Usage
Hydroxyethyl starch (HES) + Sodium Chloride is prescribed for the treatment and prophylaxis of hypovolemia (low blood volume). It is a plasma volume substitute, meaning it increases the volume of circulating blood. It belongs to the pharmacological class of plasma volume expanders or colloids. Its mechanism of action involves increasing the osmotic pressure within the blood vessels, drawing fluid from the interstitial space into the bloodstream. It is not a substitute for red blood cells or coagulation factors.
Alternate Names
HES is sometimes referred to as hydroxyethyl starch 130/0.4 depending on its molecular weight and molar substitution properties. Some popular brand names include Voluven, Volulyte, and Hespan.
How It Works
Pharmacodynamics: HES exerts its effects by increasing the colloid osmotic pressure (COP) of the blood plasma. This increased COP draws fluid from the interstitial spaces back into the intravascular compartment, resulting in plasma volume expansion that lasts for several hours. It does not have any intrinsic vasoactive properties or direct effects on cardiac function.
Pharmacokinetics: HES is administered intravenously. It is distributed primarily within the intravascular space. The metabolism of HES is limited, with the majority of the administered dose excreted unchanged in the urine via glomerular filtration. A small portion may be taken up by the reticuloendothelial system (RES) in organs like the liver and spleen, where it is slowly metabolized by α-amylase. Elimination pathways include renal (glomerular filtration) and hepatic (RES uptake and metabolism). It does not cross the blood-brain barrier. The rate of elimination depends on factors like the molecular weight and molar substitution ratio of HES, as well as patient-specific factors like renal function.
Mode of Action: HES acts by directly increasing the number of osmotically active particles within the bloodstream. HES molecules do not bind to specific cellular receptors or inhibit specific enzymes. Their action is based purely on the principles of colloid osmotic pressure and fluid shifts.
Dosage
Standard Dosage
Adults:
Up to 50 mL/kg of body weight per day, administered via intravenous infusion. The initial 10-20 mL should be infused slowly. As a reference, this equals 3500 mL for a 70 kg patient.
Children:
Dosing should be individualized according to the patient’s fluid needs. Limited data is available for children.
- < 2 years: Mean dose of 16 ± 9 mL/kg body weight/day (up to 50 mL/kg/day).
- 2-12 years: Mean dose of 36 ± 11 mL/kg body weight/day (up to 50 mL/kg/day).
- > 12 years: Same as adult dose (up to 50 mL/kg body weight/day).
Special Cases:
- Elderly Patients: Dose adjustment may be necessary depending on underlying comorbidities and organ function. Consider starting with a lower dose.
- Patients with Renal Impairment: Avoid use in patients with pre-existing renal dysfunction. Monitor renal function closely and discontinue at the first sign of renal injury.
- Patients with Hepatic Dysfunction: Use with caution as liver dysfunction may affect HES metabolism. Monitor liver function.
- Patients with Comorbid Conditions: Dose adjustments may be needed in patients with cardiovascular disease and other conditions.
Clinical Use Cases
Dosage is determined based on the patient’s specific needs and clinical status. It is difficult to provide specific guidelines for each scenario, as fluid resuscitation should be targeted to the clinical picture and overall fluid management strategy.
- Intubation: HES may be utilized for volume resuscitation in cases of hypovolemia.
- Surgical Procedures: HES may be utilized intraoperatively to maintain normovolemia and hemodynamic stability during surgeries associated with significant fluid loss.
- Mechanical Ventilation: HES is not specifically indicated for patients on mechanical ventilation unless hypovolemia is present.
- Intensive Care Unit (ICU) Use: Avoid use in critically ill adult patients, including patients with sepsis, due to increased risk of mortality and renal replacement therapy (RRT).
- Emergency Situations: HES can be used for fluid resuscitation but caution should be exercised due to the increased risk of renal issues.
Dosage Adjustments:
Adjustments may be required based on the patient’s fluid balance, hemodynamic status, and renal and hepatic function. It is important to avoid fluid overload.
Side Effects
Common Side Effects:
- Pruritus (itching)
- Elevated serum amylase (may interfere with pancreatitis diagnosis)
- Hemodilution (dilution of blood components)
Rare but Serious Side Effects:
- Anaphylactoid/hypersensitivity reactions (e.g., bronchospasm, hypotension)
- Kidney injury
- Coagulopathy (bleeding disorders)
- Fluid overload
Long-Term Effects:
- Long-term effects are generally related to cumulative doses and prolonged use, especially in patients with renal impairment. Increased risk of renal injury may persist for months after administration.
Adverse Drug Reactions (ADR):
- Severe anaphylaxis/anaphylactoid reactions
- Renal failure
- Severe coagulopathy
Contraindications
- Critically ill adult patients, including sepsis
- Severe liver disease
- Known hypersensitivity to hydroxyethyl starch
- Fluid overload (e.g., pulmonary edema, congestive heart failure)
- Pre-existing bleeding disorders
- Renal failure with oliguria or anuria not related to hypovolemia
- Patients receiving dialysis treatment
- Severe hypernatremia or hyperchloremia
- Intracranial bleeding
Drug Interactions
Limited drug interactions have been documented; however, caution is advised when using with drugs affecting coagulation as HES can exacerbate bleeding. The compatibility of HES when mixed with other medications in the same intravenous line should be checked before administering.
Pregnancy and Breastfeeding
- Pregnancy: Pregnancy Category C. HES has shown adverse effects in animal studies. Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: It is unknown whether HES is excreted in human milk. Use with caution in breastfeeding mothers.
Drug Profile Summary
- Mechanism of Action: Plasma volume expansion by increasing colloid osmotic pressure.
- Side Effects: Pruritus, elevated serum amylase, hemodilution, anaphylactoid reactions, kidney injury, coagulopathy, fluid overload.
- Contraindications: Critically ill patients, severe liver disease, hypersensitivity to HES, fluid overload, bleeding disorders, renal impairment, patients on dialysis, severe electrolyte imbalances, intracranial bleeding.
- Drug Interactions: Caution with drugs affecting coagulation. Check compatibility before mixing with other medications in IV lines.
- Pregnancy & Breastfeeding: Pregnancy Category C; use with caution in breastfeeding.
- Dosage: Adults: Up to 50 mL/kg/day IV. Children: Dose based on fluid needs (see detailed section).
- Monitoring Parameters: Blood pressure, heart rate, fluid balance, renal function, coagulation parameters, serum electrolytes.
Popular Combinations
HES is typically used alone for volume expansion. It may be administered concomitantly with crystalloid solutions as part of a comprehensive fluid management strategy, particularly in cases of dehydration where a crystalloid is typically administered first.
Precautions
- General Precautions: Monitor fluid balance, serum electrolytes, renal function, coagulation status. Infuse slowly initially to observe for potential hypersensitivity reactions.
- Specific Populations: See “Dosage - Special Cases.”
- Lifestyle Considerations: No specific lifestyle considerations.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Hydroxyethyl Starch + Sodium Chloride?
A: The adult dose is up to 50 mL/kg/day IV. Pediatric dosing is individualized based on the child’s clinical condition and fluid needs (see detailed dosage section).
Q2: What is the mechanism of action of HES?
A: HES expands plasma volume by increasing the colloid osmotic pressure of the blood, drawing fluid into the intravascular space.
Q3: What are the major contraindications for HES use?
A: Contraindications include critically ill patients (especially sepsis), severe liver disease, hypersensitivity to HES, fluid overload, renal impairment, bleeding disorders, and pregnancy (except when the benefit outweighs the risk).
Q4: What are the common side effects of HES?
A: Common side effects include pruritus (itching), elevated serum amylase, and hemodilution.
Q5: Can HES be used in patients with renal impairment?
A: HES should be avoided in patients with pre-existing renal dysfunction due to the increased risk of further renal injury. Close monitoring of renal function is essential if used in these patients.
Q6: Is HES compatible with all intravenous medications?
A: HES compatibility with other intravenous medications should be checked before co-administration. Some medications are incompatible and should not be mixed.
Q7: Can HES be used during pregnancy?
A: HES is Pregnancy Category C. It should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.
Q8: How should anaphylactoid reactions to HES be managed?
A: Immediately discontinue HES infusion if signs of hypersensitivity appear. Supportive care such as oxygen, intravenous fluids, and medications like antihistamines, corticosteroids, and epinephrine should be administered as needed.
Q9: How is HES eliminated from the body?
A: Primarily via renal excretion. A small portion is metabolized by the reticuloendothelial system, mainly in the liver.
