Norepinephrine Drip Rate Calculation
For norepinephrine, when 1 mL equals 20 drops, the drip rate would be 15-60 drops per minute (or 0.75-3 mL/minute) for a standard concentration of 4 μg/mL. 1
Standard Preparation and Concentration
Norepinephrine can be prepared in two standard ways:
- Standard concentration (4 μg/mL): Add 1 mg (1 mL) of norepinephrine to 250 mL of D5W to yield a concentration of 4.0 μg/mL 1
- Alternative concentration (10 μg/mL): Add 1 mg (1 mL) of norepinephrine to 100 mL of saline, creating a 1:100,000 solution 2
Drip Rate Calculation
When using a microdrop apparatus where 1 mL = 20 drops:
- Initial rate: 15-60 drops per minute (equivalent to 1-4 μg/min)
- Maximum rate: Up to 150 drops per minute (equivalent to 10 μg/min) 1
Titration Guidelines
- Start at the lowest effective dose (15 drops/minute or 1 μg/min)
- Titrate based on blood pressure response and clinical effect
- Target mean arterial pressure (MAP) of 65 mmHg 2
- Adjust every 10-15 minutes in increments of 0.05-0.2 μg/kg/min 2
Important Clinical Considerations
- Central line preferred: Administration through a central venous line is recommended whenever possible to reduce extravasation risk 2
- Peripheral administration: If using a peripheral line, monitor closely for extravasation
- Extravasation management: If extravasation occurs, inject phentolamine (0.1-0.2 mg/kg up to 10 mg diluted in 10 mL of 0.9% sodium chloride) intradermally at the site 1
- Solution stability: Norepinephrine solutions are chemically stable for up to seven days at room temperature in either D5W or normal saline 3
Monitoring Requirements
- Continuous cardiac monitoring
- Frequent blood pressure measurements (every minute during initial titration)
- Regular assessment of tissue perfusion
- Watch for adverse effects: tachyarrhythmias, increased myocardial oxygen consumption, lactic acidosis 2
Cautions
- Ensure adequate volume resuscitation before starting norepinephrine
- Use with caution in patients with heart failure or renal disease
- Higher doses may be required in beta-blocker overdose 2
- Weight-based dosing may need adjustment in obese patients, who typically require lower weight-based doses 4
By following these guidelines, you can safely administer norepinephrine at the appropriate drip rate to maintain adequate perfusion while minimizing adverse effects.