Norepinephrine Dosing for Hypotension
The recommended initial dosing for norepinephrine in hypotensive patients is 0.1-0.5 mcg/kg/min (equivalent to 7-35 mcg/min in a 70-kg adult), which should be titrated to achieve and maintain adequate blood pressure. 1
Preparation and Administration
- Norepinephrine must be diluted in dextrose-containing solutions prior to infusion (typically 4 mg in 1,000 mL of 5% dextrose solution, yielding 4 mcg/mL) 2
- Administration should be through a central venous line whenever possible to prevent tissue necrosis from extravasation 1
- Initial infusion rate should be 2-3 mL/min (8-12 mcg/min) with subsequent titration based on blood pressure response 2
- The average maintenance dose typically ranges from 0.5-1 mL/min (2-4 mcg/min) 2
Titration and Monitoring
- Titrate to achieve a target mean arterial pressure (MAP) of 65-100 mmHg, sufficient to maintain vital organ perfusion 1, 2
- In previously hypertensive patients, aim for a systolic blood pressure no higher than 40 mmHg below the pre-existing systolic pressure 2
- Continuous hemodynamic monitoring is essential during administration 1
- Monitor for signs of extravasation; if it occurs, infiltrate 5-10 mg of phentolamine diluted in 10-15 mL of saline into the site to prevent tissue necrosis 1
Clinical Considerations and Precautions
- Norepinephrine is indicated for severe hypotension (e.g., systolic BP ≤70 mmHg) with low peripheral vascular resistance 1
- It is relatively contraindicated in hypovolemic patients; always correct volume depletion before or concurrently with norepinephrine administration 1, 2
- Use cautiously in patients with ischemic heart disease as it may increase myocardial oxygen requirements 1
- While norepinephrine typically causes renal and mesenteric vasoconstriction, it may actually improve renal blood flow and urine output in septic shock 1, 3
- Early administration of norepinephrine in septic shock (within 2-3 hours) has been associated with improved shock control and potentially reduced complications 4
Special Situations
- In refractory septic shock, doses exceeding 0.6 μg/kg/min within 24 hours of ICU admission may indicate poor prognosis and higher mortality 5
- In cardiac arrest, norepinephrine is administered after establishing effective heartbeat and ventilation to maintain adequate blood pressure 2
- For acute heart failure, the European Society of Cardiology recommends a dosage range of 0.2-1.0 μg/kg/min 1
Tapering
- Reduce norepinephrine gradually to avoid abrupt withdrawal and potential rebound hypotension 2
- In some cases of vascular collapse due to myocardial infarction, treatment may be required for up to six days 2
Potential Adverse Effects
- Increased myocardial oxygen consumption
- Tissue necrosis if extravasation occurs
- Arrhythmias at higher doses
- Excessive vasoconstriction leading to end-organ hypoperfusion