Introduction: Human body has systems that preserve its homeostasis, corresponding to a spectrum of stimuli. As for thermal stimuli, vasculatures would react most, and changes in blood flow could be observed as skin temperature measured by thermography. In case that vasculature gets sickened, its response may change. We have observed that temperature unevenness/disparity among fingers is the most useful finding to see disturbed peripheral circulation in connective tissue diseases (CTDs) patients, although low temperatures prior to immersion and their delayed recovery after immersion are distinguished. Objectives: To examine whether warm stimulus ameliorates temperature disparity, and if it works, whether any differences are between warm tap water and warm water containing CO2. Patients and methods: CTD patients with signs or symptoms of circulatory disturbance in periphery of extremities were tested for thermo-loading test. Loading was hands immersion in 42C tap water or water containing CO2 (1000 ppm) for 10’’. Coefficient of variation (CV, mean of right & left SD/mean of 5 nailfolds’ temperature) was calculated at each measuring point (baseline, 0, 3, 5, 10, 15, 20, 30 minutes after the immersion), its change from baseline was examined, and the CV change was compared between tap and CO2 warm water. Results: Twenty-one (F:20, M:1, 60.0±17.1 year-old) , and 24 (F:22, M:2 58.3±19.4 y) patients were tested for tap and CO2 water immersion, respectively. Before warm bathing, varying levels of CV was observed from patient to patient (tap, 0.020+/-0.014; CO2 0.029+/-0.029, p<0.05). Just after the immersion, CV decreased in all of the patients (0.010+/-0.003, p<0.05 vs. baseline; 0.013+/-0.005, p<0.05). Then, afterward, CV gradually re-increased toward the level at baseline prior to bathing; however, until 20’ after, CV was still lower than that at baseline, in both immersions (data not shown). Thirty minutes after the immersion, CV re-increased to a level not statistically different from that at baseline in tap water immersion (0.018+/-0.011, ns); however, CV was still statistically lower in CO2 water immersion (0.016+/-0.014, p<0.05). Conclusion: Hands immersion in warm tap water and warm CO2 water both once ameliorated varied temperature, evaluated by CV. Amelioration was dissolved 30’ after the immersion in tap water, but sustained even 30’ after the immersion in CO2 water, in spite of higher CV in CO2 group

Background: Peripheral circulation is often disturbed in patients with connective tissue diseases (CTDs) and its objective evaluation is an important issue. Infrared thermography has been used for the purpose for decades [1]. Raynaud phenomenon (RP) is prevalent in and considerably characteristic of CTDs and we have long noticed colour unevenness among fingers in patients during RP attacks. We hypothesized that temperature unevenness among fingers detected by thermography would be a useful parameter to evaluate peripheral circulation. Objectives: To evaluate temperature unevenness among fingers as a thermographic parameter by comparing it with other parameters validated in previous studies. Methods: Patients who visited our hospital and had been diagnosed as having RP by their attending physicians and underwent thermographic examinations were included and compared with healthy volunteers. Skin temperatures of dorsum of hands at 10 fingers’ nail folds and MCP joints were measured at baseline. Then hands were immersed in 10°C water for 10 seconds. Skin temperatures were measured at 0, 3, 5, 10, 15, 20, and 30 min after immersion. Mean temperature, recovery rate (temperature recovery from immersion/decrease by immersion), and coefficient of variation (standard deviation/mean temperature) of nail fold temperature were calculated. Higher coefficient of variation means temperature among fingers is more uneven. Distal-dorsal difference (DDD: measured by subtracting mean temperature of MCP from that of nail fold) was also calculated and these parameters were compared between the two groups. Receiver operating characteristic (ROC) curve was generated to compare these parameters in terms of their capability of differentiating patients with RP from HCs. Results: Thirty-one patients with RP (10 with primary Raynaud, 11 with systemic sclerosis (SSc), 11 with other CTDs) were included and compared with 25 healthy controls (HCs). Baseline nail fold temperature was significantly lower in patients of RP than in HC (30.8±3.1 °C vs. 33.2±1.8 °C, p=0.0002). Cold-water immersion of hands revealed patients with RP had lower recovery rate, lower DDD, and higher coefficient of variation than did HCs. The differences in these parameters were the most evident at 5 min after immersion (patients with RP vs HCs: recovery rate; 49.6±27.7 vs 71.5±26.8, p=0.004 DDD; -1.4±2.8 vs 0.85±2.7, p=0.0008 coefficient of variation; 0.053±0.024 vs 0.021±0.015, p=1.2x10-6). On the basis of ROC curve analyses for these parameters, coefficient of variation of nail fold temperature most effectively differentiated patients with RP from HCs (Area under the curve; recovery rate: 0.64 DDD: 0.79 coefficient of variation: 0.88). Conclusions: Unevenness of temperature among fingers was the most useful thermographic parameter to evaluate disturbed peripheral circulation.