I just finished reviewing the paper by Glaser et al
that appeared in the New England Journal of Medicine (264, 264-9, 2001) on risk
factors for cerebral edema in children with diabetic ketoacidosis (DKA).
This is a multicentered case-control study involving a total of 6977 children
with DKA of whom 61 developed cerebral edema. Of these, 13 developed
permanent neurologic sequelae and 13 died. Only 2 children without
cerebral edema died.
In comparing those with cerebral edema with those
without, using logistic regression, there appeared to be a lower pCO2 and higher
BUN in those children with cerebral edema. Of the therapeutic
variables, only administration of bicarbonate was associated with cerebral edema
(relative risk = 4.2, 95% confidence interval 1.5-12.1). Use of insulin
bolus or rate of administration of insulin and rate of IV fluid infusion were
not associated with an increased risk of developing cerebral edema.
Since the relative risk of giving bicarb for
cerebral edema is 4 and the incidence of cerebral edema is about 1% (61/6977),
does this mean that the number needed to harm is about 1 divided by (1% x 4) =
25?
Does this mean that bicarb should never be given to
children in DKA? Or is giving bicarb merely a marker for severity of
disease and therefore the risk of developing cerebral edema?
Barney Eskin
Morristown Memorial
Hospital
