Fluid and Electrolyte Balance Flashcards
intracellular fluid compartment
fluid IN the cells (ICF)
extracellular fluid compartment
fluid OUTSIDE the cell (ECF)
interstitial space, IV fluid (plasma), cerebrospinal fluid, transcellular fluid
isotonic solution
no net movement of water
hypotonic
ECF sodium concentration LOWER than ICF –> water shifts into cells –> cell swelling
hypertonic
ECF sodium concentration HIGHER than ICF –> water shifts out of cells –> cell shrinking
edema: definition
excessive accumulation of fluid within IS spaces
–> swelling or enlargement of tissues (localized or systemic); may impair tissue perfusion; may trap drugs in ISF
factors favouring movement of fluid from capillaries or lymphatic channels –> tissues
edema: causes
- increased capillary filtration pressure
- decreased capillary colloidal osmotic pressure
- increased capillary permeability
- obstruction to lymph flow
dehydration (fluid deficit)
insufficient body fluid due to inadequate intake and/or excessive fluid loss
dehydration: causes
vomiting and diarrhea
excessive sweating
diabetic ketoacidosis
insufficient water intake
use of concentrated formula in infants
edema: effects
- pain
- decreased ROM
- pitting
- tissue breakdown
- decreased arterial circulation `
dehydration: manifestations
dry mucous membranes
d. skin turgor
d. BP, weak and rapid pulse, fatigue
i. hematocrit
d. mental function, confusion, LOC
dehydration: compensations
i. thirst
i. HR
vasoconstriction of cutaneous BVs
d. urine production and i. specific gravity of urine
function of Na+
regulates ECF volume and osmolarity
AP propagation
hyponatremia: causes
- excessive water gain in ECF
2. excessive loss of Na+ from body (diarrhea, vomit, sweat, diuretics, hormonal balance, renal failure)
hyponatremia: manifestations
- muscle cramps, weakness, fatigue
- abdominal cramps, nausea, diarrhea, headache, disorientation
- seizures, brain damage, coma, death
hyponatremia: mechanism
decrease osmotic pressure –> fluid shifts into cells –> hypovolemia (decreased plasma volume) –> decreased BP
hypernatremia: causes
- water deficit in excess of Na+ deficit (GI; diarrhea, vomit or dermal; burns, excessive sweating)
- sodium gain in excess of water gain (excessive secretion of aldosterone)
hypernatremia: manifestations
thirsty
dry skin and mucous membranes
CNS changes (decreased reflexes, weakness, agitation)
hypernatremia: mechanism
increased osmotic pressure –> water shifts out of cells –> cellular dehydration
acids
release H+
strong acids dissociate completely
bases
accept H+
respiratory acidosis
hypercapnia with decreased pH (more acidic)
RA: initiating event
respiratory d/o impairs alveolar ventilation –> CO2 accumulation –> H2CO3 (acid) buildup
RA: compensation
kidneys conserve HCO3- and eliminate H+ in urine
RA: manifestation
impaired nervous system functioning:
Headache Lethargy Weakness Confusion Coma, death
metabolic acidosis
decreased serum HCO3- with decreased pH
MA: initiating event
decrease in HCO3-:
- excessive loss (diarrhea)
- renal failure
- increased buffering of HCO3- (non-volatile acids increasing; lactic, ketones, sulphate, phosphate)
MA: compensation
lungs: increase RR to blow of CO2
kidneys: conserve HCO3- and eliminate H+ in urine
MA: manifestations
impaired nervous system functioning:
Headache Lethargy Weakness Confusion Coma, death
