Chap. 58, crystalloids, colloids, Hg Flashcards
tonicity of a fluid is determined:
small effective osmoles:
The volume distribution of a crystalloid solution in the body depends on its tonicity relative to:
lower the tonicity of a crystalloid solution, the higher proportion of the fluid volume administered that will move into the intracellular space as a result of:
Hemoglobin-based oxygen-carrying solutions (HBOCs) are colloidal solutions with oxygen-carrying capacity Although the oxygen content of the blood is improved, tissue oxygenation and the hemodynamic effects of HBOCs are unpredictable because of its strong:
concentration of effective osmoles (osmoles not freely permeable through cell membranes between intracellular and extracellular space)
Na, K, may diffuse across the capillary endothelium between cell junctions readily
extracellular fluid
osmotic pressure differences
osmolarity and tonicity of intracellular versus extracellular fluid compartments are equal during homeostasis
vasopressor effect
tonicity refers solely to
effective osmoles, which do not freely permeate most cell membranes
primary regulators of cell volume by maintaining an appropriate distribution of intracellular potassium and extracellular sodium
Na+/K+-ATPase pumps on the cell membrane are the
plasma albumin accounts for ___% of plasma COP
80%
Crystalloids are fluids containing small solutes with molecular weights less than
1 dalton =
500 g/mole <500 daltons
The majority of solutes are electrolytes <50 g/mole dalton
1 g/mole
Sodium and its respective anions (i.e., chloride mostly) are the most abundant effective osmoles
5% dextrose in water is considered “free water” because
Sodium and its respective anions (i.e., chloride mostly) are the most abundant effective osmoles
readily metabolized; hence 5% dextrose in water is considered “free water” because it does not contain an effective osmole. - osmolality of 252 but tonicity of 0 mOsm
why are hypotonic fluids safer in CHF:
why hypotonic in KBr tx:
large volume of distribution safer choice for slowly treating animals that have a decreased ability to excrete excess sodium or tolerate an elevated intravascular volume (e.g., kidney and heart diseases, respectively).
Cl won’t compete with Br for reabsorp = minimize bromide loss
- 5% saline, causes a free water shift (i.e., osmosis) from the intracellular space to the extracellular space, expanding the extracellular fluid volume by:
- 4% hypertonic saline = __mEq/L Na
3 to 5 times the volume administered
initial shift is ISS to IVV then ICS- ISS - IVV
4mEq/dl
Additional benefits of NaCl 7.5%:
risks:
important that administration rates do not exceed 1 ml/kg/min because
transiently >CO via:
arteriolar vasodilation (decreased afterload)
volume loading (increased preload)
1. weak postive inotropic effect
- reduced endothelial swelling
- immune-modulatory effects including suppression of neutrophil respiratory burst activity and cytotoxic effects
- antiinflammatory effects
hypotension may result from
-central vasomotor center inhibition or peripheral vasomotor effects mediated by the acute hyperosmolarity (bradycardia and vasodilation) - baror?
osmotic diuresis
repeated administration hemolysis and phlebitis if in small peripheral veins
Acid-Base Effects of Crystalloids
Why low pH:
Does it affect the patient?:
so are they alkanizing or acidifying since most have pH of about 5
acidic bc dissolved CO2 and acidic nature of dextrose solutions
No, pH because of the lack of titratable acidity
total quantity free hydrogen ions is small & easily buffered
Acetate, gluconate, and lactate are weak buffers consumes hydrogen ions, yielding an alkalinizing effect.
Acetate risk:
Acetate metab.:
Gluconate metab.:
Hypotension due to vasodilation is associated with rapid infusion of acetate and has been reported in humans and experimental dogs
skeletal muscle
most cells in the body metabolize gluconate
Normal COP is _____ in dogs
and ____ mm Hg in cat
monitoring of COP _____ target
Refractometer measurements of total protein do not correlate well with COP (or albumin and globulin concentration) after the administration of _____
15.3 to 26.3 mm Hg in dog
17.6 to 33.1 mm Hg in cats
16 mm Hg
starch colloids
synthetic starches are characterized by:
- concentration in the solution
- molecular weight
- degree of hydroxyl substitutions by hydroxyethyl
- groups ratio of hydroxyethyl group substitutions at the C2 versus C6 position
Each associated with a longer T1/2…
what about higher oncoti pressure?
VetStarch: designated as 130/0.4 9:1 what does this mean
molecular weight range of VetStarch and Voluven is 110,000 to 150,000 Da. The reported weight average molecular weight is weight based and is more representative of the larger hetastarch molecules
comparison to Hextend (670/0.75, 4 : 1)
the half-life …
A high cumulative dosage can also prolong the half-life of synthetic starch colloids because of a saturable degradation process
larger molecular weight
higher degree of substitutions,
higher C2 : C6 ratio
only concentration
6% tetrastarch solution
MW average 130,000 Da
4 hydroxyethyl group substitutions per 10 glucose molecules (designated as 130/0.4)
C2 : C6 ratio of 9 : 1
of VetStarch and Voluven is shorter (38 hours vs. 10 hours in healthy humans
Dextrans - synthetic starch colloid solutions that are structured as linear polysaccharides - off market bc
acute kidney injury and allergic reactions in humans
oncotic effect of synthetic colloids depends soley on
number of colloidal molecules
Colloidal molecules in the urine increase urine viscosity and USG what is more accurate?
Urine osmolality is a more accurate measure of urine concentration in animals receiving colloidal fluids.
colloids interfere with the function of
platelets, von Willebrand’s factor, and factor VIII
he same characteristics of hydroxyethyl starches that enable a longer half-life also confer the greatest coagulopathic effects
larger molecular weight
higher degree of substitutions,
higher C2 : C6 ratio
dose dep >40ml/kg/day
AKI?
MoA:
- decreased glomerular filtration
- hypertonicity of glomerular filtrate
- direct hydroxyethyl starch deposits
direct association between hydroxyethyl starches and the occurrence of acute kidney injury has not been reported in veterinary medicine; however, similar risks are possible in the critically ill animals.
essential physiologic functions of albumin
oncotic 80% involve wound healing coagulation scavenging of free radicals Albumin serves as a carrier for multiple substrates, including hormones, bilirubin, fatty acids, divalent cations, toxins, and drugs
weak buffer effect via binding of hydrogen ions
Fresh frozen plasma provides:
frozen plasma:
Cryosupernatant
cryoprecipitate
Fresh whole blood
all the clotting factors and plasma protein
(everthing but plt and RBC)
plasma that remains at room temperature > 8 hours or is stored more than 1 year loses labile clotting factors
-provides plasma proteins, clotting factors II, VII, IX, X
top portion of partially thawed fresh plasma after a hard spin (5000× g for 7 minutes) and contains albumin, globulin, antithrombin, protein C, protein S, and clotting factors II, VII, IX, X, XI and XII
fibrinogen, fibronectin, factor VIII, and von Willebrand’s factor
platelets, red blood cells, plasma proteins, clotting factors
For colloid osmotic support, iso-oncotic plasma is less effective than hyperoncotic synthetic starch solutions
to raise the recipient’s plasma albumin by 1g/dl, approximately _______40 to 50 ml/kg of plasma
in critically ill animals with an accelerated loss of albumin (e.g., septic peritonitis or large area skin burns), plasma transfusion therapy may not keep up
40 to 50 ml/kg
Human Albumin Five percent (5 g/dl) human albumin is \_\_\_-osmolar and \_\_\_oncotic
whereas the most commonly used 25% (25 g/dl) human albumin exerts ___times the osmolar and oncotic effects of 5% human albumin
monitoring
human and canine albumin molecules share only __% homology
xenogenic transfusion of human albumin comes with the potential life-threatening risk of an immediate or delayed hypersensitivity reaction.
Have naturally occurring antibodies against human albumin have also been documented in healthy dogs with no prior human albumin transfusion?
Fortunately, several retrospective studies have found that the rate of severe adverse reaction is rare when used once in critically ill animals
Why is it less risky in severely ill animals and therefore unable to mount an immune response to the antigenic human albumin
.:. human serum albumin is reserved only for critically ill animals with severe hypoalbuminemia, after carefully weighing the benefit and risks of human albumin administration.
Is humn ablumin extra-label
can you give it twice?
Is hypoalbuminemia associated with poor outcome?
Does HSA help?
Human Albumin
iso-osmolar and isooncotic
5 X osmolar and oncotic effects of 5% human albumin
volume overload
79% homology
anaphylaxic
yes
hypothesized that the immune system is compromised in severely ill animals and therefore unable to mount an immune response to the antigenic human albumin
yes extra-label use and potential risk must be clearly communicated to the pet owner
No, immunoglobulin G (IgG) formation is well documented in dogs after exposure to human albumin, repeated administration within the lifetime of a given animal is not advised.
Yes, although hypoalbuminemia is associated with poor clinical outcomes
No, the effect of human albumin on mortality in small animals is currently unknown.
Hemoglobin-Based Oxygen-Carrying Solutions
Oxyglobin is the only veterinary FDA-approved HBOC for the treatment of canine anemia (currently unavailable in US)
It contains ___ g/dl of polymerized bovine hemoglobin that is ultrapurified and free of antigenic red blood cell stroma and is suspended in a modified lactated Ringer’s solution
Bovine hemoglobin depends on ____ instead of 2,3-diphosphoglycerate in the red blood cells to regulate its oxygen affinity
Bovine hemoglobin has a P50 of ____ mm Hg, similar to canine Hgb
feline Hgb
Polymerization of bovine hemoglobin tetramers creates a more stable, larger molecule, which prolongs its half-life and eliminates renal toxicity associated with hemoglobin dimers (derived from rapid breakdown of individual hemoglobin tetramers)
13 g/dl
chloride
34 mm Hg, similar to that of canine and feline hemoglobin 31.5 mmHg
35.6 mm Hg
Oxyglobin is a polydiverse colloidal solution with an average weight molecular weight of ____:
isoosmotic (300 mOsm/kg) and hyperoncotic (COP of 43 mm Hg
Increased preload, stroke volume, and cardiac output are observed after Oxyglobin administration. However, the hemodynamic effect of Oxyglobin is complicated by:
Blood typing and cross-matching are:
Hematocrit is no longer a useful measure of blood carrying capacity and may actually decrease after Oxyglobin administration because of:
most concerning side effect of Oxyglobin is:
18 to 43 hours after infusion of 10 to 30 ml/kg of Oxyglobin. Oxyglobin has a labeled shelf-life of 36 months at room temperature and does not require blood typing or cross-match before administration.
Transient yellow-orange discoloration of the skin, mucous membranes, and sclera and orange- to brown-colored urine are increasingly obvious with higher dosages of Oxyglobin. Some serum chemistry and urine dipstick parameters will be invalidated because of serum discoloration
200 kDa (MW range of 64 to 500 kDa)
its nitric oxide scavenging effect
Normally, NO has a vasodilatory effect
Peripheral vasoconstriction subsequent to the decrease in nitric oxide with Oxyglobin therapy may ironically compromise tissue perfusion and oxygen delivery
dilutional effect - hyperoncotic (COP 43mmHg)
volume overload
