11 - Fluid Replacement Therapy Flashcards
What percentage of body weight is water in the following:
- Males
- Females
- Infants
- Elderly
- Males = 60%
- Females = 50-55%
- Infants = 73%
- Elderly = 45-50%
What is the major anion in ECF and ICF?
- Phosphate in ICF
- Cl- in ECF
How much water is in each body compartment in a 70kg man?
What happens to cells in hypernatremia and hyponatremia?
The sodium only shifts between interstitial and intervascular so it is water that moves to correct this
What happens if you give someone 1L of 5% Dextrose?
- If low b.p don’t give this as won’t raise intravascular very much
- Glucose can be taken up along all compartments
What happens if you give someone 1L of 0.9% saline?
Give if someone has low b.p as saline stays in ECF
What happens if you give someone 1L of Hartman’s solution??
Why would you give Hartman’s over saline?
- Less Na and Cl
- Lactate to get HCO3-
- Used to mirror blood more
What are the contents of Hartmann’s?
Why would you give someone dextrose saline over dextrose?
- Dextrose saline used to replace water losses
- Dextrose and saline can just be maintenance fluids if can’t take orally
What would happen if you gave someone 1L of 4% dextrose, 0.18% saline?
Why is glucose fluids isoosmotic but not isotonic?
- Isoosmotic as glucose metabolised quickly to water and CO2 so no change in osmoles but more water in cell changes tonicity
- Tonicity is what the solution will do to the cells
Why may patients need IV fluids?
What are some factors you need to think about when giving patients maintenance fluids?
- Maintenance fluids fill daily requirement and replace any losses, e.g from vomiting, but factors can change requirements
- Easy to cause fluid overload
How much water, sodium, potassium, chloride and glucose is needed for maintenance and what are some processes that can change this maintenance requirement?
- Diarrhoea
- Vomiting
- Sweaing
- Urine
- Bile and pancreatic drainage loss
If someone with insulin-dependent diabetes presents with needed IV fluids what should you ensure?
- They always have a constant fluid with glucose in
- If not insulin dependent don’t have glucose in fluids unless it is low
What are some important things you need to consider when prescribing patients with fluids?
- Do I need to do anything to stop losses, e.g antiemetic?
- Max KCl in 1 hour is 10mmol
- Consider size and age of patient
- Have they lost electrolytes or just fluid?
What are the contents of the following solutions and what is their tonicity?
* Solutions are made with differing amounts of potassium in them and usually more appropriate for maintenance needs
Complete the following table.
What do isotonic fluids do to blood volume?
Don’t raise it by much just adds mainly to ICF. If want to raise blood volume by 1l would need 4l fluid. Hypotonic solutions better for raising blood volume
What is colloid?
IV fluid that has oncotic pressure due to the presence of large molecules. Will draw water from ICF and ECF as molecules cannot leave blood
How do you work out the net filtration rate at the arterial end of this capillary?
How does cancer and radiation lead to oedema?
Radiation can cause inflammation and blockage of lymph vessels, as well as cancer, so less interstitial fluid can be reabsorbed into the lymphatics like normal
Complete the following table.
All 4kg lost is purely fluid
What pathology do you suspect in this woman, and explain how this conditions leads to all of the signs and symptoms she is experiencing?
- Addision’s disease (autoimmune low cortisol)
- Hyperpigmentation due to breakdown of POMC to make ACTH, releasing a-MSH which hyperpigments and lowers appetite
- Adrenal glands attacked so also low aldosterone which explains low sodium and high potassium
In Addison’s disease, what will you expect the acid-base balance of the blood to be and why?
- Acidic
- Hyperkalemia drives H+ out of cells and K+ in
How can thiazides lead to hypokalaemia?
- Inhibit NaCl symporter
- ENaC increased activity so Na/K pump has to work harder meaning more potassium is lost
