Intravenous fluids

Question 1

What intravenous fluid bags (crystalloids and colloids) are available for patients and what are their constituents>

Answer 1

Introductory
There is a wide range of IV fluids, both crystalloid and colloid, which are available for patient with the choice of type dependant on the indication for administration;
resus, 
maintenance
replacement

Question 2

IV fluids - Crystalloids

Answer 2

Crystalloids
Are fluids that contain mineral salts and other small water soluble molecules in solution with water. Can be hypo, iso, or hypertonic preparations.

Most common is Normal saline, 0/9% NaCl. is commonly utilised in resus, for replacement, and as maintenance fluid. is most commonly used. this fluid is ISOTONIC
o can lead to acidosis with too much NS fluid replacement, therefore utilise Hartmans in alternation

Hartmans: Contains predominantly Na and Cl, with some potassium, lactate, calcium, and a small amount of magnesium. Also utilised in maintenance, resus, and would crystalloid of choice for replacement in the setting of vomiting. this fluid is ISOTONIC

Other crystalloids include NS + 5% dextrose, predominantly utilised in diabetes resus, 0.45% NS used in hypernatraemia, and hypertonic saline (3% NaCl) used in hyponatraemia/ cerebral oedema. Only administered with senior guidance/assistance.

Only need consent for albumin infusion (blood product) or iron infusion (due to risk of iron staining)

Potassium

• Require 1 mol/kg/day
• safe max rate of infusion; 10mmol/hour (higher is risk of cardiac arrhythmias)
• minibus are 10mmol, so can give 1 minibag per hour

Maintenance
- Require ~ 1.5L of maintenance fluids per day (70kg)

Question 3

IV fluids - Colloids

Answer 3

Colloids
Is a synthetic or natural solution with high molecular weight molecules which maintain a high oncotic pressure.

• 4.5 % albumin - isotonic, used in hypoalbuinaemia, albumin losing enteropathy
• Conc albumin (20%). Is hypertonic, utilised for depleted patients and fluid restricted.
• Mannitol - utilised in cerebral oedema, especially for paeds (DKA, etc)
• Haemocel/plasmalyte: colloids that are utilised for volume replacement