I have heard mention of an air-lock technique with IM and SQ injections where a very small bubble of air is included last (i.e. the medication or antigens are injected first). Supposedly it will help diminish local reactions that might occur with immunotherapy. I searched PubMed and the IT practice parameter regarding comments about this technique but could not find anything. It seems possibly risky to me. Can you weigh-in regarding this technique?


Thank you for your inquiry.

The air-lock technique is used only for intramuscular injection. Its purpose is twofold:

A. To make sure all the medication you have drawn from the vial enters the syringe.

B. To seal the needle exit track so that no medication leaks into the subcutaneous tissue.

The air-lock technique would not apply to immunotherapy since it is intended only for intramuscular injections (1). The technique is accomplished by first drawing medication into the syringe. Once the desirable volume is obtained, 0.1 to 0.3 ml of air is drawn into the syringe. The medication is injected first at a 90 degree angle (usually when the patient is lying down) directly into the muscle. The air bubble is injected after the medication.

This technique is briefly discussed in a PowerPoint presentation, Intramuscular Injections - Christine Petersen, dealing with intramuscular injections. Slide 19 of this presentation deals specifically with the air-lock technique.

In summary, since to the best of my knowledge, and according to all the literature I have read, this technique is only for intramuscular injections, it would seem to be of no value in the administration of allergy injections.

Thank you again for your inquiry and we hope this response is helpful to you.

Nursing fundamentals: Caring and clinical decision making. Edited by Rick Daniels, R.N., Ph.D., Thomson Delmar Learning, 2003.

Phil Lieberman, M.D.

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