Fluid therapy

What is the normal blood volume of dogs and cats and how much of the body weight is water?

Dog - 88ml/kg

Cat - 66ml/kg

2/3 bodyweight is water

List the aims of fluid therapy

• maintain normal physiology

• improve organ function

• correct electrolyte disturbances

• correction of hypovolaemia

• correction of acid:base disturbances

What is the fluid maintenance rate for animals?

2.5ml/kg/hour or 60ml/kg/day

What are the available crystalloid

Isotonic = good for shock. diuresis and anaesthesia maintenance. Hartmanns.

Hypotonic = saline, can include glucose

Hypertonic = draws water from intestinal space (most common in large animal e.g. colic surgery)

What are the available colloids. Compare to crystalloids.

Artificial = gelatins (largest volume expansion, shortest halflife), dextrans, starches, HBOCs

Natural = albumin, plasma

Supports circulation longer than crystalloids, but no evidence of clinical superiority

Have a more rapid initial re-expansion of volume

What are the natural colloids available?

• whole blood

• packed red blood cells

• fresh frozen plasma/frozen plasma

• cryoprecipitate

Match the fluid to the loss

List the routes of fluid therapy (6)

Intravenous

Oral

Rectal

Subcutaneous

Intraosseous

Intraperitoneal

What is this? What is the delivery rate.

Giving set (gives 15/20 drops per ml)

What is this? What is the delivery rate.

Burette. 60 drops per ml (more accurate)

What is this?

Syringe driver

At what rate should fluid loss be replaced in acute and chronic conditions?

Acute = replace half loss in first 1-2 hours, then the rest over 24-48 hours

Chronic = replace over 3-4 days

Contraindications of fluid therapy during anaesthesia

Risk of overload (cardiac patient)

Risk of anaphylactoid reactions and interference with clotting test (colloid)

Cost

What is the normal dose rate for IV crystalloids?

Cats = 3-9ml/kg/hour

Dog = 5-20/ml/kg/hour