How to mix vasopressin in a 50ml infusion pump?

How to Mix Vasopressin in a 50ml Infusion Pump

To prepare vasopressin for a 50ml infusion pump, dilute vasopressin by adding 20 units (1ml of 20 units/ml concentration) to 49ml of normal saline (0.9% sodium chloride) or D5W to create a final concentration of 0.4 units/ml.

Preparation Instructions

Materials Needed:

• Vasopressin 20 units/ml vial
• 50ml infusion pump/syringe
• 49ml of diluent (normal saline 0.9% or D5W)
• Sterile syringe and needle for drawing up vasopressin

Step-by-Step Mixing Process:

1. Draw up 1ml (20 units) of vasopressin from the 20 units/ml vial
2. Add this to the infusion pump containing 49ml of normal saline or D5W
3. Mix thoroughly to ensure uniform distribution
4. Label the infusion with:
   • Medication name and concentration (Vasopressin 0.4 units/ml)
   • Date and time of preparation
   • Expiration time (18 hours at room temperature or 24 hours if refrigerated) 1
   • Patient name and ID

Administration Guidelines

Dosing by Clinical Indication:

• Post-cardiotomy shock: 0.03 to 0.1 units/minute 1
• Septic shock: 0.01 to 0.07 units/minute 1
• Vasodilatory shock: Starting at 0.01-0.04 units/minute 2

Infusion Rate Calculation:

With a concentration of 0.4 units/ml:

• 0.01 units/min = 1.5 ml/hr
• 0.03 units/min = 4.5 ml/hr
• 0.07 units/min = 10.5 ml/hr
• 0.1 units/min = 15 ml/hr

Important Clinical Considerations

Monitoring Requirements:

• Continuous blood pressure monitoring (preferably via arterial line)
• Heart rate and cardiac rhythm
• Urine output
• Peripheral perfusion (check extremities for signs of ischemia)
• Serum electrolytes, particularly sodium

Potential Adverse Effects:

• Decreased cardiac output
• Bradycardia or tachyarrhythmias
• Hyponatremia
• Tissue ischemia (coronary, mesenteric, skin, digital) 1

Special Precautions:

• Discard unused diluted solution after 18 hours at room temperature or 24 hours if refrigerated 1
• When transitioning between infusions, use the "piggyback" technique to avoid interruptions in therapy that could cause hemodynamic instability 3
• For patients on beta-blockers who remain hypotensive, consider adding glucagon (1-2 mg) 4

Clinical Pearls

• Vasopressin is typically added as a second agent when norepinephrine requirements are escalating, not as a first-line vasopressor 5
• Fixed dosing (not weight-based) is typically used for vasopressin, with a maximum recommended dose of 0.03 units/minute 5
• Avoid bolus administration of vasopressin for shock states, as this may cause severe hypertension and adverse effects (unlike the bolus dosing used in cardiac arrest scenarios)
• Monitor for digital ischemia, which can be an early sign of vasopressin-related adverse effects

By following these specific mixing and administration guidelines, you can ensure safe and effective use of vasopressin in the critical care setting.