The Pathophysiology of Non-Freezing Cold Injury in Male and Female Military Personnel

This is the most comprehensive study of non-freezing cold injury (NFCI) examining the neural, vascular and biomarker changes associated with chronic NFCI compared to matched controls

Non-freezing cold injury (NFCI) is caused by prolonged exposure to cold conditions and often results in functional impairment to the hands and feet. This is the first research project to compare individuals with chronic NFCI to controls (individuals without NFCI) who have had a similar level of previous cold exposure and those who have had minimal exposure to cold. We examined the function of nerves and blood vessels, measured levels of important blood biomarkers and included questionnaires on pain, cold exposure and cold tolerance.

The results and further analysis from this large research project indicate that no single measure or test will be able to diagnose NFCI. The most promising tests include: a cold sensitivity test; sensitivity to touch and warmth; number of nerve fibres in the skin; the skin blood flow response to breath-holding; measurement of some blood biomarkers (interleukin-10, syndecan-1 and endothelin-1); and cold exposure and cold intolerance questionnaires.

Individuals with chronic NFCI were cold intolerant compared to controls possibly due to increased endothelin-1, had impaired sensory function and may have reduced intraepidermal nerve fibre density (IENFD), rewarmed more slowly after a cold challenge and had a reduced vasoconstrictor response to deep inspiration (IGVR). Plasma syndecan and interleukin-10 were elevated in individuals with NFCI and cold exposed controls. Based on the tests conducted, chronic NFCI did not appear to be associated with endothelial dysfunction, oxidative stress or a pro-inflammatory state.

The results and further analysis from this large research project indicate that no single measure or test will be able to diagnose NFCI. The most promising tests include the cold sensitivity test, mechanical and warm detection thresholds, IENFD, IGVR, baseline plasma [IL-10] and [syndecan-1] and post heating [endothelin-1] and cold exposure and intolerance questionnaires.