Fluid prescribing

Question 1

When are fluids prescribed?

Answer 1

1. As replacement fluids for a dehydrated/acutely unwell patient
2. As maintenance in a patient who is nil by mouth

Question 2

Which fluid should be prescribed as replacement fluids?

Answer 2

1. Give all patients 0/9% saline (a crystalloid) unless the patient:
   
   1. Is hypernatraemic or hypoglycaemic - give 5% dextrose instead
   2. Has ascites: give human-albumin solution (HAS) instead. The albumin mantains oncotic pressure; furthermore, the higher sodium content of 0.9% saline will worsen ascites
   3. Is shocked with systolic BP<90mmHg: give gelofusine (a colloid) instead as it has a high osmotic content so stays intravascularly, thus mantainin ghte BP for longer
   4. Is shocked from bleeding: give blood transfusion, but a colloid first if no blood available.

Question 3

How much fluid and at what rate should replacement fluid be given?

Answer 3

Assess HR, BP and urine output.

• If tachycardic or hypotensive - 500ml bolus STAT (250ml if HF0 then reasses patient, especially HR, BP and urine output to assess response and need for next bag
• If only oliguric (and not due to urinary obstruction e.g. enlarged prostate) then giver 1L over 2-4hour then reassess patient
• Never prescribe more than 2L of IV fluid for a sick patient.

Question 4

What are the estimated fluid loss of adult patients based on their clinical presentation?

Answer 4

• Reduced urine output (oliguric if <30ml/h; anuric if 0ml/h) indicates 500ml of fluid depletion
• Reduced urine output + tachycardia indicates 1L of fluid depletion
• Reduced urine output + tachycardia + shocked indicates >2L of fluid dpeletion

Question 5

How much maintenance fluids are required by adults/elderly?

Answer 5

Adults require 3L IV fluids per 24 hours and elderly require 2L

This is given with adequate electrolyes by providing 1L of 0.9% saline and 2L of 5% dextrose (1 salty and 2 sweet)

Question 6

How much potassium do adults need?

Answer 6

You can add 40mmol KCL per day so 20mmol KCL in two bags added to 0.9% saline or 5% dextrose bags

IV potassium should not be given at more than 20mmol/hour

Question 7

How fast should we be giving maintenance fluids?

Answer 7

If giving 3L per day = 24h/3x1L bags - 8 hourly bags

If giving 2L per day = 24h/2x1L bags - 12 hourly bags

In real life - check patients U&E to confim what to give them, and that they are not fluid overloaded (e.g. increased JVP, peripheral and pulmonary oedema)

Ensure that the patients bladder is not palpable (signifying urinary obstruction) if giving replacement fluids becasue of ‘reduced urine outputs’