Definition
Plasma Volume Expanders are fluids used to restore and maintain intravascular volume in patients experiencing hypovolemia (low blood volume), such as during shock, trauma, burns, or surgery.
They work by increasing osmotic pressure, which helps retain fluid within the vascular compartment.
Types of Plasma Volume Expanders:
Crystalloids:
Normal Saline (0.9% NaCl):
Composition: Sodium chloride.
Use: Volume replacement in hypovolemia, shock, resuscitation.
Advantages: Widely available, inexpensive.
Disadvantages: Can cause hyperchloremic metabolic acidosis with large volumes.
Lactated Ringer's Solution:
Composition: Sodium, chloride, potassium, calcium, and lactate.
Use: Similar to normal saline; preferred in surgery due to electrolyte composition.
Advantages: More physiologic electrolyte balance; buffer provided by lactate.
Disadvantages: Not suitable for patients with liver dysfunction (impaired lactate metabolism).
Dextrose Solutions (e.g., D5W):
Use: Maintenance fluids; not effective as volume expanders since dextrose is rapidly metabolized.
Advantages: Provides calories; used in combination with other fluids.
Disadvantages: Limited volume-expanding capability.
Colloids:
Albumin:
Mechanism: Natural protein that maintains oncotic pressure.
Use: Hypovolemia, burns, liver cirrhosis, nephrotic syndrome.
Advantages: Long intravascular persistence.
Disadvantages: Expensive; risk of allergic reactions.
Hydroxyethyl Starch (HES):
Use: Volume resuscitation in hypovolemia and shock.
Advantages: Effective plasma volume expansion.
Disadvantages: Risk of coagulopathy, renal impairment, allergic reactions
Dextrans:
Use: Volume expansion, prevention of surgical adhesions (historical use).
Advantages: Effective plasma volume expansion.
Disadvantages: Risk of anaphylaxis, coagulopathy, hyperglycemia.
Polygeline (Haemaccel):
Use: Volume replacement in hypovolemia.
Advantages: Effective volume expansion.
Disadvantages: Less commonly used due to availability of better alternatives; risk of allergic reactions.
Clinical Considerations:
Choice Between Crystalloids and Colloids: Dependent on clinical scenario, patient condition, and cost considerations. Current trends favor crystalloids due to safety profile.
Fluid Overload Risk: Especially with colloids; requires careful monitoring.
Electrolyte Balance: Crystalloids can affect electrolyte levels; selection based on patient needs is crucial.
Allergic Reactions: More common with certain colloids; premedication may be necessary.