What are the typical dosages of dopamine and dobutamine (inotropes/vasopressors) for neonates requiring inotropic or vasopressor support?

Neonatal Dopamine and Dobutamine Dosing

For neonates requiring inotropic support, dopamine is dosed at 2-20 mcg/kg/min (typically starting at 5 mcg/kg/min) and dobutamine at 2.5-20 mcg/kg/min (starting at 2-3 mcg/kg/min), with dopamine being more effective at raising blood pressure while dobutamine produces greater increases in cardiac output.

Standard Dosing Ranges

Dopamine

• Starting dose: 2-5 mcg/kg/min 1
• Typical range: 2-20 mcg/kg/min 1, 2
• Maximum reported: Up to 125 mcg/kg/min in scattered neonatal reports, though most use adult-equivalent dosing 1
• Dose-dependent effects: Low doses (2-5 mcg/kg/min) produce renal/mesenteric vasodilation; intermediate doses (5-10 mcg/kg/min) provide inotropic effects; high doses (>10 mcg/kg/min) cause vasoconstriction 2

Dobutamine

• Starting dose: 2-3 mcg/kg/min 3, 4
• Typical range: 2.5-20 mcg/kg/min 3, 4
• Titration: Increase progressively based on hemodynamic response 3, 4
• No loading dose recommended 3

Clinical Pharmacology in Neonates

Dopamine Pharmacokinetics

• Elimination half-life: Approximately 2 minutes in full-term neonates, 4-5 minutes in preterm infants 2
• Clearance: Highly variable (46-168 mL/kg/min), with higher values in younger patients 1
• Volume of distribution: 0.6-4 L/kg in neonates 1
• Reduced inotropic response in neonates compared to older children due to immature norepinephrine stores 2

Dobutamine Pharmacokinetics

• Elimination half-life: Approximately 2 minutes 2, 4
• Plasma clearance: 90 ± 38 mL/min/kg in neonates 4
• Threshold plasma concentration: 39 ± 8 ng/mL required for cardiac output changes 4
• Infants <12 months are less responsive to dobutamine than older children 5

Agent Selection Algorithm

For Hypotension (Low Blood Pressure)

• First-line: Dopamine is more effective than dobutamine at raising systemic blood pressure in neonates 6, 7, 8
• Dopamine reduces treatment failure rates compared to dobutamine (NNT = 4.4) 8
• Consider starting at 5-10 mcg/kg/min and titrate to blood pressure response 2

For Low Cardiac Output (Adequate Blood Pressure)

• First-line: Dobutamine produces greater increases in cardiac output and right ventricular output 6, 8
• In one trial, dobutamine increased superior vena cava flow by +9.9 mL/kg/min vs -3.2 mL/kg/min with dopamine at highest doses 6
• Start at 2.5 mcg/kg/min and titrate up to 7.5-10 mcg/kg/min 4

For Hypoxic-Ischemic Encephalopathy with Shock

• First-line: Epinephrine (0.05-0.3 mcg/kg/min) is preferred over dopamine due to concerning mortality data with dopamine in this specific population 5
• Dopamine can be used if epinephrine unavailable, but avoid as preferred agent 5
• Dobutamine should be avoided as first-line in infants <12 months 5

For Post-Cardiac Surgery

• Consider milrinone for prevention and treatment of low cardiac output syndrome following cardiac surgery 9
• Both dopamine and dobutamine improve hemodynamics, but dopamine >7 mcg/kg/min increases pulmonary vascular resistance 9

Critical Safety Considerations

Dopamine-Specific Warnings

• Avoid doses >7 mcg/kg/min when pulmonary hypertension is a concern, as α-adrenergic vasoconstriction becomes pronounced 9, 10
• Most common adverse effect is tachycardia and cardiac arrhythmias 2
• May produce adverse respiratory responses at high doses in neonates due to autonomic nervous system immaturity 2
• Do not use for "renal protection" - no proven benefit 10

Dobutamine-Specific Warnings

• Less effective than dopamine in premature neonates for raising systemic blood pressure 11
• Provides no added benefit when given to infants already receiving optimal dopamine 11
• May cause mild reduction in serum potassium; monitor levels 11
• Can facilitate AV conduction in atrial fibrillation, leading to dangerous tachycardia 3

General Inotrope Precautions

• Use lowest effective dose for shortest duration - all inotropes increase myocardial oxygen consumption and arrhythmia risk 3
• Correct hypovolemia with volume expansion before initiating inotropes 11
• 40% of neonates fail to respond to either agent - consider alternative therapies or mechanical support if inadequate response 6

Monitoring Requirements

Mandatory Monitoring

• Continuous invasive arterial blood pressure monitoring 3, 5
• Continuous ECG telemetry for arrhythmia detection 3, 5, 11
• Serial lactate measurements 5
• Urine output 5
• Mental status and perfusion parameters (capillary refill, extremity temperature) 5

Hemodynamic Targets

• Mean arterial pressure ≥65 mmHg (or age-appropriate equivalent) 3
• Cardiac index 3.3-6.0 L/min/m² 5
• Central venous oxygen saturation >70% 5
• Resolution of hypoperfusion signs 3

Key Clinical Pearls

• No inotrope is superior for reducing mortality in pediatric distributive or cardiogenic shock 9
• Individual titration is essential due to wide variability in hemodynamic responses among neonates 9, 4
• Volume expansion (10 mL/kg normal saline) produces more significant increases in superior vena cava flow than dopamine initially 6
• Consider crossover to alternative agent if treatment failure occurs 6
• If inadequate response despite optimal inotropic therapy, escalate to mechanical circulatory support rather than combining multiple inotropes 3