A serum sodium of 129 seen in immediate postoperative period.
|A||Warrants aggressive treatment with hypertonic saline to prevent seizures.|
|B||Should be treated with boluses of 0.9% Nacl until corrected.|
|C||Is a self – limiting problem due to transient increase ADH secretion|
|D||Is due to excessive fluids given intraoperatively|
(Ref: Schwartz :Principles of surgery 8th edition page no.84-86)
a. Among the mixed volume and concentration abnormalities, more common is an extracellular fluid deficit and hyponatremia.
b. This occurs in immediate post operative period when gastrointestinal losses are replaced with an inadequate volumes of only 5% dextrose in water or hypotonic sodium solution.
c. This is a self limiting condition .
d. Postoperative patients are particularly prone to increase secretion of ADH, which increases reabsorption of free water from the kidneys with subsequent volume expansion and hyponatremia.
e. A low serum sodium level occurs when there is an excess of extracellular water relative to sodium. For most cases of hyponatremia, sodium concentration is decreased as consequence of either sodium depletion or dilution.
f. Acute symptomatic hyponatremia is clinically characterized by CNS signs of increased intracranial pressure and tissue signs of increased intracellular water.
g. In severe hyponatremia there is relatively rapid development of the oligouric renal failure which may not be reversible if therapy is delayed.
h. Many chronic hyponatremic states are asymptomatic but until the serum sodium level falls below 120meq/L.
i. One important exception is patient with increased cerebro-spinal flid pressure, following closed head injury,in whom mild hyponatremia may be fatal.
j. CNS signs of hyponatremia are muscle twitching, hypeactive tendon reflexes, convulsions.
k. Tissue signs are salivation, lacrimation, watery diarrhea, fingerprinting of the skin.
l. CVS signs are changes in blood pressure and pulse secondary to increased intracranial pressure.
m. Renal signs are oligouria progressing to anuria.