Fluid Management

Question 1

What are the fluid compartments of the body?

Answer 1

• Roughly 2/3 body weight is made up of water
• Of this 2/3 is found within cells
• 80% of the remaining third is found in interstitial fluid
• Only 20% is in plasma

Question 2

Explain input and output in the body

Answer 2

Input

• Only 60% fluid intake is from enteral fluids
• The rest is from food and metabolism

Output

• Fluid loss from non-urine sources are called Insensible Losses
• In unwell patients insensible losses will increase

Question 3

Explain the daily requirements of fluids

Answer 3

Average Daily Requirements in Health (NICE Guidelines)

• Water
  
  • 25-30ml/kg per day
• Glucose
  
  • 50-100 grams per day
• Potassium
  
  • 1mmol/kg per day
• Sodium
  
  • 1mmol/kg per day
• Chloride
  
  • 1mmol/kg per day

Question 4

What are the types of fluid?

Answer 4

• Crystalloid – Normal saline, glucose, hartmann’s
  
  • Contains simple ionic/crystalline molecules
  • Can easily pass across semi permeable membrane
  • Water follows by osmosis
• Colloid – Blood products, Human Albumin Solution
  
  • Contains larger molecules e.g. proteins
  • Unable to pass across semi-permeable membrane
  • Can increase oncotic pressure

Question 5

How to assess fluid status?

Answer 5

• Clinical Assessment
• Daily input/output chart
• Daily weights
• Urea and Electrolytes
  
  • Na+
  • K+
  • Cl-
  • Urea
  • Creatinine

Question 6

Explain fluid depletion and fluid overload signs

Answer 6

Question 7

What are the types of shock?

Answer 7

Shock = low BP

• Hypovolaemic
  
  • Low blood volume
• Distributive
  
  • Sepsis
  • Anaphylaxis
• Cardiogenic
  
  • Heart cant pump properly
• Obstructive
  
  • PE

more info

Hypovolaemic – loss of blood or fluid

Distributive – fluid in wrong place I.e. anaphylaxis, sepsis, third space losses

Cardiogenic – related to heart pumping

Obstructive – obstruction in heart or great vessels e.g. pe

Question 8

Fluid management in surgery

Answer 8

• Patients are often NBM prior to surgery and require appropriate maintenance fluids
• Intra-operative loss e.g. blood
• Increased GI losses – these losses are often high in potassium
• Sepsis

Question 9

Explain fluid prescribing

Answer 9

• What is the goal of fluid prescribing
• Resuscitation
• Bolus needed urgently
• Maintenance
  
  • To maintain if e.g. nil by mouth
• Replacement
  
  • Loss of fluids and needs to be replaced
• Weight and Size of patient?
  
  • Older smaller patient needs less
• Co-morbidities?
  
  • E.g heart failure
• Clinical context?

Question 10

Explain fluid resuscitation

Answer 10

• If patients are shocked and hypotensive there is poor perfusion of tissues
• This can lead to ischaemia and organ failure
• The aim of resuscitation fluids is to restore intravascular volume
• Usually use Crystalloid fluid e.g. 0.9% Sodium Chloride, Hartmann’s Solution
• In usually healthy patients - 500mls STAT
  
  • In heart failure, elderly or frail consider giving 250mls

Question 11

Explain maintenance fluids

Answer 11

• If patient is euvolaemic we can calculate maintenance fluids aiming for the average requirements over 24 hours.
• Regimes will never provide exactly the right amount of electrolytes

EXAMPLE

EXAMPLE - 70kg person

Bag 1:

500mL of 0.9% saline with 20mmol/L K+ over 8 hours

All of Na+, ~1/3rd of K+, and 1/4 of water

Bag 2:

1L of 5% dextrose with 20mmol/L K+ over 8 hours

1/3 of K+, 1/2 of their water and glucose

Bag 3:

500mL of 5% dextrose with 20mmol/L K+ over 8 hours

Remaining 1/3 of K+, 1/4 of water and glucose

Question 12

What are the bags of fluid?

Answer 12

• Hartmann’s
• 0.9% NaCl
• 5% Dextrose

Bags come in:

• 250mls
• 500mls
• 1000mls

K+ can be added into:

• 0.9% NaCl
• 5% Dextrose

as 20mmol or 40mmmol of K+