What are the inotropes and chronotropes used in ICU care, and what are their starting and infusion doses?

Inotropes and Chronotropes in ICU Care: Starting and Infusion Doses

Based on ESC guidelines endorsed by the European Society of Intensive Care Medicine, the following agents with their precise dosing regimens should guide your ICU vasoactive therapy 1, 2, 3.

Primary Inotropic Agents

Dobutamine (β1-agonist)

• Starting dose: 2-3 mcg/kg/min without loading bolus
• Infusion range: 2-20 mcg/kg/min
• Titration: Increase progressively based on clinical response; may require up to 20 mcg/kg/min in patients on β-blockers
• Weaning: Decrease by 2 mcg/kg/min increments with simultaneous oral therapy optimization 1

Key consideration: Use caution when heart rate >100 bpm due to risk of tachycardia and arrhythmias 1, 2.

Dopamine (Mixed dopaminergic/β/α-agonist)

• No bolus
• Dose-dependent effects:
  • ≤3 mcg/kg/min: Renal/dopaminergic effects (limited diuretic benefit)
  • 3-5 mcg/kg/min: Inotropic (β+)

  • 5 mcg/kg/min: Inotropic + vasopressor (β+ and α+) 1, 2, 1

Critical pitfall: At higher doses, α-stimulation causes vasoconstriction and elevated systemic vascular resistance, increasing risk of tachycardia and arrhythmias. Norepinephrine is preferred over dopamine for vasopressor support due to lower mortality in shock states 3, 4, 5.

Levosimendan (Calcium sensitizer)

• Optional bolus: 12 mcg/kg over 10 minutes
• Starting infusion: 0.1 mcg/kg/min
• Range: 0.05-0.2 mcg/kg/min for 24 hours 1, 2, 1

Critical caveat: Skip the bolus in hypotensive patients (SBP <100 mmHg) to avoid precipitous hypotension 1, 2. This agent has vasodilator properties and is particularly useful in patients on β-blockers since its mechanism is independent of β-adrenergic stimulation 1, 3. Levosimendan is preferable over dobutamine to reverse β-blockade effects 3.

Milrinone (Phosphodiesterase-III inhibitor)

• Bolus: 25-75 mcg/kg over 10-20 minutes (only in well-preserved BP)
• Infusion: 0.375-0.75 mcg/kg/min 1, 2, 1

Warning: Use with extreme caution in coronary artery disease—may increase medium-term mortality 1, 2. Effects maintained during β-blocker therapy since action is distal to β-receptors 1.

Enoximone (Phosphodiesterase-III inhibitor)

• Bolus: 0.25-0.75 mg/kg
• Infusion: 1.25-7.5 mg/kg/min 1, 2, 1

Similar considerations as milrinone regarding CAD and β-blocker therapy 1.

Vasopressors (with chronotropic effects)

Norepinephrine (α1 and β1-agonist)

• No bolus
• Infusion: 0.2-1.0 mcg/kg/min 1, 2, 1

First-line vasopressor for shock states when inotropes and fluid challenge fail to maintain SBP >90 mmHg 3, 4, 5. Preferred over dopamine due to lower arrhythmia risk and mortality 3, 5.

Epinephrine (β1, β2, and α-agonist)

• Resuscitation bolus: 1 mg IV, repeat every 3-5 minutes
• Infusion: 0.05-0.5 mcg/kg/min 1, 2, 1

Reserved for persistent hypotension despite other vasoactive agents or cardiac arrest protocols 3. Higher arrhythmia risk (~15%) compared to norepinephrine 5.

Clinical Decision Algorithm by Blood Pressure

SBP >100 mmHg:

• Vasodilators (nitroglycerin, nitroprusside) ± diuretics
• If inadequate response → add inotrope 1, 2

SBP 90-100 mmHg:

• Vasodilator and/or inotrope (dobutamine or levosimendan) 1, 2, 1

SBP <90 mmHg:

• Correct preload with fluids first
• Inotrope (dopamine at inotropic doses)
• If persistent hypotension → vasopressor (norepinephrine preferred)
• Consider mechanical support 1, 2, 1

Critical Monitoring Requirements

All patients receiving inotropes/chronotropes require:

• Continuous ECG telemetry (arrhythmia risk 2-25% depending on agent) 1, 5
• Blood pressure monitoring (invasive arterial line preferred for vasopressors and dose titration) 1
• Serial lactate and mixed/central venous oxygen saturation 5
• Cardiac output assessment via echocardiography when available 6, 5

Common Pitfalls to Avoid

1. Using dopamine as first-line vasopressor—norepinephrine has superior safety profile 3, 4, 5
2. Giving levosimendan bolus in hypotensive patients—causes dangerous hypotension 1, 2
3. Continuing inotropes longer than necessary—withdraw as soon as organ perfusion restored to minimize mortality risk 1
4. Using phosphodiesterase inhibitors in acute coronary syndromes—increases mortality 1, 2
5. Inadequate weaning—taper gradually while optimizing oral therapy 1