Intravenous fluids

Question 1

Questions to ask before prescribing fluid.

Answer 1

1. Is patient euvolaemic, hypovolaemic or hyervolaemic?
2. Does the patient need IV fluid?
3. How much?
4. Which fluid? Maintenance, Replacement, Resuscitation

Question 2

Euvolaemic Presentation

Answer 2

Veins are well filled, extremities are warm, BP and heart rate are normal (depending on other pathology).

Question 3

Hypovolaemic Presentation

Answer 3

Patient may have:

• flat veins
• cool peripheries
• hypotension
• tachycardia
• tachypnoea
• oliguria
• confusion

History of fluid loss or low intake. May respond to 45˚ passive leg raise. However signs of hypovolaemia may be unreliable in elderly patients.

Question 4

Hypervolaemic Presentation

Answer 4

Patient is oedematous, may have inspiratory crackles, high JVP and history/charts showing fluid overload.

Question 5

Does patient need IV fluid?

Answer 5

Allow patients to eat and drink if possible. Only give IV fluid if not drinking or is losing fluid.

Question 6

Why does the patient need IV fluid?

Answer 6

• maintainance
• replacement of losses
• resuscitation

Question 7

When would maintained fluid alone be given?

Answer 7

• Patient does not have excess losses above insensible loss/urine.
• If no other intake, needs approximately 30ml/kg/24hrs.
• May only need part of this if receiving other fluid.
• Patients having to fast for over 6 hours for any reason should be started on IV maintenance fluid.

Question 8

When would replacement fluid be given?

Answer 8

• Replacement of fluid either previous or current.
• If losses are likely, it is best to replace these later rather than give extra fluid in anticipation of losses which may not occur.
• This fluid is in addition to maintenance fluid.

Question 9

When should resuscitation fluid be given?

Answer 9

The patient is hypovolaemic as a result of dehydration, blood loss or sepsis and requires urgent correction of intravascular depletion to correct the deficit.

Question 10

How much fluid does the patient need?

Answer 10

• Obtain weight (30ml/kg/24 hours)
• Review U&Es, other electrolytes and Hb
• Review recent events e.g. fasting, sepsis, operations, fluid losses.

Question 11

Which patients may need to be given a lower volume of IV fluids?

Answer 11

• frail elderly
• patients with renal impairment
• cardiac failure
• patients who are malnourished

Question 12

How should maintainance fluid be given?

Answer 12

Via a volumetric pump

Question 13

What solution should be given for maintainance?

Answer 13

• 0.18%NaCl/4%Glucose with 40mmol/l KCl if normal or low K+
• This fluid provides all water and Na+/K+ requirements until the patient can eat and drink or be fed.
• Excess volumes of this fluid (or any fluid) may cause hyponatraemia.

Question 14

What are the exceptions for maintainance solutions?

Answer 14

• If serum Na+ is ≤132mmol/l use PL148 for maintenance.
• If serum K+ is ≥ 5 mmol/l or rising quickly do not give extra K+.
• Diabetes: use 0.18%NaCl/4%Glucose/40mmol/lKCl with intravenous insulin at maintenance rates according to weight.

Question 15

Electrolyte requirements

Answer 15

• Sodium 1 mmol/kg/24hrs
• Potassium 1 mmol/kg/24hrs (give 40mmol/l KCl)
• Calories: 50-100g glucose/24hrs to prevent starvation ketosis.
• Magnesium, calcium and phosphate may fall in sick patients – monitor and replace as required.

Question 16

What solution should be given for replacement?

Answer 16

• Estimate replacement fluid/electrolyte requirements by adding up all the losses over the previous 24 hours and give this volume as Plasmalyte 148 (PL148).
• Use 0.9%NaCl with KCl for upper GI loss only.
• Remember this is in addition to maintenance fluid.

Question 17

What solution should be given for resuscitation?

Answer 17

For urgent resuscitation use Plasmalyte 148 (PL148) or a gelatin based colloid.