Revision - Fluid Therapy Flashcards
What is an isotonic solution?
IV fluids that have similar concentration of dissolved particles as blood.
E.g. 0.9% saline
What is a hypertonic solution?
Contain a higher concentration of solute compared to plasma and interstitial fluid; this creates an osmotic gradient and drives fluid FROM the interstitial space INTO the intravascular space.
E.g. 3% saline, mannitol
What is a hypotonic solution?
A solution with a lower concentration of electrolytes than body plasma.
E.g. 0.45% saline
Movement of fluid when giving a hypertonic solution?
Movement of fluid from interstitial space into the intravascular space.
Movement of fluid when giving a hypotonic solution?
Movement of fluid from intravascular space into the interstitial space.
Is 5% dextrose iso/hypo/hypertonic?
Hypotonic
Why should normal saline not be used as a lone fluid maintenance?
Can result in hyperchloraemic acidosis
What is the distribution of fluid intracellularly vs extracellularly?
Around 2/3 distributes in to the intracellular fluid and the remaining 1/3 distributes in to the extracellular fluid.
Of that fluid in the extracellular space, what is the distribution between intravascular and interstitium?
Of that fluid in the extracellular space, around 1/5th stays in the intravascular space and 4/5th of this is found in the interstitium, with a small proportion in the transcellular space.
If the aim is to fluid resus a patient, where is it important that fluids stay?
Within the intravascular space
What may leukonychia suggest about hydration status?
This is whitening of the nail bad associated with hypoalbuminaemia –> can result in significant third space fluid loss.
Causes of a narrow pulse pressure?
1) aortic stenosis
2) cardiac tamponade
3) cardiac failure
Causes of a wide pulse pressure?
1) aortic regurg
2) aortic dissection
3) Cushing’s reflex
Define a wide pulse pressure
more than 100 mmHg of difference between systolic and diastolic blood pressure
Define a narrow pulse pressure
less than 25 mmHg of difference between the systolic and diastolic blood pressure
What may more than 20mmHg difference in blood pressure between each arm indicate?
Aortic dissection
What does the JVP provide an indirect measure of?
Central venous pressure
What should the JVP be?
<3cm
Why should hypotonic (0.45% sodium chloride) fluids be avoided in paediatric patients?
They are at higher risk of risk of hyponatraemic encephalopathy.
What is the JVP an indirect measure of?
Pressure in the RA (and venous system).
I.e. higher pressure in RA = raised JVP
Is the internal or external jugular vein used for JVP assessment?
Internal
Why is the right IJV used for assessment of the JVP?
As this sits most directly above the RA (gives us best indication).
What does the IJV drain into?
SVC
Size of NPA for an average size male?
7mm