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Non-freezing cold injuries or NFCI occur when tissue fluids do not freeze (which usually at about -0.5C), but local temperatures remain low for several hours or days. It is likely to be much more common than currently believed, because it often goes unreported and is often under-diagnosed.

The affected individual has usually been cold and wet for a sustained period, often having been unable to dry out satisfactorily. On rewarming, it becomes apparent that the limb(s) (most commonly the lower legs) has developed a localised alteration in sensation. On rewarming there is a short period of paleness followed redness with swelling and pain. This pain is much more prolonged than the rewarming pain normally experienced in freezing cold injury, and is the most common reason for presentation. The last phase can last up to many months after initial injury, during which time persisting long term sequelae may become apparent. After the initial NFCI there is an increased sensitivity to cold.

There are often surprisingly few clinical signs for the doctor or medic to find. Infrared thermography is used by the UK military to assess an individualís response to a standardised cold stress, and this test may be helpful in confirming the diagnosis, assessing the severity of the injury, and finally monitoring the recovery or otherwise from the NFCI. There appears to be a significant variability in the response of some individuals to current infra-red thermography test.

NFCI vary in severity from mild to severe. In severe cases the cold sensitisation is so serious that individuals are unable to work outside. There is often persisting oedema and hyperhidrosis making the individual susceptible to fungal infections. Chronic pain resembling causalgia or reflex sympathetic dystrophy is reported. The profound sensory neuropathic foot can develop ulceration and tissue loss, ultimately resulting in either minor or major lower limb amputation. Ongoing care within a specialist foot clinic using custom made shoes and insoles appear to improve functional outcome. Multidisciplinary team approaches such as healing of the ulcerated neuropathic foot using patella bearing orthoses has been described. NFCI pain is often so severe as to require tricyclic antidepressants, and this should be instituted at an early stage. Failure to do so increases the risk of developing severe chronic pain resistant to all subsequent treatment modalities. Early involvement of pain specialists is important. Sympathectomy usually results in longer term deterioration. It is thus essential to control pain following NFCI at the earliest opportunity.

Unlike freezing cold injury, NFCI should be allowed to rewarm slowly. It is possible that hyperbaric oxygen may have value in early treatment too, although no trials appear to have assessed that use. Gross tissue damage following NFCI is relatively rare in peacetime experience, and after initial slow rewarming, management should follow the standard conservative protocol employed in freezing injury.

With the likelihood of chronic sequelae and only limited potential for treatment, the most effective approach to NFCI is to try to prevent its occurrence. There is a need to raise awareness to those most susceptible, particularly junior military recruits, for example. Ultra-early recognition of NFCI, even in the field, might be possible by the introduction of a simple field scoring system (not dissimilar to the Lake Louise Scoring System currently used for field assessment of acute mountain sickness). Although almost all cases of NFCI involve the feet, as many as 25% may also have injured hands. Afro-Caribbeans appear to have a significantly increased susceptibility to NFCI as well as freezing cold injury. This may be a result of an impaired or reduced cold induced vasodilatory response in Afro-Caribbeans as compared to Caucasians. These ethnic differences remain when Afro-Caribbeans move to colder areas.



C Imray, A Grieve, S Dhillon, the Caudwell Xtreme Everest Research Group. Cold damage to the extremities: frostbite and non-freezing cold injuries.
Postgraduate Medical Journal 2009; 85:481-488.

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