What is the initial dose of Levophed (norepinephrine) for a patient with hypotension, considering their past medical history, age, and weight?

Norepinephrine Initial Order

Start norepinephrine at 8-12 mcg/min (0.1-0.5 mcg/kg/min) via continuous IV infusion through central venous access, targeting a mean arterial pressure of 65 mmHg, after administering at least 30 mL/kg crystalloid bolus. 1, 2

Preparation and Dilution

• Standard concentration: Add 4 mg norepinephrine to 1,000 mL of 5% dextrose solution to yield 4 mcg/mL 1
• Alternative concentration: Add 4 mg to 250 mL D5W to yield 16 mcg/mL 3
• Never dilute in saline alone—dextrose-containing solutions protect against oxidation and loss of potency 1

Critical Pre-Administration Requirements

• Administer minimum 30 mL/kg crystalloid bolus before or concurrent with norepinephrine initiation 2, 3
• Use balanced crystalloids (lactated Ringer's or Plasma-Lyte) preferentially over normal saline 2
• In severe hypotension (systolic <70 mmHg), start norepinephrine as emergency measure while continuing fluid resuscitation rather than delaying 2
• Blood volume depletion must be corrected as fully as possible before vasopressor administration 1

Administration Route

• Central venous access is strongly preferred to minimize extravasation risk and tissue necrosis 2, 4, 3, 1
• If central access unavailable or delayed, peripheral IV or intraosseous administration can be used temporarily 2
• Insert plastic IV catheter through suitable bore needle well advanced centrally into vein, securely fixed with adhesive tape 1
• Place arterial catheter as soon as practical for continuous blood pressure monitoring 2

Initial Dosing

• Starting dose: 8-12 mcg/min (0.1-0.5 mcg/kg/min) 2, 1
• Alternative starting dose for hepatorenal syndrome: 0.5 mg/h 2, 3
• For pregnant patients: 0.02 mcg/kg/min 2
• Pediatric starting dose: 0.1 mcg/kg/min 2

Target Blood Pressure and Monitoring

• Target MAP ≥65 mmHg for most patients 2, 4, 3
• In previously hypertensive patients, raise blood pressure no higher than 40 mmHg below pre-existing systolic pressure 1
• Monitor blood pressure every 5-15 minutes during initial titration 2, 3
• Assess tissue perfusion markers: lactate clearance, urine output >50 mL/h, mental status, capillary refill 2

Titration Strategy

• Maintenance dose: 2-4 mcg/min (0.5-1 mL/min of standard dilution) 1
• For hepatorenal syndrome: increase by 0.5 mg/h every 4 hours to maximum 3 mg/h 2, 3
• Titrate according to patient response to establish and maintain adequate blood pressure 1
• Great individual variation occurs—dosage must be titrated to response 1

Escalation 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 2, 3
• Alternative second agent: epinephrine 0.1-0.5 mcg/kg/min 2
• For persistent hypoperfusion despite adequate vasopressors with myocardial dysfunction, add dobutamine up to 20 mcg/kg/min 2
• Do NOT use dopamine as first-line agent—associated with higher mortality and arrhythmias compared to norepinephrine 2, 4
• Do NOT use phenylephrine as first-line—may raise blood pressure while worsening tissue perfusion 2

Special Population Considerations

Obese Patients

• Obese patients require lower weight-based doses (0.09 mcg/kg/min) compared to non-obese patients (0.13 mcg/kg/min) 5
• Similar total non-weight-based doses (approximately 8-9 mcg/min) achieve equivalent blood pressure response 5

Patients on Beta-Blockers

• May require glucagon 1-5 mg IV over 5 minutes followed by infusion for refractory cardiovascular effects 3
• Higher norepinephrine doses may be needed to overcome beta-blockade 1

Pregnant Patients

• Start at 0.02 mcg/kg/min targeting MAP 65 mmHg 2
• Consider more restrictive initial boluses (1-2 L) due to lower colloid oncotic pressure and higher pulmonary edema risk 2

Monitoring for Adverse Effects

• Watch for extravasation—if occurs, immediately infiltrate 5-10 mg phentolamine diluted in 10-15 mL saline into site 2, 4, 1
• Monitor for arrhythmias, particularly at higher doses 4
• Assess for excessive vasoconstriction: cold extremities, decreased urine output 2
• Monitor for increased myocardial oxygen consumption 4
• Use caution in patients with ischemic heart disease 4

Common Pitfalls to Avoid

• Never start norepinephrine without adequate fluid resuscitation—vasoconstriction in hypovolemic patients causes severe organ hypoperfusion despite "normal" blood pressure 2
• Never mix with sodium bicarbonate or alkaline solutions—adrenergic drugs are inactivated in alkaline solutions 2, 1
• Never use hydroxyethyl starch (HES) for fluid resuscitation—associated with increased mortality 2
• Avoid abrupt withdrawal—reduce gradually when discontinuing 1
• Do not use low-dose dopamine for "renal protection"—no benefit and strongly discouraged 2