fluid and electrolyte management

Isotonic dehydration

dehydration that does not cause osmotic water shift from ICF

ascites, diuretic therapy, GI fluid losses, aspiration of pleural effusion, inadequate fluid and salt intake

etiology of isotonic dehydration

hypertonic dehydration

-water loss exceeds salt loss

-osmotic shift of water from cells in ECF

vomiting, sweat loss, osmotic diuresis, osmotic diarrhea, inadequate water intake

etiologies of hypertonic dehydration

hypotonic dehydration

-most salt lost than water

-osmotic shift of water from ECF into cells

-sweat loss, GI fluid loss, thiazide diuretics, water replacement without adequate sodium and potassium replacement

etiologies of hypotonic dehydration

5mL solutions every 2 minutes should be obtained orally with the goal aimed at 10mL/kg for each stool

appropriate rehydration method for mild dehydration

50-100mL/kg over 3-4 hours should be obtained orally. This should be started with 5mL every 5 minutes

appropriate rehydration method for moderate dehydration

An IV bolus of 30-60mL should be started on a continuous infusion depending on the patients' weight. (For example if the pt weighs less than 20 kg give 1000 mL/d plus 50 mL/kg/d for each kilogram between 10 and 20 kg)

appropriate rehydration method for severe dehydration

%dehydrationn x Wt (kg) x 10

how do you calculate a volume deficit

-inadequate water intake

-excess water loss

-excess sodium intake (rarely)

common causes of hypernatremia

-thirst

-change in mental status---> drowsiness, restlessness, confussion, and lethargy, to seizure and coma

clinical manifestations of hypernatremia

-primary water deficit: IV NS or hypotonic fluids

-tx underlying cause

management of hypernantremia

-loss of sodium containing fluids

-excess water gain

-inadequate sodium intake (rare)

common causes of hyponatremia

-HA, irritability, difficulty concentrating

-severe: confusion, vomiting, seizures, coma

clinical manifestations of hyponatremia

-in case of water excess: fluid restriction, diureticss, small amount of hypertonic saline in case of seizures

-abnormal fluid loss: fluid replacement using isotonic sodium containing solutions, encourage oral intake

management of hyponatremia

-nausea, slow/weak pulse, sudden collapse

-numbness (usually in hands, arms, legs or feet)

-muscle weakness

-diarrhea or abdominal cramping

symptoms of hyperkalemia

depressed ST segment

diphasic T wave

prominent U wave

EKG findings of hypokalemia

-peaked T wave----> worsens to wide PR interval, wide QRS---> loss of sinusoidal p wave

ekg findings of hyperkalemia

Anorexia

Nausea

Vomiting

Sluggish bowel

Cardiac arrhythmias

Postural hypotension

Muscle fatigue

Weakness

Leg cramps

Decreased DTRs

symptoms of hypokalemia

methanol

uremia

DKA

isoniazid

lactic acidosis

ethanol/ethyllene glycol

salicylates

list the causes of metabolic acidosis (MUDPILES)

SIADH (CNS infections, head trauma, certain drugs)

CHF, nephrotic syndrome, cirrhosis (hypervolemic)

Excess hypotonic fluid intake (psychogenic polydipsia)

causes of hyponatremia

hypokalemia

constipation, muscle cramps is sin of what elecrtolyte imbalance

pseudohyperkalemia

Caused by prolonged use of tourniquet when drawing blood +/- fist clenching, causes acidosis and subsequent K loss from those cells but not true hyperkalemia

hyperkalemia

what electrolyte imbalance can cause weakness, paresthesias

-3% body weight loss as a resutl of fluid loss

-slight thirst, decreased urine frequency

classify milld dehydration

-6% decrease in body weight

-irritable or lethargic, dry mucus membranes

classiffy moderate dehydration

>10% in inants >7% in older children loss of body weight from fluid loss

classify severe dehydration

hypotension

______ is a late sign of shock