A 32-year-old man is brought to the emergency department following a motor vehicle collision with severe blunt abdominal trauma. Clinical examination reveals hypotension (BP 85/50 mmHg), tachycardia (HR 128/min), cold extremities, and altered mental status. After securing two large-bore IV lines and initiating rapid crystalloid infusion, the patient remains in hemorrhagic shock. What is the drug of choice for immediate hemodynamic support while awaiting definitive surgical intervention?

Question

Accepted Answer

C. Noradrenaline (Norepinephrine). ## Vasopressor Selection in Hemorrhagic Shock

**Key Point:** Noradrenaline (norepinephrine) is the first-line vasopressor in hemorrhagic shock because it provides both α-adrenergic vasoconstriction (restores perfusion pressure) and β-adrenergic inotropic support (maintains cardiac output).

### Mechanism in Hemorrhagic Shock

**High-Yield:** In Class III–IV hemorrhagic shock, the primary goal is to restore mean arterial pressure (MAP ≥ 65 mmHg) and tissue perfusion while awaiting hemorrhage control. Noradrenaline achieves this through:
- **α-effects:** Peripheral vasoconstriction → increased systemic vascular resistance (SVR) and MAP
- **β-effects:** Increased heart rate and contractility → improved cardiac output

### Comparative Pharmacology

| Agent | α-Effect | β-Effect | Use in Shock | Rationale |
|-------|----------|----------|--------------|----------|
| **Noradrenaline** | +++++ | ++ | First-line | Balanced α/β; restores perfusion + maintains CO |
| Dobutamine | + | +++++ | Cardiogenic shock | Pure inotrope; causes vasodilation—worsens hypotension in hemorrhagic shock |
| Hydralazine | Vasodilator | — | Hypertensive emergency | Contraindicated; reduces SVR in shock |
| Esmolol | — | β-blocker | Tachyarrhythmia control | Negative inotrope; worsens shock |

**Clinical Pearl:** Dobutamine and other pure inotropes are avoided in hemorrhagic shock because they cause peripheral vasodilation, which exacerbates hypotension. Noradrenaline's dual action is essential when fluid resuscitation alone is insufficient.

### ATLS Principle

**Warning:** The sequence is **Fluids → Vasopressors → Definitive Control**. Vasopressors are a bridge to surgery, not a substitute for hemorrhage control. Early surgical consultation is mandatory.

[cite:ATLS 10e]

Answer

A. Dobutamine

Answer

B. Hydralazine

Answer

D. Esmolol

Explanation

Vasopressor Selection in Hemorrhagic Shock

Mechanism in Hemorrhagic Shock

Comparative Pharmacology

ATLS Principle

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Agent	α-Effect	β-Effect	Use in Shock	Rationale
Noradrenaline	+++++	++	First-line	Balanced α/β; restores perfusion + maintains CO
Dobutamine	+	+++++	Cardiogenic shock	Pure inotrope; causes vasodilation—worsens hypotension in hemorrhagic shock
Hydralazine	Vasodilator	—	Hypertensive emergency	Contraindicated; reduces SVR in shock
Esmolol	—	β-blocker	Tachyarrhythmia control	Negative inotrope; worsens shock