Pharmacology of fluid therapy

Question 1

What % of body weight is body water?

Answer 1

60%

Question 2

How much of body weight is made up of the following:

• Intracellular fluid
• Extracellular fluid
• Interstitial fluid
• Intravascular fluid

Answer 2

• 40%
• 20%
• 15%
• 5%

Question 3

Dehydration leads to activation of…?

Answer 3

Baroreceptor reflex and RAAS

Question 4

Via what routes can fluids be given?

Answer 4

• Enteral e.g. oral via tube

- Parenteral e.g. IV, sub-cutaneous

Question 5

What must be functional to use oral fluid therapy?

Answer 5

The GI tract

Question 6

Compare 3rd and 4th generation oral fluids

Answer 6

3rd = high glucose, addresses nutritional demands
4th = glutamine, promotes villus repair and regeneration

Question 7

When choosing an oral fluid, what is the optimum sodium conc?

Answer 7

120-130mmol/l

Question 8

What is a crystalloid solution?

Answer 8

• Salt solutions that that freely cross capillary walls.

- Stay in vascular space for short time. Quickly (mins) leak into extracellular fluid compartment

Question 9

What is an unbalanced salt solution?

Answer 9

0.9% sodium chloride

Question 10

What is a balanced salt solution?

Answer 10

Contain electrolytes in addition to Na+ and Cl- (such as K+ Ca2+ Mg2+ ), making them similar to plasma. Lactated Ringer’s is an example of a balanced solution

Question 11

0.18% NaCl + 5% dextrose is what type of solution?

Answer 11

Hypotonic

Question 12

What type of solution is considered to be plasma expanders and why?

Answer 12

Hypertonic crystalloids because their tonicity causes water to move from interstitial and intracellular sites into the intravascular compartment

Question 13

What is a hypotonic solution?

Answer 13

5% dextrose solution

Question 14

What happens if an animal can’t drink because of e.g. face trauma and needs to be put on fluids for several days?

Answer 14

Want to give a fluid with less sodium

Question 15

What are colloid solutions?

Answer 15

Intravascular volume replacement solutions.
Non crystalline substances consisting of large molecules diluted in a crystalloid. Capillary endothelium is impermeable to these large molecules

Question 16

How are colloids plasma volume expanders?

Answer 16

Increase colloidal osmotic pressure of the plasma & “pull” water from the interstitial space

Question 17

Give examples of when colloids should be used

Answer 17

1. When it is difficult to administer sufficient volumes of fluids rapidly enough to resuscitate a patient (e.g., large patient, emergency surgery, large fluid loss).
2. In patients with large volume losses where crystalloids are not effectively improving or maintaining blood volume restoration.
3. When decreased oncotic pressure is suspected e.g. hypoproteinaemia

Question 18

Give 3 examples of natural colloids

Answer 18

• Whole blood
• Plasma
• Albumin

Question 19

Give 3 examples of synthetic colloids

Answer 19

• Starches
• Gelatins
• Dextrans