Chapter 5: Fluids and Electrolytes, Acids and Bases Flashcards
Total Body of Water (TBW)
- total of the water in all fluid compartments.
- 60% of body weight is water
- varies w/ age, gender, body mass
TBW in older adults
-older adults have 50% less body weight by water because of increased body fat due to aging.
TBW in women
less body weight (water) than men because they have a greater proportion of body fat than men of the same weight.
TBW in newborns
have about 70-80% water by weight
Fluid Compartments
- Intracellular (ICF)
2. Extracellular (ECF)
Intracellular (ICF)
insider cells (ICF)
Extracellular (ECF)
- outside and in between cells.
- includes interstitial (surrounding cells, lymph) and intravascular fluid.
Majority of body water (2/3) is located w/in
cells and is termed intracellular fluid (ICF) except in infants.
Infants have more water located in
the extracellular compartment
Fluid in extracellular space is about
1/3 of body water.
termed extracellular fluid (ECF)
Intravascular
w/in vascular space, inside blood vessels.
Transcellular fluid
part of the ISF
ex) CSF, synovial membrane
Intracellular Movement of Water
-intracellular water does not move readily out of the cell
Intravascular Movement of Water
- in capillary beds, there is constant movement of fluids between extracellular fluid (interstitial & intravascular).
- maintains equilibrium
fluid and electrolytes
move between ICF & ECF.
Process involved in movement is
- diffusion
- facilitated diffusion (rapid diffusion due to a combined specific molecule)
- active transport
Water moves between ICF & ECF due to
opposing forces: capillary hydrostatic pressure and capillary osmotic pressure.
Capillary hydrostatic pressure
force w/in a fluid compartment (ex. blood vessel)
Capillary osmotic pressure
pressure required to stop osmotic flow of water.
Active Transport
Na and K
Osmosis
- movement of water between compartments separated by membranes permeable to water only. Not permeable to solutes.
- water then moves from the more dilute compartment (has more water) to a more concentrated side.
Tonicity of fluids/solutions
- isotonic
- hypotonic
- hypertonic
ICF and ECF are
isotonic to one another = no water movement occurs
Osmolarity
measures osmotic force of solute per unit of weight of solvent.
“concentration of particles dissolved in a fluid”
Cells are affected by the
osmolarity of the fluid that surrounds them.
Electrolytes
- substances essential to life
- mostly minerals
- components of ICF & ECF
Electrolyte concentrations can be expressed in
- mg/dL= milligrams per deciliter
- mmol/L= millimoles per liter
- mEq/L= milliequivalents per liter
mg/dL, mmol/L
describes how much lipid is present in a specific amount of blood
Electrolyte Intake
through diet, medications, and blood transfusions.
Electrolyte absorption
GI tract: depends on concentration gradients, binding proteins, intestinal fluid pH
Electrolyte distribution
- medications
- hormones: epinephrine (K), insulin (K), parathyroid hormone (calcium)
- cells and bones
Electrolyte excretion
- urine
- feces (diarrhea)
- sweat
Effect of undigested fat on electrolyte excretion
undigested fat in intestines binds to calcium and magnesium ions that are secreted into the GI tract and prevents them from being reabsorbed (seen in cystic fibrosis)
Electrolyte Loss
- vomiting
- NG (nasogastric) suction
- paracentecis
- hemodialysis
- wound drainage
Fluid and Electrolyte Imbalances
- common in chronic illnesses
- for therapeutic measures
- F&E imbalances: deficits or excesses.
Examples of therapeutic measures for fluid and electrolyte imbalances
IVF replacements and meds such as diuretics
Examples of chronic illnesses that can affect fluid and electrolyte balance
CHF, burns CRF
Hyponatremia
- less salt in ECF (water excess in ECF)
- water moves into cells causing cell swelling
Pathogenesis of Hyponatremia: Causes
- IVF after major surgery
- excess water intake
- IVF administration in renal failure
- small cell lung cancer
- diuretics
- excessive beer or water ingestion
- ADH administration
Signs and Symptoms of Hyponatremia
cellular swelling -> swelling of neurons: malaise, anorexia, N/V, h.a., confusion, lethargy, twitching, increased reflex, convulsions, seizures - coma!
Treatments for Hyponatremia
- IV w/ small amount of hypertonic saline solution (3% NaCl) or 5% dextrose in water.
- In GE replacement of F&E w/ oral drinks such as gatorade.
- Drugs: arginine vasopressin (ADH) receptor antagonists, conivaptan (vaprisol)
Hypernatremia
- more salt in ECF (less water in ECF)
- water moves out of cells leading to cellular dehydration, cell shrinkage
Neurological Symptoms of Hypernatremia
causes neurons to shrink
-irritability, confusion, tremors, seizures, coma.
Cardiovascular Symptoms of Hypernatremia
Increased HR and hypotension
GI Symptoms of Hypernatremia
N/V
Skin Symptoms of Hypernatremia
dry mucous membranes, dry skin, flushed skin, edema (d/t water retention)
Hypernatremia =
hyperchloremia
Pathogenesis of Hypernatremia: Causes
- concentrated tube feedings w/o enough water (esp in older adults)
- IV infusion of hypertonic solution D5NS
- near drowning in salt water
- reduced fluid intake
- difficulty swallowing fluids such as stroke pts.
- diabetes insipidus
- prolonged diarrhea
Treatment for Hypernatremia
- D5W (dextrose in 5% water) to dilute serum Na.
- Diuretics to promote excretion of Na
Edema
excess fluid between cells (interstitial compartment)
Pathogenesis of Edema
…
Signs and Symptoms of Edema
…
Treatment for Edema
…
Hypokalemia
-low potassium in ECF
Pathogenesis of Hypokalemia
- GI tract losses
- diuretics (lasix)
- low serum magnesium
- metabolic alkalosis
- DKA
- NPO
- excess insulin
- renal problems
Signs and Symptoms of Hypokalemia
- arrhythmias
- cardiac standstill
- muscle weakness
- flaccid paralysis
- may cause polyuria (d/t interfering action of ADH at renal tubules)
Metabolic alkalosis
shifts K into cells in exchange for hydrogen, thus lowering K in the ECF
Treatments for Hypokalemia
K chloride, K in IVF
NEVER administer K via IVP
Hyperkalemia
high potassium in ECF (greater than 5.0 mEq/L)
Pathogenesis for Hyperkalemia: Cause
- by increased potassium
- renal failure (most common cause)
- massive cell destruction (burns, crush injury, tumor lysis, ACE inhibitors, potassium sparing diuretics)
Signs and Symptoms of Hyperkalemia
- Vfib
- cardiac standstill!
- causes muscle dysfunction
Hyperkalemia and muscle dysfunction
hyperkalemia causes the smooth muscle and skeletal muscle to become hypopolarized causing intestinal cramping diarrhea, weakness, flaccid paralysis
Worse hyperkalemia can cause
skeletal muscle to become hypopolarized so that their resting potentials lie above their threshold potential, once they have discharged, they are unable to contract again.
Treatments for Hyperkalemia
- IV insulin along with glucose (prevent hypoglycemia)
- calcium gluconate
- kayexalate (binds K in exchange for Na and renin is excreted in feces)
- hemodialysis in RF
Table 5-7 lists additional
electrolyte abnormalities
Nursing Process and patient centered care teaching
pp 473-479
