IV fluids

Question 1

What are the 4 questions we have to ask when prescribing fluid?

Answer 1

1) What is my patient’s fluid status?
2) Do they need IV fluid?
3) How much fluid?
4) What type of fluid?

Question 2

What do we look at when assessing fluid status?

Answer 2

• Airway e.g. on a ventilator
• Breathing (signs of pulm oedema)
• Circ (signs of fluid overload e.g. raised JVP)
• Disability
• Extremities (skin turgor, temp & mucous membranes)

Also vitals e.g. HR & BP

Urine

Sweat

Question 3

How do we recognise hypovolaemia?

Answer 3

• Thirsty
• Flat veins
• Cool peripheries
• Not sweating
• Low or postural BP (maybe dizzy)
• Tachycardic
• Concentrate oliguria

Question 4

What are the signs of hypervolaemia?

Answer 4

• Breathless
• Distended veins
• warm, oedematous extremeties
• Sweating
• High BP & HR
• Dilute polyuria

Question 5

Be aware”

Answer 5

A patient may have signs of hyper or hypovolaemia for a different reason
E.g. just because a patient has pulm oedema doesn’t mean they’re fluid overloaded
Also a euvolaemic or hypervolaemic patient could have cold fingers as well

Question 6

What are the different types of fluids in terms of purpose?

Answer 6

Resuscitative (very rapid bolus for shock patients)
Routine maintenance (Saline for patient’s who can’t drink)
Replacement (fluid tailored to replace electrolytes)

Question 7

How do we determine how much fluid they need?

Answer 7

Work out the water deficit from intake and output:

• Input chart
• Catheters & Drains
• Vomit bowels & sputum pots
• Stool charts & stoma losses
• Estimate insensible losses e.g. sweat, ventilation, wounds, burn an bleeding

Question 8

What are the different physical types of fluids?

Answer 8

Dextrose
Crystalloids e.g. normal saline or hartmann’s
Plasma expanders

Question 9

What is dextrose used for?

Answer 9

Chronically dehydrated (need fluid that moves into other compartments)
Hypernatraemic patients (can't have crystalloids)

Question 10

What are crystalloids used for?

Answer 10

Acute dehdyration, AKI & Resus.

It’s good for restoring fluid/blood volume because it remains in the ECF

Question 11

What do we use plasma expanders for?

Answer 11

Shown to be no better than crystalloids for resus but can be useful with blood for haemorrhage

Question 12

Difference between diffusion & osmosis?

Answer 12

Diffusion is when solute moves through a permeable membrane from high to low conc.

Osmosis is when water moves through a solute impermeable membrane from high to low conc

Question 13

Difference between osmolarity and osmolality?

Answer 13

Osmolarity = solute conc per unit volume of solvent

Osmolality = Solute conc per unit mass of solvent

Question 14

Difference between osmolarity and tonicity?

Answer 14

Osmolarity takes into account all solutes in the solvent including ones that can cross the membrane and so don’t apply osmotic pressure

Tonicity is only a measure of those solutes that can’t cross the SPM so exert osmotic pressure, ergo its a measure of osmotic pressure