Fluid Therapy And Parenteral Nutrition Flashcards by Harrie Long

What are the two considerations when giving fluid therapy?

Replacement of fluids lost

Maintenance of fluid needs

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How can fluids be lost?

Haemorrhage
Excessive urination (polyuria)
Vomiting and diarrhoea
Sequestered fluid

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What percentage of body weight is made up of total body water?

60%

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What can total body water be subdivided into?

What proportions?

Extracellular fluid (1/3) and intracellular fluid (2/3)

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What can extracellular fluid be subdivided into?

Interstitial fluid 3/4

plasma (intravascular volume) 1/4

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How can we calculate blood volume?

Plasma volume / (1-haematocrit)

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Why are fluids indicated for general anaesthesia?

Replacement of blood lost from surgical bleeding
Counteract CV depression from anaesthetic drugs - vasodilation leads to lowered BP
Replace insensible fluid loss
Maintain normal fluid volumes despite reduced intake pre and post op
Warmed fluids can help maintain body temp

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What is meant by insensible fluid losses?

Evaporation from surgical site etc.

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What are some other indications for fluid therapy ?

Flushing things out
Animals with azotaemia (pre, renal and post) may help improve glomerular filtration rate and removing renal toxins
Animals intoxicated with water soluble substances - flush out - e.g. chocolate, NSAIDs
Correction of acid-base disturbances

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How can fluids be used to correct electrolyte disorders?

Fluids may be supplemented with potassium and glucose if needed .

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When might drugs be delivered using fluid therapy?

Some drugs have to be diluted before administration

Some drugs require constant infusion over sever hours

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What are the common types of fluids available?

Crystalloids

Synthetic colloids

Blood products

Osmotic diuretics

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What are the three types of crystalloids?

Isotonic

Hypertonic

Hypotonic

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What is the most common type of fluid to administer?

Isotonic crystalloids

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What are crystalloids composed of ?

Water and small molecules which can freely move out of the intravascular space.

Vary in exact composition

Electrolytes - Na+,Cl-, K+, Mg2+, Ca2+
Buffers - lactate, gluconate
Dextrose

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How does hypertonic fluid affect blood volume?

Water is attracted into blood

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How does hypotonic fluid affect blood volume?

fluid moves into interstitial space

Causes cellular oedema

What are some examples of isotonic crystalloids?

Hartmann’s

Compound Sodium Lactate (CSL)

0.9% NaCl

Lactated Ringer’s Solution (LRS)

What happens after isotonic fluid is administered?

Fluid distributes equally amongst all fluid compartments

Only a third of volume remains intravascularly after equilibration due to the movement of sodium

What are the complications which can be associated with isotonic crystalloid therapy?

-Inadequate volume resuscitation or replacement

VOLUME OVERLOAD
- Peripheral oedema formation
- Pulmonary oedema or pleural effusion

-Possible dilutional coagulopathy

When might hypertonic saline be indicated?

SEVERE shock, particularly larger patients

Cerebral oedema - attracts water into blood from brain

MUST NOT USE AS A CONSTANT INFUSION

What is a contraindication of hypertonic fluids?

Dehydration / hypernatremia

When might hypotonic crystalloids be indicated?

Hypernatraemic patient or for some drug infusions

NOT USED OFTEN

What are synthetic colloid fluids composed of?

LARGE molecules (>30 KDa) suspended in an ISOTONIC crystalloid

How are Synthetic Colloids useful?

Need molecules which persist in the vascular space and continue to attract water - Generate COLLOID OSMOTIC PRESSURE with PROLONGED EFFECT This delays equilibration of fluid with other compartments

When may synthetic colloids be considered?

Hypoperfusion (shock) To restore circulating volume

When are synthetic colloids indicated?

Require rapid intravascular resuscitation - mainly haemorrhagic Want to increase COP in patients with low protein - hepatic synthetic failure, protein losing conditions (e.g. PLE, PLN), haemorrhage TYPICALLY when the patient is oedematous or does not respond to isotonic crystalloids

What are some possible complications of using synthetic colloids?

Fluid overload (more likely than isotonic crystalloids) - NOT AS SAFE Coagulopathy -Dilution of platelets and clotting factors and other additional effects Inaccuracy of total solids and urine specific gravity measurements Risk of acute kidney injury

How can synthetic colloids potentially result in a coagulopathy?

Dilute platelets and clotting factors | Additional direct effects on coagulation

What lab diagnostics can be effected by the use of synthetic colloids?

Total solids | Urine specific gravity

What are natural colloid solutions?

Blood products - whole blood, plasma, packed RBCs Concentrated albumin solutions -human or canine

Give an example of an osmotic diuretic. What is its effect?

Mannitol Shift fluid into intravascular space to be excreted by kidneys - Increased vascular volume

When is mannitol indicated?

Most common: BRAIN OEDEMA | Also, acute glaucoma, oliguric acute kidney injury (AKI)

What do you need to monitor when giving mannitol?

Fluid depletion or volume overload

What does parenteral nutrition contain? When should it be given?

A mixture of amino acid solutions, dextrose, and lipids (via IV line) When animals cannot receive nutrition via the GIT (enteral nutrition)

What are the advantages of enteral nutrition?

Directly supports enterocytes Preserves mucosal barrier - prevents bacterial translocation Immunomodulatory Stimulates motility, secretions and neuroendocrine pathways Fewer complications Relatively inexpensive IF THE GUT WORKS, USE IT !!!

What are some options for enteral nutrition?

Nasogastric feeding tube Oesophagostomy feeding tube Gastrotomy/PEG tube Jejunostomy tube (bypass stomach)

When is parenteral nutrition indicated?

Uncontrolled GI dysfunction - V/R Existing malnutrition or high risk malnutrition Individualised feeding Contraindication for enteral feeding (e.g. CV instability or unable to protect airway) Reserved for cases of convincing GIT failure

What are some negatives associated with parenteral nutrition?

More expensive than enteral feeding More challenging to manage in practice Needs a central venous catheter Can cause sepsis

Why does total parenteral nutrition need to be delivered via the jugular vein?

High osmolarity fluid Can cause vasculitis in small peripheral vessels

When would you see parenteral nutrition used?

In referral practice - requires special expertise and equipment for patient specific prescriptions Needs to be handled COMPLETELY ASEPTICALLY Metabolic complications possible

What negatives are associated with parenteral nutrition?

``` Expensive Often can give nutrition enterally Can cause sepsis Need a central venous catheter Need 24/7 monitoring ```