What is the recommended use and dosage of catecholamines, such as norepinephrine, in treating hypotension?

Catecholamine Use and Dosage in Hypotension Treatment

Norepinephrine is the first-choice vasopressor for treating hypotension, with a recommended initial dosage of 0.1-0.5 mcg/kg/min (7-35 mcg/min in a 70-kg adult) targeting a mean arterial pressure (MAP) of 65 mmHg. 1, 2, 3

First-Line Vasopressor Selection

• Norepinephrine is recommended as the first-line vasopressor due to its superior efficacy and safety profile compared to other catecholamines 1, 2, 4
• Norepinephrine should be diluted in 5% dextrose solution or 5% dextrose with sodium chloride before administration 3
• Administration requires central venous access whenever possible, and arterial catheter placement is recommended for continuous blood pressure monitoring 2, 3

Dosing Protocol for Norepinephrine

• Initial preparation: Add 4 mg of norepinephrine to 1,000 mL of 5% dextrose solution (resulting in 4 mcg/mL concentration) 3
• Starting dose: 2-3 mL/min (8-12 mcg/min) with titration based on patient response 3
• Maintenance dose: Average 0.5-1 mL/min (2-4 mcg/min), but significant individual variation exists 3
• Target MAP: 65 mmHg for most patients; consider higher targets (e.g., 80-85 mmHg) in patients with chronic hypertension 1, 5

Refractory Hypotension Management

• When norepinephrine alone is insufficient to maintain target MAP, consider adding:
  • Vasopressin (0.03 U/min) to either raise MAP or decrease norepinephrine dosage 1, 2, 6
  • Epinephrine (0.1-0.5 mcg/kg/min) as an additional agent 1, 7
• Doses of norepinephrine above 1 μg/kg/min are associated with mortality rates over 80%, suggesting the need for adjunctive agents before reaching this threshold 6

Special Considerations

• Early administration of norepinephrine (simultaneously with fluid resuscitation) should be considered in profound hypotension to prevent prolonged organ hypoperfusion 5, 8
• Norepinephrine may be particularly beneficial in patients with low systemic vascular resistance 1, 2
• Avoid norepinephrine in hypovolemic patients until adequate fluid resuscitation has been achieved 1, 3
• Monitor for extravasation; if it occurs, infiltrate 5-10 mg of phentolamine diluted in 10-15 mL of saline into the site to prevent tissue necrosis 1

Alternative Catecholamines

• Dopamine (5-10 mcg/kg/min) may be considered as an alternative only in highly selected patients with low risk of tachyarrhythmias or with bradycardia 1, 2
• Epinephrine (0.1-0.5 mcg/kg/min) can be used for severe hypotension (systolic BP <70 mmHg) or anaphylaxis with hemodynamic instability 1
• Phenylephrine (0.5-2.0 mcg/kg/min) should be reserved for specific situations such as when norepinephrine causes serious arrhythmias or when cardiac output is high but blood pressure remains low 1, 2

Monitoring During Catecholamine Therapy

• Continuous arterial blood pressure monitoring is essential 2, 7
• Gradually reduce infusion rates to avoid abrupt withdrawal 3
• Norepinephrine has been shown to reduce the incidence of arrhythmias compared to other vasopressors 4
• Duration of therapy should continue until adequate blood pressure and tissue perfusion are maintained without vasopressor support 3