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Flashcards in CAL - fluid therapy Deck (31):

Fluids appropriate for volume resuscitation in severe/ decompensated hypovolaemic chock

- Hypertonic (7%) saline
- Synthetic colloid
*** (FIRST CHOICE) Hartmann’s solution (Lactated Ringer’s solution or Compound Sodium Lactate) ****
- Gelofusin
- 0.9% saline.


Why is hartmann's usually preferable to saline?

it is slightly more physiological and less likely to contribute to acid-base abnormalities (e..g hyperchloraemic metabolic acidosis)


An hour after isotonic crystalloid fluid, how much fluid will remain in intravascular space?

only 25% (the rest will be in the interstitium)


How does body try and recover lost blood?

- splenic contraction
- movement of extravascular fluid into intravascular space
- release of ADH (retention of fluid and Na)
- other homeostatic mechanisms


What happens if fluids are given slowly?

- they won't increase intravascular volume but will replace lost extravascular fluid (i.e. how to address dehydration)


Bolus rate of fluids for hypovolaemia

a 10, 20 or 30 ml/kg bolus over 15 minutes and then reassess.


Rate of insensible losses

1-3ml/kg/hr depending on size (less for larger dogs). Affected by if V/D, panting etc


When do you stop fluid therapy?

once eating or drinking


How to assess a patient for dehydration

- complete PE (especially indicators of interstitial hydration))


Laboratory finding ssuggestive of dehydration

- haemoconcentration findings (increased haematocrit)
- increased TP
- but in isolation cannot establish hydration status - look at PE


CS dehydration status

No CS detectable


Dehydration of what severity may manifest with signs of hypovolaemia?

severe dehydration (>12%)


CS - dehydration of 5-6%

subtle loss of skin elasticity


CS - dehydration of 6-8%

- definite prolongation in return of skin to normal position
- slight CRT prolongation
- possible dry MM
- eyes possibly sunked inorbits


CS - dehydration of 8-10%

- tented skin stands in place
- dry MM
- eyes sunken into orbits


CS - dehydration of >10%

- may manifest signs of shock (more common in cats)
- prolonged CRT


Appropriate fluids - dehydration

any balanced crystalloid:
- 0.9% saline
- Hartmann's (LRS or CSL)


Tx - dehydration

- rehydrate over 24-48 hours
- only if concurrent hypovolaemia (i.e. dehydration >10%) should you give a fluid bolus
- otherwise CRI
- if eating/drinking normally, no additional fluids
- fluids SC is an option but not in one tx


How much fluids SC do cats tolerate?

no more than 100-120ml/tx as painful/uncomfortable


Equation for calculating fluid deficit

Fluid deficit = dehydration deficits + maintenance + on-going losses


Dose - maintenance fluid requirement



Define sensible losses

a measured amount of fluid loss (e.g. urine output). Can range from 27-40ml/kg/day. Can be quite high for animals with severe PU. Potentially fluid losses via vomiting can also be estimated.


Define insensible fluid losses

faecal, cutaneous and respiratory losses. Ranges from 10-20ml/kg/day, higher in dogs with excessive panting


Findings suggestive of over-hydration

Chemosis, Gelatinous skin, Jugular venous distension, Weight gain, Tachypnoea/dyspnoea, Serous nasal discharge


Differentiate dehydration and hypovolaemia

- HYPOVOLAEMIA: decease in circulating blood volume which requires immediate tx
- DEHYDRATION: loss of interstitial fluid volume without change in intravascular volume


CS - hypovolaemia

• Increased heart rate,
• Decreased pulse pressure
• Reduced jugular filling
• Increased respiratory rate
• Cold extremities
• Decreased urine output


CS - dehydration

• Prolonged skin tent
• Tacky mucous membranes
• Sunken eyes (rarely seen in adult horses)


Is it common for dehydration and hypovolaemia to co-exist?

Yes - in horses but not in small animals. They will co-exist in horses as the intersititial volume will be quickly moblised to replenish the intravascular volume.


Laboratory findings supportive of hypovolaemia and dehydration

• Haemoconcentration (increased PCV, TP) can support the assessment of dehydration, however, it cannot be used solely to determine hydration status. Animals that lose a great deal of interstitial fluid will invariably have haemoconcentration.
• The dehydration masks in this case a pre-existing hypoproteinaemia.
• Increased serum creatinine and BUN (decreased renal perfusion; pre-renal azotaemia)
• Increased USG
• Increased plasma lactate (decreased peripheral perfusion → decreased oxygen delivery to peripheral tissues → anaerobic glycolysis → increased lactate production)


What size catheter would you use in a horse for dehydration/hypovolaemia?

- a 10G or 12G over-the needle catheter. Aim = high flow rate (only possible if you minimise resistance to fluid flow - by increasing catheter radius)
- alternatively two 14-G catheters, one in R and L jugular veins


How to expand intravascular volume rapidly in horses?

you can bolus 1-2L of hypertonic saline first (2-4ml/kg), followed by the balanced electrolyte solution.