Fluid Imbalance lecture Flashcards
1L = ? of water in the body
1L = 2.2 lbs
normal plasma osmolality level; number meaning associated with water excess or deficit
275-295 mOsm/kg
below -> water excess
above -> water deficit -> solute conc. increase
what are the electrolytes in and outside of the cell?
IN: K, PO4, Mg
OUT: Na, Cl, Ca, HCO3
what are some relationship with electrolytes IN and OUT of the cell
Na with K
Ca with PO4
INVERSE relationship
what is moving during diffusion
solutes move from low to high concentration
what are the electrolytes and molecules that require active transport
Na, K, Ca, H, amino acids, and some sugars
what is osmosis
water moves from low concentration solutes to high concentration solutes
osmolarity vs. osmolality
osmolarity: total solute per unit fluit outside the body; mOsm/L
osmolality: osmatic force per solvent within the vascular system; mOsm/kg
how does estimating serum osmolality work
add up all the electrolyte lab numbers;
doesn’t work for someone with abnormal glucose
urine osmolality level
100-1300 mOsm/kg
isotonic vs. hypotonic vs. hypertonic
isotonic: fluid will remain in vascular space
hypotonic: fluid leaves vascular space into cells (leading to edema)
hypertonic: fluid goes into vascular space from cells
what are the isotonic fluids
- normal saline - 0.9% NaCl
- lactated ringers
- D5W
what is normal saline 0.9% NaCl fluid used for
Big idea: expands intravascular volume/space
* shock
* hyponatremia, hypocalcemia
* blood transfusions
* increase BP, replace fluids
what is lactated ringers fluid used for
Big idea: rehydrating most types of dehydration
* burns
* acute blood loss
* hypovolemia due to 3rd spacing
* lower GI loss - N&V&D
what is D5W used for
fluid loss from dehydration
hypernatremia
what is a hypotonic fluid
1/2 NS (0.45% NaCl)
what is 1/2 NS (0.45% NaCl) fluid used for
water replacement
diabetic ketoacidosis after initial normal saline
hypertonic dehydration
gastric fluid loss (NG, V)
what are the hypertonic fluids
- dextrose 5% in 1/2 normal saline
- dextrose 5% in normal saline
- dextrose 5% in lactated ringers
dextrose 5% in 1/2 normal saline usage
- severe dehydration
- expands plasma volume
- burns
- diabetic ketoacidosis after NS and 1/2 NS
dextrose 5% in NS usage
- hypotonic dehydration
- temp fluid replacement in shock
dextrose 5% in LR usage
- replaces ECF losses - replace electrolytes
- mild metabolic acidosis
what is oncotic pressure
the osmotic pressure induced by plasma proteins, mainly albumin
causes of elevated venous hydrostatic pressure
heart failure
liver failure
fluid volume overload
causes of decreased plasma oncotic pressure
malnutrition
liver/renal disease
causes of elevated interstitial oncotic pressure
trauma
burns
inflammation
what is first fluid spacing
normal distribution of fluid
what is second fluid spacing
edema
what is considered third fluid spacing
ascites: fluid accumulation in the abdomin
what are the hormones that help maintain balance of fluids
- hypothalamus - ADH
- adrenal cortex - aldosterone
- kidneys - renin
- heart - ANP&BNP
- GI - oral intake of water & Na insensible water loss
function of ANP & BNP
released by the atria and ventricles, respectively, to dilate the blood vessels to decrease BP and volume; also promote the kidneys to increase water/Na excretion
changes in the elderly
- decreased renin & aldosterone effectiveness
- increased ADH & ANP (heart issues)
- more moisture loss through skin
- thirst center less effective - more likely for hypernatremia
what medication is dangerous with hypokalemia
digoxin
which diuretic is potassium sparing
spironolactone
dehydration
- serum osmolality & Na conc. increase
- loss of water ONLY
hypovolemia
- solute loss
- blood loss
- third space shift
causes of dehydration
- less water intake
- uncontrolled diabetic mellitus (osmotic diuresis)
- diabetes insipidus (less ADH)
- overuse of diuretics
difference between diabetes insipidus vs. mellitus
insipidus: doesn’t produce enough ADH or kidneys ignore signal
mellitus: something wrong with insulin somehwere
lab values to look out for due to dehydration
- elevated hematocrit (HCT)
- elevated serum osmolality - 300 mOsm/kg
- elevated serum Na - 145 mEq/L
- urine specific gravity can be below or above depending on cause
what fluid to give for dehydration
D5 in water, but don’t give too fast and not more than 1 L
causes of hypovolemia
- GI losses - NV, diarrhea, suction, fistula drainage
- hemorrhage - inside and outside trauma
- third spacing
lab value changes in hypovolemia
- normal or high Na levels
- decreased Hgb & Hct due to blood loss
- increased BUN & creatinine
- increased urine specific gravity & serum osmolality
hypervolemia vs. water intoxication
hypervolemia: excess fluid in extracellular space
water intoxication: excess fluid from extracellular space into intracellular space
causes of hypervolemia
- heart failure
- renal failure
- increased Na intake
- increased cortisol secretion (Cushing’s syndrome)
- long term use of corticosteroids
what’s up with pink frothy sputum in hypervolemia
pulmonary edema - fluid & small amounts of blood leak from capillaries into the alveoli
WHICH COULD mean pt has CHF WHHHAAAAAT
wait why can CHF lead to pulmonary edema
heart can’t pump efficiently, blood back up into veins and into the lungs DAMN
what are the lab values that indicate hypervolemia
- low HCT
- low serum K and BUN
- decreased serum osmolality
- low oxygen level due to pulmonary edema
how is hypervolemia treated
- Na & fluid restriction
- diuretics
- pulmonary edema: morphine, nitroglycerine
- HF: digoxin, oxygen
causes of water intoxication
- increased ADH secretion
- drink lots of water
- altered thirst mechanism
- continuous hypo-osmolar IV fluid (1/2NS, D5W)
labs for water intoxication
- decreased Na
- decreased serum osmolality
treating water intoxication
restrict fluids, NO hypotonic fluid
hypertonic fluids used in close monitoring
