How to initiate noradrenaline (norepinephrine) in a patient with shock?

Initiating Noradrenaline (Norepinephrine) in Shock

Norepinephrine should be initiated at a dose of 0.25-0.375 mL/min (8-12 mcg/min) via central venous access with continuous arterial pressure monitoring, targeting a mean arterial pressure (MAP) of 65 mmHg. 1, 2, 3

Initial Setup and Administration

• Ensure central venous access is established, as norepinephrine must be administered through a central line to prevent tissue necrosis from extravasation 2, 4
• Place an arterial catheter as soon as practical for continuous blood pressure monitoring 1, 2
• Prepare norepinephrine solution: standard concentration is 4 mg/4 mL (1 mg/mL) 3
• Initial dosing should be 0.25-0.375 mL/min (8-12 mcg/min) and titrated to achieve target MAP 3
• Average maintenance dose ranges from 0.0625-0.125 mL/min (2-4 mcg/min) 3

Timing of Initiation

• Ideally, adequate fluid resuscitation should precede vasopressor therapy, but early administration of norepinephrine is necessary in severe shock when diastolic blood pressure is critically low 1, 5
• Early norepinephrine administration (within 1-2 hours of shock recognition) improves shock control rate and may reduce fluid requirements 5, 6
• Consider immediate norepinephrine initiation in patients with profound hypotension (diastolic BP ≤40 mmHg) or high diastolic shock index (heart rate/diastolic BP ≥3) 5

Titration Protocol

• Target a MAP of 65 mmHg as the initial goal 1, 2, 4
• Higher MAP targets (75-85 mmHg) may be appropriate in patients with chronic hypertension 1, 4
• Titrate dose upward every 5 minutes if target MAP is not achieved 2
• Assess response using multiple parameters beyond just blood pressure:
  • Urine output (target >0.5 mL/kg/hr)
  • Lactate clearance
  • Mental status
  • Skin perfusion 1, 2, 6

Management of Refractory Hypotension

• If maximum doses of norepinephrine (up to 1 mcg/kg/min) fail to achieve target MAP, consider adding:
  • Vasopressin 0.01-0.03 U/min (do not exceed 0.04 U/min except as salvage therapy) 1, 2
  • Epinephrine as a second-line agent (0.1-0.5 mcg/kg/min) 1, 4
• For patients with persistent hypoperfusion despite adequate MAP, consider adding dobutamine 1

Safety Considerations

• Monitor for extravasation; if it occurs, infiltrate the area with 10-15 mL saline containing 5-10 mg of an adrenergic blocking agent (phentolamine) 3
• Watch for cardiac arrhythmias, particularly in patients with underlying heart disease 3
• Norepinephrine is associated with fewer arrhythmic events compared to dopamine (12.4% vs 24.1%) 1, 7
• Avoid abrupt discontinuation; gradually reduce infusion rate to prevent rebound hypotension 3

Special Situations

• Very high doses of norepinephrine (>4 mcg/kg/min) may be required in catecholamine-resistant shock and can be used safely when necessary 8
• Dopamine should only be considered as an alternative to norepinephrine in highly selected patients with low risk of tachyarrhythmias or with bradycardia 1, 4
• Phenylephrine should be reserved for specific situations: when norepinephrine causes serious arrhythmias, when cardiac output is high but blood pressure remains low, or as salvage therapy 1, 4