How do I initiate and titrate a noradrenaline (norepinephrine) infusion in a hypotensive patient?

Norepinephrine Infusion Protocol for Hypotension in a 70-Year-Old Male

For a hypotensive 70-year-old male patient, prepare norepinephrine by adding one ampoule (4 mg) to 50 mL of 5% dextrose solution, start at 2-4 mcg/minute, and titrate every 5 minutes based on blood pressure response, targeting a MAP of 65-100 mmHg. 1, 2

Preparation of Norepinephrine Infusion

• Add one ampoule (4 mg) of norepinephrine to 50 mL of 5% dextrose solution to produce a concentration of 80 mcg/mL 1
• Use 5% dextrose solution rather than normal saline alone as dextrose reduces loss of potency due to oxidation 1
• Administer through a central venous line whenever possible to prevent tissue necrosis from extravasation 2
• If central access is not immediately available, use a large peripheral vein with a large-bore cannula while central access is being established 3

Initial Dosing and Administration

• Start with an initial dose of 2-4 mcg/minute (1.5-3 mL/hour of the 80 mcg/mL solution) 1
• For severe hypotension (systolic BP ≤70 mmHg), consider starting at 8-12 mcg/minute (6-9 mL/hour) 1
• Always address hypovolemia before or concurrently with norepinephrine administration 1, 2
• Monitor blood pressure every 2 minutes until desired hemodynamic effect is achieved 1

Titration Protocol

• Once target blood pressure is achieved, monitor blood pressure every 5 minutes 1
• Typical maintenance dose ranges from 2-4 mcg/minute 1
• Titrate to achieve a target mean arterial pressure (MAP) of 65-100 mmHg 2
• For this elderly patient, consider targeting the lower end of the range (MAP 65-75 mmHg) to avoid excessive vasoconstriction 4
• If blood pressure remains inadequate despite increasing doses, consider adding a second vasopressor agent 5

Monitoring During Infusion

• Continuous hemodynamic monitoring is essential during administration 2
• Monitor for signs of extravasation; if it occurs, infiltrate 5-10 mg of phentolamine diluted in 10-15 mL of saline into the site 2, 5
• Watch for cardiac arrhythmias, especially in patients with underlying heart disease 2
• Monitor urine output as an indicator of adequate renal perfusion 6
• Assess peripheral perfusion regularly (skin temperature, capillary refill) 5

Weaning Protocol

• Once the patient is hemodynamically stable, reduce the flow rate gradually 1
• Avoid abrupt withdrawal as this may result in marked hypotension 1
• Decrease by 25% of the current dose every 30 minutes as tolerated 5

Special Considerations for Elderly Patients

• Elderly patients may be at greater risk of developing adverse reactions to norepinephrine 1
• Use cautiously in patients with ischemic heart disease as it may increase myocardial oxygen requirements 2
• Higher doses (>10 mcg/minute) are associated with increased mortality and should be avoided if possible 5, 2
• Norepinephrine may actually improve renal blood flow in hypotensive states, contrary to traditional concerns 2, 6

Potential Complications and Management

• Excessive vasoconstriction leading to end-organ hypoperfusion 2
• Tissue necrosis if extravasation occurs - treat immediately with phentolamine 2
• Cardiac arrhythmias, especially at higher doses 2
• Increased myocardial oxygen consumption potentially worsening ischemia 2