Colloids serve as plasma substitutes, primarily utilized for the short-term replacement of fluid volume while addressing the underlying cause, such as hemorrhage control. They are effective in replacing blood loss at a 1:1 ratio or restoring intravascular volume, especially useful when fluid replacement needs surpass 3-4 liters. The high-molecular-weight substances within colloids contribute to plasma colloid oncotic pressure activity, aiding in retaining these solutions within the vasculature by drawing fluid from interstitial and extracellular spaces. Colloids can rapidly correct severe intravascular fluid deficits but come with notable costs and potential complications, including fluid overload, dilution of red cells and coagulation factors, and risk of anaphylactoid and anaphylactic reactions.
Blood-derived Colloids
Albumin: With a half-life of 10-15 days, albumin solutions come in 5% isotonic and 20% or 25% hypertonic concentrations. The 25% solution is specifically used for hypoalbuminemia. Risks include anaphylaxis and pulmonary edema.
Plasma Protein Fraction (PPF): PPF has a 3-4.5 days half-life, derived from human blood, and is similar to human plasma. It's indicated for injuries predominantly involving plasma fluid loss rather than red cells. Contraindications include severe anemia, CHF, or increased blood volume, with potential for hypotension due to anaphylaxis and the risk of containing infectious agents.
Synthetic Colloids
Dextran 40 or 70: These have a half-life of 6-8 hours, decrease blood viscosity, and improve circulation. However, they can decrease platelet adhesiveness, prolong bleeding time, affect von Willebrand's factor, and are associated with renal failure and anaphylactoid reactions. They are low-cost options.
Hetastarch (hydroxyethyl starch): Not recommended for patients with conditions such as bleeding disorders, CHF, renal failure, or lactic acidosis. Hetastarch has a half-life of 12-16 hours and serves as a plasma volume expander, containing electrolytes like sodium, calcium, potassium, and magnesium. Though less expensive than albumin, it can negatively impact coagulation and renal function but is associated with fewer anaphylactoid reactions. Recommended doses are smaller to minimize bleeding risks.
In summary, while colloids are invaluable for rapid volume restoration in critical situations, their use requires careful consideration of the patient's overall condition, potential risks, and specific contraindications to avoid adverse effects.
| Colloid | Half-life | Key considerations |
|---|---|---|
| Albumin | 10–15 days | 5% isotonic, 20% or 25% hypertonic; the 25% solution is for hypoalbuminemia; risks anaphylaxis and pulmonary edema |
| Plasma protein fraction | 3–4.5 days | For injuries losing plasma rather than red cells; contraindicated in severe anemia, CHF, or increased blood volume; hypotension from anaphylaxis, may carry infectious agents |
| Dextran 40 or 70 | 6–8 hours | Lowers blood viscosity and improves circulation; decreases platelet adhesiveness, prolongs bleeding time, affects von Willebrand's factor; renal failure and anaphylactoid reactions; low cost |
| Hetastarch | 12–16 hours | Plasma volume expander containing sodium, calcium, potassium, and magnesium; avoid in bleeding disorders, CHF, renal failure, or lactic acidosis; impairs coagulation and renal function but fewer anaphylactoid reactions; use smaller doses |
