Vascular access and fluid therapy

Question 1

What can peripheral IV catheters be used for?

Answer 1

Infusion of fluids (including blood products)
Blood sampling
Administration of drugs

Question 2

Why might a central venous catheter be placed?

Answer 2

Longer-term administration of fluids (>5 days)
Administration of hypertonic medications/fluids
Administration of multiple medications
Requirement for multiple/serial blood sampling
Administration of total parenteral nutrition
Measuring central venous pressure

Question 3

What are most catheters made of?

Answer 3

Silicone or polyurethane

Question 4

What type of catheter is preferable for administration of fluids and why?

Answer 4

Short and wide for faster fluid flow

Question 5

What different types of catheters are available?

Answer 5

Over the needle
Through the needle
Butterfly/winged
Peel-away
Over the wire/guide wire

Question 6

What are the most commonly used type of catheters?

Answer 6

Over the needle

Question 7

Over the needle catheters are suitable for…

Answer 7

Short to medium term use

Question 8

What drops per minute is a standard drop chamber?

Answer 8

20dpm

Question 9

What drops per minute is a paediatric drop chamber?

Answer 9

40-60dpm

Question 10

What % of the body weight is total body water?

Answer 10

60%

Question 11

How much of the total body water is found intracellulary?

Answer 11

65%

Question 12

What percentage of total body weight is found extracellularly?

Answer 12

35%

Question 13

How is the extracellular body water split and by what percentage?

Answer 13

25% intravascular, 8% interstitial

Question 14

By what methods can fluid and electrolytes move between compartments?

Answer 14

Osmosis, diffusion or starling’s force

Question 15

Define dehydration

Answer 15

Deficit of the interstitial and intracellular compartments

Question 16

Define hypovolaemia

Answer 16

Deficit of the intravascular compartment

Question 17

What are examples of isotonic crystalloids?

Answer 17

0.9% saline, lactated ringers (hartmanns) and ringer’s solution

Question 18

What can isotonic fluids be used for?

Answer 18

Hypovolaemia, dehydration, replacing ongoing losses and maintenance and replacement of electrolytes

Question 19

Why might 0.9% saline be chosen if a patient has hypercalcaemia?

Answer 19

It increases calcium excretion via the kidney

Question 20

Why is lactated ringers (hartmanns) preferable for metabolic acidosis?

Answer 20

It contains a bicarbonate precursor

Question 21

Why are the effects of isotonic crystalloids temporary?

Answer 21

Capillary fluid shifts

Question 22

Why might 0.9% saline contribute to existing metabolism acidosis?

Answer 22

High concentration of chloride

Question 23

What is the electrolyte composition of isotonic fluids comparable to?

Answer 23

Extracellular fluid

Question 24

What can prolonged usage of isotonic fluids lead to?

Answer 24

Hypokalaemia due to low potassium, particularly in 0.9% saline

Question 25

What is the blood volume of dogs?

Answer 25

90ml/kg

Question 26

What is the blood volume of cats?

Answer 26

60-66ml/kg

Question 27

In hypovolaemic patients, over how long is a bolus performed?

Answer 27

15 minutes

Question 28

Roughly how many ml/kg may a mildly hypovolaemic dog require in a bolus?

Answer 28

10-20ml/kg of isotonic crystalloid

Question 29

Roughly how many ml/kg may a severely hypoperfused (i.e. onngoing severe haemorrhage) dog require in a bolus?

Answer 29

70-90ml/kg

Question 30

What ml/kg may a hypovolaemic cat require within a bolus?

Answer 30

10-15ml/kg

Question 31

What potential issues may arise with administering isotonic crystalloid therapy?

Answer 31

Prolonging coagulation by dilution Theoretical compounding of acidosis (0.9% NaCl is acidic) Hypothermia

Question 32

In what circumstances can hypertonic saline be administered?

Answer 32

Large dogs with severe hypovolaemia who would require a large volume of isotonic crystalloids Resuscitation of dogs with GDV Patients with head trauma

Question 33

How does hypertonic fluid work?

Answer 33

Results in a large osmotic gradient that draws water from the interstitial and intracellular fluid compartments resulting in rapid expansion of intravascular volume

Question 34

Why should caution be exercised when using hypertonic saline in patients with ongoing haemorrhage?

Answer 34

Due to a rapid rise in blood pressure

Question 35

Why should ECG monitoring be used when administering hypertonic saline?

Answer 35

It can cause ventricular dysrhythmias

Question 36

When are the effects of hypertonic saline diminished?

Answer 36

30 minutes

Question 37

Why is hypertonic saline advantageous in patients with raised intra-cranial pressure?

Answer 37

Smaller volumes can be administered to reduce the risk of cerebral oedema whilst restoring blood pressure and cerebral perfusion

Question 38

How should hypertonic saline be administered?

Answer 38

Alongside or just prior to infusion of isotonic crystalloids

Question 39

In which patients is hypertonic saline not suitable?

Answer 39

Dehydrated or patients with hypernatramia (high sodium)

Question 40

Describe hypotonic fluids

Answer 40

There is a net movement of fluid from the vascular space into the interstitial and intracellular space

Question 41

Describe colloids

Answer 41

Macromolecules in solution so are retained intravascularly due to their size

Question 42

How do colloids differ from isotonic crystalloids?

Answer 42

It encourages gthe fluid to stay intravascularly by increasing the oncotic pressure, mimicking the role of albumin

Question 43

When might synthetic colloids be contraindicated?

Answer 43

Patients with coagulopathies or in patients with vascular leaks (SIRS/sepsis) or acute kidney injury

Question 44

What are some examples of synthetic colloids?

Answer 44

Gelatins Dextrans Hydroxyethyl starches

Question 45

What are some examples of natural colloids?

Answer 45

Plasma (fresh/frozen Packed RBCS Albumin

Question 46

What are some indications for fluid therapy?

Answer 46

Correct a deficit Correct electrolyte and acid-base derangement's To provide maintenance fluids To meet ongoing losses

Question 47

Why is correction of hypovolaemia important?

Answer 47

Normalising the haemodynamic status maintains adequate oxygen delivery and prevents shock/MODS/death

Question 48

How is hypovolemia corrected?

Answer 48

IVFT & stopping ongoing loss of intravascular volume

Question 49

By what technique should fluid resuscitation in a hypovolaemic patient be performed?

Answer 49

Fluid challenge technique (bolus therapy)

Question 50

Define the fluid challenge technique

Answer 50

A volume should be given over a set time rather than a rate for a predetermined amount of time, with assessment of end-points of resuscitation following each bolus

Question 51

What clinical findings will indicate an improvement in perfusion status?

Answer 51

Improved mentation Decrease in heart rate (some cats may increase as often develop bradycardia during shock) Return/stronger peripheral pulses Return to normal mucous membrane colour Return to normal CRT Increase in urine production to normal 1-2ml/kg/hr - may not be immediately evident

Question 52

What objective end points of resuscitation can be used?

Answer 52

Arterial blood pressure Central venous pressure Mixed/central venous oxygen levels Quantification of urine output Lactate measurements

Question 53

Over how long should dehydration be correct?

Answer 53

24 hours

Question 54

What calculation can be used to calculate the volume of replacement fluids needed to correct dehydration?

Answer 54

Deficit (ml) = body weight (kg) x 10 x % dehydrated

Question 55

Why is IVFT recommended for metabolic acidosis in shock patients?

Answer 55

High lactate levels from anaeorbic respiration can be resolved from correcting hypovolaemia

Question 56

Why is 0.9% NaCl described as an acidifying fluid?

Answer 56

It contains no bicarbonate precursors

Question 57

Why are alkalising fluids used in metabolic acidosis?

Answer 57

They contain bicarbonate precursors such as lactate

Question 58

How soon after administration of hartmanns is the lactate metabolised in the liver and what is it metabolised into?

Answer 58

1-2 hours Bicarbonate

Question 59

How does bicarbonate