B-BLOCKERS
|
Drug |
Selectivity |
Key ICU Role |
|
Esmolol |
β1 selective |
Rapid titration, unstable ICU patients |
|
Metoprolol |
β1 selective |
Chronic control, stable patients |
|
Labetalol |
β1 + β2 + α1 |
Hypertensive emergencies |
|
Parameter |
Esmolol |
Metoprolol |
Labetalol |
|
Onset |
1–2 min |
5–10 min (IV) |
2–5 min |
|
Duration |
10–20 min |
6–12 hrs |
3–6 hrs |
|
Effect |
Esmolol |
Metoprolol |
Labetalol |
|
HR ↓ |
Strong |
Moderate |
Strong |
|
BP ↓ |
Mild |
Mild |
Marked ↓ (due to α1 block) |
|
SVR |
↔ / slight ↑ |
↔ |
↓ significantly |
|
Dose |
Titrate every 5–10 min |
|
|
Key concept:
- Labetalol reduces SVR (vasodilation) → ideal in hypertensive crisis
- Esmolol mainly controls HR
4. ICU INDICATIONS
Esmolol
Drug of choice when rapid control required
- Atrial fibrillation/flutter (rate control)
- SVT
- Thyroid storm
- Aortic dissection (with vasodilator)
- Septic shock (selected patients – HR control)
Guideline pearl:
Used in septic shock (tachycardic) to improve ventricular filling (controversial but supported in select cases)
Metoprolol
- Chronic HF (stable)
- Post-MI
- Rate control in stable AF
- Hypertension (non-emergency)
Not ideal in ICU instability
Labetalol
First-line in hypertensive emergencies
- Intracranial hemorrhage / stroke
- Aortic dissection (with esmolol or alone)
- Pregnancy hypertension (preeclampsia/eclampsia)
- Sympathetic crises (cocaine, pheochromocytoma*)
Avoid pure β-blocker in cocaine → labetalol preferred due to α action
6. ADVERSE EFFECTS
|
AE |
Esmolol |
Metoprolol |
Labetalol |
|
Bradycardia |
✓ |
✓ |
✓ |
|
Hypotension |
Mild |
Moderate |
Severe (vasodilation) |
|
Bronchospasm |
Low |
Low |
Higher (β2 block) |
|
Heart block |
✓ |
✓ |
✓ |
|
Mask hypoglycemia |
✓ |
✓ |
✓ |
|
Hepatic issues |
No |
Rare |
Rare |
7. CONTRAINDICATIONS
|
Condition |
Safer Option |
|
Shock / unstable BP |
Avoid metoprolol/labetalol → use esmolol cautiously |
|
Asthma |
Avoid labetalol |
|
Acute HF |
Avoid all (use carefully) |
|
Bradycardia / AV block |
Avoid all |