Chapter 5: Fluids

Question 1

Canine blood donors ideally should be erythrocyte antigen ____ and ___, negative if possible? and why is this?

Answer 1

1.1 and 7, as a dog is most likely to have a clinically significant transfusion reaction to these.

Question 2

How many naturally occurring dog erythrocyte antigens have been identified?

Answer 2

8

Question 3

How do you work out how much blood is needed in a transfusion?

Answer 3

Vol(ml) = 1.5 x desired PCV x kg BW

Question 4

What is the blood volume of a dog and of a cat?

Answer 4

dog - 90ml/kg
cat - 50ml/kg

Question 5

Animals with colloid osmotic pressure of <___mmHg may benefit from synthetic colloid administration?

Answer 5

<16mmHg

Question 6

What antigen is associated with incompatible cross match results in cats?

Answer 6

Mik antigen

Question 7

Type A cats rarely have naturally occurring anti-B antibodies, but type B cats often have strong naturally occurring anti-A antibodies - What results if type A blood is given to type B cat?

Answer 7

Severe and potentially fatal transfusion reactions and RBC lifespan of aprrox. 1 hour

Question 8

What are the most common side effects in dogs associated with synthetic colloid administration?

Answer 8

coagulopathies - decrease in factor 8 and vWF, impairement of platelet function, interference with stability of fibrin clots making clot more susceptible to fibrinolysis

Question 9

Patients with severe head trauma should be administered what fluid?

Answer 9

0.9% NaCl - as has higher sodium and is less likely to cause a decrease in osmolarity and subsequent water movement into brain interstitium

Question 10

What fluid should you use for hyperchloremic metabolic acidosis?

Answer 10

0.9% NaCl

Question 11

Fluid type for patient with severe metabolic acidosis?

Answer 11

LRS

Question 12

what are the two most common transfusion reactions in dogs?

Answer 12

• TACO (transfusion associated circulatory overload)
• non-hemolytic febrile reactions

Question 13

Chronic hyponatremia should be corrected slowly (no more than 0.5mEq/L/h)- if not it could result in what?

Answer 13

Osmotic demyelination syndrome (central pontine myelinolysis)

Question 14

Clinical signs of hypernatremia are usually only seen over what number in dogs?

Answer 14

170mEq/L dogs
Cats 175mEq/L

Question 15

Chronic hypernatremia can result in the formation of what?

Answer 15

Idiogenic osmoles
- maintain the intracellular osmolarity similar to that of the extracellular and prevent fluid from moving out of the cell
- if the cell was to shrink it can result in vascular damage and hemorrhage within the brain

Question 16

How is free water deficit usually replaced?

Answer 16

FW is most commonly replaced using 5% dextrose in water IV - as dextrose is rapidly metabolized - effectively leaving free water

Loop diuretics can facilitate natriuresis particularly in animals with hypervolemic hypernatremia

Question 17

potassium moves intracellularly with?
Potassium moves extracellularly with?

Answer 17

• Intracellular: glucose, insulin, catecholamines and metabollic alkalosis
• Extracellular: metabolic acidosis or hyperosmolarity

Question 18

What is meant by the term paradoxical aciduria?

Answer 18

From vomiting, when chloride is low, sodium is reabsorbed from the kidneys in exchange for K+ and H+ (acids in urine)
- worsens the hypokalemia and metabolic alkalosis

Question 19

If K+ serum concentration is<3 what can result?
<2?

Answer 19

< 3: muscle weakness, cardiac arrythmias and PU
< 2: rhabdomyolysis with increased CK concentrations and respiratory muscle paralysis

Question 20

Animals with refractory hypokalemia should have what checked?

Answer 20

Their serum Mg levels checked and supplementation instituted

Question 21

What are expected ECG changes with K+ of:
5.7-6 ?
7-8.5?
>8.5?
10-12?

Answer 21

5.7-6: Spiked T waves and shortened QT interval
7-8.5: Prolonged PR interval and widening of QRS
>8.5: P waves disappear, R-wave amplitude decreases and S-wave prominence increases resulting in a sinoatrial wave
10-12: asystole and atrial fibrillation

Question 22

Treatment options for hyperkalemia? (5)

Answer 22

Calcium gluconate - raises threshold membrane potential
Insulin and glucose - moves potassium into the cell
Sodium bicarbonate - moves potassium into the cell
Beta-2 agonists (albuterol or terbutaline) -moves potassium into the cell
Dialysis

Question 23

Kidney failure can cause hypocalcemia how?

Answer 23

Reduced ability of kidney to convert 25-hydroxycholecalciferol to vitamin D - resulting in decreased intestinal absorption of calcium

Question 24

Does hypoalbuminaemia affect ionised calcium levels?

Answer 24

no

Question 25

What is the most common cause of hypercalcemia in dogs / cats?

Answer 25

Malignancy in dogs Idiopathic in cats

Question 26

HypoMg+ causes?

Answer 26

malabsorption: Decrease absorption: pancreatic insufficiency, cholestatic liver disease, short bowel syndrome, generalised malabsorption syndrome or starvation excessive urinary losses: Renal tubular abnormalities - decreased resorption - renal tubular acidosis, postop diuresis, polyuric renal failure and diuresis, drugs: aminoglycosides, digoxin, cisplatin and cyclosporin redistribution: insulin, catecholamines,

Question 27

Causes of hypermagnesemia?

Answer 27

Renal failure: acute or chronic Endocrine disorders: hypoadrenocorticism, hyperparathyroidism, hypothyroidism Iatrogenic over administration - cathartic, laxatives, antacids

Question 28

Causes of hypophosphatemia?

Answer 28

Increased renal loss: primary hyperPTH, Diabetes, eclampsia, diuretic, Cushing's, hyperaldosteronism Decreased Gut absorption: vitamin D deficiency, malabsorption, vomiting, diarrhea, phosphate binders and antacids, diet deficiency Translocation: DKA, insulin admin, glucose, bicarbonate, total parenteral nutrition, refeeding syndrome, hypothermia, resp alkalosis or hyperventilation

Question 29

Causes of hyperphosphatemia?

Answer 29

Increased intestinal absorption: vitamin D toxicosis, phosphate containing enemas, IV over admin Decreased renal excretion: renal failure, urinary obstruction, uroabdomen, hypoPTH, Translocation: tumor cell lysis, tissue trauma or rhabdomyolysis, hemolysis, metabolic acidosis young growing animals lab error

Question 30

Calculation for corrected Chloride?

Answer 30

Cl measured x 146/Na measured - dog Cl measured x 156/Na measured - cat

Question 31

Causes of hypochloridemia?

Answer 31

Excessive loss - GI loss - vomiting, other GI disease - trichuriasis, salmonellosis, duodenal perforation Renal loss - thiazide or loop diuretics, chronic resp acidosis, HAC Excessive gain of sodium relative to chloride - sodium bicarbonate administration

Question 32

Causes of hyperchloridemia?

Answer 32

Excessive loss: diarrhea Excessive gain: NaCl, total parenteral nutrition, salt poisoning Renal chloride retention: renal failure, renal tubular acidosis, Addisons, diabetes, Chronic resp alkalosis and spironolactone Pseudohyperchloremia - potassium bromide therapy

Question 33

What is Whipple's triad?

Answer 33

Hypoglycemia Clinical signs of hypoglycemia Resolution of signs once supplemented

Question 34

Causes of hypoglycemia?

Answer 34

Excess insulin: overdose, insulinoma, PNS, toxins and meds - xylitol Excess glucose use: infection, exercise induced, pregnancy, pns, polycythemia, leukocytosis Decreased glucose production: liver, neonatal, toy breed, PSS, neoplasia, cirrhosis, glycogen storage disease, Addison's, betablockers

Question 35

Causes of hyperglycemia?

Answer 35

Postprandial hyperglycemia Endocrine - Diabetes, pancreatitis Increased gluco-counterregulatory hormones: glucocorticoids, stress, critical illness, catecholamines - pain, exertion, excitement, growth hormones, progesterone, hyperthyroidism Drugs: adrenocorticotropic, progesterone, xylazine, ketamine, morphine, glucose/dextrose containing fluids

Question 36

What is the only significant volatile acid in the body?

Answer 36

Carbonic acid

Question 37

Dissociation of a weak acid is described by what equation?

Answer 37

Henderson - Hasselbach Equation

Question 38

In terms of Acid/Base - what is a buffer? Main buffers in body? What is the main extracellular buffer? Main intracellular buffers? Other part of the body with buffering capacity?

Answer 38

A buffer is a weak acid and its conjugate salt that can accept or donate a proton to minimize changes in fluid pH after the addition of a strong acid or base Main: Bicarbonate, proteins, phosphate Main extracellular: Bicarbonate - open buffering system Main intracellular: Hemoglobin, plasma proteins and organic/inorganic phosphate - closed buffering system Bone also has important buffering capacity in the body.

Question 39

What is the pKa of bicarbonate?

Answer 39

6.1

Question 40

How do you calculate anion gap? What are the causes of increased anion gap?

Answer 40

AG = (Na + K) - (Cl + HCO3) DKA, lactic acidosis, ethylene glycol, salicylate toxicosis, uremic states (DUELS) *Albumin can be associated with an increase in AG

Question 41

What are the causes of respiratory acidosis? What are the acute and chronic compensations?

Answer 41

Hypoventilation - Less commonly increased CO2 production by tissues - (CPR, malignant hyperthermia, heatstroke) For every 1mmHg increase in PaCO2: - acute 0.15mEq/L increase in HCO3 - chronic 0.35mEq/L increase in HCO3

Question 42

You suspect a patient has a chronic respiratory acidosis - you give oxygen but hypercapnia worsens, why?

Answer 42

In some chronic cases the respiratory center is no longer sensitive to elevated CO2 levels - instead ventilation is driven by hypoxia and so supplemental oxygen may decrease ventilatory drive and worsen hypercapnia

Question 43

What is the compensatory response in acute and chronic respiratory alkalosis?

Answer 43

For every 1mmHg decrease in PaCO2: - Acute decrease of 0.25mEq/L of HCO3 - Chronic decrease of 0.55mEq/L of HCO3

Question 44

Causes of metabolic acidosis?

Answer 44

- Normochloremic (increased anion gap): DUELS - Hyperchloremic - diarrhea, renal tubular acidosis, giving carbonic anhydrase inhibitors - Hypochloremic: Addison's

Question 45

Compensation for metabolic acidosis?

Answer 45

For every decrease 1mEq/L of HCO3 - 0.7mmHg decrease in PaCO2

Question 46

Dose of bicarbonate required to return base deficit to 0 is calculate by what formula?

Answer 46

Bicarb Dose = 0.3 x bodyweight (kg) x base deficit (mEq/L)

Question 47

Causes of metabolic alkalosis?

Answer 47

Vomiting, suctioning gastric contents, admin of diuretics that induce chloride excretion (Furosemide) Hyperaldosteronism Cushing's

Question 48

What are the four questions to ask in interpreting a blood gas?

Answer 48

1. Is an acid-base disturbance present? (check pH, HCO3, PaCO2) 2. What is the primary disturbance? - alkalosis vs acidosis - metabolic vs respiratory - Is is compensated? Mixed? 3. Is the compensatory response appropriate? - if not consider a mixed 4.What underlying diseases are present?