To The Editor:
I recently read the article "Ketamine Sedation for the
Reduction of Children’s Fractures in the Emergency Department" (82-A:
912-8, July 2000), by McCarty et al. I congratulate the authors
for highlighting an easy and safe technique for sedation in pediatric emergency
procedures. As an anesthesiologist working in a third-world country
and having eighteen years of experience with ketamine sedation,
I would like to make the following observations.
First, children (even those younger than nine years of age) may
experience dysphoria without knowing how to communicate it once
they are awake. One does see expressions of fear, cringing, and
startle responses in children after ketamine administration, although
they may be too young to tell the caregivers later. So it is preferable
to use midazolam as a prophylactic rather than as a "rescue" medication
after the child has already suffered the dysphoria. It would not
be acceptable to most third-world anesthesiologists to give ketamine alone
without a benzodiazepine or thiopentone sodium. Second, a common finding
in children administered ketamine is increased muscle tone that manifests
as rigidity of the lower jaw. This may lead to airway complications and,
if combined with laryngospasm, can be dangerous. Use of a benzodiazepine
or thiopental reduces this rigidity and makes jaw retraction easier.
So the routine use of midazolam before ketamine would be preferable
to the use of ketamine alone.
E.C. McCarty, G.A. Mencio, L.A. Walker, and N.E. Green
reply:
First of all, we appreciate Dr. Vas’ kind comments about
our article as well as her constructive criticism. The emergency
physician among us (L.A.W.) is particularly gratified to hear from
a physician in the third world, since the emergency department can
sometimes be the third world of American medicine.
Dr. Vas has some excellent observations that are quite applicable
to her practice of anesthesiology in India; however, we must respectfully
disagree with some of her comments. While it is true that young
children are not as articulate as adults, they almost always find
a way to communicate their needs, which can be perceived with close
attention to their vocal and bodily expressions. In our experience,
a few toddlers do seem to have visual hallucinations as they emerge
from ketamine sedation, but they rarely act as though this is unpleasant.
Only one child of the seventy-three in our series who were not treated
with midazolam exhibited behavior consistent with dysphoria; this
low incidence was reflected in the high rate of parental satisfaction
with our sedation regimen. Other studies have also found that the
emergence reaction of dysphoria is not a frequent problem1-5.
Even if dysphoric reactions are not a significant problem, would
the prophylactic administration of midazolam reduce the incidence
further and thus still be beneficial? If so, are there any drawbacks
to its use? These questions have been addressed in two recent, well-designed,
prospective, randomized, double-blind clinical trials4,5. Sherwin et al. found that the
prophylactic administration of 0.05 mg/kg of intravenous
midazolam did not have any benefit when used adjunctively with ketamine
for sedation4. Wathen et al. found
that intravenous midazolam at a dose of 0.1 mg/kg not only
did not reduce the incidence of emergence reactions, it increased
the frequency of hypoxia5.
Finally, we have not noted the lower-jaw rigidity that Dr. Vas
mentions, even though collectively we have now treated hundreds
of children with ketamine. Several studies have verified the very
low incidence of airway complications with ketamine1-5.