Fluids Flashcards
what percentage of a mature dog is water? young animal?
60%; 70%
what are the two main types of BODY fluids
Intracellular and extracellular
what creates and maintains the differences between ICF and ECF
cells (via cell membranes)
ECF consists of (3)
- interstitial fluid (ISF)
- plasma
- transcellular fluid
what is the 60-40-20 rule
60% of BW is water
40% of BW is intracellular (2/3)
20% of BW is extracellular (1/3)
what is ICF a mixture of? is this homogenous?
potassium, organic ions and proteins
not homogenous
what is the pH of ICF? what determines and what maintains this?
close to 7; maintained by Na/K ATPase and determined by K+ in the ICF
what is ECF a mixture of?
NaCl and NaHCO3
describe the following fluids:
- Interstitial fluid
- Plasma
- Transcellular fluid
Interstitial fluid: surrounds cells but does not circulate (3/4 ECF or 15% BW)
Plasma: extracellular component of blood (1/4 ECF or 5% BW)
Transcellular fluid: extracellular fluid oustide the normal compartments (CSF, digestive juices, mucus…) (<1% BW)
what is the pH of ECF?
7.4-7.45
what is electroneutrality
the number of cations (+) and anions (-) in the ICF and ECF (interstitial and plasma) balances to a net 0 charge in each compartment, although the total number of molecules in each compartment may differ
In a spun sample of blood, what is the percentage of:
- plasma
- PCV
plasma: 55-65%
pcv: 35-45%
What is the blood volume of the following species (in ml/kg and % bw)
1) dog
2) cat
3) horse
4) ruminant
5) pig
1) dog: 80 ml/kg (8% bw)
2) cat: 50-70 ml/kg (5-7% bw)
3) horse: 100 ml/lg (10% bw)
4) ruminant: 60 ml/kg (6% bw)
5) pig: 65-75 ml/kg (6.5-7.5% b)
what is osmolality? how do we calculate it
= ratio of solutes/volume
= 2 x Na + Glucose + BUN mOsm/L
what is the normal osmolality of ICF, ECF and plasma
290 +/- 10 mOsm/L
what is Starlings equation
J = k (Pc-Pi) - σ (πc - πi) - Qlymph
what is P and π in Starling’s equation and what do they do
P = hydrostatic pressure (pushes fluid out)
π = oncotic pressure (draws fluid in)
what is the net effect of fluid dynamics on:
- arterioles
- venules
Fluid moves out of arterioles and goes into venules
What is the Endothelial Glycocalyx Layer
web of membrane-bound glycoproteins and proteoglycans on the luminal side of endothelial cells associated with various GAG; acts as an active interface between blood and the capillary wall
what has been replaced in Starling’s equation
πi has been replaced with subglycocalyx
what is the endothelial glycocalyx layer semi permeable to
anionic macromolecules (ex. albumin)
what are some situations that compromise that endothelial glycocalyx layer
systemic inflammatory states
- diabetes
- hyperglycemia
- trauma
- sepsis
- surgery
what are 4 drugs that protect or restore the endothelial glycocalyx layer
- N-acetylcysteine
- antithrombin III
- hydrocortisone
- sevoflurane
T/F absorption through venous capillaries and venules does not occur
T
Does πc oppose or reverse filtration? What does it do to absorption?
opposes; it does NOT promote absorption
What happens to most of the fluid filtered into the interstitial space
returns to circulation as lymph
what determines if the capillary bed will filter big molecules or not (ex. albumin)
the endothelial glycocalyx layer and basement membrane fenestrations in the capillary
Fill out the following for plasma characteristics of herbivores/humans:
- type of buffer
- osmolality
- Na+
- K+
- Cl-
type of buffer: bicarbonate
osmolality: 290 mOsm/L
Na+: 140
K+: 3-5
Cl-: 100
Maintenance solutions match ___________ whereas replacement solutions match _______________
daily losses of electrolytes; electrolytes composition of the blood
State whether the following solutions are isotonic, hypotonic, or polyionic (can use more than one)
1) Maintenance solutions
2) Replacement solutions
Maintenance solutions: polyionic, hypotonic
Replacement solutions: polyionic, isotonic
When would we use replacement fluids? Maintenance fluids?
Replacement fluids: to replace blood loss or dehydration
Maintenance fluids: ICU patient anorexic with no other problems
T/F we can we replacement fluids as maintenance but not maintenance fluids as replacement
T
what are 4 examples of maintenance solutions
- Plasmalyte-56
- Normosol-M
- NaCl 0.45% (+KCl)
- Replacement + KCl
Maintenance solutions can be used to replace two types of losses, what are they and what are the maintenance ratets?
1) sensible losses (urine production)
2) Insensible losses (breathing, sweating, feces)
2-4 ml/kg/h
what are some examples of replacement solutions
- Normosol-R
- Plasmalyte-A
- Plasmalyte-148
- LRS
- NaCl 0.9% (+/- KCl)
what is the replacement rate when using replacement fluids
5-10 ml/kg/h
The rate of replacement fluid administration consists of
maintenance requirements + blood/fluid loss
what is another name for replacement fluids
crystalloids
what percentage of replacement fluids/crystalloids stay within the vascular space after 1-2h and what is the practical consequence when treating blood loss
30%; we replace the amount of blood loss with 3x the amount of crystalloids
T/F crystalloids have oncotic pressure
F
blood loss of less than what % can be effectively treated with crystalloids under anesthesia
10%
what is the shock rate
60 ml/kg/h
what is the rate when administering hypertonic saline
1-2 ml/kg/h
what is the effect of hypertonic saline
draws fluid into the vascular space; effect lasts <60min
what are some examples of colloids
natural: plasma
synthetic: dextrans, starches (hetastarch, pentastarch, tetrastarch)
what is the rate of colloid administration and ratio
1:1; 5-10 ml/kg/h
how long do colloids stay in the blood and what effect on oncotic pressure do they have
6-16h; 1.5-2x oncotic pressure of blood
it is best to use what relative size of colloids
smaller; less impact on clotting and less risk of kidney damage
are synthetic colloids currently recommended? why or why not?
no
- can achieve shock reversal equally fast with crystalloids
- marginally lower volumes needed with colloids
- risk of renal damage with pentastarch
hemoglobin is what proportion of PCV
1/3
when would the following be indicated:
- blood transfusion
- plasma transfusion
blood: if PCV < 20-25%
plasma: if TP < 3.5-4 g/dL
(make sure you review how to calculate volume of plasma and volume of blood to give)
what ratio should plasma or blood be given in relation to blood loss
1:1
what is the plasma/blood transfusion rate
5-10 ml/kg/h
when correcting dehydration you should give fluids over how many hours
12-24
