Cold-induced whealing in patients with typical ColdU is linked to markedly increased blood perfusion and PPG amplitudes
Patients with typical ColdU had high blood perfusion at skin sites that developed wheals in response to ICT, with an average PPG amplitude of 41.4·10-4 ± 5.8·10-5 AU. This was markedly higher than their blood perfusion at baseline (PPG amplitude: 6.2·10-4 ± 5.7·10-6 AU) as well as that of cold-exposed skin sites in patients with atypical ColdU (PPG amplitude: 9.9·10-4 ± 1.4·10-4 AU) and HCs (PPG amplitude: 9.5·10-4 ± 1.5·10-4 AU). Patients with atypical ColdU and HCs did not develop wheals at CST skin sites.
Patients with typical ColdU exhibit distinct pre-post CST changes in PPG amplitudes The ratio of post-provocation and baseline PPG amplitudes (R PPG) was markedly higher in typical ColdU patients (6.7 ± 0.3) than in atypical ColdU patients (1.9 ± 0.4) and HCs (1.9 ± 0.5). Of 39 typical ColdU patients, 38 (97.4%) had anR PPG >3, but only 3 of 24 patients with atypical ColdU (12.5%) and one of 15 (6.7%) HCs (Figure 4 ).