A blood vessel compression device including a C-shaped spring and a clamp at an end of the spring to compress a blood vessel. The clamp may have a flat shaped cross section or spatulate cross section with an edge where the edge confronts a blood vessel to compress it. The clamp may have a channel and a sac inflatable with air to compress the blood vessel. The device may be positioned on body to clamp an external jugular vein or cephalic vein for cannula insertion. The C-shaped spring may be spaced from a front of the neck to not compress a windpipe of the neck.