Advanced Fluid Therapy for the Small Patient Flashcards
what is the purpose in giving fluids (2)
- dehydration
- shock: provide maintenance requirements, treat electrolyte imbalances, maintain oncotic pressure, diuresis
what is dehydration
deficit in total body water
what is the normal maintenance for dogs and cats
50 ml/kg/day
why might there be low consumption of water
- anorexia
- starvation
what might pathological fluid losses be due to (5)
- vomiting/diarrhea
- renal disease
- panting (pyrexia)
- exudation from wounds
- 3rd space losses
what are clinical signs of dehydration (3)
different than shock (tachycardia, collapse, poor pulses)
- tacky mm
- delayed skin tent
- eyes sunken into orbit
what are the clinical signs of <5% dehydration
no clinical signs
what are the clinical signs of 5-6% dehydration
subtle loss of skin elasticity
what are the clinical signs of 6-10% dehydration
definite loss of skin elasticity
eyes possibly sunken in orbits
possibly dry mucous membranes
what are the clinical signs of 10-12% dehydration
tented skin stands in place
eyes sunken in orbit
dry mucous membranes
what are the clinical signs of a patient 12-15% dehydrated
same as with 10-12% but with additional signs of hypovolemic shock progressing to collapse and death
what is the issue with using PCV/TP as estimators of dehydration
will both rise with dehydration
BUT
we rarely know the starting values
may change with disease
what fluid is used in most cases for dehydration
isotonic crystalloid
when is isotonic crystalloid not indicated to treat dehydration
where dramatic abnormalities in sodium concentrations are present
what are replacement fluids
containing water and electrolytes with a similar composition to ECF
these will diffuse throughout the ECF
what are examples of replacement fluids
0.9% NaCl (normal saline)
ringer’s solution (added potassium)
hartmann’s solution (also called lactated ringer’s or compound sodium lactate)
describe the differences of replacement fluids
ringer’s and hartmanns have added K and Ca
hartmann’s contains lactate
how fast should the fluid deficit be replaced
over 24 hours
but also add maintenance and ongoing losses
4k cat with 8% dehydration, calculate the amount of fluid you would administer per hour in ml in the first 24 hours to this patient to correct for any deficits and provide maintenance requirements
8% x 4l = 0.08 x 4000ml = 320 ml
4kg x 50ml/kg/day = 200 ml
= 520ml total in 24 hours
= 22ml/hr
how do you deal with ongoing losses
estimation can be difficult
reassess at an appropriate interval (normally 12-24 hours) but may need to be 4 hours
check INS vs OUTS
add additional deficit to next period’s fluids
what are causes of potassium abnormalities (3)
- decreased intake
- translocation (ECF –> ICF)
- increase loss
which is an emergency hyperkalemia or hypokalemia
hyperkalemia
leads to bradycardia
what might the clinical signs be of hypokalemia
muscle weakness
PU/PD
what are decreased intake causes of hypokalemia
admin of potassium free (ex. 0.9% NaCl) or deficient fluids (lactated ringer’s solution over several days)
what are translocation causes of hypokalemia (6)
- alkalemia
- insulin/glucose containing fluids
- catecholamines
- hypothermia
- hypokalemic periodic paralysis
- albuterol overdosage
what are increased losses of hypokalemia
- GI: vomiting, diarrhea
- urinary: chronic renal failure, distal renal tubular acidosis
- drugs: loop diuretics, thiazide diuretics, penicillins
how is potassium supplemented
NaCl and hartmann’s may need to be spiked with potassium
when is hypernatremia commonly seen
due to hypotonic fluid loss/salt intoxication
but intense thirst protects against
only commonly seen with neurological disorders and diabetes insipidus
why must severe hypernatremia be corrected slowly
when giving fluids osmolarity increases and will draw water away from other organs such as the brain –> this produces idiogenic osmoles to protect itself from increases in serum sodium
if fluids without sodium are given you can drop the serum sodium faster than the brain causing the idiogenic osmoles to flood into the brain and cause cerebral edema
what should the rate of change of serum sodium be in hypernatremia
0.5 mmol/l
why must chronic severe hyponatremia be corrected slowly
risk of myelinosis
the rapid rise in sodium concentration is accompanied by the movement of small molecules and pulls water from brain cells
at what level is hypoalbuminemia critically low
<15 g/l
how do you treat the hypoalbuminemic patient
increasing production
and reducing loss
colloid osmotic pressure (COP) may be supported by using synthetic colloids
at what rate should synthetic colloids be used to treat hypoalbuminemia
20ml/kg/day
what are the side effects of colloids (3)
- coagulopathy
- renal damage
- anaphylaxis
describe the differences between haemacel and pentastarch/tetrastarch 6%
what is the issue with administering albumin
can be assocaited with severe anaphylaxis shock esp in relatively healthy dogs
$$$$
not nearly enought albumin in fresh frozen plasma to get concentrations up
what electrolyte imbalances can chronic diarrhea or severe acute losses lead to
can lead to hypokalemia and metabolic acidosis
what electrolyte imbalances does pre pyloric vomiting cause
loss of K+, Na+ and Cl- resulting in hypochloremic metabolic alkalosis
why is metabolic alkalosis self perpetuating
increased renal reabsorption of bicarbonate in the presnece of volume, chloride and potassium depletion
ECF volume is preserve preferentially to pH
kidneys prioritize volume over acid/base balance
what is paradoxical aciduria
acidic urine pH despite extracellular alkalemia
what fluid would be indicated in a metabolic alkalosis due to vomiting
use an acidifying fluid with high chloride concentration
(not hartmann’s Cl isn’t high enough)
normal saline with some potassium mixed in
what fluid would you use in a dehydrated patient with pancreatitis
evaluate degree of shock
commonly used hartmanns
why is fluid therapy an important treatment for pancreatitis
fluid therapy is important to maintain pancreatic microcirculation
why would fresh frozen plasma be used in pancreatitis
replenishes antiproteases primarily a-macroglobulins
how do bowel obstructions cause fluid imbalances
marked loss of fluid and electrolytes into the intestine
increased secretion of sodium, potassium and albumin into the lumen
metabolic acidosis is a consequence of bicarb loss
perforation/breakdown of GI barrier may lead to septic shock
what liver diseases can cause fluid imbalances (8)
- impaired ability to metabolize lactate (hartmann’s) in severe hepatic dysfunction
- hypoalbuminemia
- coagulopathy
- hypokalemia (due to enteric losses, hyperaldosteronism)
- variable acid/base changes
- hypoglycemia
- hepatic encephalopathy (worsened by hypokalemia and alkalosis)
- ascites
what if there are patients that only require maintanence fluids (ex. comatose patients, patients with feeding tubes)
compared to the composition of hartmann’s or NaCl these patients need less Na and more K to compensate for normal losses
maintenance fluids generally contain less sodium and more potassium
glucose is usually added to make them isotonic and prevent hemolysis
what should %5 dextrose not be used for
- calorific support
- treatment of shock: very rapidly metabolized leaving a hypotonic fluid which is not retained in the vascular space
- treatment of most dehydrated patients: most of these patients have electrolyte losses as well
what are complications with fluid therapy (4)
- iatrogenic electrolyte disturbances
- overzealous use of fluids can lead to volume overload
- catheter issues
- complications with products (coagulopathy with colloids)
what can volume overload cause (7)
- chemosis
- serous nasal discharge
- increased resp rate, effort and noise
- restlessness
- peripheral edema
- polyuria
- pulmonary and interstitial edema
