When a child needs to be treated with IVs, numbing the skin in advance can help ease or eliminate the pain of needle insertion, making the procedure easier for the child, parents and health care professionals.

A new review of studies suggests that one numbing medicine does the job more quickly and thoroughly than another in common use.

Amethocaine, a topical anesthetic gel, was compared with EMLA, a topical anesthetic cream, for reducing the pain of intravenous insertions in children. Although both are effective, amethocaine was better at reducing pain and did not need to be applied as far in advance as EMLA, according to the review.

“The perception of the staff in the emergency room is that they don’t have time to wait. The bottom line is that it might be better to use amethocaine,” said lead author Janice Lander, Ph.D.

The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

The reviewers evaluated six clinical studies comparing EMLA (a combination of lidocaine and prilocaine) and amethocaine (trade name: Ametop) in 534 children ages three months to 15 years. Both need to be applied to the spot where the IV will be put in or the blood drawn and then covered with an occlusive bandage.

EMLA takes up to 90 minutes to completely numb the skin, while amethocaine takes between 30 and 60 minutes, the studies showed.

Researchers used several methods to assess pain, but primarily they listened to reports from the children or had observers assess their behavior, such as crying or grimacing. The meta-analysis showed that amethocaine was superior to EMLA in reducing pain no matter what the duration of time was since it had been applied.

For a scheduled procedure, the parent may be told where to put the cream at home so the area is numb well in advance. But in other situations there may not be enough time for a topical anesthetic to take effect before an IV insertion or before blood is drawn, said Lander, a professor of nursing at the University of Alberta in Edmonton, Canada.

In addition, if the IV cannot be started at the site that has been numbed, it must be started somewhere else. Two or three sites might be chosen to be numbed so that a second or third site is ready if the first does not work, Lander said.

Many facilities are now switching to a third topical anesthetic, ELA-Max, which contains only lidocaine and also has a fast onset of action, said Lynne Gerson Maxwell, M.D., an associate professor of anesthesiology at the University of Pennsylvania.

There is also an anesthetic patch that can be used in advance of a needle stick, added Maxwell, who is a member of the American Academy of Pediatrics’ Section on Anesthesiology and Pain Medicine.

Both Lander and Maxwell noted that EMLA is slightly vasoconstrictive, meaning that it causes blood vessels to contract. Amethocaine causes blood vessels to dilate slightly. Anything that causes blood vessels to narrow could make getting a needle into a vein more difficult, but this has not been studied.

But the biggest problem with using any topical anesthetic on children is that while it can eliminate pain, it does not eliminate the child’s cognitive response of fear and pulling away, Maxwell said. “It does not mean that they will sit there with their hand out and stay quiet.”

Lander JA, Weltman BJ, So SS. EMLA and Amethocaine for reduction of children’s pain associated with needle insertion. Cochrane Database of Systematic Reviews 2006, Issue 3.

Health Behavior News Service