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Overview :
Knize et al
identified several prognostic factors that can help predict outcome in patients
with frostbite. The authors are from the University of Colorado
in Denver.
Factors
affecting injury:
(1) likelihood of exposure (alcoholism or
mental instability)
(2) underlying disease (peripheral
vascular disease)
(3) extent of exposure (based on lowest
temperature and duration of exposure)
(4) modifying factors (contact of bare
flesh with metal or moisture; presence or absence of protective clothing;
mobility vs immobile)
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Parameter
|
Finding
|
Points
|
|
duration of
exposure
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< 30
minutes
|
1
|
|
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30 – 60
minutes
|
2
|
|
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1.01 – 4 hours
|
3
|
|
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4.01 – 12
hours
|
4
|
|
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12.01 – 24
hours
|
5
|
|
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> 24 hours
|
6
|
|
temperature
|
30 – 40°F
|
1
|
|
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20 – 29°F
|
2
|
|
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10 – 19°F
|
3
|
|
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0 – 9°F
|
4
|
|
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-1 to –10°F
|
5
|
|
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-11 to –20°F
|
6
|
|
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< - 20°F
|
7
|
where:
• The duration ranges overlapped at 1, 4,
and 12 hours. I modified the values above to prevent this.
• The options for temperature would be
lowest temperature or mean temperature of the exposure.
unit of injury =
= (points for
duration) * (points for depth of exposure temperature)
Outcomes
following frostbite injury:
(1) no residua
(2) causalgia or
contracture
(3) partial loss
of a digit (tip, etc.)
(4) complete
loss of a digit
(5)
transmetatarsal amputation
(6) below the
knee or below the elbow amputation
General rules:
(1) All victims exposed for > 1 hour
at a temperature < 20°F and in contact with metal or moisture lost some
tissue.
(2) The higher
the units of injury the more extensive the tissue loss.
(3) Mobility was
associated with less tissue loss (page 759).
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Units
of Injury
|
Outcome
|
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< 2
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no residua
|
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2 – 8
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no residua,
causalgia or contracture, partial loss of digit
|
|
9 - 20
|
partial or
complete loss of digit, rarely more extensive amputation
|
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> 20
|
amputation
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from Figure 6,
page 753
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