Numbing with Bacteriostatic Normal Saline

In my early years as a nurse on the IV team, one of our responsibilities was to start all the pre-op IV’s using 18g catheters. Because of the large gauge size catheters we were inserting, we would use buffered Lidocaine 1% to numb the site prior to IV insertion. If the patient is allergic to Lidocaine, we would use bacteriostatic 0.9% Sodium Chloride (normal saline) instead. When we used bacteriostatic normal saline to numb the site prior to insertion, patients appeared to have the same pain less  level as those whom we have used Lidocaine on. I always wondered if it really worked as patients did not complain of pain during the insertion at all.

Then, I was told that the skin stretching with the wheal created by the intradermal injection of bacteriostatic normal saline decreased the skin surface causing less pain upon insertion. Now, there are recent articles (see suggested articles below) stating benzyl alcohol, the preservative in bacteriostatic normal saline serves as the local anesthetic, numbing the site.

At that time, it was not routine to use intradermal anesthetic prior to IV insertion, it was reserved for insertion of large gauge catheters. Today, in an effort to decrease pain and promote patient’s comfort during painful invasive procedures such as IV insertion, most hospitals and healthcare facilities routinely use intradermal anesthetics prior to IV insertion.

Nurses vary in their opinions and beliefs on the use of intradermal injections prior to IV insertions.  Even with evidence, some nurses don’t routinely offer to their patients or use intradermal anesthestic.  Aside from intradermal injections, there are several methods available to achieve this purpose, including topical creams, dermal patches and iontophresis.

Suggested articles:

Brown D. Local anesthesia for vein cannulation. J Infusion Nurs. 2004;27(2):85-88.

Windle P, Kwan M, Warwick H, Sibayan A, Espiritu C, Vergara J. Comparison of bacteriostatic normal saline and lidocaine used as intradermal anesthesia for the placement of intravenous lines. J Perianesth Nurs. 2006;21(4):251-258.

Halm M. Effects of Local Anesthetics on Pain with Intravenous Catheter Insertion: Recommendations based on Current Evidence. Am J Critical Care. 2008;17(3):265-268