Medical history of freezing injury is associated with persistent decrease in local response to cold. A case control study

Purpose: Tolerance to cold and cold injuries are characterized by a high inter-individual variability. We investigated the influence of frostbite history on physiological responses to local cold exposure during a hand cold water immersion test. Methods. 18 subjects with a frostbite history (FS, >1 year, mean 5.0±6.5 years), and 18 control subjects (CS), immersed their right hand for 30min in a 5°C water bath (CWI), followed by 30min recovery (passive recovery) at ambient air temperature (Tdb=22°C), then 30min in a 43°C water bath (active recovery). Fingers and core temperatures, skin blood flow, heart rate and blood pressure were continuously recorded. Evaluation of pain and blood samples were made before, during immersion, and after recovery (active and passive). Results. Fingers temperatures and cutaneous vascular conductance (CVC) of the FS subjects were lower than CS during CWI (-0.8±0.5°C, p<0.03). Higher pain was reported during immersion in FS. After cold exposure, rewarming during passive recovery was slower for FS (-3.1±2.5°C, p<0.01). FS had higher endothelin levels since the beginning of the test until the active recovery and more elevated pCO 2 levels. No significant differences were observed in core temperature, heart rate, arterial blood pressure and arterial gas between the two groups throughout the experiment. Conclusion. Frostbite history is associated with persistent changes in tolerance and physiological responses during cold exposure and recovery. Our results suggest that the slow rewarming kinetic could be an index of high vulnerability trait, with a reduced blood flow to the extremities caused by a stronger vasoconstrictor tone compared to uninjured subjects.