Fluid Therapy - Pt 2

What fluids do we have available?

- Crystalloids

- Colloids

- Blood and blood products

What is the most common type of fluid to use in practice?

Crystalloids

What are crystalloids?

Solutions that contribute to osmotic pressure depending on the electrolytes in the solution.

What are the components of solutions classified as crystalloids?

Water with dissolved glucose and/or electrolytes.

The addition of electrolytes to crystalloids creates..

Hypotonic solutions

Isotonic solutions

Hypertonic solutions

What is a hypotonic solution?

A solution with a solute concentration less than that of the extracellular fluid.

What happens to cells when a hypotonic solution is given intravenously?

Fluid shifts into the cellular space, causing the cells to swell.

What conditions can a hypotonic solution be used to treat?

Conditions causing intracellular dehydration, such as ketoacidosis.

What is an isotonic solution?

A solution with the same solute concentration as extracellular fluid.

What happens to isotonic solutions when given intravenously?

They distribute evenly throughout interstitial and vascular space.

What is the effect of isotonic solutions on fluid movement?

There is no significant shift of fluid.

What is one benefit of isotonic solutions?

They support circulation and rehydrate tissues.

What is an example of an isotonic solution?

Lactated Ringer's solution (Hartmann's).

What is a hypertonic solution?

A solution with a higher solute concentration than extracellular fluid.

What happens when a hypertonic solution is given IV?

It causes an increase in concentration, leading to water moving from the interstitium and intracellular space.

What effect does a hypertonic solution have on cells?

It causes crenation of cells.

Why should hypertonic solutions be used with caution in dehydrated patients?

Dehydrated patients do not have the 'spare fluid' to accommodate the solution.

How should hypertonic solutions be administered?

They should be given slowly.

What is one benefit of administering hypertonic solutions slowly?

It can help support circulation by locking water in the vessels for a short period of time.

What is an example of a hypertonic solution?

7% NaCl.

What conditions can hypertonic solutions be used to treat?

Increased intracranial pressure or intraocular pressure.

What is the purpose of glucose or dextrose in fluids?

To provide osmolarity and make the solution isotonic.

Does glucose in fluids have calorific value?

No, it has no calorific value.

How is glucose in fluids metabolised?

It is rapidly metabolised to leave water.

What are colloids/plasma expanders used for?

They are used to expand the vasculature and increase perfusion to vital organs.

How do colloids/plasma expanders compare in usage to other types of fluids?

They are not used as commonly as others but are still very useful.

What do colloids contain that distinguishes them from other fluids?

Colloids contain larger molecules, specifically proteins.

What is the role of oncotic pressure of proteins in fluid retention?

Oncotic pressure of proteins retains fluid in the intravascular space and draws fluid in from the interstitial space.

How do colloids differ from crystalloids?

They don't move from intravascular space to interstitial space

How long do colloids last in the body?

Up to 24 hours, eventually broken down.

How should colloids be administered?

Give slowly!

What are colloids often given alongside?

Crystalloids.

What is the purpose of giving colloids with crystalloids?

To rehydrate the tissue.

Name two examples of colloids.

Gelofusin and Haemocel.

What effect do colloids have on interstitial to intravascular fluid balance?

They dehydrate tissue, so they need to be rehydrated.

What are colloids commonly used to treat?

- Severe shock

- Haemorrhage where PCV is less than 20% but does not require blood products

- Plasma protein levels are less than 35g/l leading to oedema and ascites

- Severe dehydration

What is the indicated use of blood products for blood loss?

To replace RBCs

What is the indicated use of blood products for clotting disorders?

To help replace RBCs and clotting factors

What is the indicated use of blood products for hypoproteinaemia?

To replace albumin

Blood transfusions - dogs

Dogs don't have pre-existing antibodies to blood groups so are able to be given any blood for the first transfusion

Blood transfusions - cats

Cats have pre-existing antibodies to blood groups so MUST be cross matched

What is a common route of administration that involves taking a fluid by mouth?

Oral - electrolyte containing rehydration fluid

Which route of administration depends on peripheral circulation?

Subcutaneous

What is the most common route of administration that allows for large volumes to be given?

Intravenous

What route of administration is good but requires strict asepsis and involves the bone?

Intraosseous

Which route of administration is not used in small animals and is performed in the abdomen?

Intraperitoneal

Routes of administration

- Oral - electrolyte containing rehydration fluid

- Subcutaneous - depends on peripheral circulation

- Intravenous - Most common, large volumes can be given

- Intraosseous - good but strict asepsis, in the bone

- Intraperitoneal - not used in SA, in the perineum (abdomen)

Catheters

- Butterfly needle

- Over the needle IV catheter

- Jugular catheter

Catheters - Butterfly needle

- Not recommended

- Rigid needle will damage vessel

Catheters - Over the needle IV catheter

- With or without wings

- Most common

Catheters - Jugular catheter

- Stay in place for longer - 3 ports instead of just one so the IVFT can be given

- Used a lot in referral medicine

- Take bloods

- Give meds

Giving sets - Burettes

- Fluid held in container

- Good for smaller patients

- Less chance of fluid overload if accidently left open

- Commonly have drip factor of 60 drops per ml

Giving sets - Blood administration set

- Has a filer to remove any blood clots

- Commonly have a drip factor of 15 drops/ml

Reasons as to why a drip may have stopped?

- Catheter is blocked

- Too close to the elbow

- Has come out of the vein

- Drip line is kinked

- Been closed off

- Become disconnected

- Fluids have run out

What is a problem associated with over infusion in fluid therapy?

Too much fluid given or urine output impaired, circulation becomes overloaded.

What can happen to lungs and other tissues due to over infusion?

Lungs and other tissues become oedematous.

How does over infusion affect oxygen absorption?

Oxygen absorption is impaired.

Clinical signs of over infusion

- Increased heart rate

- Increased respiration rate

- Cyanosis of mucous membranes

- Dull demeanour due to cerebral oedema

What can cause bleeding out during fluid therapy?

Dog chews through drip line or connector unscrews.

What happens when blood flows back out of the catheter?

Blood will flow back out of the catheter.

How likely is it for bleeding out to occur during fluid therapy?

Extremely unlikely that bleeding out will occur as clots form quickly.

What is a potential consequence of bleeding out during fluid therapy?

It can get very messy.

IV catheter care!

- Check under bandage at least once daily

- Look for any redness, swelling of limb, signs of infection

- Check if any problems with flow

- Check toes for swelling if not included in the bandage

- Change bandage if becomes wet or soiled

- Flush at least once daily to maintain patency

- Check line occasionally to ensure not been chewed