Ch. 5 Fluid Therapy Flashcards
What percent of body weight constitutes water in an adult cat or dog
60%
what is the osmolarity of the two major water compartments (extra and intracellular fluid)
similar to each other, they are both about 310 mOsm/L
what are the primary cation and anions of extracellular fluid
Na+
Cl-
HCO3-
how does the NaK/ATPase pump contribute to the electrolytes in the cell
extrudes Na+ from the cell
brings K+ into the cell
consumes ATP as it does that
End result is that the Na concentration is low within the cell and K is high within the cell
What are the major anions and cations of the intracellular fluid
High K+
some contribution by Mg2+ and Na+
PO4-
what is the glycocalyx
this is a layer of glycoproteins and proteoglycans produced by the endothelium that aids in the endothelial barrier
it has a negative charge that allows it to act as a sieve
What is the endothelium of the capillary freely permeable to?
water
small molecular weight particles (ions, glucose, acetate, lactate, bicarb)
gases like CO2 and O2
what determines hydrostatic pressure
related to the volume of blood that is confined within the vessel walls and is determined by intravascular blood pressures and vascular resistance
What is the maximum rate of sodium correction recommended
do not increase by more than 0.5 mEq/hr
do not decrease by more than 1 mEq/hr
what is the sequela of loss of hypotonic fluids from the body (loss of water in excess of solute)
loss of hypotonic fluids from the body would be a loss of extracellular fluid which would lead to an increase in extracellular tonicity. Fluid will then shift from intracellular to extracellular –> that leads to intracellular fluid deficits like in cerebral obtundation and hypernatremia (this is called a hypertonic dehydration)
what clinical signs are indicative of poor tissue perfusion from intravascular volume deficits
pale mucous membranes poor pulse quality tachycardia prolonged CRT cold extremities
What clinical signs are associated with 5-8% dehydration
decreased skin turgor, dry MM
what perfect dehydration is associated with 8-10% dehydration
decreased skin turgor, dry MM, sunken eyes, slight prolongation of CRT
what clinical signs are associated with 10-12% dehydration
severe skin tenting, prolonged CRT, dry MM, eyes sunken in orbit, maybe signs of shock
what is the current IV crystalloid rec for cats and dogs under GA
5 ml/kg/hr for dogs
3 ml/kg/hr for cats
why is 0.9% NaCl considered an unbalanced isotonic crystalloid
it is isotonic because the osmolarity is 308, similar to the body, but the Na and Cl are 154 mEq/L which is higher than the body’s
A mild increase in sodium will occur, a marked increase in Cl, and a moderate decrease of K and bicarb
what is the role of lactate or acetate in LRS, Plyte, and NormR? Which has a greater effect, lactate or acetatew
lactate and acetate are bicarb precursors and are metabolized by gluconeogenesis or oxidation mostly in the liver and some in the muscle (more acetate in the muscle) and kidneys. This has an alkalinizing effect on the blood. The effect with acetate is greater than alkalinization by lactate
what isotonic crystalloid might be a good option for a patient with a hypochloremic, hyponatremic, or hypochloremic metabolic alkalosis?
0.9% NaCl
what is the composition of LRS
osmolarity: 273 Na: 130 K: 4 Cl: 109 Mg: none Ca: 3 Lactate: 28 Acetate: none Gluconate: none
what is the composition of Plyte 148 and normR
osmolarity: 295 Na: 140 K: 5 Cl: 98 Mg: 3 Ca: none Lactate: none Acetate: 27 Gluconate: 23
What would be a desirable fluid for a patient with head trauma
0.9% NaCl because this is the highest sodium concentration and therefore lease likely to cause a decrease in osmolarity and subsequent water movement into the brain interstitium
What would be a desirable fluid for a patient with severe hyponatremia or hypernatremia for resuscitation
a crystalloid with a sodium concentration that matches the patient’s current sodium
what would be a desirable resuscitation crystalloid for an animal with a hypochloremic metabolic alkalosis?
0.9% NaCl because highest Cl fluid and will improve blood pH by dilution
also it tends to be acidifying
what would a desirable resuscitation crystalloid for an animal with a metabolic acidosis (not from lactic acidosis) be?
a crystalloid with a bugger like acetate, gluconate, or lactate
*large quantities of acetate can cause vasodilation and a decrease in blood pressure in animals with preexisting hypovolemia
How can large quantities of acetate can cause vasodilation and a decrease in blood pressure in animals with preexisting hypovolemia
Adenosine is released from muscle tissue as acetate is metabolized and adenosine is a vasodilator
What do all maintenance fluids have in common?
Hypotonic crystalloids that are low in sodium, chloride, and osmolarity but might be high in potassium compared with normal plasma concentrations (because losses from the body are usually high in potassium anyway)
Ex. 0.45% NaCl w/ or w/out dextrose, P lyte 56, plyte M with dextrose, normosol M with dextrose, 5% dextrose in water
how can we give free water IV without using a dangerously hypotonic fluid, like for animals with free water deficits
D5W which is 5% dextrose to an osmolarity of 252 mOsm/L
What rate of D5W will lead to a decrease in sodium concentration by 1 mEq/hr?
3.7 ml/kg/hr of D5W
what can occur from too rapid hypertonic fluid administration
rates exceeding 1 ml/kg/min may result in osmotic stimulation of pulmonary c fibers –> vagally mediated hypotension, bradycardia, bronchoconstriction
What other benefits may hypertonic saline have in addition to shifting extravascular water to the intravascular space
may reduce endothelial swelling, increase cardiac contractility, cause mild peripheral vasodilation, modulate inflammation, decrease intra cranial pressure
how does hypertonic solution vs colloid solution improve the intravascular volume
hypertonic solution will cause a transient osmotic shift of water from the extravascular to intravascular compartment whereas colloids will increase the colloid osmotic pressure of the plasma (those molecules are too big to cross the vascular membrane) and then the plasma is hyperoncotic to the extravascular fluid and then fluid is pulled into the plasma
weight average vs number average molecular weight
weight average molecular weight = mean of all particle molecular weights
number average molecular weight = median of the molecular weights and considered more accurate
The ratio of these two is called the polydisperity index
What is the importance of higher molecular weight molecules not getting metabolized or excreted as quickly as smaller particles?
the higher weights will persist longer in the intravascular space but that also means they will contribute to the side effects like interference with coagulation
how do synthetic colloids disrupt normal coagulation
decrease in factor VIII and vWF
impair platelet function
interfere with stability of fibrin clots making it more susceptible to fibrinolysis
why do hydroxyethyl starch synthetic colloids need their hydroxyl groups replaced with hydroxyethyl
replacement of hydroxyl with hydroxyethyl at C2, C3, or C6 will prevent rapid degradation by amylase
the ratio of substitution at the C2 versus C6 prolonges the solution
what is the recommended dose of hypertonic solution?
4-6 ml/kg over 10 to 20 min
what is the recommended dose of synthetic colloids
0.5 - 2 ml/kg/day
or as a bolus as 5-20 ml/kg in dog or 2.5-10 ml/kg in cats
what is the colloid osmotic pressure, molecular weight, molar substitution, C2/C6 ratio of vetstarch
36 osmotic pressure
130 molecular weight (lower than other hydroxyethyl starches)
0.38-0.45 substitution (lower than other hydroxyethyl starches for example Hetastarch is 0.75)
C2/C6 ratio 9:1
what should you measure to monitor response to colloid therapy
NOT total protein refractometer readings
measure the colloid osmotic pressure - goal is greater than 16 mm Hg for most animals unless chronically hypoproteinemic
what is oxyglobin
not currently available but it was a bovine hemoglobin solution of high molecular weight that did not require blood typing
what is acute normovolemic hemodilution
a potential alternative to autologous blood donation
blood is collected immediately before surgery and the volume is replaced with three times the amount in an isotonic crystalloid or the same amount in a colloid solution. Then, when the animal bleeds during surgery, it will contain less protein and red cell volume and the collected blood will be available to replace the loss
how soon does whole blood need to be administered
within 8 hours of collection - platelets dont last long and are definitely all gone after 24 hours, clotting factors also decrease greatly by 24 hours
what effects do storage have on packed RBCs
decreased ATP concentration decreased 2,3 DPG concentration increased ammonia nitric oxide scavenging oxidative damage RBC deformability increased procoagulant properties
What is the difference between fresh frozen plasma and frozen plasma?
frozen has been stored for more than a year and no longer has the labile coag factors V, VIII, and vWF
what is cryoprecipitate high in?
factor VIII, vWF, fibrinogen, fibronectin
what is cryopoor plasma (cryosupernatent) high in?
serine protease clotting factors - the vitamin K dependent factors (II, VII, IX, X), anticoag and fibrinolytic factors, albumin, globulins
why do we need to monitor calcium in big transfusion patients?
blood products often contain citrate, which can lead to chelation and hypocalcemia
theoretically, what percent of first time canine blood transfusions should be associated with an adverse immunologic reaction from naturally occurring alloantibodies
15% of first time canine blood transfusions
what is CPDA-1
citrate phosphate dextrose adenine - the product for anticoagulation in blood storage bags
how should whole blood and packed RBC be stored?
4 degrees +/- 2 degrees C for up to 35 days
What temp should plasma be stored?
less than 20 degrees C
what size filter should be used for blood transfusion administration
170 um pores to remove red cell and platelet aggregates
What is TACO?
sadly TACO is not a taco. TACO is transfusion associated circulatory overload secondary to fluid overload secondary to a significant oncotic pull from blood products
what percent of plasma oncotic pressure is attributable to albumin
80%
what are causes of pseudohyponatremia
hyperproteinemia
hyper lipidemia
what is the primary determinant of extracellular osmolarity
sodium
what is the serum sodium concentration for dogs and cats in hyponatremia
less than 140 for dogs
less than 149 for cats
what are examples of hyponatremia with hypervolemia
heart failure, severe liver disease, nephrotic syndrome, advanced renal failure
what is an example of hyponatremia with normovolemia
psychogenic polydipsia, inappropriate ADH release, ADH drugs, hypothyroid myxedema coma, hypotonic fluid administration
what are clinical signs of acute hyponatremia
CNS depression, ataxia, coma, seizures secondary to cerebral edema
cerebral edema usually develops at concentrations less than 120 mEq/L or with decreasing rates more rapid than 0.5 mEq/L/hr
what is central pontine myelinolysis
osmotic demyelination syndrome from increasing the sodium in a hyponatremic patient too quickly
what concentration of sodium is hypernatremia
greater than 150 in dogs
greater than 160 in cats
what will hyperaldosteronism and hyperadrenocorticism do to serum sodium
may result in hypervolemic hypernatremia
what percent of the body’s total potassium in the body is within the cells?
95%
what is the net resting membrane potential
-90 mV
what shifts potassium from extracellular to intracellular space?
glucose, insulin, catecholamines, metabolic alkalosis
what shifts potassium extracellularly?
nonorganic metabolic alkalosis
hyperosmolarity
ECG abnormalities due to hypokalemia
increased amplitude and width of P wave, ST segment depression, decreased amplitude of T waves, prolonged PR intervals, prominent U waves, various ventricular and supraventricular arrhythmias
what is the most common cause of hyperkalemia
decreased renal potassium excretion
what is solvent drag
diabetes mellitus may be associated with an extracellular hypertonicity from increased serum glucose which will draw water out of cells and bring potassium with it. will result in a hyperkalemia
what breeds have increased potassium concentrations in their red blood cells
Akitas and English Springer Spaniels
hemolysis in these breeds can lead to hyperkalemia
What ECG changes might you see at 5.7-6.0 mEq/L potassium
spiked T waves
shortened QT interval
What ECG changes might you see at greater than 8.5 mEq/L potassium
P wave disappears
R wave amplitude decreases and S wave prominence increases –> sinoatrial wave
What ECG changes might you see at greater than 10-12 mEq/L potassium
aystole and ventricular fibrillation
how does calcium gluconate improve arrhythmias with hyperkalemia?
will raise the threshold membrane potential to restore cell excitability
give 10% calcium gluconate at 0.5-1 ml/kg over 10-20 minutes
bradycardia can develop if given too quickly
works within minutes and lasts about an hour
how does dextrose help with hyperkalemia
give dextrose at 0.5 to 1 g/kg with or without insulin (0.5-1 units/kg) to help drive potassium into cells
works within 30 min and lasts for 1-2 hours
how can sodium bicarb treat hyperkalemia
drives potassium into cells in exchange for hydrogen to move out to titrate the bicarb
dose is 0.5-2 mEq/kg IV
what percent of the body’s calcium is in bone?
99%
how can a sodium phosphate enema result in hypocalcemia
elevated phosphorus levels will precipitate with calcium, decrease PTH mediate bone resorption, and decrease vit D production
what ionized calcium levels are considered hypocalcemic in the dog and cat
in dogs, less than 1.2 mmol/L (5.0 mg/dL)
in cats, less than 1.1 mmol/L (4.5 mg/dL)
what percent of the body’s magnesium is intra vs extracellular
99% is intracell and 1% is extracellular
what is the concentration for hypomagnesemia
less than 1.7 mg/dL in dogs
less than 1.8 mg/dL in cats
what are clinical signs of hypomagenesemia
ventricular arrhythmias, atrial arryhthmias, hypertension, muscular weakness, hyperesthesia, muscle tremors, ataxia, CNS depression, seizures, nausea, anorexia
what are ECG signs of hypermagnesemia
prolongation of the PR interval, widening of the QRS complex, heart block and asystole
may also see muscular effects similar to hypercacelmia like weakness and decreased tendon reflexes
what percentage of phosphorus is in bone vs intracellular vs extracellular
85% in bone
15% in intracellular
less than 15 in extracellular
where is phosphorus reabsorbed
primarily in the proximal tubule of the kidney - 85% gets reabsorbed
renal excretion is the primary mechanism for regulating total body phosphate levels
what clinical signs are seen with hypophosphatemia
mild hypophosphatemia may result in weakness, disorientation, joint pain, anorexia
severe hypophosphatemia can result in hemolysis, rhabdomyolysis, coma, seizures, cardiac arryhthmias, acute respiratory failure
What kind of dogs will develop hemolysis secondary to hypophosphatemia
Japanese or Korean origin - like Akita, shiba, jindo do NOT use a phosphorus independent red blood cell regulation system and
what are the clinical signs of hyperphosphatemia
usually caused by the associated hypocalcemia
what is the most common cause of hyperphosphatemia
decreased renal excretion and occurs in animals with acute or chronic renal failure, post renal azotemia, hypoparathyroidism, hyperthyroidism
where is chloride reabsorbed
it is the primary anion that is reabsorbed in the proximal tubule of the kidney
What is Whipple’s triad
a low blood glucose concentration
concurrent signs of hypoglycemia
resolution of clinical signs when blood glucose level is normalized
How does sepsis induce hypoglycemia
increased circulating levels of cytokines like TNF alpha, IL 6 cause increased utilization of glucose by the tissues
decreased hepatic responsiveness to counterregulatory hormones like catecholamines, glucagon, glucocorticoids, and growth hormone lead to a decreased hepatic production of glucose
why should you avoid a bolus of glucose in insulinoma patients
may actually stimulate insulin production and worsen the hypoglycemia. It is better to give an infusion of glucagon
what contributes to stress hyperglycemia in critically ill patients
increased secretion of counter regulatory hormones like glucocoricoids, catecholamines
insulin resistance because of circulating cytokines
use of hyperglycemia inducing treatment modalities in critically ill patients like adrenergic agonists or total parenteral nutrition
what is a nonvolatile acid?
Hydrogen ions are a non volatile acid
they are acids that must be metabolized by the hepatic or renal route and do not rely on the pulmonary system
what is a volatile acid
carbonic acid is a volatile acid
volatile acids depend on a gas phase component for their concentration
carbon dioxide will act as an acid because it can combine with water to make carbonic acid, which then dissociates to H+ and HCO3-
what does a negative base excess represent
a base deficit which is a nonrespiratory acidosis
what does a base excess represent
a non respiratory alkalosis
what are the clinical signs of respiratory acidosis
usually related to subsequent catecholamine release and include tachyarrhythmias, increased or normal P, increased cardiac output
what are the clinical effects of metabolic acidosis
cardiac arrhythmias decreased cardiac output refractory hypotension decreased renal and hepatic blood flow reduced sensitivity to catecholamines tighter binding of oxygen by hemoglobin insulin resistance ionized hypercalcemia CNS depression chronic metabolic acidosis can result in bone demineralization
what are some adverse reactions of administering sodium bicarb
very hyperosmolar so can cause fluid shifts
electrolyte abnormalities such as hypokalemia, hypocalcemia, hypernatremia
iatrogenic metabolic alkalosis can occur
what are clinical manifestations of metabolic alkalosis
rare but when they do, shows as agitation, disorientation, stupor, coma, muscle twitching, seizures
