What is the recommended dose of norepinephrine (norepi) in the hypotensive post cardiac arrest phase during Advanced Cardiovascular Life Support (ACLS)?

Norepinephrine Dosing in Post-Cardiac Arrest Hypotension

For hypotensive patients in the post-cardiac arrest phase, norepinephrine should be administered at an initial rate of 0.5-1 mL/minute (2-4 mcg/minute) and titrated to maintain a target systolic blood pressure of 80-100 mmHg or 40 mmHg below pre-existing systolic pressure in previously hypertensive patients. 1

Preparation and Administration

• Dilution: Norepinephrine must be diluted in dextrose-containing solutions prior to infusion

  • Standard dilution: 4 mg (4 mL) of norepinephrine in 1,000 mL of 5% dextrose solution
  • This creates a concentration of 4 mcg/mL 1

• Administration route:

  • Administer through a large vein, preferably via a central venous catheter
  • Use a plastic intravenous catheter advanced centrally into the vein
  • Secure with adhesive tape rather than tie-in technique to avoid stasis 1

Dosing Protocol

1. Initial dose: 2-3 mL/minute (8-12 mcg/minute) to assess response
2. Maintenance dose: Adjust to 0.5-1 mL/minute (2-4 mcg/minute) based on blood pressure response
3. Titration: Adjust to maintain adequate perfusion pressure (usually 80-100 mmHg systolic)
4. Higher doses: May be necessary in refractory hypotension, but always suspect and correct occult blood volume depletion 1

Monitoring and Considerations

• Use an IV drip chamber or other metering device to ensure accurate flow rate
• Central venous pressure monitoring is helpful to detect and treat occult volume depletion
• Fluid volume requirements should be considered when determining the concentration of norepinephrine
• More dilute solutions (<4 mcg/mL) may be needed if large fluid volumes are required
• More concentrated solutions (>4 mcg/mL) may be appropriate when fluid restriction is necessary 1

Special Considerations

• Norepinephrine may be preferable to epinephrine in the post-arrest phase as it is associated with 63% lower odds of recurrent cardiac arrest (OR 0.47,95% CI 0.24-0.92) 2
• Early administration of norepinephrine in severely hypotensive patients can increase cardiac output through increased cardiac preload and contractility 3
• Avoid abrupt withdrawal; taper gradually when discontinuing therapy 1
• Ensure adequate volume resuscitation before and during vasopressor administration 1

Cautions

• In patients with poor cardiac contractility (LVEF ≤45%), achieving MAP ≥75 mmHg with norepinephrine may not improve cardiac output 3
• Norepinephrine-induced hypertension significantly increases oxygen consumption in post-ischemic myocardium, which may be detrimental if excessive 4
• Monitor for signs of peripheral ischemia due to vasoconstriction

While epinephrine is the primary vasopressor during cardiac arrest resuscitation, norepinephrine is often preferred for post-arrest hypotension management due to its more selective alpha-adrenergic effects and potentially lower risk of causing recurrent arrest compared to epinephrine.