>> -----Original Message-----
>> From: Doobinin, Kathy [SMTP:[log in to unmask]]
>> Sent: Wednesday, March 04, 1998 1:29 PM
>> To: Multiple recipients of list PED-EM-L
>> Subject: Electrolytes in dehydration
>> A few questions for the list:
>> 1. When hydrating otherwise healthy children with dehydration, in which
>> cases to you obtain serum electrolytes?
I get lytes in all such cases to evaluate Na & HCO3. If they need IVF
they are at least in the moderate to severe range of dehydration, b/o
my clinical assessment. Hyper or hyponatremia impacts on duration of
therapy & type of hydrating fluid. Moreover, a low bicarbonate assists
me in determining extent of hypovolemia as well as degree of stool
HCO3 loss in the face of diarrhea. I refer you to Vega & Jeff Avner's
prospective study in the June 1997 issue of PEC. They used PLBW (%
loss of body weight before & after reaching well state) to evaluate
accuracy of a clinical exam in determining severity of dehydration.
Just using clinical criteria had a sensitivity of 77% for moderate
dehydration. This increased to 94% when combined with a HCO3 of <
17.The mean age group in their study was less than 2 years I believe.
PLBW is a reasonable objective criteria to base studies on. The issue
of which ones will progress to decompensted shock as Dr. Fischer suggests,
dependant on your assessment of "ongoing losses" & severity of
Ultimately, dehydration and it's correction is a dynamic process that does
happen in 2-4-6 hours but over days! Our job with hydration in the ED is
to "fill part of the tank", hopefully turn off the ketone production in
starvation etc and make sure PO fluids are tolerated with as always, a
mechanism for good FU if things go backwards.
>> 2. Do you get electrolytes in all kids or just when the history or
>> physical exam make you suspicious for a clinically relevant abnormality?
Only when clinical exam suggests moderate to severe dehydration.
Occult IDDM can present as emesis, severe dehydration with acidosis.
Along with lytes I also like to get a glucose for the above reason and
because hypoglycemia is not uncommon in a lethargic dehydrated infant.
Also in the young infant RTA can present with diarrhea and acidosis
>> 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?
No, i don't, unless i have another explanation for the acidosis besides
diarrhea and hypovolemia.
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