A team of physicians at the Hospital
for Sick Children in Toronto has discovered a combination
of drugs that effectively treats pain in infants. Their
work appears in a study published in the February 15
issue of the Journal of the American Medical Association.
"The combination is a topical numbing cream, similar
to the stuff dentists use, and intravenous morphine,"
explains Dr Anna Taddio, PhD, the study's lead author
and a pharmacist at Sick Kids. "We thought each of these
drugs has its own individual advantages. The cream is
safe and has few heavy side effects. Morphine is very
effective at treating pain."
When using the topical anesthetic
tetracaine and morphine in tandem, babies felt significantly
less pain, notes Dr Taddio. "Pain response was reduced
by 60% with the morphine, 30% with the cream and 70%
when they were used in combination," she says.
THE
OUCH FACTOR
But for many physicians, figuring out if a baby is smarting
badly is far from child's play. "It can be challenging
to determine pain in infants because of their non-verbal
nature," says Dr Hani Hadi, a Coquitlam, BC, pediatrician.
Dr Taddio agrees. "It's difficult in the sense that
you can't ask them where and how much it hurts," she
says but adds that babies have their own way of telling
you. "The biggest cue is vocalization, certain types
of cries are linked to pain. Another cue is facial expressions
and lastly physiological changes, like an increase in
heart rate."
In her study, facial expressions
— specifically bulging of the brow, when a child's
eyebrows come together, with eyes shut and mouth open
— were the most important cues measured. "It's
easily observed and is pretty well specific to pain,"
says Dr Taddio. "We also don't measure the face in isolation
to make sure we are capturing the whole picture." She
stresses that her team also looked for elevated blood
pressure and changes in pulse.
For Dr Hadi, it's important to
bear in mind that procedures that are painful in adults
cause pain in infants and children — even if they
can't explain it to you — so it's a good idea to
prepare for treating it beforehand. The importance of
treating infant pain is critical and there are two major
lines of reasoning behind it, says Dr Hadi. "The first
one is that there is a moral obligation to do no harm
and to minimize pain in patients, whether child or adult,"
he says. "It has been shown that using a pacifier dipped
in glucose water or cradling a child during a painful
procedure such as a heel-poke reduces crying time and
diaphoresis."
The second line of reasoning, Dr
Hadi explains, is evidence that suggests performing
painful procedures on neonates lowers the pain threshold
and leads to more pain. "There have been numerous well
designed studies looking at reducing pain in children,"
says Dr Hadi.
TREATING
THE PAIN
Despite the importance of treating pain in babies, few
guidelines exist concerning the drugs that should be
used. Dr Taddio set out to find the best protocol to
follow. Her team looked at 132 neonates' response during
the implantation of a central line — from needle
poke to threading the catheter through to the heart.
She explains that in most neonatal intensive care units
(NICU) babies get something for pain. But prior to this
study, there was little evidence to support the use
of either analgesic. "Some kids were getting morphine,
others weren't," she says.
Dr Hadi confirms this. "Most NICUs
use one analgesic such as morphine for invasive procedures,"
he says. "This recent study shows that a topical analgesic
may also be beneficial and can be used safely." He does
point to one downside: doctors would have to wait 45
minutes for the topical analgesic to take effect.
Nevertheless, the findings from
the study make an excellent case for using the two drugs
in tandem. "I think we now have the evidence needed
to develop protocols for our unit," says Dr Taddio.
"This trial shows these drugs work and we aren't basing
our decision on recommendations or people's opinions."
That proof is clear. Dr Hadi thinks
the results are compelling enough to make one strongly
consider using the two analgesics for non-urgent invasive
procedures in the NICU. "However, more importantly it
leads me to wonder whether we should also look beyond
the NICU to determine if we are using enough analgesia
in the older age group," he adds.
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