Fluid therapy Flashcards
Describe fluid compartments.
Intracellular fluid 60% (of total body water)
Extracellular fluid 40%
(intravenous 25% of the 40 & interstitial 75% of the 40)
Total body water comprises what % of total mass.
60%
Describe the 2 main points of Starling’s forces.
hydrostatic pressure - pushes fluids out of vessels
oncotic pressure - pulls fluids into vessels
types of crystalloids broadly
iso
hypo
hypertonic
3 attributes of Fluid disturbances to assess
changes in volume (dehydration, blood loss)
changes in content (e.g. hyperkalemia, protein loss)
changes in distribution (third spacing, e.g. pleural effusion)
Signs of pleural effusion.
pale mucous membranes
increased respiratory rate and respiratory effort. breathes can be shallow.
later open-mouthed breathing with abdominal effort.
Alternative to urine output measurement (when e.g. hospitalization not possible)
measure body weight to get an approximation of fluid retained or lost
serum lactate shows you…?
tissue perfusion quality
dehydration causes tissue hypoxia which in turn causes lactate to accumulate in tissues. requires fluids to correct.
if the lactate is high but the patient is not dehydrated, it is probably…?
septic
pre-renal azotemia is usually caused by
fluid loss/dehydration (decreases GFR)
use urine specific gravity to check
blood gases will allow you to assess..?
physiological pH, acidosis/alkalosis state
hydration deficit =
dehydration % * body weight (kg)
in liters
Maintenance equation for cats
80 * kg^0.75
rule of thumb 2-3 ml/kg
Maintenance equation for dogs
132 * kg^0.75
rule of thumb 2-6 ml/kg
Pediatric patients require how many ml per kg per day?
60-180 ml/kg/24h
Ongoing losses can be hard to evaluate, a rule of thumb:
0.5-1 ml/kg/h
(Tip: vomitus or diarrhea can be weighed by weighing the bedding/absorbent pad its on)
hypertonic solutions can be used in two situations (2)
hypovolemic shock (but NOT when dehydration is present!)
cerebral edema/high intracranial pressure (but mannitol is better for this if available)
(bonus: in very rare cases acute onset hyponatremia may utilize hypertonic solutions)
hypotonic solutions can be used in what situations (3)
severe dehydration with no hypovolemia, so only cellular and tissue level crenation.
e.g. in some heart failure patients who have too much intravenous fluid but their cells are dehydrated (ie. CKD cats).
in severe hypER natremia cases
most common hypotonic solution 5% GLU solution (with no electrolytes in), may be administered s.c. (in exotics)
skin turgor a bit decreased.
% dehydration?
5-6% dehydration
skin turgor markedly decreased + CRT decreased, sunken eyes, tacky MMs.
% dehydration?
6-8% dehydration
12-15% dehydration =
shock, death unavoidable.
skin turgor markedly decreased + CRT decreased, sunken eyes, dry MMs.
signs of shock. Dehydration %?
10-12% dehydration
5 main negative physiological effects of anesthesia
hypothermia
hypoventilation
hypotension
hypoxemia
brady-+tachyarrhythmias
Hypovolemic shock rates (IVFT)
dogs: 80-90 ml/kg IV
cats: 50-55 ml/kg IV
Begin by rapidly administering 25% of the calculated shock dose. Reassess in 15-20 min. Boluses given up to 3 times.
If no change - consider colloids (no change may = septic shock which could use vasopressors as well).
When to administer colloids?
When it is difficult to administer sufficient volumes of fluids rapidly enough.
Where crystalloids are not effectively improving or maintaining blood volume.
If edema develops prior to adequate blood volume restoration.
When decreased oncotic pressure is suspected.
When there is a need for longer duration of effect.
doses for colloids
dogs: 20 ml/kg/24h
Divide into 5ml/kg boluses and reassess.
cats: 10-20 ml/kg/24h
Typically 10ml/kg in 2,5-3ml/kg boluses.
