Types of Fluids

Question 1

Isotonic Crystalloid Fluids

Answer 1

• Isotonic solutions have the same tonicity as the fluid in body cells
• Aim is to maintain or increase the volume of fluid in the intravascular space and interstitial compartments and restore ion imbalances
• Hartmanns, 0.9% Sodium Chloride and Plasmalyte 148

Question 2

Crystalloid Fluids

Answer 2

• Crystalloids contain solutes (electrolytes) that readily dissolve in water and have the potential to form crystals
• Crystalloid solutions travel easily through capillary walls from the intravascular space into the surrounding tissue

Question 3

Hypotonic Crystalloid Fluids

Answer 3

• 0.45% Sodium Chloride
• Lower osmotic pressure than fluid in the body cells, water leaves the solution to enter the cells
• Used as maintenance for patients likely to retain sodium due to cardiac or liver disease
• Contraindicated in acute renal failure or head trauma

Question 4

Hypertonic Crystalloid Fluids

Answer 4

• 3%/5%/7% Sodium Chloride, 20% Osmitrol, Mannitol
• Higher osmotic pressure that fluid in the body cells
• Promotes fluid retention and increases intravascular volume
• Can treat hypovolaemic shock
• Mannitol can reduce intracranial pressure
• Not for maintenance or with blood products and are rarely used

Question 5

Colloid Fluids

Answer 5

• Voluven, fresh frozen plasma, whole blood and packed red blood cells
• Contain proteins or other large solutes and cannot pass through semi-permeable membranes
• Prevent water moving out of the intravascular space
• More effective than isotonic crystalloids for rapidly increasing fluid volume in hypovolaemic patients