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Topical anaesthetic creams


Six-year-old Angela comes into your department with a three-day history of diarrhoea and vomiting. You determine that she needs cannulation to assess her renal function and begin treatment. You know that cannulating children can be a painful and traumatic experience, and are keen to make it as stress-free as possible. The nurses ask you what you want them to put on the child.

Bottom line pearls

IV cannulation can be a painful experience for children; by making it less distressing we can reduce potential anxiety if further cannulation is required.

A variety of local anaesthetic creams are available.

Topical amethocaine seems to work better than EMLA

It should be liberally applied to several potential cannulation sites but has uses beyond just cannulation

Do children really need something to make cannulation less painful?

Of course, they do! Reducing pain and anxiety can make life much easier for ourselves and our colleagues in future visits.

What topical anaesthetic creams are available?

The three commonly available topical anaesthetic creams are EMLA (5%),  AmetopTM/AnGelTM (4% amethocaine) and LMX-4.

How do topical anaesthetic creams work?

For a beautiful video reminder of how local anaesthetics work, watch this video by Armando Hasudungan.

The cream should be placed on normal, intact skin on a minimum of two (ideally four) possible cannulation sites and covered with an occlusive dressing. This does two things: it improves absorption and stops the cream covering everything the child comes into contact with.

They are rapidly absorbed from inflamed skin, highly vascularized areas and mucous membranes and should be avoided in these areas.

I must get this patient out of the department in four hours.  How long do they take to work?

Both work very quickly, with amethocaine taking 30 minutes before any clinically significant analgesia is obtained. EMLA takes a little longer, up to an hour. If you think a child is going to need cannulation then get some cream on them sooner rather than later.

What is EMLA?

EMLA is an acronym for Eutectic Mixture of Local Anaesthetic. The science geeks amongst you will know what this means, but in lay terms, this  ‘eutectic’ mixture displays unique physical properties different from its composite parts. Both prilocaine and lignocaine are crystalline solids at room temperature, but when combined in an oil-water base have a much lower melting point and act as an oil.

Enough about the science.  What do I need to know?

EMLA is a mixture of lidocaine 2.5% and prilocaine 2.5%. It is licensed for use in all children from the neonatal period, but care must be taken in dosing, as with all medications. There is the theoretical risk of inducing methaemoglobinaemia if its use is combined with other agents that may precipitate such a state, e.g. sulphonamides or dapsone. It should be left on for an hour before removal and may cause noticeable skin blanching around the application site.  The numbness will last one to two hours.  It can be stored at room temperature.

What is AnGel™?

The active ingredient in AnGel™ or Ametop™ is amethocaine (tetracaine) 4%. It can be used in children over one month of age. Clinically acceptable analgesia is achieved in about 30 minutes. The numbness lasts up to six hours. It may cause erythema and vasodilatation around the application site.  It should be stored below 8°C.

What about LMX-4?

The active ingredient is 4% lidocaine. A proprietary liposomal formulation leads to the rapid onset of action, and like AnGel™ it is effective within 30 minutes of application. It appears to have some of the advantages of EMLA in that it does not require refrigeration coupled with the speed of onset of AnGel™. It is only approved for use in children over two years of age.

So is one better than the other?

Theoretically, topical amethocaine should be better.  It has a faster onset of action and may cause less vasoconstriction than the alternative. A BestBets review in 2008 revealed a paucity of quality literature around the subject, with many heterogeneous trials involving small numbers of participants. The overall trend did seem to favour topical amethocaine though some hospitals are moving towards the newer LMX-4.

Other than IV cannulation, what else can we use these topical anaesthetics for?

They can be used for any potentially painful invasive procedure such as lumbar puncture, nerve block and SPA.

What non-pharmacological alternatives are available?

Locally, we have had some success using Buzzy – an electronic device that utilizes cold and vibration to distract from the discomfort of cannulation.

For expert tips on paediatric cannulation, read this blog post by a paediatric anaesthetist, Andrew Weatherall.

Also, please consider using bedside ultrasound to help find those elusive veins in chubby toddlers.

You ask the nurses to liberally apply AnGelTM to both cubital fossae and the backs of the hands. When you return 30 minutes later she lets you expertly place a 22g cannula without flinching. Job done with three hours left before she had to leave the department.

Selected references

Boyd, Russell, and Michelle Jacobs. “EMLA or amethocaine (tetracaine) for topical analgesia in children.” Emergency medicine journal: EMJ 18.3 (2001): 209. full text

Browne, John, et al. “Topical amethocaine (Ametop™) is superior to EMLA for intravenous cannulation.” Canadian Journal of Anesthesia 46.11 (1999): 1014-1018.

McNaughton, Candace, et al. “A randomized, crossover comparison of injected buffered lidocaine, lidocaine cream, and no analgesia for peripheral intravenous cannula insertion.” Annals of emergency medicine 54.2 (2009): 214-220.

Moadad, Nemat, et al. “Distraction Using the BUZZY for Children During an IV Insertion.” Journal of pediatric nursing (2015).

Morgan‐Hughes, N. J., and C. B. Kirton. “EMLA–is one hour long enough?.” Anaesthesia 56.5 (2001): 495-496. full text

Pywell, Alison, and Andreas Xyrichis. “Does topical Amethocaine cream increase first-time successful cannulation in children compared with a eutectic mixture of local anaesthetics (EMLA) cream? A systematic review and meta-analysis of randomised controlled trials.” Emergency Medicine Journal (2014): emermed-2014

Speirs, A. F., et al. “Anaesthetics: A randomised, double-blind, placebo-controlled, comparative study of topical skin analgesics and the anxiety and discomfort associated with venous cannulation.” British dental journal 190.8 (2001): 444-449. full text

Young, Kelly D. “Topical anaesthetics: What’s new?.” Archives of disease in childhood-Education & practice edition 100.2 (2015): 105-110.



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2 thoughts on “Topical anaesthetic creams”

  1. There isn’t much in it when it comes to vapocoolant sprays and EMLA (See – Farion, Ken J., et al. “The effect of vapocoolant spray on pain due to intravenous cannulation in children: a randomized controlled trial.” Canadian Medical Association Journal 179.1 (2008): 31-36.) but coming at a small child with a freeze ray can be a little intimidating.

  2. Gavin Doolan (anaestricks)

    I use the CoolSense device when there is not enough time for cream (eg emergency surgery). It used cold to anaesthetise the skin in 10 seconds. You get about 20 seconds of anaesthesia. I think the creams are better, but it’s something at least. By the way, the 4 hour ED rule is just rediculous! Twitter = @anaestricks