To the Editor.—In a prospective study comparing the relative merits of catheterization of the subclavian vein v the antecubital vein, thrombophlebitis was found in 12.5% of patients in the former group and 18.9% in the latter.1 In view of this high incidence of thrombophlebitis, we used a noninvasive technique to investigate the incidence of asymptomatic thrombosis in the subclavian vein.
Patients and Methods.—Twelve consecutive patients from each group (subclavian and antecubital) who were catheterized for reasons other than hyperalimentation were studied. A 14-gauge 50-cm polyethylene catheter was introduced through either the subclavian or antecubital vein and remained indwelling for varying periods of time. Five patients in each group were given 1,000 IU of heparin sodium for 12 hours intracutaneously from the time of catheterization until they were discharged. The same precautions were used before, and daily thereafter, at the point of venipuncture in both groups. Six patients