A<unk>  on the return arm during a plateletpheresis donation. During venipuncture, the butterfly is held by its wings between thumb and index finger. This grasp very close to the needle facilitates precise placement. The needle is generally inserted toward the vein at a shallow angle, made possible by the<unk> 's design. When the needle enters the vein, venous blood pressure generally forces a small amount of blood into the<unk> 's transparent tubing providing a visual sign, called the "flash" or "flashback", that lets the practitioner know that the needle is actually inside of a vein. The butterfly offers advantages over a simple straight needle. The butterfly's flexible tubing reaches more body surface and tolerates more patient movement. The butterfly's precise placement facilitates venipuncture of thin, "rolling", fragile, or otherwise poorly accessible veins. The butterfly's shallow-angle insertion design facilitates venipuncture of very superficial veins, e.g. hand, wrist, or scalp veins (hence name "scalp vein"<unk> .
Winged infusion set
Infusion pump
Target controlled infusion
Rate of infusion
Jet injector
Machine perfusion
Banana equivalent dose
Dye tracing