Effect of the cold pressor test on diffusing capacity. Comparison of normal subjects and those with Raynaud's disease and progressive systemic sclerosis.

Single-breath carbon monoxide diffusing capacity (Dsb) was measured before and during immersion of one hand in ice water (cold pressor test) in the following three groups of subjects: (1) normal subjects; (2) patients with isolated Raynaud's disease; and (3) patients with Raynaud's phenomenon and progressive systemic sclerosis. No change in Dsb was found in normal subjects or patients with progressive systemic sclerosis. Patients with isolated Raynaud's disease showed a rise in Dsb during cold pressor testing, the mean increase being 8 percent. These results suggest that a rise in Dsb during exposure to cold is a response unique to patients with isolated Raynaud's disease or Raynaud's phenomenon without progressive systemic sclerosis, and not a normal physiologic response to cold. The lack of change in Dsb in response to cold in progressive systemic sclerosis, interpreted by other authors as an indicator of pulmonary vascular disease, resembles the normal response to a challenge with cold.