Fluid therapy Flashcards
indications
replacing what was lost, keeping up with what the pet is losing, maintaining balance when the animal can’t do it themselves
keys to fluid therapy planning
right type of fluid, right amount of fluid, right speed of administration
how much of the total body weight does fluid make up?
~60% of TBW
young animals: 70-80%
older animals: 50-55%
obese animals: <60%
emaciated animals: >60%
where are fluids kept in the body?
intracellular and extracellular spaces
ICF: 40% TBW
ECF: 20% TBW
what are the two compartments that fluid in the extracellular space is divided between?
interstitial fluid (ISF) and intravascular fluid (IVF)
interstitial fluid (ISF)
tissue space
surrounds the cell and is outside of the blood vessels
separated by cell membrane and vascular endothelium
intravascular fluid (IVF)
in blood vessels
separated by the vascular endothelium
plasma
barrier permeability to different substances
water: moves across all barriers, moves through osmosis
electrolytes: moves across vascular endothelium but not cell membranes without active transport (only 1/4 of administered electrolytes stay in IVF, 3/4 move to ISF)
large molecules: (plasma proteins) hard to move from IVF, can draw fluid into IVF from the ISF by oncotic pressure
where does sodium and potassium hang out in the sodium potassium pump?
sodium in extracellular and potassium in intracellular
SodiumEX ICK+
electrolyte roles
maintain acid-base status, osmotic pressure, and regulates movement of body water between compartments
concentration of electrolytes in intracellular body compartment
most abundant cation: potassium
most abundant anion: phosphate
concentration of electrolytes in extracellular body compartment
most abundant cation: sodium
most abundant anion: chloride
hyponatremia
low sodium levels
hypernatremia
high sodium
types of fluids
colloids and crystalloids
choice based on composition of fluid and the physiochemical properties
also based on osmolarity and electrolyte composition
osmolarity
how similar the fluid is to cat/dog blood
cat/dog blood osmolarity= 300 mOsm/kg
crystalloids
fluids with electrolytes and water
characterized by their osmolarity compared to blood (hypertonic, isotonic, hypotonic)
hypotonic fluids
provide more water than electrolytes
uses: hypernatremia, patients with cardiac or renal issues
contraindications: resuscitation fluids
ex: Dextrose 5% in water, 0.45% NaCl, Normolsol M, Plasmalyte 56
why should you never give D5W SQ?
the sugar in dextrose provides a medium for bacterial growth which causes cellulitis +/- abscess
isotonic fluids
equal portions water and electrolytes
most commonly used: resuscitation, rehydration, replacement of ongoing losses, hyponatremia
contraindications: caution with long term use and large volume: can lead to tissue edema and acid-base disturbances
ex: 0.9% NaCl, Plasmalyte 148, Plasma-Lyte A, Normosol R, LRS
hypertonic fluids
more electrolytes than water
uses: resuscitation, head trauma/traumatic injury (causes decreased intracranial pressure)
contraindications: don’t admin fast (no faster than 0.5-1 mL/kg/min= bradycardia)
ex: 3-7% hypertonic NaCl, dilute and never admin >7.5%
colloids
solutions containing protein or starch molecules that contain a high-molecular weight and are suspended in an isotonic crystalloid
remain in vasculature and offer prolonged volume expansion
uses: hypoproteinemia, resuscitation, when crystalloids can’t handle the job
contraindications: renal patients (oncotic force decreases renal filtration pressure), have been associated with causing coagulopathies
normal fluid ins
drinking and eating
normal metabolic processes (oxidation of food materials)
normal fluid outs
normal urine loss, water loss, respiration/panting, sweating (more for horses)
