Its really not a question of saving a few pennys. There are two reasons nurses do this:
1.) to administer the correct dosage of the drug
2.) to prevent the drug from "leaking" out of the musscle therefore rendering it useless.
AIRLOCK TECHNIQUE (page 539, Craven & Hirnle)
The air lock technique, which clears excess medication from the needle following injection, is thought to prevent medication from leaking into the subq tissues and skin surface as the needle is withdrawn, thereby preventing irritation and staining of tissues. Air lock is recommended in combination with Z-Track Method but may be used with non-Z-Track I.M.'s.
Withdraw the desired volume of medication into the syringe.
Draw in a additional 0.2ml of air.
Insert the needle at a 90 degree angle.
Watch the position of the needle when injecting the air-lock. [Air goes upward, remember?] The air must be at the top of the fluid to go in last and "lock" the medication in the muscle.] If the patient is at an awkward angle, your air bubble may not be "on top".
Z-TRACK METHOD (page 539)
This method is used for certain medication that advise "for deep IM use only" or "given deeply into the body of a relatively large muscle".
When preparing the injection site, pull the skin and subcutaneous tissues about 1 - 1.5 inches to one side of the selected site.
Insert the syringe at a 90 degree angle.
Aspirate and administer medication while continuing traction on the skin.
Leave the needle inserted an additional 10 seconds.
Simultaneously remove needle and release traction on the skin. This zig zag pathway seals medication into the muscle.
##spiderbaby##