A 32-year-old man is brought to the emergency department following a motor vehicle collision with severe crush injury to the abdomen and pelvis. He is in hemorrhagic shock (Class III). Regarding the physiological responses and management principles in hemorrhagic shock, all of the following are true EXCEPT:

Explanation

## Analysis of Hemorrhagic Shock Management ### Key Physiological Responses in Hemorrhagic Shock **Key Point:** Hemorrhagic shock triggers a coordinated cascade of neuroendocrine and hemodynamic compensations aimed at maintaining perfusion to vital organs (brain and heart) at the expense of peripheral and splanchnic beds. ### Evaluation of Each Statement | Statement | Accuracy | Rationale | |-----------|----------|----------| | Catecholamine-mediated vasoconstriction prioritizes vital organs | ✓ Correct | This is the fundamental survival mechanism in hemorrhagic shock. Sympathetic activation causes selective vasoconstriction in skin, muscle, GI tract, and kidneys while maintaining cerebral and coronary perfusion. | | Lactate elevation and clearance as resuscitation marker | ✓ Correct | Anaerobic metabolism in hypoperfused tissues produces lactate. Persistent elevation or failure to clear lactate indicates ongoing tissue hypoperfusion and inadequate resuscitation. | | MAP target of 65 mmHg for all trauma patients | ✗ **INCORRECT** | This is the critical error. While MAP ≥65 mmHg is a reasonable target in most patients, **permissive hypotension** (target SBP 90 mmHg or MAP 60 mmHg) is now recommended in penetrating trauma with ongoing hemorrhage awaiting definitive surgical control, to avoid excessive fluid administration and coagulopathy. | | Compensatory mechanisms (tachycardia, vasoconstriction, oliguria) | ✓ Correct | These are hallmark early responses in Class II–III hemorrhagic shock, mediated by sympathetic nervous system activation and RAAS. | ### Clinical Pearl **Permissive Hypotension Strategy:** - **Penetrating trauma with active bleeding:** Target SBP 90 mmHg (MAP ~60 mmHg) until hemorrhage control - **Blunt trauma:** More liberal resuscitation (SBP >100 mmHg) due to risk of occult internal bleeding - **Rationale:** Excessive early fluid administration increases coagulopathy, dilutional anemia, and re-bleeding risk ### High-Yield Concept **Key Point:** The modern ATLS approach emphasizes **damage control resuscitation** with permissive hypotension in uncontrolled hemorrhage, not aggressive fluid boluses to achieve "normal" MAP in all patients. [cite:ATLS 10th Edition, American College of Surgeons]