Chapter 5 Fluid Therapy Flashcards
What proportion of bodyweight does total body water make up?
What are the propiortions of intra vs extracellular fluid?
And of extracellular fluid, what proportion is plasma vs interstitial?
Total body water = 60% of bodyweight
Intracellular fluid = 2/3rds of total body water
Extracellular fluid (i.e. plasma and interstitial fluid) = 1/3 of total body water
Of extracellular fluid, 25% is plasma, 75% interstitial fluid.
What are the main intracellular cations and anions?
Intracellular cations:
K+
(And Mg2+ and Na+)
Intracellular anions:
PO42- (phosphate)
What are the main extracellular cations and anions?
Extracellular cations
Na+
Extracellular anions
Cl-
HCO3- (bicarb)
What are the guidelines for rehydrating patients with evidence of interstitial dehydration
% dehydration x BW(kg)
+
On-going losses
+
Maintenance
What is the formula for estimating daily fluid requirement?
70(BWkg)0.75
List physical exam characteristics for the following percentages of dehydration:
<5%
5-8%
8-10%
10-12%
>12%
What is meant by “hypotensive resuscitation” and in what situation is it recommended ?
Resuscitation to MAP of 60mmHg or systolic BP of 90mmHg - applicable in animals with uncontrollable bleeding (because aggressive ivft can worsen bleeding)
Human study found it may offer survival benefit
List 4 therapy recommendations from “surviving sepsis guidlines” (human)
- Early quantitative resuscitation during first 6 hours
- Abx administration within 1 hour of recognition of sepsis
- Early administration of norepinephrine as first choice vasopressor after ivft resuscitation
- Close monitoring of indices of perfusion
What is the osmolarity of plasma?
300mOsm/L
What is a balanced fluid
Contains electrolytes similar to those of extracellular space
What is an isotonic fluid
Isotonic crystalloid fluids does not significantly change the osmolarity of the vascular or extravascular (both interstitial and intracellular) space.
Fluid type shoudl be used in head trauma patients?
0.9% NaCl or hypertonic saline as least liekly to cause water movement into brain
What volume of hypertonic saline (7.5% NaCl) should be administered and how long do th effects last?
What is the osmolarity of 7.5% NaCl
4-6 ml/kg over 20 minutes
(Effects last approx 30 minutes therefore additional ivft necessary to maintain intravascular volume.)
Osmolarity of 7.5% NaCl 2400 mOsm/L
N.B. mannitol osmolarity about half that of hypertonic saline.
Below which rate must plasma sodium concentration be changed?
<0.5 mEq/L/hr
What ivft type is recommended in caes with hypochloraemic metabolic alkalosis (typically upper GI obstruction)
0.9% NaCl as has highest concentration of Cl. (
Also ‘acidifying’ as Cl supplementation will lead to reduced bicarb concentration.
What are the characteristics of a “maintenance fluid”
Hypotonic (as obligate fluid losses are hypotonic)
Contain more potassium (15-30 mEq/L)and less sodium (40-60 mEq/L) than replacement fluids
e.g. Plasma-Lyte or Normosol
What is a safe starting rate of D5W administration?
What is the osmolarity of D5W?
3.7 ml/kg/hr + monitor Na closely
252 mOsm/L
List X potential side effects of synthetic colloids
- Coagulation abnormalities (dereased factor VIII and vWf), impaired platelt funtion, interference with firbin clots
- Renal impairment
What are two formulae for calculating the volume of transfused pRBC necessary for desired rise in PCV?
(pRBC PCV approx 80%)?
1.5 x desired rise in PCV x BW(kg)
What is contained within fresh whole blood ?
Why is use of whole blood generally avoided?
RBCs, platelets (best administered within 8 hours), all clotting factors
Avoided due to cancerous and immunological effects
What % acute blood loss requires blood transfusion?
>20%
What is the dose of pRBCs or FFP?
10-15 ml/kg (if not calculated according to formulas!)