
off - an unsightly but usually painless process.
By far the most important emergency treatment after re-warming is to keep the skin as clean as possible to avoid any infection.
Risks and implications of frostbite
The
disability caused by frostbite often leads to increased risks in
descending difficult ground and usually means abandoning a climb.
Anything more than very trivial frostbite means the end of climbing for
the patient for a few months at least. It is wise to warn newcomers to
cold conditions of these implications - adequate clothing, spare gloves
and dry socks should always be carried; boots should not be too tight
and if using plastic boots, consider carrying spare inners.
Long term management
There
are widely disparate views on the use of drugs in frostbite, a tacit
admission that few are really effective. It is imperative to keep
damaged tissue free of infection: antibiotics may be necessary, and
tetanus toxoid prophylaxis is often recommended.
It is extremely
difficult to predict the outcome in the first few weeks after frostbite,
and remarkable recoveries occur. Surgery is usually best avoided for
several weeks or even months, until it is clear that there is no other
alternative.
Summary
Frostbite on a climb is a major emergency,
yet with competent nursing care most cases can be looked after in the
field, e.g. at a Himalayan base camp. Frostbite can frequently be
avoided, but when it does occur, it increases the risks both to the
sufferer and their colleagues. Rapid re-warming is recommended and
strict adherence to hygiene, but surgery is usually best delayed for at
least several weeks, or months.
The UIAA Mountain Medicine Centre is supported by:
Mount Everest FoundationFoundation of Sport and the ArtsBritish Mountaineering Council.
Reference: UIAA Mountain Medicine Centre