1. Using your dominant hand, grasp the cannula or the cannula's wings (if butterfly). If using an over-the-needle administered a local you previously anesthetic, its effectiveness will extend for only to inch (0.6 to 1.9 cm) from the injection site. Touch the spot with the cannula tip and ask the patient if it feels sharp. If she says no you know the site is properly anesthetized. Proceed at once with venipuncture. Note: If you didn't use a local anesthetic, encourage the patient to relax. Tell her to breathe slowly in and out as you insert the cannula.
2. Insert the cannula at a 5- to 25- degree angle, depending on the vein's depth. Insert the cannula bevel up to reduce the risk of piercing the vein's back wall. Position your fingers so you can see blood backflow in the tubing. While keeping the vein immobilized, advance the cannula through the skin and vein with one quick motion. Don't always expect to feel a popping or giving-way sensation. Look for blood backflow in the cannula tubing or hub to tell you that you've entered the vein lumen.
3- Upon visualization of backflow, lower the cannula almost parallel to the skin and advance it slightly to en sure the cannula tip is in the lumen of the vein. While immobilizing the vein advance the cannula completely into the lumen of the vein. Refer to the recommendations for manufacturer's further details on this step. Also see Advancing the Cannula: Four options.
4. Release the tourniquet, apply digital pressure beyond the cannula tip, stabilize the hub. With the safety device shown here, push the white activation button to shield the needle. Dispose of the barrel immediately into an approved sharps container. Be sure you're familiar with the techniques unique to the device you're using. If the initial insertion isn't successful, you can try repositioning the cannula as long as you don't remove its tip from the skin. A deeper or more superficial approach to the vein may work. If necessary, tighten the vein stretch to prevent the vein from rolling. Then make one or two more attempts to enter the vein without removing the cannula from the skin. If the vein seems to have decreased in fewsize, release the tourniquet, wait seconds, and reapply it.