Fluid Management Flashcards
What are the fluid compartments of the body?
- 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
Explain input and output in the body
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
Explain the daily requirements of fluids
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
What are the types of fluid?
-
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
How to assess fluid status?
- Clinical Assessment
- Daily input/output chart
- Daily weights
- Urea and Electrolytes
- Na+
- K+
- Cl-
- Urea
- Creatinine
Explain fluid depletion and fluid overload signs
What are the types of shock?
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
Fluid management in surgery
- 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
Explain fluid prescribing
- 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?
Explain fluid resuscitation
- 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
Explain maintenance fluids
- 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
What are the bags of fluid?
- 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+