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Flashcards in Fluid therapy Deck (55)
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List ways in which healthy animals lose body water

- Urine
- Sweat
- Water vapour during breathing
- Faeces


List abnormal ways in which water can be lost from the body

- Vomiting
- Diarrhoea
- Burns
- Haemorrhage
- Polyuria
- Third space oss


What is third space loss and give an example?

- Fluid accumulates in body cavity but lost from circulation i.e. effusions, internal haemorrhages, peritonitis, obstructions etc
- e.g. ascites


What are the kinds of fluid losses that can occur in an animal?

- Primary water loss
- Mixed water and electrolyte loss


How does primary water loss occur?

- Water intake decreased, only losing water
- Hypotonic loss
- When patient unable to increase intake sufficiently
- Occurs from ECF, ICF to ECF translocation to compensate


Why do the clinical signs of primary water loss take time to develop?

- Water moves from ICF to ECF to compensate
- ICF is a large reserve


What are the important factors to consider when estimating water loss?

- Duration of illness
- Vomiting/diarrhoea? frequency and volume
- Water intake (quantify, unusual habits)
- Source of loss e.g. open wounds, asscites ec
- What kind of fluid loss has occured


How does mixed water and electrolyte loss occur?

- Vomiting or diarrhoea
- Haemorrhage and effusion


What are the important features of mixed electrolyte and water loss?

- Osmolarity does not change, no movement from ICF
- Loss borne by ECF alone
- Clinical signs develop quickly


What should be included in patient assessment when considering fluid loss?

- Pulse quality (peripheral, changes sooner)
- CR
- Heart rate
- Skin tenting
- Regular blood pressure (can change with stress, may no be accurate)
- Tackiness of mucus membranes
- Eye position
- Demeanour


What may happen to eye position in severe dehydration?

- May sink into socket
- Third eyellid (nictitating membrane) may move over the top


How can the degree of hypovolaemia be assessed?

- Using approximate ranges for heart rate, pulse quality, mucous memrbane colour, CRT, mentation and extremity temperature


What does loss of a distal pulse indicate?

Severe hypovolaemia


What is the difference between cats and dogs as hypovolaemia progresses?

- Cats more likely to show bradycardia
- Dogs more likely to show tachycardia


How can fluid deficit be estimated?

- %age
- Comparison of clinical signs usually show when at a particular % fluid deficit
- Multiply by animal's weight to get volume of deficit i.e. 20kg dog with 10% dehydration = 2 litre deficit


What is the approximate maintenance fluid requirement for a dog?

- or 1.5-4ml/kg/hour


List the main therapeutic fluids

- Crystalloids (hypotonic, isotonic, hypertonic)
- Colloids
- Blood products
- Haemoglobin based oxygen carrying solutions (HBOCS)


What are the main aims of fluid therapy?

- Improvement of organ function (need adequate perfusion)
- Correction of electrolyte disturbances
- Correction of hypovolaemia
- Correction of acid base disturbances
- Total or partial parenteral nutrition (usually PPN)


What is Lactated Ringer solution?

Isotonic crystalloid solution


What is contained in LRS?

- Na+: 130mEq/l
- Cl-: 109mEq/l
- Lactate as a bicarbonate precursor (so is buffered)
- Tiny amounts of potassium


Why is LRS buffered?

- Controlled alkalinisation
- Avoids dilutional acidosis


Why is LRS not suitable for long term administration?

Inadequate potassium


What is LRS used for?

- Shock
- Diuresis
- Anaesthesia
- Maintenance
- Can add other things e.g. glucose


What are the disadvantages of LRS?

- Contains calcium, cannot use if hypercalcaemic
- Only 1/4 will remain in vascular space, rest is excreted, not efficiet in bringing up and maintaining fluid levels


Describe hypotonicc crystalloid fluids

- 0.18% NaCl, or 0.18% NaCl and 5% glucose
- Hypotonic
- Very few indications - Like giving pure water
- Useless, causes dilution, likely to make patient sicker


What is the effect of administration of hypertonic crystalloid fluid?

- Draws water from interstitial space
- Causes pulmonary-vagal reflex (vasoconstriction, bypass pulmonary circulation)
- Transient effect (10-15 min)


When is use of hypertonic crystalloid fluid indicated?

- Usually large animals e.g. prior to colic surgery
- Low volume resus (life threatening hypovolaemia and raised ICP)


When is use of hypertonic crystalloid fluid contraindicated?

- Hypernatremia
- Hypokalaemia
- Haemolysis
- Thrombosis
- Fall in BP
- Repeat use


When is use of colloid fluids indicated?

- Support of circulating blood volume is needed
- Severe hypovolaemia
- Systemic inflammatory response syndrome
- Haemorrhage
- Hypoproteinaemia


What types of colloid fluids are available?

- Artificial: oxypolygelatins, dextrans, starches, HBOCs
- Natural: albumin, plasma etc


Describe gelatin colloids

- Oxypolygelatins
- Plasma half life 2-4 hours
- No need for concurrent crystalloid but often do give both
- Produces osmotic diuresis
- No direct coagulation effects


Describe starch colloids

- Plasma half life 25 hours due to molar substitution
- Initial elimination by tissue uptake
- Excretion by metabolism
- Volume expanded by volume given
- Reversal of microvascular permeability
- Direct coagulation effects


How do starch colloids reverse microvascular permeability?

Anti-inflammatory effect


How do starch colloids have a direct coagulation effect?

Increase APT in dogs
- Factor VIII precipitation


What are the indications for use of blood colloids?

- Haemorrhage
- Clotting disorders
- Hypoproteinaemia


Outline how hypertonic saline can be used for emergency fluid resuscitation in clinical practice

- Life threatening hypovolaemia and raised intra-cranial pressure (ICP)
- Draws water from interstitial space
- Causes pulmonary vagal reflec
- Expands blood palsma for short period of time


Give an example of haemoglobin replacement products in fluid therapy

- Haemoglobin based oxygen carrying HBOC


When are haemoglobin replacement products commonly used and why?

- Hypoxaemic crisis where there has been massive blood loss
- Artifically carries oxygen


What are the limitations to using haemoglobin replacement products?

- Very expensive
- Many practices do not stock so difficult to get hold of in crisis
- Exerts high osmotic pressure, need to infuse slowly and carefully


List the ways in which fluids can be administered

- Orally
- IV
- Rectal
- SubCut
- Intraosseous
- Intraperitoneal


What veins can be used for intravenous administration of fluids?

- Cephalic
- Saphenous
- Jugular
- Auricular
- Lateral thoracic


What complications can occur in fluid administration?

- Extravasation
- Thrombosis
- Infection
- Emboli (incl. catheter emboli)
- Exsanguination


What may cause an unexplained tachycardia following fluid therapy be indicative of?



What should a fluid plan consist of?

- Replace what is already lost, maintain, and counteract ongoing losses
- Sum of deficit, mainteance amount and ongoing losses


What are the advantages of oral administration of fluids?

- More physiological
- Non-invasive (lower risk of infection)


What are the disadvantages of oral administration of fluids?

- Too slow
- May be impossible due to clinical presentation (vomiting, unconscious, unable to swallow)


What are the advantages of IV administration of fluids?

- Large volume can be administered faster
- Precise (know how much is going in)


What are the disadvantages of IV administration of fluid?

- Can overload
- Large volume too fast, come out of veins causing oedema
- Invasive = risk of infection, thrombi and emboli


What are the advantages of subcut administration of fluids?

- Useful if can't find vein
- Can train owner to do this


What are the disadvantages of subcut administration of fluids?

- Risk of infection
- Slow
- Can be painful (large pocket of fluid under skin)


What are the advantages of intraosseus administration of fluids?

- No veins found
- Small animals e.g. puppies, kittens, rabbits, birds
- veins in birds very fragile (prone to haematoma)


What are the disadvantages of intraosseus administration of fluids?

- pianful
- Cannot be done in humerus or femur of birds


Why can intraosseus administration of fluids not be done in the humerus or femur of birds?

- Pneumatic bones with air sacs
- Would drown bird


What are the sites for intraosseus administration of fluids in dog or cat?

- Femur
- Humerus
- Pelvis


What are the sites for intraosseus administration of fluids in birds?

- Ulna
- Radius
- Tibia