What is the recommended starting dose of noradrenaline (norepinephrine) for a typical adult patient in a critical care setting with hypotension?

Norepinephrine Starting Dose for Hypotension in Critical Care

Start norepinephrine at 8-12 mcg/min (0.1-0.5 mcg/kg/min for a 70 kg adult) via continuous IV infusion, targeting a mean arterial pressure (MAP) of 65 mmHg. 1

Initial Dosing Parameters

The FDA-approved starting dose is 8-12 mcg/min via intravenous infusion, which corresponds to approximately 0.1-0.5 mcg/kg/min in a typical 70 kg adult. 1 This should be initiated after or concurrent with at least 30 mL/kg crystalloid bolus to address hypovolemia. 2, 3

• For septic shock specifically, norepinephrine is the mandatory first-choice vasopressor (strong recommendation, moderate quality evidence), preferred over dopamine, epinephrine, or phenylephrine. 4, 2
• The typical maintenance dose ranges from 2-4 mcg/min once hemodynamic stability is achieved. 1

Preparation and Administration Route

Dilute 4 mg of norepinephrine in 1,000 mL of 5% dextrose to create a 4 mcg/mL solution. 1 Dextrose reduces potency loss from oxidation and is preferred over saline alone. 1

• Central venous access is strongly preferred to minimize extravasation risk and tissue necrosis. 2, 3, 5
• If central access is unavailable, peripheral IV or intraosseous administration can be used temporarily during initial resuscitation, but transition to central access as soon as practical. 3
• Avoid infusion into leg veins in elderly patients or those with peripheral vascular disease. 1

Target Blood Pressure and Monitoring

Target MAP of 65 mmHg for most patients with septic shock. 4, 2, 5 This represents the minimum threshold for adequate organ perfusion based on strong guideline recommendations. 2, 3

• Monitor blood pressure every 2 minutes until the desired hemodynamic effect is achieved, then every 5 minutes during the infusion. 1
• Place an arterial catheter as soon as practical for continuous monitoring in all patients requiring vasopressors. 2, 3
• Assess tissue perfusion markers beyond MAP: lactate clearance, urine output >50 mL/h, mental status, capillary refill time, and skin temperature. 2, 3, 5

Titration Strategy

Adjust the infusion rate to maintain the target MAP, with typical adjustments every 4 hours as needed. 3, 5

• In the first 60 minutes, titrate more frequently based on blood pressure response every 2-5 minutes. 1
• The typical dosing range in septic shock is 0.1-2 mcg/kg/min, though doses up to 0.4 mcg/kg/min may be required. 3, 6
• Doses >0.4 mcg/kg/min are considered high-dose and associated with significantly increased mortality (40% hospital mortality vs 14% with low-dose <0.2 mcg/kg/min). 6

Critical Pre-Administration Requirements

Address hypovolemia FIRST with at least 30 mL/kg crystalloid bolus before or concurrent with norepinephrine initiation. 2, 3, 1 Vasoconstriction in hypovolemic patients causes severe organ hypoperfusion despite "normal" blood pressure readings. 3, 5

• Use balanced crystalloids (lactated Ringer's or Plasma-Lyte) preferentially over normal saline. 3
• In profound, life-threatening hypotension (systolic BP ≤70 mmHg or diastolic BP ≤40 mmHg), start norepinephrine as an emergency measure while fluid resuscitation continues rather than waiting for complete volume repletion. 2, 3, 7

Escalation Strategy for Refractory Hypotension

When norepinephrine reaches 0.25 mcg/kg/min and hypotension persists, add vasopressin 0.03-0.04 units/min as second-line therapy rather than continuing to escalate norepinephrine alone. 4, 3, 5

• Alternatively, add epinephrine 0.1-0.5 mcg/kg/min if vasopressin is unavailable. 4, 3
• For persistent hypoperfusion despite adequate vasopressors, add dobutamine up to 20 mcg/kg/min if there is evidence of myocardial dysfunction. 4, 3
• Consider hydrocortisone 50 mg IV every 6 hours (or 200 mg continuous infusion) for refractory shock requiring high-dose vasopressors. 4, 5

Special Populations

In obese patients, use actual body weight for weight-based dosing calculations. Obese patients require lower weight-based doses (0.09 mcg/kg/min) compared to non-obese patients (0.13 mcg/kg/min), but similar total doses (8-9 mcg/min). 8

In pregnant patients with sepsis, start at 0.02 mcg/kg/min with more restrictive initial fluid boluses of 1-2 L due to lower colloid oncotic pressure and higher pulmonary edema risk. 3

Pediatric dosing: start at 0.1 mcg/kg/min, titrating to effect, with typical range 0.1-1.0 mcg/kg/min. Maximum doses up to 5 mcg/kg/min may be necessary in exceptional circumstances. 3

Extravasation Management

If extravasation occurs, immediately infiltrate 5-10 mg of phentolamine diluted in 10-15 mL of saline into the affected site to prevent tissue necrosis. 2, 3, 1 Pediatric dose: 0.1-0.2 mg/kg up to 10 mg. 3

Discontinuation Protocol

Reduce the infusion rate gradually when discontinuing. Avoid abrupt withdrawal, which can cause marked rebound hypotension. 1

• Decrease by 25% of the current dose every 30 minutes as tolerated. 2

Critical Pitfalls to Avoid

• Never use dopamine as first-line therapy - it is associated with higher mortality and more arrhythmias compared to norepinephrine. 4, 3
• Do not use low-dose dopamine for "renal protection" - it provides no benefit and is strongly discouraged. 3
• Avoid phenylephrine as first-line therapy - it may raise blood pressure while worsening tissue perfusion. 3
• Do not mix norepinephrine with sodium bicarbonate or other alkaline solutions - adrenergic agents are inactivated in alkaline solutions. 3
• Never delay norepinephrine in profound hypotension (diastolic BP ≤40 mmHg or diastolic shock index ≥3) while waiting for complete fluid resuscitation, as prolonged hypotension independently increases mortality. 9, 7