On 3/4/98, Kathy Doobinin wrote: in a series of questions that required
answers that highlight the art, more than the science, of medicine. I agree
with the responses of Drs. Pershad, Steele, and Fisher and would like to add
a few comments.
>A few questions for the list:
>1. When hydrating otherwise healthy children with dehydration, in which
>cases to you obtain serum electrolytes?
I do not get serum electrolytes unless there are facts in the history or age
risk factors that make me suspect severe dehydration, diabetes, excessive
salt or free water intake, etc.
>2. Do you get electrolytes in all kids or just when the history or physical
>exam make you suspicious for a clinically relevant abnormality?
...the latter. One response suggested getting electrolytes to help with
sensitivity in determining degree of dehydration. A urine dip gives plenty
of information with a lot less hastle. No glucose in urine...no DKA; a high
spec grav is reasonably sensitive indicator to assess mod to severe
dehydration in conjunction with the history. Spec grav in a normal range
doesn't rule out impending shock nor significant dehydration but it makes it
a lot easier to feel comfortable in sending home the chubby 8 month old who
is sucking down pedialyte that hadn't kept "anything down for 2 days and
hasn't wet his diaper all day".
>3. If child who has a low bicarb (rest of lytes are normal) looks well after
>rehydration and has proven they can tolerate oral fluids , will you admit
>them based on a low bicarb. If so, how low?
When the bicarb gets below 10, for every one point decrease in serum HCO3,
there is an exponential decrease in pH starting in the 7.25 range and lower.
Therefore, I have been rarely successful in sending home children when
bicarbs are less than 12-13. All others, 14 or greater...clinical judgment.
For mild to mod dehydrated children, I am a rapid bolus person - 30 cc/kg in
ED over 2 hours (Reid SR, Ann Emerg Med Sep 1996; Luten RC, editorial, Ann
Emerg Med Sep 1996.) I find the fluid bolus temporarily repletes
intravascular volume, makes the child feel better and may help partially
reverse the acidosis.
One respondent also mentioned the importance of reversing ketosis. I agree
but fluids alone cannot do this. Therefore, I give glucose with my 30 cc/kg
bolus like we do with pregnant women with hyperemesis gravidarum. Osmotic
diuresis from the glucose has never been clinically significant. I just make
sure I check an accucheck or BG before pgiving the glucose.
Good questions Dr. Doobinin...people are always asking them and not getting
Mike Gerardi, M.D.
Saint Barnabas Medical Center
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