Dopamine
|
Dose (µg/kg/min) |
Receptor |
Effects |
Clinical Result |
|
0.5–2 |
D1 (dopaminergic) |
Renal, mesenteric vasodilation |
↑ Renal blood flow ( no outcome benefit) |
|
2–10 |
β1 |
↑ Contractility + HR |
↑ Cardiac output |
|
>10 |
α1 |
Vasoconstriction |
↑ SVR, ↑ BP |
Important: “Renal dose dopamine” is obsolete (no mortality or renal protection benefit)
Pharmacokinetics
- Route: IV infusion only
- Metabolism: MAO & COMT
- Does NOT cross BBB
Hemodynamic Effects
- ↑ Cardiac output (β1)
- ↑ Heart rate → risk of tachyarrhythmias
- ↑ SVR at higher doses
- Variable effect on MAP depending on dose
Indications
Septic Shock Preferred
- NOT first-line (per **Surviving Sepsis Campaign)
- May be used in:
- Patients with low risk of tachyarrhythmias
- Patients with bradycardia + hypotension
Cardiogenic Shock
- Limited role
- May be considered when:
- Hypotension + low CO + bradycardia
Preferred:
- Dobutamine (inotrope)
- Noradrenaline (vasopressor)
Other Uses
- Symptomatic bradycardia (temporary)
- Not recommended in:
- Hypovolemic shock
- Routine renal protection
Why Dopamine Fell Out of Favor
Evidence (SOAP II Trial)
- Compared dopamine vs noradrenaline in shock
- Findings:
- ↑ Arrhythmias with dopamine
- ↑ Mortality in cardiogenic shock subgroup
Conclusion: Noradrenaline superior and safer
Adverse Effects
Cardiovascular
- Tachycardia
- Atrial fibrillation
- Ventricular arrhythmias
Others
- Increased myocardial oxygen demand
- Immunosuppression (controversial)
Local
- Extravasation → tissue necrosis
Management:
- **Phentolamine infiltration
Comparison with Other Vasopressors
|
Feature |
Dopamine |
Noradrenaline |
Dobutamine |
|
Primary effect |
Dose-dependent |
α1 > β1 |
β1 |
|
HR effect |
↑↑ |
Mild ↑ |
↑ |
|
Arrhythmia risk |
High |
Low |
Moderate |
|
First-line shock |
No |
Yes |
No |
|
Renal benefit |
No |
No |
No |