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IM - VOLUME DISORDERS AND SODIUM

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tonystep1's version from 2017-08-01 03:54

VOLUME DISORDERS DDx and CLINICAL FEATURES

Question Answer
Hypovolemia DDxCauses l. GI losses due to vomiting, nasogastric suction, diarrhea, fistula drainage, etc. 2. Third-spacing due to ascites, effusions, bowel obstruction, crush injuries, burns 3. Inadequate intake 4. Polyuria-e.g., diabetic ketoacidosis (DKA) 5. Sepsis, intra-abdominal and retroperitoneal inflammatory processes 6. Trauma, open wounds, sequestration of fluid into soft tissue injuries 7. Insensible losses-evaporatory losses through skin ( 75%) and the respiratory tract (25%)
Hypervolemia DDxl. Iatrogenic (parenteral overhydration) 2. Fluid-retaining states: CHF, nephrotic syndrome, cirrhosis, ESRD
Hypovolemia CNS findingsmental status changes, sleepiness, apathy, coma
Hypovolemia Cardiovascular findingsorthostatic hypotension, tachycardia, decreased pulse pressure, decreased central venous pressure ( CVP) and pulmonary capillary wedge pressure (PCWP)
Hypovolemia Skin findingspoor skin turgor, hypothermia, pale extremities, dry tongue
Hypovolemia abdominal and renal findingsOliguria, ileus and weakness
Hypervolemia findingsWeight gain // Peripheral edema (pedal or sacral) , ascites, or pulmonary edema // Jugular venous distention // Elevated CVP and PCWP // Pulmonary rales // Low hematocrit and albumin concentration
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TREATMENT AND MANAGEMENT OF VOLUME DISORDERS

Question Answer
Hypovolemia Acute ManagementUse bolus to achieve euvolemia. Begin with isotonic solution (lactated Ringer's or NS). // Again, frequent monitoring of HR, BP, urine output, and weight is essential // Maintain urine output at 0.5 to 1 ml/kg per hour. // Blood loss-Replace blood loss with crystalloid at a 3:1 ratio.
Hypovolemia Maintenance fluidsD5 l/2NS solution with 20 mEq KCIJL is the most common adult maintenance fluid. (Dextrose is added to inhibit muscle breakdown.) // 4/2/1 rule: • 4 ml/kg for first 10 kg, 2 ml/kg for next 10 kg, 1 ml/kg for every 1 kg over 20 • For example, for a 70-kg man: 4 x 1 0 = 40; 2 x 10 = 20; 1 x 50 = 50. Total = 1 1 0 mLJhr
Hypervolemia Managementl. Fluid restriction 2. judicious use of diuretics 3.. Monitor urine output and daily weights, and consider Swan-Ganz catheter placement depending on the patient's condition
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SODIUM DISORDERS DDx

Question Answer
Hypovolemic Hypotonic hyponatremia with Low urine sodium ( <10 mEq!L) DDxextrarenal losses (e.g., diarrhea, vomiting, nasogastric suction, diaphoresis, third-spacing, burns, pancreatitis)
Hypovolemic Hypotonic hyponatremia with High urine sodium (>20 mEq!L) DDxrenal salt loss is likely-e.g., diuretic excess, decreased aldosterone (ACE inhibitors) , ATN
Euvolemic Hypotonic hyponatremia DDxSIADH //Psychogenic polydipsia // Postoperative hyponatremia // Hypothyroidism // Administration/intake of a relative excess of free water//Drugs-haloperidol (Haldol), cyclophosphamide, certain antineoplastic agents
Hypervolemic (low urine sodium) Hypotonic hyponatremia DDxCHF//Nephrotic syndrome (renal failure)// Liver disease
Isotonic hyponatremia (pseudohyponatremia)a. An increase in plasma solids lowers the plasma sodium concentration. But the amount of sodium in plasma is normal (hence, pseudohyponatremia) b. This can b e caused b y any condition that leads to elevated protein o r lipid levels.
Hypertonic hyponatremiaCaused by the presence of osmotic substances that cause an osmotic shift of water out of cells. These substances cannot cross the cell membrane and therefore create osmotic gradients./// Glucose, Mannitol, sorbitol, glycerol, maltose // Radiocontrast agents
Hypovolemic hypernatremiaRenal loss-from diuretics, osmotic diuresis (most commonly due to glycosuria in diabetics), renal failure • Extrarenal loss-from diarrhea, diaphoresis, respiratory losses
Isovolemic hypernatremia• Diabetes insipidus • Insensible respiratory (tachypnea)
Hypervolemic hypernatremia• Iatrogenic-most common cause (e.g., large amounts of parenteral NaHC03 , TPN) • Exogenous glucocorticoids • Cushing's syndrome • Saltwater drowning • Primary hyperaldosteronism
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CLINICAL FEATURES HYPONATREMIA AND HYPERNATREMIA

Question Answer
HyponatremiaNeurologic symptoms predominate-caused by "water intoxication"-osmotic water shifts, which leads to increased ICF volume, specifically brain cell swelling or cerebral edema a. Headache, delirium, irritability b. Muscle twitching, weakness c. Hyperactive deep tendon reflexes // Increased salivation and lacrimation
HypernatremiaNeurologic symptoms predominate a. Altered mental status, restlessness, weakness, focal neurologic deficits b. Can lead to confusion, seizures, coma //Tissues and mucous membranes are dry; salivation decreases.
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TREATMENT AND MANAGEMENT OF HYPO/HYPERNATREMIA

Question Answer
Isotonic and hypertonic hyponatremiasDiagnose and treat the underlying disorder
Hypotonic hyponatremia Mild (Na+ 120-130 mmol/L)Withhold free water, and allow the patient to reequilibrate spontaneously.
Hypotonic Hyponatremia Moderate (Na+ 110 to 120 mmol!L)loop diuretics (given with saline to prevent renal concentration of urine due to high ADH)
Hypotonic Hyponatremia (Na+ <110 mmol/L or if symptomatic)Give hypertonic saline to increase serum sodium by l to 2 mEq!L per hour until symptoms improve and Do not increase sodium more than 8 mmol/L during the first 24 hours // Anoverly rapid increase in serum sodium concentration may produce central pontine demyelination.
Hypovolemic hypernatremiaGive isotonic NaCl to restore hemodynamics // Correction of hypernatremia can wait until the patient is hemodynamically stable, then replace the free water deficit
Isovolemic hypernatremiaPatients with diabetes insipidus require vasopressin. Prescribe oral fluids, or if the patient cannot drink, give D5W
Hypervolemic hypernatremiaGive diuretics (furosemide) and D5W to remove the excess sodium. Dialyze patients with renal failure.
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