a special program of the National Emergency Medicine Association (NEMA)

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Week: 578.6

Guest: Dr. Anna Taddio, Hospital for Sick Children, Toronto, Canada

Topic: Should we always numb before circumcision

Host/ Producer: Steve Girard

NEMA: Thanks for being with us. Today we're talking about a pain relieving cream...it's called Emla. Now, a pain relieving cream is nothing new...but where it's used, when it's used and on whom it's used is new - on newborns, at the time of circumcision, and on the tiny boy's.....well, you know where I'm talking about. Today, we're with Dr. Anna Taddio, researcher at the Hospital for Sick Children in Toronto, Ontario....

TADDIO: Well, there have been a number of myths that have surrounded pain in infants, and the myths include: One, that infants cannot perceive pain...so they're not neurologically mature at the time of delivery to be able to perceive pain. And there's evidence in the literature that this is not true, and that the baby's nervous system is sufficiently developed at the time of delivery to feel pain. So then there's the question of, "why is baby's pain not being treated then...if the babies are mature enough to feel pain"? Another myth that surrounded pain and infants is that we couldn't measure it. So because an infant can't verbalize to us in a way we can understand, how much pain they feel...then people would say, "well, there's no way of measuring accurately, so there's no point in doing anything about it". But then, we've come along way also with research, and showing that babies respond to painful procedures in objective and measurable ways...and we can use these responses to judge how much pain they have. But this wasn't even enough. Then came the concerns for the toxicity of medications, so people have been afraid to give medications to babies because they thought they were too sensitive to the side effect of drugs. So then we had to do research, of course, with the medication...to be able to prove that they're safe and that they help to decrease the pain. And then there's another myth, the final myth, is that babies don't remember their pain. So, because infants can't tell us, years beyond the event, that they remember the pain, then people thought there was no consequence of it...so there was no point in measuring it. So what we've done in our research is to address some of these myths. And namely, we've looked mainly at the one that has to do with the side effects of medications, and the toxicity of medications...and we've shown that there are medications that you can use safely in a baby. And we've also looked at the myth that there are no long term consequences of pain. So, we've looked to see if there is, indeed, a pain memory in babies.

NEMA: What did your study show about giving babies pain relief?

TADDIO: Well, in our research, what we did was look at the effect of a topical anesthetic cream...this is a cream that numbs pain, and we use this cream for circumcision pain. And we looked at whether this medication could decrease a baby's reaction to circumcision...so we look at things like facial activity, and crying, and changes in physiologic measures...like heart rate and blood pressure. And these are all responses that adults have when they have painful procedures. And we looked to see how well the cream could change these responses, but then we also looked for side effects of the medications in the baby's system. And with this particular medication, we know that if we get an overdose of it, then we see a certain chemical in the body go up. And in our research, we found that using a normal dose, that was able to decrease the pain from circumcision, there was no side effect...so the amount of this chemical in the blood did not go up. So that we then concluded that the drug was safe to use.

NEMA: What is the chemical?

TADDIO: The name of the chemical is methemoglobin, and most people are familiar with a molecule in the body called hemoglobin, and this is the molecule that carries oxygen around to the tissues. Methemoglobin is simply hemoglobin that doesn't work...so it can't carry oxygen. And all of us have a bit of methemoglobin in our system anyway...about 1 or 2 % of our hemoglobin is methemoglobin...and that's okay. But if we have a lot of methemoglobin, say 40 or 50% of our hemoglobin, that means that about half of the hemoglobin in our body is not carrying oxygen to the tissues, and that would not be a good thing. So it means that the tissues are not getting enough oxygen. Now, it just so happens with this toxicity, methemoglobinemia, that it usually doesn't lead to any long term damage because it's easy to diagnose. So you would know somebody had methemoglobinemia because the color of their skin would change...they would turn brownish, or bluish, and we call that cyanosis. So someone would know you had it if they were looking for it...and it can also be reversed, there's an antidote. So, we're not too concerned if it does occur. But nevertheless, with the study that we performed, we saw that the methemoglobin amounts didn't change at all after using this medication...so the medication was safe to use in the doses that we used.

NEMA: How was the study set up to discover whether they remembered the pain from circumcision?

TADDIO: Well, what we did was we enrolled babies of parents who had decided to circumcise their infants into two groups. Half of the babies got the cream with the active ingredients in it, and half of the babies got what we call the placebo cream, or a dummy cream...that looks exactly the same. And we applied the cream on the baby's penis before the circumcision, and gave it some time to penetrate through the skin. And then, right before the circumcision, the cream was wiped away, and the physician performed the circumcision in the usual manner. While the circumcision was being performed, we monitored the babies and we also videotaped them during the entire time. And then we had someone, who didn't know who got what, assess how much pain the babies had. And what they did was they looked at the videotape, and they looked at how much facial action, or what kinds of facial grimaces the babies had during the procedure, or how much of them, and also how much crying the babies had during the procedure. And we compared the babies who got the cream with the babies who didn't. We also looked at physiologic measures, which included heart rate and blood pressure during the procedure, and again compared the infants who got the medication with the infants who got the placebo cream. And we found differences between the two groups, in that the babies who got the cream cried for less time, they showed less facial grimacing, they had lower changes in heart rate, and lower changes in blood pressure. Which tell us they had less pain than the babies who got the placebo cream. So that means that the cream effectively reduced the circumcision pain.

NEMA: Now you also followed these kids into their immunization sessions with their doctor....following up on the circumcision procedure...

TADDIO: What we were doing in that study is that we were trying to see if there was a long term effect....or some kind of memory of the circumcision pain. And the reason that we thought there might be one is that in a previous study, where we were looking at this medication for decreasing the inoculation pain, as you mentioned, we observed differences at the four and six month needle, and the reaction of baby boys with baby girls. We found that the baby boys had a bigger reaction to the needle than the girls did. So in this study, then, we thought it might be interesting to see if these differences were due to whether the baby had been circumcised or not. So we followed three groups of infants: Uncircumcised male infants, male infants who were circumcised with that cream, and then male infants who were circumcised without a pain reliever. And we looked at their pain responses during the routine inoculation. And we found that the babies who had been circumcised had the biggest reaction to the needle, and the babies who were not circumcised had the lowest reaction. And then those babies who had been circumcised with that cream scored somewhere in between. So they weren't different from the other two groups. But it suggests to us that there is some kind of long term memory of the circumcision event...at least for 4 or 6 months.

NEMA: And what were your conclusions?

TADDIO: So, the results tell us that firstly...circumcision may be associated...and other painful procedures...may be associated with some change in the central nervous system, and how the baby reacts to pain later on in life. So that there is a pain memory. And secondly, if we prevent the pain, then we may prevent these changes. So this is further evidence against those myths about infant pain that we mentioned earlier...that there's no long term memory of pain - there appears to be one. So that we really should be striving at decreasing or preventing pain in infants.

NEMA: So, you believe that we should do more than just dull the pain babies feel during circumcision...and find a way to safely block it...for the benefit of the child later on...?

TADDIO: Right, at least for the first 4 or 6 months...and we're not there yet. This cream did not totally prevent the pain...we still had babies crying during the procedure. And they still exhibited other responses that are indicative of pain. So what we did was decrease the pain a little bit, but we're hopeful that in the future, people will look at combining different kinds of medication to try to prevent the pain totally. And that hopefully, this will also translate into preventing those long term changes that we observed in our study.

NEMA: What about the reaction to your study?

TADDIO: Well, what I can say is that, of course, since we published our research, the people who have heard about it and have read about it have become more in tune with infant pain. And some of the hospitals have changed their practices about how they manage pain in infants. So in the hospital, for instance, where we performed the circumcision study, they've now started to use this cream, this topical anesthetic cream, for all the babies who get circumcised. And before that, the routine practice was to not use a pain reliever. So, we've got them using pain relievers more often in this age group, and thinking pain was more important than they used to. We've also then been able to educate parents about the pain associated with procedures such as circumcision, because we found in our research that a lot of times, parents are not aware that the babies are able to experience pain, and that the myths that have been propagated about pain in infants also extend to the parents. So we've made people be more aware that infants feel pain, and that there are ways to alleviate it.

NEMA: Our thanks to Dr. Anna Taddio, researcher at the Hospital for Sick Children in Toronto, Ontario.

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NEMA: Thanks for joining us for today's program. If you have any comments or suggestions, contact this station. Or visit our home page at: www.nemahealth.org/ ...for a look at transcripts of this or past programs, or to find out more about the National Emergency Medicine Association. I'm Steve Girard at The Heart of the Matter.



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