July 1998

Lidocaine iontophoresis for topical anesthesia before intravenous line placement in children.
Zempsky WT, Anand KJS, Sullivan KM, Fraser D, Cucina K. J Pediatr. 1998;132:1061-1063.
[ see abstract below ]

Zempsky et al performed a double-blind randomized study of the use of lidocaine iontophoresis as a means for reducing the pain of intravenous catheter insertion in children. It is always a major issue to insert an intravenous catheter in children of just about any age. This is because fear of the needle, even a 30 gauge for injection of local anesthetic, often supersedes any logic in terms of pain being related to the diameter of the needle. Having spent many a day "negotiating" with a fearful child, the availability of alternate methods for pain relief is quite desirable.

The first method for "painless" catheter insertion was EMLA (eutectic mixture of local anesthetics) cream. At first glance, this seemed like a wonderful addition to our armamentarium; but it has not, in practical terms, proved very useful in the operating room. The reason for this is that in order for it to be effective, it must be applied at least one hour prior to catheter insertion. In a very busy outpatient department, it is not often possible to bring children into the preadmission area until only 20-30 minutes prior to induction. This makes the need for a 60-minute application time somewhat impractical. On another note, a previous study by Soliman et al demonstrated that children were just as upset by the thought of the needle as they were by actual insertion, so that even though analgesia was achieved, patient upset was not necessarily avoided. [1] A further disadvantage of EMLA is that often the blood vessels constrict rather than dilate, thereby making catheter insertion more difficult.

Lidocaine iontophoresis offers the potential to save time because the entire process usually takes approximately 10-15 minutes, thus making it of more practical value in busy surgical settings. In addition, blood vessels seem to dilate rather than constrict (personal observation). The main disadvantage of this technology is that it causes tingling and itching in about 50% of patients (in the Zempsky study, two patients out of 42 dropped out because of discomfort). It would seem that this technology is better suited for use in older patients who can be coaxed, cajoled, and reasoned with to "stay with it" until the local anesthetic has been absorbed. Unfortunately, the population that would most likely benefit from this technology are younger and more fearful children; and my guess is that this age group, which often objects even to application of a pulse oximeter, would also object to the application of a much larger device that causes some degree of mild discomfort. Time will tell whether this technology will come to play a significant role in managing fearful pediatric patients in the operating room.

Reference

• Soliman IE, Broadman LM, Hannallah RS, McGill WA: Comparison of the analgesic effects of EMLA (eutectic mixture of local anesthetics) to intradermal lidocaine infiltration prior to venous cannulation in unpremedicated children. Anesthesiology. 1988;68:804-806.
  

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ABSTRACT