Colloids (Plasma Substitutes) -
Examples
- Gelatins
- Albumin
Colloids (Plasma Substitutes) -
Indications
- Colloids are used to expand circulating volume in states of impaired tissue perfusion (shock)
- In cirrhotic liver disease : albumin is used to prevent effective hypovolaemia in large-volume paracentesis (ascitic fluid drainage)
Colloids (Plasma Substitutes) -
MOA
- Intravenous (IV) colloid preparations contain comparatively large, osmotically active molecules, such as albumin or modified gelatin, in solution or suspension.
- In principle, these molecules cannot readily cross a semipermeable membrane (including vascular endothelium) and their osmotic effect ‘holds’ the infused volume in the intravascular compartment.
Colloids (Plasma Substitutes) -
Adverse Effects
- Oedema
- Pulmonary oedema : excessive plasma volume expansion —> increase left ventricular filling –> decrease cardiac output (startling cruve) –> PO
- Hypersensitivity reactions (anaphylaxis)
Colloids (Plasma Substitutes) -
Caution
1) Heart failure
2) Renal impairement
Colloids (Plasma Substitutes) -
Interactions
No clinically important interactions
Colloids (Plasma Substitutes) -
Monitoring
- Close monitoring of haemodynamic status
Colloids (Plasma Substitutes) -
Patient Education
- Used to improve BP
Crystalloid - examples
1) Hartmann’s Solution - Compound sodium lactate
2) Glucose - Dextrose
3) Sodium Chloride
Hartmann’s Solution - Indication
1) To provide sodium and water in patients unable to take enough orally.
2) To expand circulating volume in states of impaired tissue perfusion (including shock).
- This may be done as a ‘fluid challenge’, where a bolus of fluid (e.g. 500 mL) is infused rapidly.
Hartmann’s Solution - MOA
- Compound sodium lactate is a balanced crystalloid solution.
- Its electrolyte composition approximates serum: one litre contains Na+ 131 mmol, Cl– 111 mmol, K+ 5 mmol, Ca2+ 2 mmol and lactate 29 mmol.
- The infused lactate is readily metabolised, generating bicarbonate.
- This makes it a suitable choice for providing sodium and water in patients unable to take enough orally.
- As compound sodium lactate contains sodium in a concentration similar to extracellular fluid, the infused volume is largely retained in the extracellular water compartment.
- As intravascular water accounts for about 20% of extracellular water, about 20% of the infused volume will remain in vessels to expand circulating volume.
- This makes it a viable choice for use in fluid resuscitation.
- Its main advantage over sodium chloride 0.9% is its lower chloride content, making it less likely to cause hyperchloraemic acidosis.
Hartmann’s Solution - Adverse Effects
- Oedema : sodium diffusion into interstitium promotes oedema
- Pulmonary oedema
Hartmann’s Solution - Contraindications
- Severe liver disease : may not have enough capacity to metabolise lactate
Hartmann’s Solution - Caution
1) Heart Failure - due to risk of pulmonary oedema
2) Renal impairement
Hartmann’s Solution - Interactions
None
Hartmann’s Solution - Monitoring
- Haemodynamic status
- Fluid balance
Hartmann’s Solution - Patient Education
- Fluid is given because pt unable to take enough by mouth
- Drink more
Glucose - Indication
1) Glucose 5% = used to provide water in patients unable to take enough orally.
2) Glucose 10%, 20% and 50% = are used to treat hypoglycaemia when this is severe or cannot be treated orally.
- -> Glucagon is an alternative.
3) Glucose 10%, 20% and 50% = used with insulin to treat hyperkalaemia.
- -> Calcium gluconate may also be given in this setting (to stabilise the myocardium).
4) Glucose 5% = used for reconstitution and dilution of drugs intended for administration by injection or infusion.
- -> Sodium chloride 0.9% and sterile water are alternatives
Glucose - MOA
- Glucose (C6H12O6) is a monosaccharide that is the principal source of energy for cellular metabolism.
- It exists in several isomeric configurations: D-glucose (dextrose) is most relevant in mammalian biology.
- Glucose 5% solution is primarily a means of providing water.
- The glucose content ensures it is initially isotonic with serum, so that it does not induce osmotic lysis of red cells on initial mixing with blood.
- Glucose is rapidly taken up by cells and metabolised, leaving ‘free’ (hypotonic) water that distributes across all body water compartments.
- Higher-concentration glucose solutions are used to treat hypoglycaemia; the mechanism for this is self-explanatory.
- In hyperkalaemia, soluble insulin is given to stimulate Na+/K+-ATPase and shift potassium into cells.
- In this context, glucose is given to prevent hypoglycaemia.
- As less than 10% of an infused glucose solution remains in the intravascular space, it not used to expand circulating volume
Glucose - Adverse Effects
- Glucose 50% = irritant to veins
- Hyperglycaemia
Glucose - Interactions
Glucose + Insulin have antagonistic effects
Glucose - Monitoring
- Fluid balance : input + output
- Plasma electrolytes : serum glucose and potassium conc
Glucose - Monitoring
- Fluid balance : input + output
- Plasma electrolytes : serum glucose and potassium conc
Sodium Chloride - Indications
1) Sodium chloride 0.9% and 0.45% = used to provide sodium and water in patients unable to take enough orally.
2) Sodium chloride 0.9% = used to expand circulating volume in states of impaired tissue perfusion (including shock).
- -> Compound sodium lactate and colloids are alternatives.
3) Sodium chloride 0.9% = used for reconstitution and dilution of drugs intended for administration by injection or infusion.
- -> Glucose solutions and sterile water are alternatives.
