Relationship between Tourniquet Pressure and a Cross-Section Area of Superficial Vein of Forearm

This study investigated the appropriate tourniquet pressure (TP) and duration of tourniquet application for venipuncture by calculating the venous cross-section (VCS) area on ultrasonography. Twenty healthy volunteers without cardiovascular risk factors were enrolled in this study. A target vein (either a cephalic or median cubital vein) was selected on ultrasonography. The pneumatic tourniquet was inflated using a rapid cuff inflator system at setting pressure for 120sec. TP strength was varied from 20mmHg to 100mmHg, in 20mmHg increments. The order of TP was randomized. Compari-sons among more than 3 groups were performed by one-way repeated-measures ANOVA and the Bonferroni method. The VCS area increased rapidly until 10sec after tourniquet inflation. The VCS area then increased gradually until 30sec after tourniquet inflation. After that, the VCS area did not increase remarkably. The VCS area increased with TP strength up to 80mmHg, but the VCS area at TP 100mmHg decreased to less than that at TP 40mmHg. Based on these results, we recommend a tourniquet pressure of 60mmHg, and duration of tourniquet application is 30 to 60sec for venipuncture.