Colloids (Lanaux) Flashcards
1
Q
Fliud compartments
A
- Intracellular (2/3)
- Extracellular (1/3)
- Intravascular (1/5)
- Plasma
- Extravascular (4/5)
- interstitial
- Intravascular (1/5)
2
Q
Which is most permeable part of vasculature?
A
Capillaries
3
Q
Permeability
Intravascular space
A
- Conducting vessels relatively impermeable
- Arteries, Arterioles
- Venules Veins
- Capillaries
- Semipermeable membrane
- water
- small ions (Na+, K+, Cl-)
- Small molecules
- Semipermeable membrane
4
Q
Permeability
Intracellular space
A
- Phospholipid bilayer
- Semipermeable
- water
- glucose - facilitated diffusion
- Semipermeable
5
Q
Colloids
A
- Fluids that contain large, insoluble molecules that don’t freely cross a semipermeable membrane
- Act to hold water within the vascular space for longer than crystalloids
6
Q
Volume of distribution
A
7
Q
Volume of distribution
A
- Directly related to plasma volume expansion
- saline approx 20% of infused volume
- rest diffuses out to interstitial space
- Colloid theoretically 100% of infused volume
- varies by type of colloid
- saline approx 20% of infused volume
8
Q
J
A
- transcapillary fluid flux
- net movement of fluid into interstitium
- returned to systemic circulation via lymphatics
9
Q
K
A
- Filtration coefficient
- correlates to permeability of the vessel
- varies along circulatory system
- arteries and veins less permeable than capillaries
10
Q
reflection coefficient (omega?!?!)
A
- Degree to which membrane prevents transfer of colloid molecules
- value between 0 and 1
- 0 indicates free passage
- 1 indicates no passage
- The lower the value the less effect colloid will have on fluid dynamics
11
Q
Starling forces and dz states
A
- changes in filtration and reflection coefficients
- difficult to predict pharmacokinetics of colloids in vivo
12
Q
Colloid osmotic pressure (COP)
A
- pressure exerted by large molecules
- don’t leave vasculature easily in health
- hold water within vascular space
- albumin major contributor (80%)
*COP measured using colloid osmometer
13
Q
Normal COP
A
- Dogs
- 15.3 to 26.3 mmHg
- Cats
- 17.6 to 33.1 mmHg
14
Q
Proposed benefits of colloids
A
- Longer Intravascular effects
- smaller volume requriements for intravascular expansion
- Less dilutional coagulopathies
- dec tissue edema formation
15
Q
Pharmacology of colloids
A
- Size of particle is unimportant
- Na is as imp as albumin
- large molecules persist in the circulation longer
- Charge is important
16
Q
Gibbs-Donnan effect
A
- Electroneutrality must be maintained
- Large proteins
- negatively charged
- nondiffusible across semipermeable membrane
- Draws posibitve ions across membrans
- Increases COP by 7-8 mmHg
17
Q
Types of Colloids
A
- Natural colloids
- Albumin
- Blood products
- Synthetic colloids
- hydroxyethyl starch
- gelatin
- dextran
18
Q
Natural colloids
A
- Albumin products
- human albumin 5% and 25%
- lyophilized canine albumin
- Fresh frozen plasma
- Whole blood
19
Q
Albumin
A
- uniform size
- > 95% of particles have weight of 69 kDa
- only monodisperse colloid known
- Highly preserved across species
- Accounts for 80% of colloid osmotic pressure in health
- Carrier molecule
- divalent cations (Ca2+ and Zn2+)
- hormones
- drugs
- Maintain oncotic pressure
- coagulation and inflammation
- role in healing
20
Q
Lyophilized canine albumin
A
- purified canine albumin
- sold as 5 gram vials
- adverse reactions less frequent and less sever than huma albumin in dogs
- not currently available
21
Q
Human albumin
A
- Human albumin 5% and 25%
- May be used in critically ill patients
- Adverse reactions
- Anaphylaxis
- Delayed hypersensitivity reactions
-
never admin to a healthy patientf
- Sever anaphylaxis
- Delayed hypersensitivity reactions
- death
- never give to a patient that had human albumin in the past
22
Q
Blood products
A
- Fresh frozen plasma
- Whole blood
- weak colloids
- used primarily for replacement of clotting factors
- patients with coagulopathy
23
Q
normal amount albumin in a patient
A
3-4g/dL
24
Q
Synthetic colloids
A
- Starches
- hetestarch
- pentastarch
- tetrastarch (voluven)
- Gelatines
- Dextrans
25
Adverse Effects
* acute renal failure
* anaphylaxis
* volume overload
* coagulopathy
* immunosuppresion
26
Hydroxyethyl starch
| (Hetestarch)
* Primary synthetic colloid used in vet med
* Polydisperse solutions
* many sized particles
* reported molecular weight is calculated based on different particle sizes and distribution
27
Hydroxyethyl starch
* Described by
* molecular weight
* degree of substitution
* proportion of glucose moieties that have been substituted with hydroxyethyl groups
* ranges from 0-1
28
Hydroxyethyl starch
* 6% hetastarch in 0.9% saline
* molecular weight = 670kDa
* DS = 0.75
* 10% pentastarch
* molecular weight = 200kDa
* DS = 0.5
* 6% Tetrastarch (volvulen)
* molecular weight = 130 kDa
* DS = 0.4
\*I think degree of substitution is related to potential adverse effects
29
Hydroxyethyl starch
Reported adverse reactions
* Reported adverse reations
* acute renal failure
* anaphylaxis
* immunosuppression
* volume overload
* coagulopathy
30
**Which has the greater correlation wtih negative effects on coagulation?**
## Footnote
**A. Degree of substitution**
**B. Molecular weight**
* A. Degree of substitution
31
Hydroxyethyl starches and coagulation
* Higher degree of substitution corelates to greater negative effect on coagulation
* Interferes with factor VIII and von Willebrand factor
* leads to plately dysfunction
* May also be incorporated into fibrin clot
* weakens clot
32
Hetestarch recommendations
* Higher degree of substitution
* greater adverse effect on coagulation
* Daily recommended max dose is 20 mL/kg
* admined as 2-5 mL/kg IV bolus
* unclear if CRI is efficacious
* Larger molecules persist in vasculature longer
* minimal effect due to much fewer numbers of large molecules
33
Voluven
* 130/0.4
* lesser degree of substitution
* minimal effect on coagulation
* Daily max dose 40 mL/kg
* admined as 2-5 mL IV boluses
* shorter half-life than Hetastarch (16 vs 46 hours)
34
Colloidsd and COP
* Hetestarch 6%
* Volvulen
* Human albumin 5% / 25%
* Canine fresh frozen plasma
* Hetestarch 6%: 32.7 +/- 2%
* Volvulen: 37.1 +/- 0.8
* Human albumin 5% / 25%: 23.2 +/- 0.1/ \> 200
* Canine fresh frozen plasma: 17.1 +/- 0.6
35
Monitoring colloid therapy
* CS: clinical response
* what is HR, BP
* Can you stabilize them
* Can do COP but most people don't have one
36
Effect of HES
* osmalality and specific gravity probably won't correlate in presence of large molecules
37
Summary
WHAT TO KNOW
* Know characteristics of maintenance fluid vs Replacement fluids
* resembles plasma
* lower sodium
* higher potassium
* Know examples of replacement fluids
* LRS
* 0.9% saline
* Normosol R
* Be aware of adverse effects and such
