Basic Concepts of Fluid and Electrolyte Therapy

Monitoring
Monitor blood glucose, urinary ketones, acid-base status, serum
potassium, sodium, chloride and, if appropriate, osmolality, every
hour or two initially. Watch particularly for a fall in serum potassium
and correct this with increased potassium input to maintain
serum K + in the range of 3.3-4.5 mmol/l. Monitor clinical status,
vital signs, kidney function and urine output.
Fluid prescription
Traditionally, 0.9% saline has been used for resuscitation, followed by
0.45% saline with 5% dextrose and KCl as the volume deficit nears
restoration. Recent studies suggest that using a balanced electrolyte
solution avoids the hyperchloraemic acidosis associated with administration
of 0.9% saline.
Hypotonic solutions pose a risk of too rapid a fall in osmolality unless
the plasma sodium and osmolality are monitored carefully and the
infusion rate controlled accordingly. It should be remembered that
glucose acts like Na + as an ECF osmotic agent, so that as the blood
glucose falls with insulin treatment, water passes from the ECF to the
ICF, thereby concentrating the ECF sodium by 1.6 mmol/l for every
5.6 mmol/l fall in blood glucose. It is common, therefore, particularly
in HONK, to see the plasma Na + rise with treatment necessitating a
switch to a more hypotonic solution. It is at this point that switching
from 0.9% to 0.45% saline may be useful gradually to reduce the
plasma Na + to normal.
Although there is a phosphate deficit in decompensated diabetes, and
phosphate levels fall with treatment, phosphate supplementation has
not been shown to be beneficial.
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