What is the recommended dosage and administration of noradrenaline (norepinephrine) infusion for treating hypotension?

Norepinephrine (Noradrenaline) Infusion for Hypotension

The recommended dosage of norepinephrine for treating hypotension is an initial infusion of 8-12 mcg/minute, followed by maintenance doses of 2-4 mcg/minute, titrated to maintain a target mean arterial pressure (MAP) of 65 mmHg. 1

Preparation and Administration

Solution Preparation

• Add 4 mg (4 mL) of norepinephrine to 1,000 mL of 5% Dextrose Injection or sodium chloride solution containing 5% dextrose to produce a 4 mcg/mL dilution 1
• Dextrose reduces potency loss due to oxidation 1
• Visually inspect for particulate matter and discoloration (solution should be colorless) 1
• Store diluted solution for up to 24 hours at room temperature (20-25°C) and protect from light 1

Administration Route

• Infuse into a large vein, preferably using an 18-20G catheter 2
• Recommended sites include medium-to-large caliber veins such as the antecubital fossa or above, or the external jugular vein 2
• Avoid infusions into leg veins in elderly patients or those with occlusive vascular disease 1
• Verify blood return before starting the infusion 2

Dosing Protocol

Initial Dosing

• Start with 8-12 mcg/minute (0.1-0.5 mcg/kg/min) 2, 1
• Monitor blood pressure every 2 minutes until desired hemodynamic effect is achieved 1

Maintenance Dosing

• Typical maintenance dose: 2-4 mcg/minute 1
• Adjust every 10-15 minutes in increments of 0.05-0.2 mcg/kg/min 2
• Maximum dose: 0.1-0.5 mcg/kg/min or up to 20 μg/min 2
• Continue monitoring blood pressure every 5 minutes for the duration of infusion 1

Duration

• Maximum recommended duration is less than 24 hours (ideally less than 12 hours) 2
• When discontinuing, reduce the flow rate gradually to avoid abrupt withdrawal and resulting hypotension 1

Monitoring and Precautions

Required Monitoring

• Continuous electrocardiographic monitoring 2
• Frequent blood pressure measurements (every minute if continuous monitoring unavailable) 2
• Regular inspection of the infusion site 2

Important Precautions

• Correct hypovolemia before initiation - norepinephrine is relatively contraindicated in hypovolemic patients 2, 1
• If patient does not respond to therapy, suspect occult hypovolemia 1
• Avoid contact with iron salts, alkalis, or oxidizing agents 1
• Do not administer whole blood or plasma in the same IV line (administer separately if needed) 1

Managing Complications

Extravasation

• Risk of extravasation is low (2.3-4.5%) when strict protocols are followed 2
• If extravasation occurs, immediately stop the infusion 2
• Infiltrate the area with 5-10 mg of phentolamine diluted in 10-15 mL of saline solution 2

Other Adverse Effects

• May cause supraventricular arrhythmias, especially in patients with cardiac conditions 2
• Can increase myocardial oxygen consumption, potentially worsening ischemia in patients with coronary artery disease 2
• May cause decreased cardiac output due to increased afterload 2
• Renal and mesenteric vasoconstriction can impair organ perfusion 2

Special Considerations

• Patients on beta-blockers may require IV glucagon (1-2 mg) 2
• Digital ischemia can occur due to peripheral vasoconstriction 2
• Severity of shock can be classified based on norepinephrine dose requirements:
  • Low dose: <0.2 μg/kg/min
  • Intermediate dose: 0.2-0.4 μg/kg/min
  • High dose: >0.4 μg/kg/min 3

By following these guidelines for norepinephrine administration, clinicians can effectively manage hypotension while minimizing the risk of adverse effects.