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Risks of occupational exposures to hand-transmitted vibration: VIBRISKS
No full textVIBRISKS seeks to improve understanding of the risk of injury from hand-transmitted vibration and whole-body vibration by means of epidemiological studies supported by fundamental laboratory
research. VIBRISKS is a consortium of six partners from six European countries (France, Germany, Italy, Sweden, The Netherlands, UK). The four-year research project, which commenced in 2003, involves three work packages devoted to hand-transmitted vibration and three work packages devoted to whole-body vibration. This paper summarizes the hand-transmitted vibration research. Work package 1 defines methods to be used in studies of disorders caused by hand-transmitted
vibration in work package 2 and integrates the results of the epidemiological studies in work package 2 with the results of experimental and modeling studies in WP3 so as to define procedures that can be applied by occupational health workers for minimizing risk, screening exposed individuals and managing individuals with symptoms. Work package 2 involves longitudinal studies in workers
exposed to hand-transmitted vibration. Work package 3 involves experimental studies of the acute effects of hand-transmitted vibration on vascular and neurological function and the development of a finite element model of the biodynamic responses of the finger to vibration and force
Acute vascular responses to the frequency of vibration transmitted to the hand
No full textOBJECTIVES - To investigate the acute effects of the frequency of hand transmitted vibration on finger circulation. A further aim was to investigate whether the frequency weighting assumed in current standards for hand transmitted vibration reflects the haemodynamic changes which occur in the fingers exposed to vibration with different frequencies but with the same frequency weighted acceleration magnitude.
METHODS - Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. With a static load of 10 N, the right hand was exposed for 15 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vertical vibration: 5.5 m/s2 at 16 Hz; 11 m/s2 at 31.5 Hz; 22 m/s2 at 63 Hz; 44 m/s2 at 125 Hz; and 88 m/s2 at 250 Hz. These exposures to vibration produce the same frequency weighted acceleration magnitude (5.5 m/s2 rms) according to the frequency weighting included in the international standard ISO 5349. A control condition consisted of exposure to the static load only. Finger circulation was measured before application of the vibration and static load and at fixed intervals during exposure to vibration and a 45 minute recovery period.
RESULTS - No significant changes in finger circulation were found with only the static load. The FST did not change significantly during or after acute exposure to vibration. In the vibrated right finger, exposures to vibration with frequencies of 31.5-250 Hz provoked a greater reduction in FBF than did vibration of 16 Hz or the static load only. In the non-vibrated left finger, the FBF measured with vibration at each frequency of 63-250 Hz was significantly lower than that measured with static load only. The reduction in FBF during exposure to vibration with any frequency was stronger in the vibrated finger than in the non-vibrated finger. In both fingers, there was a progressive decrease in FBF after the end of exposure to vibration with frequencies of 31.5-250 Hz. The higher the frequency of vibration, the stronger the decrease in FBF in both fingers during recovery.
CONCLUSIONS - Acute exposures to vibration with equal frequency weighted magnitude reduce the FBF in both vibrated and non-vibrated fingers for frequencies between 31.5 and 250 Hz. The extent of digital vasoconstriction after exposure to vibration increases with increasing frequency. The frequency weighting given in current standards tends to overestimate the vasoconstriction associated with acute exposures to vibration frequencies around 16 Hz
Acute effects of vibration on digital circulatory function in healthy men
No full textObjectives - To investigate the local and central pathophysiological mechanisms involved in the acute effects of unilateral vibration on the digital circulation of healthy men. Methods - Finger blood flow (FBF) and finger skin temperature (FST) in thermoneutral conditions, and the percentage change in finger systolic pressure (FSP%) after local cooling from 30 to 10°C were measured in the fingers of both hands in eight men (aged 23-47 years) who were not occupationally exposed to hand transmitted vibration. The right hand was exposed for 30 minutes to sinusoidal vibration with a frequency of 125 Hz and an acceleration of 87.5 m · s-2 rms (root mean square). A control condition consisted of exposure to static load only (10 N) without vibration. The measures of digital circulation were taken before exposure to vibration and static load and at 0, 30, 60, and 90 minutes after the end of each exposure. Results - Exposure to static load caused no significant-changes in FBF, FST, or FSP% in either the test right or the control left finger. Immediately after vibration exposure, there was a temporary increase in FBF in the vibrated right finger, whereas the non-vibrated left finger showed no vasodilation. In both the vibrated and non-vibrated fingers, FBF and FST were significantly reduced during the recovery time. A large variability between subjects was found for FBF and, to a lesser extent, for FST. In the vibrated right hand the decrease in FBF was significantly related to cold induced vasoconstriction in the digital vessels. Such a relation was not found in the non-vibrated left hand. Conclusions - The results of this investigation suggest that acute vibration can disturb the function of digital vessels through two different and opposite mechanisms. Vibration seems to produce local vasodilation and to trigger a central sympathetic reflex vasoconstriction that can be recorded in the ipsilateral and the contralateral finger to vibration. Both local and central vasoconstrictor mechanisms are likely to be involved in the responsiveness to cold found in the digital vessels of a vibrated finger.</p
Vascular responses to acute vibration in the fingers of normal subjects
No full textThe aim of this experimental study was to investigate the pathophysiological mechanisms involved in the acute effects of unilateral vibration on the digital circulation of healthy men. In the fingers of both hands of eight male subjects (age 23-47 years) who had never worked with vibrating tools, finger blood flow (FBF) and finger skin temperature (FST) in thermoneutral conditions, and the percentage change of finger systolic pressure (FSP %) after local cooling from 30 to 10 °C were measured. The right hand was exposed for 30 min to sinusoidal vibration with a frequency of 125 Hz and an acceleration of 87.5 m.s.-2 r.m.s. A control condition consisted of exposure to the same static load (10 N) but without vibration. The measures of digital circulation were taken before exposure to vibration and static load and at 0, 30, 60, and 90 min after the end of each exposure. Exposure to static load caused no significant changes in FBF, FST, or FSP% in either the test right or the control left finger. Immediately after vibration, there was a temporary increase in FBF in the vibrated right finger, while the non-vibrated left finger exhibited no vasodilation. In both the vibrated and non-vibrated fingers, FBF and FST significantly reduced during the recovery time. A large intersubject variability was observed for FBF and, to a lesser extent, for FST. In the vibrated right finger the decrease in blood flow was significantly related to cold-induced vasoconstriction in the digital vessels. Such a relation was not observed in the non-vibrated left finger. The results of this investigation suggest that acute vibration can disturb the function of digital vessels through two different and opposite mechanisms. Vibration appears to produce local vasodilation and to trigger a central sympathetic reflex vasoconstriction which can be recorded in the ipsilateral and the contralateral finger to vibration. Both local and central vasoconstrictor mechanisms are likely to be involved in the response to cold observed in the digital vessels of a vibrated finger.</p
Effect of prior exposure to hand-transmitted vibration on cold response of digital arteries
No full textOBJECTIVES: To investigate whether prior exposure to hand-transmitted vibration on the day of a cold provocation test affects the cold response of digital arteries. METHODS: Each of ten healthy men attended two experimental sessions in which their right hands were exposed for 60 min to either contact force alone (5 N) or a combination of contact force (5 N) and 125-Hz vertical vibration with an acceleration magnitude of 64 m s(-2) r.m.s. (unweighted). Finger systolic blood pressure (FSBP) during local cooling to 10 degrees C was measured in the second right finger (exposed hand) and the second left finger (unexposed hand) before exposure and at 30 and 70 min after the end of both exposure conditions. RESULTS: Analysis of repeated measures of FSBP during local cooling by means of an autoregressive model revealed no significant difference in cold-induced vasoconstriction of the digital arteries between exposure to contact force alone and combined exposure to contact force and vibration. There were no significant changes in the cold response of digital arteries over time in either the right or the left hand after exposure of the right hand to either the contact force alone or the combined contact force and vibration. CONCLUSIONS: The results of this experimental study of the influence of prior vibration exposure on the cold test results suggest that in healthy men recent exposure to contact force and moderate levels of hand-transmitted vibration does not affect the response of finger circulation to cold provocation. These findings may be of practical importance for the definition of test conditions in the field, especially the length of time required between the last occupational exposure to tool vibration and the commencement of objective vascular testing.<br/
Linee guida per la prevenzione dei disturbi e delle patologie da esposizione a vibrazioni meccaniche negli ambiendi di lavoro
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Associazione tra angioneurosi e malattie di Dupuytren in esposti a vibrazioni. Inquadramento generale e casistica personale
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