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[The effect of standing in the workplace and the development of chronic venous insufficiency].

In the paper published by Shemesh et al. in this issue of Harefuah the authors present a theory according to which mechanical hydrostatic pressure generated by long periods of standing at the workplace is a major etiologic factor in the development of chronic venous insufficiency of the superficial venous system in the legs. Despite their opening remarks, concerning the complexity and controversiality of the etiology of this condition, the authors recommend that doctors and health authorities will take this "fact" into consideration when discussing working conditions and pass appropriate regulations ensuring enforcement. Unfortunately, there is insufficient evidence to support this conclusion. Both varicose veins and working while standing are very common, so it is not surprising to find a high percentage of varicose veins amongst those who work standing up. This, however, does not mean they are directly related. Ambulatory venous pressure while sitting is about 60-80 mm of water, as opposed to 20 mm while walking, and the number is only slightly higher (about 100) while standing. If venous pressure alone was the cause of CVI, we should have found relatively high incidence of CVI amongst workers in sitting positions. Yet, this is not the case. In the normal anatomy, venous valves are absent from the heart to the mid external iliac vein in the majority of the population, leading to high hydrostatic pressure on the first valves in the groin area. Recent work by J. Bergan and his group demonstrated (in laboratory animals) that increased venous pressure will lead to the disappearance of the valve leaflets. This can explain the high frequency of venous reflux amongst young people (13%) and the even higher frequency (35%) found amongst the elderly population. However, despite the high frequency of venous reflux and high venous pressure that are recorded, the majority of patients are asymptomatic. Today it is widely agreed that hydrostatic pressure alone is not enough to create CVI. Muscle pump failure and venous outflow obstruction, are as important contributors as the increased venous pressure. Moreover, new works by Zamboni and his group demonstrate that complicated inflammatory mechanisms play a major role in the etiology of varicose veins. The attempt to blame working conditions (i.e. standing) as an important and significant factor in the development of this complex disease process is far from established. Given the high economic costs (workers' compensations, creating new work environments etc.) that the writers' recommendation will inflict if implemented, one should exercise extreme caution in the interpretation of Dr Shemesh's work.