What is the maximum dose of vasopressin in cubic centimeters per hour (cc/hr)?

Maximum Vasopressin Dosage in cc/hr

The maximum dose of vasopressin is 0.1 units/minute (6 units/hour) for post-cardiotomy shock and 0.07 units/minute (4.2 units/hour) for septic shock, which would need to be converted to cc/hr based on the specific concentration of the prepared solution. 1

Vasopressin Dosing Guidelines

Standard Dosing

• Initial dosing:
  • Post-cardiotomy shock: 0.03 units/minute 1
  • Septic shock: 0.01 units/minute 1
• Titration: Increase by 0.005 units/minute at 10-15 minute intervals until target blood pressure is reached 1
• Maximum doses:
  • Post-cardiotomy shock: 0.1 units/minute 1
  • Septic shock: 0.07 units/minute 1
  • Vasodilatory shock: 0.03-0.04 units/minute 2

Preparation and Administration

Vasopressin must be diluted in normal saline (0.9% sodium chloride) or 5% dextrose in water (D5W) prior to intravenous administration 1. The FDA-approved labeling indicates that unused diluted solution should be discarded after 18 hours at room temperature or 24 hours under refrigeration 1.

To calculate the actual cc/hr rate:

1. Determine the concentration of your diluted vasopressin solution
2. Apply the formula: cc/hr = (units/minute × 60) ÷ concentration (units/mL)

For example, if using a standard concentration of 1 unit/mL:

• Maximum for post-cardiotomy shock: 0.1 units/min × 60 min = 6 units/hr = 6 cc/hr
• Maximum for septic shock: 0.07 units/min × 60 min = 4.2 units/hr = 4.2 cc/hr

Clinical Considerations

Weaning Protocol

After target blood pressure has been maintained for 8 hours without catecholamines, vasopressin should be tapered by 0.005 units/minute every hour as tolerated to maintain target blood pressure 1.

Safety Concerns

• Adverse reactions increase with higher doses 1
• Common adverse reactions include decreased cardiac output, bradycardia, tachyarrhythmias, hyponatremia, and ischemia (coronary, mesenteric, skin, digital) 2
• Higher doses than those recommended are associated with increased risk of adverse effects and are not supported by clinical evidence 2, 1

Special Situations

• In variceal hemorrhage, vasopressin can be administered at a continuous IV infusion of 0.2-0.4 units/minute, which can be increased to a maximal dose of 0.8 units/minute, but only for a maximum of 24 hours due to significant side effects 3
• Vasopressin should always be accompanied by IV nitroglycerin when used for variceal hemorrhage 3

Practical Application

• Use the lowest dose compatible with a clinically acceptable response 1
• Monitor for end-organ perfusion during vasopressin therapy 2
• Consider that the norepinephrine dose at baseline may predict response to vasopressin, with doses >0.38 mcg/kg/min associated with improved microcirculation when vasopressin is added 4
• Continuous arterial blood pressure monitoring is recommended for patients receiving vasopressors 2

Remember that vasopressin is typically used as an adjunct to norepinephrine in shock states rather than as a first-line agent 2, 5.