Anaesthetics- Use of IV fluids Flashcards
What percent of the body is total body water?
60%
What is total body water (TBW) divided into?
- Intracellular fluid
* Extracellular fluid
How much of TBW does intracellular fluid make up?
40% body weight (28L)
How much of TBW does extracellular fluid make up?
20% body weight (14L)
What is extracellular fluid divided into
- Interstitial fluid (11L)
* Plasma (3L)
What is interstitial fluid?
Fluid in the spaces between cells
What is transcellular fluid?
Fluid that fills the cavities in the body e.g. aqueous humour in the eye
What is osmosis?
water moves from a dilute solution to a concentrated solution across a semi-permeable membrane
What is the role of osmotic pressure?
Stop osmosis occurring, by applying pressure to the concentrated solution
What does more particles in solution mean?
Higher the rate of osmosis therefore the higher the osmotic pressure
What does hypertonicity cause?
Cellular dehydration
What does hypotonicity cause?
Cell swelling
What are the symptoms of tonicity changes?
Neurological
What neurological symptoms does swelling of cells cause?
Raised icp
Compromised cbf
Herniation
What neurological symptoms does Shrinkage of cells cause?
Ich venous sinuous thrombosis
What are crystalloids?
Aqueous liquids that are soluble in water
What are some examples of crystalloids?
- 5% dextrose
- 0.9% saline
- Hartmann’s solution
What are the advantages of crystalloids?
- Cheap
* Non-allergenic
What are some disadvantages of crystalloids?
- Ecf expansion
* (oedema/increased vascular pressure)
What are colloids?
Aqueous liquids in insoluble in water
What are some examples of colloids?
- Gelatins
- Starches
- Dextrans
- Albumin
What are the disadvantages of colloids?
- Anaphylaxis
- Coagulopathy
- Renal failure
- rheology
What are sensible losses?
Things you can measure
What are examples of sensible losses?
Urine
Faeces
What are insensible losses?
Things you cant measure
What is an example of an insensible loss?
Sweat
What is the maximum maintenance fluid you should give someone?
!00ml/hr
Why should you not give someone more than 100ml/hr of maintenance fluid?
Risk of hyponatraemia
What do you need to subtract when giving someone maintenance fluid?
Other oral intake
How is IV maintenance fluid administered?
ml/hr via volumetric pump
How should you alter maintenance fluid in the elderly?
Reduce it
Which patients should be started on maintenance fluid immediately?
Patients fasting for ≥ 6hours
Before giving replacement fluid, what do you need to add up?
Losses in the last 24hrs e.g. bleeding, D & V, drain output, fistulae and give this volume back
Remember
What is replacement fluid given in addition to?
Maintenance fluids
What do you need to remember when giving replacement fluid?
- Urine output is a poor guide to fluid requirements
* Oliguria does not always require fluid therapy
What replacement fluid could you give?
• PlasmaLyte 148
What fluid would you give for upper GI losses?
0.9% NaCl with KCl
How is replacement fluid administered?
Gravity giving set or volumetric pump
What is resuscitation fluid used for?
For severe dehydration, sepsis or haemorrhage leading to hypovolaemia & hypotension
How much resuscitation fluid should you administer?
Give fluid challenge of 250-500ml over 5-15 mins and reassess
What fluid would you give as resuscitation fluid?
PlasmaLyte 148/colloid/blood
