NORADRENALINE
1. BASIC OVERVIEW
|
Feature |
Detail |
|
Drug class |
Endogenous catecholamine |
|
Receptors |
α1 >>> β1 > β2 (minimal) |
|
Primary action |
Potent vasoconstrictor |
|
First-line use |
Septic shock (guideline preferred) |
|
Route |
IV infusion (never IM/SC) |
|
Half-life |
1–2 minutes |
- Surviving Sepsis Campaign → FIRST-LINE vasopressor in septic shock
2. PHARMACODYNAMICS
α1 EFFECT (Dominant)
- Peripheral vasoconstriction
- ↑ SVR → ↑ MAP
- ↓ venous capacitance → ↑ venous return
β1 EFFECT
- ↑ Contractility (mild)
- ↑ Stroke volume
- Minimal increase in HR (reflex bradycardia may occur)
β2 EFFECT
- Negligible (unlike adrenaline)
3. HEMODYNAMIC EFFECTS
|
Parameter |
Effect |
|
MAP |
↑↑ (primary goal) |
|
SVR |
↑↑ |
|
CO |
↔ or ↑ (depends on preload) |
|
HR |
↔ or ↓ (reflex vagal) |
|
Coronary perfusion |
↑ |
|
Renal perfusion |
Variable (improves if MAP restored) |
Key Concept
- Raises BP mainly by SVR increase, not tachycardia
4. INDICATIONS
1. SEPTIC SHOCK (FIRST LINE)
- Target: MAP ≥ 65 mmHg
- After adequate fluid resuscitation
2. OTHER DISTRIBUTIVE SHOCK
- Neurogenic shock (with bradycardia caution)
- Anaphylaxis (second-line after adrenaline)
3. CARDIOGENIC SHOCK (SELECTED CASES)
- When hypotension predominates
4. PERI-INTUBATION HYPOTENSION
- Prevent post-intubation collapse
5. DOSING
Standard Dose
- 0.05 – 1 mcg/kg/min IV infusion
Titration
- Start low → titrate every 2–5 min
- Goal: MAP ≥ 65 mmHg
Common ICU Preparation
- 4 mg in 50 mL (80 mcg/mL)
- Central line preferred
6. ADMINISTRATION PEARLS
Central vs Peripheral
- Central line = preferred
- Peripheral allowed temporarily (large bore, proximal vein)
Extravasation Risk
- Causes severe tissue necrosis
Management:
- Stop infusion
- Inject Phentolamine
7. ADVERSE EFFECTS
Cardiovascular
- Arrhythmias (less than adrenaline)
- Reflex bradycardia
- Increased afterload → ↓ CO in weak heart
Peripheral
- Digital ischemia
- Limb necrosis
Others
- Mesenteric ischemia
- Skin mottling
8. COMPARISON WITH OTHER VASOPRESSORS
|
Drug |
Receptors |
Key Feature |
|
Noradrenaline |
α1 >>> β1 |
Best for septic shock |
|
Adrenaline |
α + β1 + β2 |
↑ lactate, tachycardia |
|
Dopamine |
Dose-dependent |
Arrhythmogenic |
|
Vasopressin |
V1 receptor |
Add-on agent |
|
Phenylephrine |
Pure α |
↓ CO |
10. SPECIAL ICU CONCEPTS
1. “Decatecholaminization”
- Reduce catecholamine dose early
- Add vasopressin to limit toxicity
2. Lactate Elevation
- Unlike adrenaline → noradrenaline does NOT significantly increase lactate
3. Microcirculation
- May impair microcirculation at high doses
- But improves global perfusion by restoring MAP
4. Renal Effects
- Old myth: renal vasoconstriction
- Reality: improves renal perfusion if hypotension corrected