AS ISO 5349.1:2013 Mechanical vibration—Measurement and evaluation of human exposure to hand-transmitted vibration
Workers exposed to hand-transmitted vibration may complain of episodes of pale or white finger, usually triggered by cold exposure. This disorder, due to temporary abolition of blood circulation to the fingers, is called Raynaud’s phenomenon (after Maurice Raynaud, a French physician who first described it in 1 862). It is believed that vibration can disturb the digital circulation making it more sensitive to the vasoconstrictive action of cold. To explain cold- induced Raynaud’s phenomenon in vibration-exposed workers, some investigators invoke an exaggerated central vasoconstrictor reflex caused by prolonged exposure to harmful vibration, while others tend to emphasize the role of vibration-induced local changes in the digital vessels. Various synonyms have been used to describe vibration- induced vascular disorders: dead or white finger, Raynaud’s phenomenon of occupational origin, traumatic vasospastic disease, and, more recently, vibration-induced white finger (VWF). VWF is a prescribed occupational disease in many countries.
Initially attacks of blanching involve the tips of one or more fingers but, with continued exposure to vibration, the blanching can extend to the base of the fingers. Sometimes, an attack of blanching is followed by cyanosis, i.e. a bluish discoloration of the affected fingers due to increased extraction of oxygen from the sluggish digital circulation. In the recovery phase, commonly accelerated by warmth or local massage, redness, eventually associated with tingling and/or pain, may appear in the affected fingers as a result of a reactive increase of blood flow in the cutaneous vessels. The blanching attacks are more common in winter than in summer and last from a few minutes to more than one hour. The duration varies with the intensity of the triggering stimuli and the severity of the vasospasm, the attack usually ending when the whole body is warmed. If vibration exposure continues, the blanching attacks become more frequent and may occur all year around.