<b>Vasomotor, autonomic, and immune responses of people with history of idiopathic chilblains during cold exposure and rewarming: a randomized clinical trial</b>

Idiopathic chilblains (IC) is a cold-induced inflammatory condition of the acral regions, whose underlying physiological mechanisms remain poorly understood. This randomized matched-controlled clinical trial investigated the vasomotor, microvascular, and immune responses of adults with (HIC+) and without (HIC−) a history of IC during progressive cold exposure (22°C to 10°C) and subsequent rewarming (22°C). Sixteen participants (n = 8 per group) underwent a structured cold exposure protocol inside an environmental chamber. Skin blood flow (SkBF) in the fingers and toes was assessed via laser Doppler, and peripheral temperature and mean skin temperature were recorded using thermistors and iButton sensors. Microvascular oxygenation (O2Hb, HHb, tHb, TSI%) was measured noninvasively with functional near-infrared spectroscopy (fNIRS) on the dorsal foot. Additionally, serum cortisol levels were evaluated pre-, post-, and 24 hours after exposure, along with a panel of hematological and biochemical markers (e.g., vitamin D3, ferritin, WBC, RBC, and platelet indices).