Dobutamine

Dobutamine is a synthetic catecholamine primarily used as an inodilator in ICU practice.

1. Pharmacology & Receptor Profile

Mechanism of Action

• β1-adrenergic agonist (predominant) → ↑ myocardial contractility
• Mild β2 activity → peripheral vasodilation
• Minimal α1 effect (balanced by β2 effect)

Unlike dopamine, it has no significant dopaminergic renal effect.

2. Hemodynamic Effects

 In hypotensive patients, dobutamine may worsen hypotension → often combined with norepinephrine.

3. Dose range:

• 2–5 mcg/kg/min → low inotropic effect
• 5–10 mcg/kg/min → standard ICU dose
• 10–20 mcg/kg/min → increased tachyarrhythmia risk

No renal dose adjustment required.

4. Indications in Critical Care

A. Cardiogenic Shock (Most Important)

Used in:

• Acute MI with low cardiac output
• Decompensated heart failure
• Post-cardiotomy low-output state
• Myocarditis

Guideline Position

• ESC Cardiogenic Shock guidelines: Dobutamine preferred in low-output state with adequate MAP.
• Surviving Sepsis Campaign: Add dobutamine if:
• Persistent hypoperfusion despite fluids + norepinephrine
• Myocardial dysfunction with low cardiac output

B. Septic Shock with Myocardial Dysfunction

When:

• Low ScvO₂ despite adequate MAP
• Echo shows depressed LV function

Used as add-on to norepinephrine, not monotherapy.

C. Right Ventricular Failure

Useful in:

• RV infarction
• Pulmonary hypertension with low output
• Massive PE (careful use)

Because:

• Improves contractility
• Reduces PVR (via β2 effect)

D. Stress Echocardiography

Pharmacologic stress testing agent (non-ICU indication).

5. Comparison with Other Inotropes

6. Adverse Effects

• Tachycardia
• Atrial fibrillation
• Ventricular arrhythmias
• Hypotension (vasodilatory effect)
• Myocardial ischemia
• Tolerance after 48–72 hrs (β-receptor downregulation)

 Avoid in:

• Hypertrophic obstructive cardiomyopathy (increases LVOT obstruction)
• Uncontrolled arrhythmias

7. Hemodynamic Monitoring in ICU

Should be guided by:

• Echo (LV/RV function)
• Cardiac output monitoring (PiCCO, PAC, FloTrac)
• Lactate trends
• ScvO₂
• Urine output

Target:
✔ CI > 2.2 L/min/m²
✔ Improving lactate
✔ End-organ perfusion

8. Dobutamine vs Milrinone