When injected into the adipose (fatty) tissues beneath the skin, a drug moves into the bloodstream more rapidly than if given by mouth. Subcutaneous (S.C.) injection allows slower, more sustained drug administration than I.M. injection; it also causes minimal tissue trauma and carries little risk of striking large blood vessels and nerves.
Absorbed mainly through the capillaries, drugs recommended for S.C. injection include nonirritating aqueous solutions and suspensions contained in 0.5 to 2 ml of fluid. Heparin and insulin, for example, are usually administered S.C. (Some diabetic patients, however, may benefit from an insulin infusion pump.)
Drugs and solutions for S.C. injection are injected through a relatively short needle, using meticulous sterile technique. The most common S.C. injection sites are the outer aspect of the upper arm, anterior thigh, loose tissue of the lower abdomen, upper hips, buttocks, and upper back. (See Locating subcutaneous injection sites, page 238.) Injection is contraindicated in sites that are inflamed, edematous, scarred, or covered by a mole, birthmark, or other lesion. It may also be contraindicated in patients with impaired coagulation mechanisms.
Prescribed medication â€¢ patient's medication record and chart â€¢ 25G to 27G 5/8â€³ or Â½â€³ needle â€¢ gloves â€¢ 1- or 3-ml syringe â€¢ alcohol pads â€¢ 2â€³ Ã— 2â€³ gauze pad â€¢ optional: antiseptic cleaning agent, filter needle, insulin syringe, insulin pump. (See Types of insulin infusion pumps.)
Preparation of equipment
Verify the order on the patient's medication record by checking it against the physician's order. Also note whether the patient has any allergies, especially before the first dose.
Inspect the medication to make sure it isn't abnormally discolored or cloudy and doesn't contain precipitates (unless the manufacturer's instructions allow it).
Wash your hands. Choose equipment appropriate to the prescribed medication and injection site, and make sure it works properly.
Check the medication label against the patient's medication record. Read the label again as you draw up the medication for injection.
For single-dose ampules
Wrap an alcohol pad around the ampule's neck and snap off the top, directing the force away from your body. Attach a filter needle to the needle and withdraw the medication, keeping the needle's bevel tip below the level of the solution. Tap the syringe to clear air from it. Cover the needle with the needle sheath.
Before discarding the ampule, check the medication label against the patient's medication record. Discard the filter needle and the ampule. Attach the appropriate needle to the syringe.
For single-dose or multidose vials
Reconstitute powdered drugs according to instructions. Make sure all crystals have dissolved in the solution. Warm the vial by rolling it between your palms to help the drug dissolve faster.
Clean the vial's rubber stopper with an alcohol pad. Pull the syringe plunger back until the volume of air in the syringe equals the volume of drug to be withdrawn from the vial.
Without inverting the vial, insert the needle into the vial. Inject the air, invert the vial, and keep the needle's bevel tip below the level of the solution as you withdraw the prescribed amount of medication. Cover the needle with the needle sheath. Tap the syringe to clear any air from it.
Check the medication label against the patient's medication record before discarding the single-dose vial or returning the multidose vial to the shelf.
- Confirm the patient's identity by asking his name and checking the name, room number, and bed number on his wristband.
- If your facility utilizes a bar code scanning system, be sure to scan your ID badge, the patient's ID bracelet, and the medication's bar code.
- Explain the procedure to the patient and provide privacy.
- Select an appropriate injection site. Rotate sites according to a schedule for repeated injections, using different areas of the body unless contraindicated. (Heparin, for example, should be injected only in the abdomen if possible.)
- Put on gloves.
- Position and drape the patient if necessary.
- Clean the injection site with an alcohol pad, beginning at the center of the site and moving outward in a circular motion. Allow the skin to dry before injecting the drug to avoid a stinging sensation from introducing alcohol into subcutaneous tissues.
- Loosen the protective needle sheath.
- With your nondominant hand, grasp the skin around the injection site firmly to elevate the subcutaneous tissue, forming a 1â€³ (2.5-cm) fat fold.
- Holding the syringe in your dominant hand, insert the loosened needle sheath between the fourth and fifth fingers of your other hand while still pinching the skin around the injection site. Pull back the syringe with your dominant hand to uncover the needle by grasping the syringe like a pencil. Don't touch the needle.
- Position the needle with its bevel up.
- Tell the patient he'll feel a needle prick.
- Insert the needle quickly in one motion at a 45- or 90-degree angle. (See Technique for subcutaneous injection.) Release the patient's skin to avoid injecting the drug into compressed tissue and irritating nerve fibers.
- Pull back the plunger slightly to check for blood return. If none appears, begin injecting the drug slowly. If blood appears on aspiration, withdraw the needle, prepare another syringe, and repeat the procedure.
- Don't aspirate for blood return when giving insulin or heparin. It isn't necessary with insulin and may cause a hematoma with heparin.
- After injection, remove the needle gently but quickly at the same angle used for insertion.
- Cover the site with an alcohol pad or a 2â€³ Ã— 2â€³ gauze pad and massage the site gently (unless contraindicated, as with heparin and insulin) to distribute the drug and facilitate absorption.
- Remove the alcohol pad, and check the injection site for bleeding and bruising.
- Dispose of injection equipment according to your facility's policy. To avoid needle-stick injuries, don't resheath the needle.
- When using prefilled syringes, adjust the angle and depth of insertion according to needle length.
For insulin injections
- To establish more consistent blood insulin levels, rotate insulin injection sites within anatomic regions. Preferred insulin injection sites are the arms, abdomen, thighs, and buttocks.
- Make sure the type of insulin, unit dosage, and syringe are correct.
- When combining insulins in a syringe, make sure they're compatible. Regular insulin can be mixed with all other types. Prompt insulin zinc suspension (Semilente insulin) can't be mixed with NPH insulin. Follow your facility's policy regarding which insulin to draw up first.
- Before drawing up insulin suspension, gently roll and invert the bottle. Don't shake the bottle because this can cause foam or bubbles to develop in the syringe.
For heparin injections
- The preferred site for a heparin injection is the lower abdominal fat pad, 2â€³ (5 cm) beneath the umbilicus, between the right and left iliac crests. Injecting heparin into this area, which isn't involved in muscle activity, reduces the risk of local capillary bleeding. Always rotate the sites from one side to the other.
- Inject the drug slowly into the fat pad. Leave the needle in place for 10 seconds after injection; then withdraw it.
- Don't administer an injection within 2â€³ of a scar, a bruise, or the umbilicus.
- Don't aspirate to check for blood return because this can cause bleeding into the tissues at the site.
- Don't rub or massage the site after the injection. Rubbing can cause localized minute hemorrhages or bruises.
- If the patient bruises easily, apply ice to the site for the first 5 minutes after the injection to minimize local hemorrhage and then apply pressure.
Concentrated or irritating solutions may cause sterile abscesses to form. Repeated injections in the same site can cause lipodystrophy. A natural immune response, lipodystrophy can be minimized by rotating injection sites.
Record the time and date of the injection, medication and dose administered, injection site and route, and patient's reaction.