2. Total Body Water 50 to 60% of total body weight 80% of total body weight- New-borns Muscle and solid organs have higher water content than fat and bone
14. Treatment Mild-Free water restriction Moderate- Administration of sodium- 0.9% NaCl Severe- 3% normal saline- used to increase the sodium by no >1 meq/L per hour until the level reaches 130 meq/L Complications- Pontine Myelinolysis, Seizures, Weakness, Paresis, Akinetic Movements, Unresponsiveness, Permanent Brain Damage and Death
17. Treatment Treatment of the associated water deficit- 5% D Rate of fluid administration-achieve a decrease in serum sodium concentration of no more than 1 mEq/h Complications- Cerebral Edema and Herniation
20. Treatment Potassium removal Kayexalate Oral administration is 15–30 g in 50–100 mL of 20% sorbitol Rectal administration is 50 g in 200 mL of 20% sorbitol Dialysis Shift potassium Glucose 1 ampule of D50 and regular insulin 5–10 units IV Bicarbonate 1 ampule IV Counteract cardiac effects Calcium gluconate 5–10 mL of 10% solution
21. Hypokalemia Inadequate intake Dietary, potassium-free intravenous fluids, potassium-deficient TPN Excessive potassium excretion Hyperaldosteronism Medications GI losses Direct loss of potassium from GI fluid (diarrhea) Renal loss of potassium (gastric fluid, either as vomiting or high nasogastric output)
23. treatment Serum potassium level <4.0 mEq/L: Asymptomatic, tolerating enteral nutrition: KCl 40 mEq per enteral access x 1 dose Asymptomatic, not tolerating enteral nutrition: KCl 20 mEq IV q2h x 2 doses Symptomatic: KCl 20 mEq IV q1h x 4 doses Recheck potassium level 2 h after end of infusion; if <3.5 mEq/L and asymptomatic, replace as per above protocol
25. Magnesium Magnesium level 1.0–1.8 mEq/L: Magnesium sulfate 0.5 mEq/kg in normal saline 250 mL infused IV over 24 h x 3 d Recheck magnesium level in 3 d Magnesium level <1.0 mEq/L: Magnesium sulfate 1 mEq/kg in normal saline 250 mL infused IV over 24 h x 1 d, then 0.5 mEq/kg in normal saline 250 mL infused IV over 24 h x 2 d If patient has gastric access and needs a bowel regimen: Milk of magnesia 15 mL q24h per gastric tube; hold for diarrhea Hypermagnesemia-Calcium chloride (5 to 10 mL) should be administered to immediately antagonize the cardiovascular effects. If elevated levels or symptoms persist, hemodialysis
26. Calcium Normalized calcium level <4.0 mg/dL: With gastric access and tolerating enteral nutrition: Calcium carbonate suspension 1250 mg/5 mL q6h per gastric access; recheck ionized calcium level in 3 d Without gastric access or not tolerating enteral nutrition: Calcium gluconate 2 g IV over 1 h x 1 dose; recheck ionized calcium level in 3 d Hypercalcemia- serum level exceeds 12 mg/dL Repletingthe associated volume deficit Inducing a brisk diuresis with normal saline
In an average young adult male 60% of total body weight is TBW, whereas in an average young adult female it is 50%of TBW is found in newborns, with approximately 80% of their total body weight comprised of water. This decreases to approximately 65% by 1 year of age
The extracellular fluids (ECF), plasma and interstitial fluid, together comprise about one third of the TBW and the intracellular compartment the remaining two thirds
To clear the products of metabolism, the kidneys must excrete a minimum of 500 to 800 mL of urine per day, regardless of the amount of oral intake
Changes in serum sodium concentration are inversely proportional to TBW. Therefore, abnormalities in TBW are reflected by abnormalities in serum sodium levels
Excessive oral water intake or iatrogenic IV excess free water administration can cause hyponatremia. Postoperative patients are particularly prone to increased secretion of antidiuretic hormone (ADH), which increases reabsorption of free water from the kidneys with subsequent volume expansion and hyponatremia. This is usually self-limiting in that both hyponatremia and volume expansion decrease ADH secretion. Additionally, a number of drugs can cause water retention and subsequent hyponatremia, such as the antipsychotics and tricyclic antidepressants as well as angiotensin-converting enzyme inhibitors. The elderly are particularly susceptible to drug-induced hyponatrem
Most cases of hyponatremia can be treated by free water restriction and, if severe, the administration of sodium. In patients with normal renal function, symptomatic hyponatremia does not occur until the serum sodium level is ≤20 mEq/L. If neurologic symptoms are present, 3% normal saline should be used to increase the sodium by no more than 1 mEq/L per hour until the serum sodium level reaches 130 mEq/L or neurologic symptoms are improved
Hypervolemic hypernatremia usually is caused either by iatrogenic administration of sodium-containing fluids, including sodium bicarbonate, or mineralocorticoid excess as seen in hyperaldosteronism, Cushing's syndrome, and congenital adrenal hyperplasia. Urine sodium concentration is typically >20 mEq/L and urine osmolarity is >300 mOsm/L. Normovolemic hypernatremia can result from renal causes, including diabetes insipidus, diuretic use, and renal disease, or from nonrenal water loss from the GI tract or skin, although the same conditions can result in hypovolemic hypernatremia
rate of fluid administration should be titrated to achieve a decrease in serum sodium concentration of no more than 1 mEq/h and 12 mEq/d for the treatment of acute symptomatic hypernatremia. Even slower correction should be undertaken for chronic hypernatremia (0.7 mEq/h)
Potassium can be removed from the body using a cation-exchange resin such as Kayexalate that binds potassium in exchange for sodium. It can be administered either orally, in alert patients, or rectally
