Nursing - fluid balance
Terms
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- intracellular fluid
- 40% of total body weight
- extracellular fluid
- 20% of total body weight
- formula for plasma osmolarity
-
2(Na) + BUN/5 + glucose/20
normal range is 275-295 milliosmoles/L - antidiuretic hormone - ADH
- Secreted by posterior pituitary in response to increased serum osmolarity
- Parathyroid hormone
- Secreted by parathyroid gland in response to low serum calcium
- Atrial natriuretic factor
- Released from cardiac muscle cells in response to atrial distention from fluid overload
- Aldosterone
- Secreted by the adrenal cortex in response to decreased blood volume, decreased renal perfusion, angiotensin
- renin
- secreted by kidneys in response to aldosterone
- angiotensinogen
- produced in liver, normally found in blood, acted upon by renin to form angiotensin
- angiotensin
- stimulates adrenal gland to produce aldosterone
- causes of hypovolemia
- excess urine output, diabetes insipidus, burns, fever, wound drainage, NG suction, diarrhea, vomiting, diuretics
- s/s of hypovolemia
- orthostatic changes, neg. I&O, fever, increased heart rate, weak thready pulses, weight loss
- isotonic fluid volume deficit
- fluid and electrolyte losses are equal
- In isotonic hypovolemia, what happens to EC and IC fluids?
- Volume & solute are lost from EC space; IC fluid unchanged
- Causes of isotonic hypovolemia
- Hemorrhage, diarrhea, decreased po intake, third spacing (trauma, burns, sepsis, cirrhosis)
- compensatory mechanisms for isotonic hypovolemia
- renin-angiotensin-aldosterone mechanism, SNS shunts blood to vital organs
- assessment of isotonic hypovolemia
-
Increased Hgb and Hct
Na+ normal
Urine SG >1.010 slightly conc.
BUN increased - treatment for isotonic hypovolemia
- NS or LR, blood, albumin, antidiarrheals, increased PO intake and nutrition, ABX
- hypotonic hypovolemia
- solute loss is greater than fluid loss
- In hypotonic hypovolemia, what happens to EC and IC fluids?
- EC fluid hypotonic; EC fluid shifts to IC space, cells swell & lyse
- causes of hypotonic hypovolemia
- CRF, malnutrition, rehydration with hypotonic fluids
- compensatory mechanisms for hypotonic hypovolemia
- Renin-angiotensin-aldosterone mechasism, stim. by decr. arterial pressure
- assessment of hypotonic hypovolemia
-
Increased Hgb & Hct
Na+ decreased
Urine SG<1.010, slightly dilute - treatment for hypotonic hypovolemia
-
NS or 3% saline w/ Lasix
K+, nutrition - Hypertonic fluid volume deficit
- Fluid loss greater than solute loss
- In hypertonic hypovolemia, what happens to EC and IC fluids?
- EC fluid hypertonic, IC fluid shifts to EC space, cell dehydrate
- Causes of hypertonic hypovolemia
- excess sweat, hyperventilation, fever, ketoacidosis, high osmolarity tube feeds
- compensatory mechanisms for hypertonic hypovolemia
- increased ADH (posterior pituitary stim by hyperosmolar ECF), increased thirst (hypothalamus)
- assessment of hypertonic hypovolemia
-
Hgb & Hct normal or increased
Na+ increased
Urine SG>1.030 more conc. - treatment for hypertonic hypovolemia
- 1/2 NS, treat the cause (w/ insulin, antibiotics, tylenol...)
- causes of hypervolemia
- kidney probs, heart probs, corticosteroids, excess Na+ or fluid intake, hypotonic fluids, SIADH, low protein, venous return probs, immobility
- s/s of hypervolemia
- incr. HR, bounding pulses, incr. BP & CVP, JVD, dysrhthmias, incr. RR, dyspnea, moist crackles, skin cool & pale, edema, muscle weakness, diarrhea, ascites
- isotonic hypervolemia
- serum osmolarity is normal
- what happens to EC and IC fluids in isotonic hypervolemia?
- EC space is expanded
- causes of isotonic hypervolemia
- excess isotonic fluids infused, ingested, retained
- compensatory mechanisms for isotonic hypervolemia
-
decr. ADH & aldosterone, incr. urine output
incr. natriuretic factor r/t atrial distension, incr. urine output - hypotonic hypervolemia
- AKA water intoxication, serum electrolytes decreased
- what happens to EC and IC fluids in hypotonic hypervolemia?
- hypotonic EC fluid moves into IC space, all compartments expand
- causes of hypotonic hypervolemia
- SIADH, excess water consumption
- hypertonic hypervolemia
- rare occurence, incr. serum osmolarity
- what happens to EC and IC fluids in hypertonic hypervolemia?
- IC fluid shifts to EC space; EC space expands, IC space contracts, cell shrivel
- causes of hypertonic hypervolemia
- excessive sodium intake
- treatments for hypervolemia
- caution with IV fluids, electrolyte solutions only, no free water, Lasix (furosemide)/Bumex (bumetanide), fluid restrictions
- What condition can result from too rapid IV infusions or blood transfusions?
- result - isotonic hypervolemia
- what is anasarca?
- generalized body edema from isotonic hypervolemia
- what are symptoms of anasarca?
- respiratory distress, weight gain, venous distension, incr. blood pressure
- what condition can results from intake of hypertonic fluids or extreme Na+ ingestion or retention (as from steroids or liver/rental failure)?
- result - hypertonic hypervolemia
- You see pitting edema and circulatory overload - what is the condition?
- dx - hypertonic hypovolemia