Fluid therapy

Question 1

What portion of the body is water (ICF +ECF)?

Answer 1

2/3 body weight

Question 2

What is the fluid amount given per kg to dogs and cats?

Answer 2

~100ml per kg for a dog and ~70ml per kg for a cat- do NOT treat cats as small dogs as the constitution of their blood volume is a lot different

Question 3

What is primary water loss?

Answer 3

This type of water loss occurs when intake is decreased e.g. a cat has been locked in shed.
Occurs when the patient unable to increase intake sufficiently (output exceeds input)
Occurs from ECF, water moves from ICF to ECF to compensate.
Hypotonic water loss.

Question 4

What is mixed water and electrolyte loss?

Answer 4

Occurs when patient has vomiting or diarrhoea- haemorrhage and effusion also cause this type. This is when water and electrolytes are lost together. Osmolarity does not change as there is no movement from ICF. Loss borne by ECF alone. Clinical signs develop quickly.

Question 5

How can the eye suggest dehydration?

Answer 5

Increased dehydration can mean that the eyes sink back and the third eyelid may come across.

Question 6

What are the qualities of a isotonic crystalloid solution?

Answer 6

It has a very close constitution to plasma (very alike) with respect to sodium and chloride.
If in doubt choose Hartmann’s!

Question 7

What are the qualities of a hypotonic crystalloid solution?

Answer 7

This type of crystalloid fluid is very rarely used as it is close to pure water- it has FAR LESS sodium and chloride in it. Can have detrimental effects if given long term.

Question 8

What are the qualities of a hypertonic crystalloid solution?

Answer 8

Draws water from interstitial space
Causes a pulmonary-vagal reflex
Vasoconstriction
Bypass of pulmonary circulation
Transient effect (10-15 mins) VERY FAST
Rapid restoration of MAP, increased myocardial contractility, CO & O2 delivery
4ml/kg over 10 min, don’t repeat
Must ALWAYS follow with isotonic fluids

Question 9

What are common colloids used in veterinary practice?

Answer 9

Most common colloids used in the veterinary profession:

1. Starches e.g. Hetastarch, pentastarch (difficult to get hold of)
2. Oxypolygelatin
3. Dextran 40
4. Plasma

Question 10

When are blood colloids (natural colloids) used?

Answer 10

• Used in severe fluid deficits and so rely on infusing bloods
  
  • Blood products – available from commercial pet blood bank
  • Different indications, haemorrhage, clotting disorders, hypoproteinaemia etc
  • Albumin crosses capillary membrane
  • Human albumin also available

Question 11

Which veins can be used to deliver IV fluids?

Answer 11

Cephalic, saphenous, jugular, auricular, lateral thoracic

Question 12

What volume and how fast should you give the fluids?

Answer 12

• First calculate total deficit (% fluid deficit + losses)
  
  • Add on maintenance fluids
  • Aim to replace approx ½ total deficit over first 1-2 hours then decide on a rate thereafter (over 24 or 48 hours) – keep monitoring & can change rate, it depends on your patient and how they respond
  • In cases of shock can give 60-90ml/kg/hr (<1hr though, and MUCH less in cats)