Background
It has previously been shown, that cold induced vasodilatation (CIVD) is a specific individual response and can serve as a tool to estimate subjects’ cold (in)tolerance. In the present doctoral thesis we investigated vascular cold reactivity after digit cold injury in alpinists. The aim of this study was to assess the utility of CIVD as a diagnostic test to identify alpinists that are more susceptible to frostbite.
Methods
Immersion of extremities (hand and foot) in cold water maintained at 8 °C was used to study the response of the digit microcirculation in alpinists. Skin temperature and thus blood flow were measured with thermocouples attached to the skin at the nailbed of digits. Using this protocol, the following studies were conducted: 1) CIVD before and after an expedition to an 8-thousand meter peak was used to evaluate cold acclimatisation in alpinists. 2) After a cold water immersion test of hands and feet of 2 groups of alpinists (with and without amputations), spontaneous rewarming between both groups was evaluated with infrared (IR) thermography. 3) We compared skin temperature responses during cold water immersion of (amputated) stumps with non-injured digits of the healthy, contralateral side of the same injured alpinist. 4) We developed a clinical algorithm for the management of frostbite (Appendix).
Results
We confirmed that after a 35-day Himalayan expedition, alpinists experienced a slight cold acclimatisation of the hands: average skin temperature during the cooling phase was higher (pre: 9,9±1,1oC, post: 10,1±0,7 oC; p=0,031), amplitude of CIVD waves was greater, and and average skin temperature during spontaneous rewarming was higher. There were no signs of cold acclimatisation in the toes. Comparison of the results of a group of alpinists with a history of freezing cold injury resulting in amputations with with a group of ability matched elite alpinists with no frostbite history, revealed a significantly lower average skin temperature of fingers immediately after the cooling phase and also during the rewarming phase (20 % lower skin temperature after 5 minutes, p=0.04 and 18 % lower skin temperature after 10 minutes, p=0.03), but with no differences in the skin temperature rewarming rates. Comparison of skin temperatures between the stumps and corresponding contralateral digits within the cohort of injured alpinists showed that stumps cooled much faster (p<0,001) during the immersion phase and attained lower average skin temperatures (p<0,001). Indeed, all toes on the injured foot showed faster cooling rates in comparison with the toes on the uninjured foot. We did not see any differences in finger skin temperatures betwen the injured and non-injured hands. In the group of injured alpinists we present skin temperature values of an individual alpinist with probable frostbite susceptibility: although he never suffered frostbite in hands, his finger skin temperature during cold phase was ~2 °C lower and almost 6 °C lower during spontaneous rewarming compared with the control group. Testing individual alpinists prior to high altitude expeditions can be of benefit in predicting frostbite susceptibility.
Conclusion
In this study, we present CIVD as a good diagnostic tool for past frostbite in stumps after amputations. The value of CIVD as a prognostic test (frostbite susceptibility), should be further confirmed with prognostic CIVD measurements in non-injured alpinists prior to high altitude expeditions.
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