Fluids

Question 1

What is Total Body Water as a percentage in Males and Females?

Answer 1

63% of Lean Body Weight in Men

52% of Lean Body Weight in Women

Question 2

In a 70kg man, how much is their Total Body Water?

Answer 2

45L

Question 3

How is total body water divided into extracellular/intracellular fluids?

Answer 3

Intracellular = 2/3
Extracellular = 1/3

Question 4

Under normal circumstances, what should daily fluid intake be?

Answer 4

2400ml - Drink 1500ml, Food 500ml, Metabolism 400ml

Question 5

Under normal circumstances, what should daily fluid output be?

Answer 5

2400ml - Urine 1500ml, Insensible Loss 900ml

Question 6

What are some symptoms of Volume Depletion?

Answer 6

Evidence of Fluid Loss
Thirst, Syncope, Reduced Urine Output
Resting Tachycardia
Postural Hypotension
Reduced JVP
Prolonged CRT
Dry Mouth
Increased Skin Turgor

Question 7

What are some symptoms of Volume Overload?

Answer 7

Background of relevant disease
Symptoms of volume excess
Peripheral/Sacral oedema
Increased JVP
Bibasal inspiratory crackles
Third Heart Sound

Question 8

Why is dextrose a poor choice of fluid for acute BP control?

Answer 8

The glucose is quickly metabolised leaving water, which distributes evenly across all compartments

Question 9

What are Colloids?

Answer 9

Fluids that contain large insoluble molecules

Question 10

Name an example of a Colloid

Answer 10

Albumin

Gelofusine

Question 11

What are Crystalloids?

Answer 11

Fluids with mineral salts or other water soluble molecules

Question 12

Name some Isotonic Crystalloid solutions

Answer 12

Saline - 0.9% NaCl

Hartmans - NaCl, KCl, CaCl

Question 13

Name a Hypotonic Crystalloid Solution

Answer 13

Dextrose 5%

Question 14

What is the 4-2-1 rule for maintenance fluid application?

Answer 14

4ml/kg/h for the first 10kg of lean body mass
2ml/kg/h for the second 10kg of lean body mass
1ml/kg/h for the remaining lean body mass

Question 15

Give some examples of when IV fluid prescription would be appropriate

Answer 15

Patient is NBM such as prior to surgery
Pt is vomiting or has severe diarrhoea
Pt is hypovolaemic as a result of blood loss

Question 16

What are the 5 ‘Rs’ of fluid prescription?

Answer 16

Resuscitation
Routine Maintenance
Replacement
Redistribution
Reassessment

Question 17

What are some reasons why fluid prescription is necessary?

Answer 17

Resuscitation
Maintenance
Replacement

Question 18

What are some important factors to consider before prescription of fluids?

Answer 18

Weight and size of patient
Co-morbidities, particularly HF/CKD
Reason for admission
Recent U&E

Question 19

Why do septic patients need significant volumes of fluid?

Answer 19

Sepsis leads to increased vascular permeability, meaning more vascular fluid enters tissues. Larger volumes must be given to maintain intra-vascular volume

Question 20

If patients clinically improve, what happens to their fluid excess?

Answer 20

They correct themselves by urinating out the excess fluid

Question 21

What are the daily electrolyte requirements?

Answer 21

Water - 25mL/kg
Na+ - 1mmol/kg
K+ - 1mmol/kg
Glucose - 50g

Question 22

What rule can be used to calculate hourly fluid requirements for anaesthatised patients?

Answer 22

4-2-1 rule

Question 23

What is the 4-2-1 rule?

Answer 23

For maintenance fluids, per hour a patient needs:

4ml/kg for the first 10kg of Lean Body Weight
2ml/kg for the next 10kg of Lean Body Weight
1ml/kg for the remainder of Lean Body Weight

Question 24

What are the hourly fluid requirements of a 70kg man while anaesthatised?

Answer 24

4ml * 10 = 40ml
2ml * 10 = 20ml
1ml * 50 = 50ml

Total = 40+20+50 = 110ml/h