What does a dosage of 8 micrograms (mcg) per minute of norepinephrine indicate?

Norepinephrine 8 mcg/min Dosing Context

A norepinephrine infusion rate of 8 mcg/min (not weight-based) represents a low-to-moderate absolute dose that falls well within the standard maintenance range for vasopressor support in septic shock. 1

Understanding the Dosing

The FDA-approved norepinephrine dosing provides critical context for interpreting 8 mcg/min 1:

• Initial dose: 8-12 mcg/min (2-3 mL/min of standard 4 mcg/mL dilution) 1
• Average maintenance range: 2-4 mcg/min (0.5-1 mL/min) 1
• Your dose of 8 mcg/min: Falls at the lower end of initial dosing or upper end of maintenance dosing 1

Clinical Significance

This dose indicates moderate vasopressor requirements that do not yet warrant escalation to second-line agents. 2, 3

When to Consider Adding Vasopressin

Guidelines recommend adding vasopressin (0.03 units/min) when norepinephrine requirements remain elevated, but the specific threshold varies 4, 2:

• Conservative approach: Add vasopressin when norepinephrine reaches 0.25 mcg/kg/min (approximately 15-20 mcg/min in a 70 kg patient) 5
• Alternative threshold: Some centers initiate vasopressin at ≥50 mcg/min of norepinephrine 6
• At 8 mcg/min: You are well below these thresholds and should continue norepinephrine monotherapy 2, 3

Weight-Based vs. Absolute Dosing

The 8 mcg/min dose you're asking about is an absolute rate, not weight-based. 1

For context, weight-based dosing equivalents 4:

• Norepinephrine range: 0.1-2 mcg/kg/min in pediatrics 4
• Adult septic shock: Typically 0.05-0.5 mcg/kg/min initially 4, 7
• 8 mcg/min in a 70 kg patient: Equals approximately 0.11 mcg/kg/min (low-moderate dose) 1

Critical Monitoring at This Dose

At 8 mcg/min, you should have arterial line monitoring in place and be assessing for adequate tissue perfusion. 4, 2

Key monitoring parameters 4, 3:

• Target MAP: ≥65 mmHg (higher targets of 80-85 mmHg only if chronic hypertension) 4, 3
• Perfusion markers: Lactate clearance, urine output, mental status, skin perfusion 3
• Fluid status: Ensure adequate volume resuscitation (≥30 mL/kg crystalloid) before escalating vasopressors 3, 1

Common Pitfalls to Avoid

Do not add dopamine for "renal protection" at this or any norepinephrine dose—this practice is strongly discouraged and provides no benefit. 4, 2

Additional pitfalls 4, 2:

• Avoid phenylephrine as an alternative unless norepinephrine causes serious arrhythmias or cardiac output is documented to be high 4, 2
• Do not use vasopressin as monotherapy—it must be added to norepinephrine, never used alone 2, 3
• Suspect occult hypovolemia if requiring dose escalation beyond 20-30 mcg/min despite adequate initial resuscitation 1, 8

When to Escalate Beyond Norepinephrine Alone

If MAP remains <65 mmHg despite titrating norepinephrine upward from 8 mcg/min, continue increasing the dose before adding second agents. 2, 1

Escalation algorithm 2, 3:

• Continue norepinephrine titration until reaching 15-50 mcg/min (institutional protocols vary) 2, 6
• Add vasopressin 0.03 units/min if target MAP not achieved with norepinephrine alone 2, 3
• Consider epinephrine as an alternative second agent 2, 3
• Add dobutamine if persistent hypoperfusion despite adequate MAP and vasopressor support 4, 2