Tests employed in Japan for the investigation of peripheral circulatory disturbances due to hand-arm vibration exposure.

MATSUMOTO T. Tests employed in Japan for the investigation of peripheral circulatory disturbances due to hand-arm vibration exposure. Scand J Work Environ Health 13 (1987) 356-357. Tests for the investigation of peripheral circulatory function are thought, in Japan, to be of primary importance for the proper diagnosis of the hand-arm vibration syndrome. The complaints presented in connection with Raynaud's phenomenon (finger skin blanching, numbness, cold sensation, and pain in the hands) should bethoroughlyassessed. In evaluatingthe resultsof skintemperaturemeasurementsand the nailcompression test before and after cold provocation by immersion of the hands in cold water, seasonal and diurnal variation, as well as differencesin room temperature, temperatureof the coolingwater, duration of cooling time, etc, must be taken into account. results of skin measurements and the nail compression test at rest and after the and in

In 1973, the Japanese Ministry of Labour issued rules for the examination of persons with suspected damage caused by hand-held vibrating tools (9). The examination procedures currently used in Japan consist of the assessment of complaints (frequency, distribution on the hand, and seasonal occurrence of Raynaud's phenomenon, numbness, pain, etc, in the upper and lower extremities) and laboratory tests. For~linical purposes the laboratory tests include skin temperature measurements with contact thermometry and/or thermography. In research, or in some cases needing a special examination, blood flow measurement, nail bed capillaroscopy, angiography, assessment of beta-thromboglobulin and hemagglutination capacity, etc, are also used. Vibratory and pain perception thresholds and peripheral nerve conduction velocity -dysfunctions in which are considered in Japan to occur in parallel with signs of peripheral circulatory disturbances -are often assessed.

Factors influencing skin temperature measurements and the nail compression test
In the evaluation of the results of skin temperature measurements and the nail compression test at rest and after cold provocation, seasonal and diurnal variation and differences in room temperature, in the temperature of the water used for cooling the hands, and in the duration of cooling must be taken into account.

Seasonal variation
The results of cold provocation by hand immersion in cold water have been shown to vary with the time of year. In an investigation by Azuma (2), one hand was immersed to the wrist in water at 5, 10, and 15°C for 10 min at a room temperature of 20°C. Fingertip skin temperature in the autumn was lower than in spring but similar to that measured in the winter. Finger skin temperature measured in the spring was observed to be similar to the summer values. The same differences were noted for recovery time after cold provocation. The recovery after cold water immersion in summer and spring was faster than in autumn and winter. In work by Harada et al (5) and Hirosawa et al (6), cold provocation consisted of immersing one hand to the wrist in 10°C water for 10 min at room temperatures of 10, 20, and 30°C at four different times of the year (August, November, February, and May). The finger skin temperature and nail compression values and the vibration sense thresholds were better evaluated in summer and spring than in autumn and winter.

Diurnal variation
Finger skin temperature has been found (I) to depend on several factors which vary during the day, such as the interval after meals, duration of sunshine, rhythm of body functions, etc, but the precise circumstances of this variation are still unclear.

Room temperature
Skin temperature, nail compression test results, and vibration sense thresholds have been shown to be influenced by room temperature (4), most pronouncedly around 20 o e . These findings seem to be supported by the results of Kurumatani and his col-laborators (8) that room temperatures bet ween 18 and 22°C produce a great er d ifference bet ween a vibra tionexposed gro u p and a reference group than room temperatures of 18-22°C and > 22°C.

Temperature of the cooling water
It has be en claimed (7) to be possible to d iscriminat e subject s with th e hand-a rm vibra tio n syndrome fro m healthy persons by co ld water immersion o f th e hand to the wr ist in water at 10 a nd SoC. The results of Cheng-Po (3) sugges t that measuring th e rat e of recovery at 5 and IO min aft er cold pr ovocation with a water temperature o f IOoC is optimal for the evaluation . In th e la st-m entioned wo rk , self-r a ting sco res reveal ed th at the co mpla ints o f pain at immersion were milder with 10°than with 5°C water. C ur re ntly, cold pr ovo cat ion is most fre quently per formed with a wa ter temperature of soc.

Duration of cooling.time
T he q uesti on o f th e ad equate duration fo r th e cold pr ovocation ha s not been full y clarified in J apan , but cold wa ter im me rsion for IO m in in 5°o r 1Q0C water is co m mo nly co ns idered ap pro pria te (7).

Optimization of the clinical examinations
A question often d iscu ssed in J apan co ncerns the optimal co nd itio ns under wh ich laborat ory exam inations with regard to cir culato ry disturban ces sho uld be performed . Among the fact or s in volv ed are , for insta nc e, whe ther the procedure is too co mplica te d or troublesome for the patient an d whethe r the exa m ination takes to o lon g. The commonly noted discrepancy bet ween compla int s and o bjec tive findi ngs has a lso been d iscu ssed .
A lar ge variatio n in th e examination methods currentl y used ap pea rs to exist in Japan . According to th e repli es to a questi onnaire (4) co nd uc ted in 1977 , most clinics perfor m skin temperature measur ements and th e nail co m pressio n test ; some also use plethysmography. In some clin ics, additional exam inatio ns are made, includ ing th ermogr aphy, capillaro scopy, and angi ogr aph y. Th e ph ysical exa m ina tion is pr imarily carried out a t room tem per atures of 20 to 23°C. Blo od circ u-latory di sturban ces are genera lly assessed by co ld provocation in 5°or IOoC water for 10 m in . It wa s pointed o ut that a clear de scription of the conditions under which the test s wer e mad e sho uld accompany all medical certificates concerning th e assessment of per ipheral circulatory distu rbances .
Finally, it should be mentioned that a worker usin g hand-held vibrating to o ls mu st have a specia l exam ination made at regular intervals. Th e aim of the examination sho uld be the a ssessment of various pathological sym pto ms a nd signs. This procedure is con sid ered to be an important regulation fo r the ea rly detection o f the hand-arm vibration syndrome.