Maximum venous outflow and development of deep vein thrombosis.

To evaluate the relationship between maximum venous outflow (MVO) of the leg and development of deep vein thrombosis (DVT), venous occlusion plethysmography (VOP) using a Mercury strain gauge was carried out in 56 unilateral DVT patients. The data from these patients were compared with those obtained from several control groups. Then, the relationship between plethysmographic and 9 clinical variables was statistically analysed in the normal legs of these patients. The mean MVO of the normal legs of these patients was significantly higher than that of the affected legs, but it was significantly lower than those of normal controls and patients with mild congestive heart disease. However, it was similar to those in patients with lymphedema and obese men. A decrease in the MVO of the normal legs of these patients was noted in older females with femoral vein obstruction of the left leg, with a shorter number of days from the onset of symptoms or with higher values for the obesity index and calf circumference. Significant correlations between the MVO and the obesity index (r=-0.59), venous capacitance (VC, r=0.49) and the number of days from the onset of symptoms (r=0.40) were found in the normal right legs of these patients (n=40). In the normal left legs (n=16), on the other hand, significant correlations were found between the MVO and the VC (r=0.65) and the MVO and age (r=-0.65). The MVO of the normal legs of these patients was predicted from clinical variables by multivariate analysis, and a multiple correlation coefficient of 0.64 was achieved using 4 variables (F-value>2); i.e. the obesity index, the side of venous obstruction, the number of days from the onset of symptoms and calf circumference. From these results, we concluded that in the normal right legs of these patients, the MVO was more closely related to the obesity index than to the VC or the number of days from the onset of symptoms. In the normal left legs, however, the MVO was influenced by another factor; i.e. the iliac compression syndrome, which might become more apparent with age. Finally, it was concluded that a decrease in the MVO of the normal legs could increase the occurrence of DVT.