NURS 205 Chapter Notes - Chapter 19: Heart Failure, Water–Electrolyte Imbalance, Plasma Osmolality
23 Nov 2016
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Na dominates ecf, determinant of ecf osmolality. Generate +transmit nerve impulses and regulate acid-base balance. Primarily regulated by kidney (excrete/retain na with adh). Aldosterone also promote sodium reabsorption from renal tubule. Serum na level reflects ratio of na:h2o. Changes in serum na reflect: water imbalance, sodium imbalance, both. ^ na hyperosmolality water out of cell dehydration. May be life-threatening at levels >155mmol/l; high mortality rate at levels >180 mmol/l. 1% across the spectrum of all hospital patients ; more common in neurologic & critically ill patients, hf, on diuretic, tube feeding. Water depletion esp common in ic setting (9% incidence of na > 150 mmol/l). Up to 1/5 of congestive heart failure suffer hypernatremia due to excess diuresis. Hypernatremia due to high protein tube feedings in elderly, debilitated, hospitalized patients (supplementary water should be added to feeds) Common causes: gain na>h2o or loss h2o> na. Usually related to water deficiency: inadequate water supple/ water loss.
