Crystalliods (Lanaux) Flashcards
How much of body is made of water?
What proportion is inside cells?
- Intracellular fluid (40% of BW)
- Extracellular fluid (20% of BW)
- intravascular and extravascular
- Intravascular fluid (5% of BW)
- Interstitial fluid (15% of BW)
- fluid around cells and outside blood vessels
Na is actively pumped….
out of our cells
Electrolyte fluid characteristics
Intracellular
Extracellular
- Intracellular
- Low sodium
- High potassium
- Extracellular
- High sodium
- Low potassium
*Water follows Na
*Na concentration determines IV volume
*Total body sodium determines hydration
Methods to calculate daily water requirements
- based on daily resting energy requirement equations
- 70 x BW0.75 = mL/kg/24 hours
Difference between dehydration and hypovolemia?
- Dehydration: interstitial/intracellular fluid loss
- usually occurs slowly (days to weeks)
- can be replaced slowly
- Hypovolemia: intravascular fluid loss
- usually occures more rapidly
- requires rapid restoration of blood volume
fluid loss
sensible
insensible
- Sensible
- Urine output
- feces
- vomitus
- wound exudates
- Insensible (20-30 mL/kg/day)
- Sweat
- Saliva
- Excessive panting
Fluid Gain
Fluid Loss
- Gain
- drink
- food
- foodstuff oxidation
- metabolism
- Loss
- Hemorrhage
- Vomit/Diarrhea
- Urine
- Wound exudates
- Respiratory evaporation
- Salivation
Calculating fluid deficit
BW (kg) x % dehydration = volume of fluid deficit (L)
5% dehydration
- Mild dehydration
- no CS
5-7% dehydrated
- moderate
- CS
- mildly prolonged skin tent
- mucous membranes normal to tacky
- CRT normal ( < 2s)
8-10% dehydrated
- Severe dehydration
- CS
- prolonged skin tent
- dry mucous membranes
- eyes may be sunken
- tachycardia and poor pulse quality possible
- urine prod may be decreased
> 10% dehydration
- critical dehydration causing hypovolemia
- CS
- markedly prolonged skin tent
- dry mucous membranes
- sunken eyes
- signs of shock
- tachycardia
- hypotension
- prolonged CRT
- cool extremeties
- hypothermia
- Decreased urine production
Signs of hypovolemia
- Tachycardia
- Prolonged CRT
- Hypotension
- Hypothermia, cool extremities
- Weak pulses
- Weakness, lethargy
Tx hypovolemia
- Goal directed therapy
- 10-20 ml/kg bolus crystalloids
Crystalloid
- solution containing electrolyte and nonelectrolyte solutes
- capable of entering all fluid compartments
Two major fluid determinants of fluid balance w/in the body
- Na
- albumin
Three characteristics used to describe a crystalloid soln.
- Tonicity
- buffer
- balance
Tonicity
- effective osmolality of a solution
- Osmole generates osmotic pressure by causing shift of water across a semipermeable membrane
- Mannitol
- Sodium
- Crystalloids classified based on tonicity relative to extracellular fluid
- hypotonic
- Isotonic (between 270-350 mOsm/kg)
- Hypertonic
Buffers
- Excess chloride in some fluids have a mild acidifying effect
- Anions added as source of base
- acetate
- gluconate
- lactate
- metabolism of these make bicarb
- Acetate bolus to cats can cause hypotension
- Normosol-R
- Avoid lactate buffered solns in end stage liver dz
Balanced solutions
- Major electrolytes similar proportion to extracellular fluid
- LRS
- Normosol R
- Plasmalyte 148
- Unbalanced solns
- normal saline (0.9% NaCl)
- 5% dextrose in water (D5W)
If you bolused water IV….
Red blood cells would swell and rupture
Has a tonicity of zero
Maintenance fluids
- Used to replace daily obligate losses of water and solutes in patients not eating/drinking
- This fluid loss occurs via kidneys
- low in Na
- higher in K (compared to extracellular fluid)
- This fluid loss occurs via kidneys
- tend to be hypotonic
- some have dextrose
- Na about 50-70 meq/L
- K about 10-20 meq/L
Dextrose
- False osmol
- increases tonicity
- diffuses across plasma membrane quickly
Maintenance fluid therapy
- Never bolus maintenance fluids
- intended for use at maintenance rates
- Rarely used in vet med
- Examples
- half stregnth saline (0.45%NaCl)
- normosol M
- Home-made concoctions: replacement with 5% dextrose)
- Plasmalyte 56