Fluid Therapy

Question 1

What is the fluid intake required for a normal person

Answer 1

• roughly 2-2.5L in a normal person (70kg) over 24 hour

Question 2

What is the normal losses for fluid in a normal person

Answer 2

• normal daily losses are through urine (1500ml), stool (200ml) and sensible losses (800ml)

Question 3

How do people tend to get fluid intake

Answer 3

• 1000ml through food

- 1500ml through drink

Question 4

What does an underfilled fluid balance look like

Answer 4

• tachycardia
• postural drop in BP (or low BP but late sign)
• slow capillary refill
• reduced urine output
• cool peripheries
• dry mucous membranes
• reduced skin turgor
• sunken eyes

Question 5

What does overfilled fluid balance look like

Answer 5

• raised JVP
• pitting oedema (sacrum, ankles/legs)
• tachypnoea
• bibasal crepitations
• pulmonary oedema on CXR

Question 6

how much fluid is in each of the fluid compartments in the body

Answer 6

• for a 70kg man, total body fluid = 42L (60% of body weight)
• 2/3 is intracellular 28L
• 1/3 is extracellular 14L
• different types of IV fluids will equilibrate with the different fluid compartments depending n the osmotic content of the given fluid

Question 7

What are the two types of IV fluid

Answer 7

• Crystalloids

- Colloids

Question 8

Name the types of crystalloids

Answer 8

• 5% glucose (dextrose)
• 0.9% sodium chloride (normal saline)
• hypertonic glucose (10% or 50%)
• glucose with sodium chloride (1/5 of normal saline)
• Hartmann’s solution

Question 9

Describe 5% glucose

Answer 9

• Isotonic, but contains only a small amount of glucose (50g/L) and so provides little energy (~10% of daily energy per litre)
• The liver rapidly metabolises all the glucose leaving only water, which rapidly equilibrates throughout all fluid compartments

Question 10

What is 5% glucose used in

Answer 10

• not used in fluid resuscitation

- suitable for maintaining hydration

Question 11

What does excess 5% glucose lead to

Answer 11

• water overload and hyponatraemia

Question 12

Describe 0.9% sodium chloride

Answer 12

• Has about the same Na+ content as plasma (150mmol/L) and is isotonic with plasma
• Will equilibrate rapidly throughout the extracellular compartment only, and takes longer to reach the intracellular compartment than 5% glucose

Question 13

What is 0.9% sodium chloride used for

Answer 13

• fluid resuscitation - this is because it remains in the extracellular space and thus 1/3 of the given volume in the intravascular space
• maintain hydration

Question 14

What is hypertonic glucose (10%-50%) used for

Answer 14

• may be used in the treatment of hypoglycaemia

Question 15

What is the negatives of hypertonic glucose (10-50%) and what can you do about it

Answer 15

• irritant to veins so care in its use is needed

- infusion sites should be inspected regularly and flushed with 0.9% saline after use

Question 16

when is glucose with sodium chloride used

Answer 16

• Isotonic, containing 0.18% saline (30mmol/L of Na+) and 4% glucose (222mol/L)
• Roughly the quantity of Na+ required for normal fluid maintenance, when given 10-hourly in adults, but is now most commonly used in paediatric setting

Question 17

What is Hartmann’s solution

Answer 17

• alternative to 0.9% saline

Question 18

What are colloids

Answer 18

• have a high osmotic content similar to that of plasma and therefore remain in the intravascular space for longer than other fluids
• therefore appropriate for fluid resuscitation but not for general hydration
• expensive and may cause anaphylactic reactions

Question 19

What fluid do you use in acute blood loss

Answer 19

resuscitate with 0.9% saline via large-bore cannulae until blood is available

Question 20

What fluid do you use in children

Answer 20

• use glucose with sodium chloride for fluid maintenance

- 100ml/kg, then 10kg, then 50ml/kg for the next 10kg then 20ml/kg thereafter (all per 24 hour)

Question 21

What fluid do you use in GI losses

Answer 21

(diarrhoea, vomiting, NG tubes)

- replace lost potassium as well as lost fluid volume

Question 22

What should you use for liver failure

Answer 22

patients often have a raised total body sodium, so use salt-poor albumin or blood for resuscitation, and avoid 0.9% saline for maintenance

Question 23

What should you use in poor urine output

Answer 23

• aim for >1mg/kg/h, minium is >0.5ml/kg/h
• give fluid challenge , e.g. 500ml 0.9% saline over 1 hour
• recheck urine output
• if not catheterised, exclude retention
• if catheterised ensure catheter is not blocked

Question 24

What should you do for fluid balance in post operative

Answer 24

– check the operation notes for intraoperative losses, and ensure you chart and replace added losses from drains etc

Question 25

What should you do with shock for fluid balance

Answer 25

– resuscitate with colloid or 0.9% saline via large-bore cannulae; identify type of shock

Question 26

Where can potassium ions be given in fluid

Answer 26

Potassium ions can be given with 5% glucose or 0.9% saline, usually 20mmol/L or 40mmol/L

Question 27

What should you be aware of when giving potassium

Answer 27

• potassium may be retained in renal failure, so beware of giving too much IV

Question 28

When will you need to give increased potassium fluid loss

Answer 28

GI fluids are rich in K+ so increased fluid loss from the gut (eg diarrhoea, vomiting, high-output stoma, intestinal fistula) will need increased K+ replacement

Question 29

What is the max concentration of potassium that you can give

Answer 29

Max concentration of K+ that is safe to infuse via a peripheral line is 40mmol/L, at a max rate of 20mmol/h in a cardiac monitored patient

Question 30

What are the risks of potassium fluid

Answer 30

• Fluid-restricted patients may require higher concentrations or rates in life-threatening hypokalaemia

Faster rates risk cardiac arrhythmias and asystole
- Use ECG monitoring for rates >10mmol/h

Higher concentrations risk thrombophlebitis, depending on the size of the vein
- Give concentrated solutions >40mmol/L via central venous catheter