A 28-year-old woman with a penetrating stab wound to the right upper quadrant is in the resuscitation bay. She is in Class II hemorrhagic shock (BP 95/60 mmHg, HR 110/min, anxious, normal urine output). Two large-bore IVs are running. The trauma surgeon is preparing for the operating room. Which fluid is the drug of choice for initial resuscitation in this hemorrhagic shock scenario?

Question

Accepted Answer

D. Lactated Ringer's solution. ## Crystalloid Choice in Hemorrhagic Shock Resuscitation

**Key Point:** Lactated Ringer's (LR) solution is the preferred crystalloid for initial resuscitation in hemorrhagic shock because it is physiologically balanced, contains lactate (metabolized to bicarbonate), and does not cause hyperchloremic acidosis.

### Why Lactated Ringer's Over Normal Saline?

**High-Yield:** The ATLS guideline recommends LR as the crystalloid of choice for trauma resuscitation.

| Feature | Lactated Ringer's | Normal Saline (0.9%) |
|---------|-------------------|---------------------|
| **Sodium** | 130 mEq/L | 154 mEq/L (hypernatremic) |
| **Chloride** | 109 mEq/L | 154 mEq/L (hyperchloremic) |
| **Potassium** | 4 mEq/L | 0 (hypokalemic risk) |
| **Calcium** | 3 mEq/L | 0 |
| **Lactate** | 28 mEq/L (buffer) | None |
| **pH** | 6.5 (physiologic) | 5.5 (acidic) |
| **Osmolality** | 273 mOsm/L | 308 mOsm/L |
| **Risk** | Minimal | Hyperchloremic acidosis, dilutional coagulopathy |

### Mechanism of Benefit

1. **Lactate metabolism:** Lactate is converted by the liver to bicarbonate, providing a physiologic buffer and correcting metabolic acidosis from shock.
2. **Electrolyte balance:** Sodium and chloride concentrations are closer to plasma, reducing hyperchloremic acidosis.
3. **Coagulation:** Hyperchloremia impairs platelet function and coagulation cascade; LR avoids this.

**Clinical Pearl:** In prolonged resuscitation (>2 L crystalloid), normal saline causes hyperchloremic metabolic acidosis and dilutional coagulopathy, worsening outcomes. LR is superior for massive transfusion protocols.

### Resuscitation Principles

**Mnemonic:** **CRASH** — **C**rystalloid first, **R**apid infusion (wide-bore IV), **A**ssess response, **S**urgery for control, **H**emostasis.

**Warning:** Avoid over-resuscitation ("damage control resuscitation"). Target BP 90 mmHg systolic in penetrating trauma until bleeding is controlled—excessive fluids increase bleeding and dilute clotting factors.

[cite:ATLS 10e; Harrison 21e Ch 296]

Answer

A. 5% Dextrose in water

Answer

B. Hypertonic saline (3% NaCl)

Answer

C. Normal saline (0.9% NaCl)

Explanation

Crystalloid Choice in Hemorrhagic Shock Resuscitation

Why Lactated Ringer's Over Normal Saline?

Mechanism of Benefit

Resuscitation Principles

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Feature	Lactated Ringer's	Normal Saline (0.9%)
Sodium	130 mEq/L	154 mEq/L (hypernatremic)
Chloride	109 mEq/L	154 mEq/L (hyperchloremic)
Potassium	4 mEq/L	0 (hypokalemic risk)
Calcium	3 mEq/L	0
Lactate	28 mEq/L (buffer)	None
pH	6.5 (physiologic)	5.5 (acidic)
Osmolality	273 mOsm/L	308 mOsm/L
Risk	Minimal	Hyperchloremic acidosis, dilutional coagulopathy