What is the recommended initial dose of norepinephrine (NE) for a patient requiring vasopressor support due to hypotension?

Initial Dosage of Norepinephrine for Hypotension

The recommended initial dose of norepinephrine for a patient requiring vasopressor support due to hypotension is 0.05-0.1 μg/kg/min, which should be titrated by 0.05-0.1 μg/kg/min every 5-15 minutes to achieve target blood pressure. 1

Preparation and Administration

• Norepinephrine must be diluted in dextrose-containing solutions prior to infusion:
  • Standard dilution: Add 4 mg (4 mL) of norepinephrine to 1,000 mL of 5% dextrose solution, resulting in a concentration of 4 μg/mL 2
  • Administration via central venous access is strongly preferred to avoid tissue necrosis from extravasation 3, 2
  • Use an infusion pump or syringe pump for accurate dosing 1

Dosing Strategy

• Initial dose: 0.05-0.1 μg/kg/min (equivalent to 3.5-7 μg/min for a 70 kg adult) 3, 1
• For an average 70 kg adult, this translates to approximately 2-4 mL/hour of the standard dilution
• Titration: Increase by 0.05-0.1 μg/kg/min every 5-15 minutes based on blood pressure response 1
• Target MAP: ≥65 mmHg for most patients; consider higher targets (75-85 mmHg) for patients with chronic hypertension 1

Clinical Considerations

• Blood volume depletion should be corrected as fully as possible before or concurrently with norepinephrine administration 2
• In profound, life-threatening hypotension, early administration of norepinephrine simultaneously with fluid resuscitation should be considered 4
• Early administration of norepinephrine has been associated with:
  • Reduced fluid requirements during resuscitation 4, 5
  • Improved cardiac output through increased cardiac preload and contractility 6
  • Potentially improved survival outcomes in some patient populations 5

Monitoring During Initiation

• Continuous arterial blood pressure monitoring is recommended 1
• Assess tissue perfusion markers (lactate levels, skin perfusion, mental status, urine output) 1
• Monitor for signs of extravasation if peripheral administration is necessary 3
• If extravasation occurs, infiltrate 5-10 mg of phentolamine diluted in 10-15 mL of saline into the site to prevent tissue necrosis 3

Special Situations

• In refractory hypotension (inadequate response after 10 minutes), consider:

  • Adding vasopressin (up to 0.03 U/min) 3, 1
  • Adding other vasopressors like phenylephrine (0.5-2.0 μg/kg/min) 3
  • Consider glucagon (1-2 mg IV) if the patient is on beta-blockers 3

• Early norepinephrine initiation is particularly beneficial in:

  • Patients with profound hypotension (e.g., diastolic BP ≤40 mmHg) 4
  • Patients with high diastolic shock index (heart rate/diastolic BP ≥3) 4
  • Patients at risk for fluid overload or where fluid accumulation would be particularly harmful 4

Remember that norepinephrine administration should be gradually reduced to avoid abrupt withdrawal when discontinuing therapy 2.