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Flashcards in CAL - fluid therapy Deck (31):
1

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.

2

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)

3

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

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

4

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

5

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)

6

Bolus rate of fluids for hypovolaemia

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

7

Rate of insensible losses

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

8

When do you stop fluid therapy?

once eating or drinking

9

How to assess a patient for dehydration

- complete PE (especially indicators of interstitial hydration))

10

Laboratory finding ssuggestive of dehydration

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

11

CS dehydration status

No CS detectable

12

Dehydration of what severity may manifest with signs of hypovolaemia?

severe dehydration (>12%)

13

CS - dehydration of 5-6%

subtle loss of skin elasticity

14

CS - dehydration of 6-8%

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

15

CS - dehydration of 8-10%

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

16

CS - dehydration of >10%

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

17

Appropriate fluids - dehydration

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

18

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

19

How much fluids SC do cats tolerate?

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

20

Equation for calculating fluid deficit

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

21

Dose - maintenance fluid requirement

50-80ml/kg/day

22

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.

23

Define insensible fluid losses

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

24

Findings suggestive of over-hydration

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

25

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

26

CS - hypovolaemia

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

27

CS - dehydration

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

28

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.

29

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)

30

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

31

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.