The effect of changes in temperature on peripheral blood flow in systemic sclerosis

Patients with systemic sclerosis (SS) suffer from acral ischaemia and decreased peripheral blood flow,1 which worsens with cold.2 The blood flow response to increased temperature is unknown. Finger pulp blood flow was therefore measured by laser‐doppler flowmetry in 11 patients (10 female) with SS and Raynaud's phenomenon, and nine normal controls (eight female). After equilibration at room temperature (28°C), resting blood flow was lower in the patients (0·45 ± 0·32 volts) than in the controls (1·63 ± 0·47 volts) (Wilcoxon rank test, P≤ 0·01). After hand warming (10 min in water at 35°C), flow rose more in the patients, resulting in similar flows in both groups. During subsequent cooling (delivered by blowing air at a constant rate through an ice‐box for 10 min), flow fell to similar minimal levels in 8·3 min in the patients and in 9·3 min in the controls. During recovery after cold stress, flow was maximal by 8·6 min in the patients (and was maintained for up to 3 h) and reached similar maximal levels by 7·6 min in the controls. The relationship to skin temperature was complex. This study demonstrates that impaired finger blood flow in SS can be returned to normal by simple warming. For some hours after warming the response to cooling is similar to that of controls. Therapeutically, it suggests that patients with SS should warm themselves thoroughly before entering cold environments.