Raynaud's syndrome in workers who use vibrating pneumatic air knives

Purpose: The use of vibrating tools has been shown to cause Raynand's syndrome (RS) in a variety of workers, including those who use chain saws, chippers, and grinders. The diagnosis of RS in workers who use vibrating tools is difficult to document objectively. We studied a patient cohort with RS caused by the use of a vibrating pneumatic air knife (PAK) for removal of automobile windshields and determined our ability to document RS in these workers by means of digital hypothermic challenge testing (DHCT), a vascular laboratory study that evaluates digital blood pressure response to cooling. Methods: Sixteen male autoglass workers (mean age, 36 years) with RS were examined by means of history, physical examination, arm blood pressures, digital photoplethysmography, screening serologic studies for underlying connective tissue disorder, and DHCT. Results: No patient had RS before they used a PAK. The mean onset of RS (color changes, 100%; pain, 93%; parathesias, 75%) with cold exposure was 3 years (range, 1.5 to 5 years) after initial PAK use (mean estimated PAK use, 2450 hours). Fifty-six percent of workers smoked cigarettes. The findings of the physical examination, arm blood pressures, digital photoplethysmography, and serologic testing were normal in all patients. At 10°C cooling with digital cuff and patient cooling blanket, a significant decrease in digital blood pressure was shown by means of DHCT in 100% of test fingers versus normothermic control fingers (mean decrease, 75%; range, 25% to 100%; normal response, less than 17%; P < .001). The mean follow-up period was 18 months (range, 1 to 47 months). No patient continued to use the PAK, but symptoms of RS were unchanged in 69% and worse in 31%. Conclusion: PAK use is a possible cause of vibration- induced RS. The presence of RS in workers who use the PAK was objectively confirmed by means of DHCT. Cessation of PAK use in the short term did not result in symptomatic improvement.