Physiological responses of individuals with idiopathic chilblains during cold exposure and rewarming: a nonrandomized clinical trial.

Idiopathic chilblains (IC) is a localized inflammatory disorder affecting acral areas, with unclear pathophysiology and pathogenesis. This study aimed to investigate the vasomotor, autonomic, and inflammatory responses of adults with (HIC+) and without (HIC-) a history of IC during cold exposure and rewarming. Sixteen healthy adults (8 HIC+, 8 HIC-; 10 females, 6 males; aged 19-60 yr) underwent a controlled environmental protocol involving progressive cooling (22-10°C) followed by rewarming (22°C). Skin blood flow (SkBF); finger and toe temperatures (Tf and Tt); mean skin temperature (Tsk); microvascular oxygenation parameters including tissue saturation index (TSI), oxyhemoglobin (O2Hb), and deoxyhemoglobin (HHb); and total blood volume (tHb) were recorded throughout. Serum cortisol, ferritin, vitamin D3, antinuclear antibodies (ANAs), and scleroderma antibody (SCL-70) were also assessed. Compared to HIC- participants, the HIC+ group showed significantly lower SkBF (|d| = 0.43-0.56; P < 0.05) and Tf and Tt (|d| = 0.07-0.75) during cold exposure, along with reduced O2Hb (|d| = 0.33 at 10°C) and increased HHb (|d| = 0.43-0.46 at 14 and 10°C), suggesting impaired oxygen delivery. No between-group differences were observed in TSI. During rewarming, SkBF (47.06 ± 54.94 vs. 22.69 ± 21.48 PU) and HHb levels (5.53 ± 3.64 vs. 3.07 ± 2.84 μM) in the right finger were higher in the HIC+ than the HIC- group (|d| = 0.35-0.54). No significant differences were observed in serum cortisol or thermal perception. No participants developed chilblains or acral symptoms during the 8-wk follow-up. These findings indicate that individuals with a history of IC exhibit heightened cold-induced vasoconstriction and peripheral microvascular hypoxia, which may underlie susceptibility to chilblains and nonfreezing cold injuries.NEW & NOTEWORTHY This is the first study to investigate the vascular and oxygenation responses to cold and rewarming conditions in otherwise healthy adults with a history of idiopathic chilblains. By combining controlled environmental exposure with thermophysiological assessment, the study identifies a hyperconstrictive-hypoxic microvascular phenotype. Future work should explore the role of adrenergic receptor polymorphisms and rewarming kinetics as potential modulators of vascular stress and therapeutic targets for preventing nonfreezing cold injuries.