A 32-year-old man with a history of peptic ulcer disease presents to the emergency department with acute upper gastrointestinal bleeding. He has active hematemesis and is hemodynamically unstable (BP 88/54 mmHg, HR 118/min). He last ate 2 hours ago. The anesthesiologist decides to perform rapid sequence induction (RSI) for emergency endoscopy. Which of the following is the MOST appropriate choice for induction agent in this patient?

Explanation

## Induction Agent Selection in Hemodynamically Unstable RSI **Key Point:** Etomidate is the agent of choice in hemodynamically unstable patients undergoing RSI because it maintains cardiovascular stability through preserved sympathetic tone and intact baroreceptor reflexes. ### Why Etomidate in This Case This patient has: - Active hemorrhage with hemodynamic instability (BP 88/54, tachycardia) - Full stomach (aspiration risk — RSI indicated) - Need for rapid airway control Etomidate's unique properties make it ideal: 1. **Minimal cardiovascular depression** — maintains BP and HR better than alternatives 2. **Preserved airway reflexes** — adequate for RSI 3. **Rapid onset** — suitable for emergency intubation 4. **No histamine release** — safe in hemorrhagic shock ### Comparison of Induction Agents in Hemodynamic Instability | Agent | CV Effect | Airway Reflex | Onset | Aspiration Risk | Use in Shock | |-------|-----------|---------------|-------|-----------------|---------------| | **Etomidate** | Minimal ↓BP | Preserved | 30–45 sec | Suitable | **BEST** | | Thiopental | Marked ↓BP | Depressed | 20–30 sec | Poor | Avoid | | Propofol | Marked ↓BP | Depressed | 20–30 sec | Poor | Avoid | | Midazolam | Moderate ↓BP | Depressed | 60–90 sec | Poor | Avoid | **Clinical Pearl:** Etomidate causes transient adrenocortical suppression (single dose), but this is acceptable in acute emergency settings. The immediate hemodynamic stability outweighs the theoretical risk of single-dose adrenal suppression. **High-Yield:** In hemorrhagic shock or hemodynamic instability, **etomidate is the gold standard induction agent** for RSI. Propofol and thiopental cause profound vasodilation and myocardial depression — both catastrophic in this setting. **Mnemonic — RSI Agent Selection in Shock:** - **E**tomidate = **E**mergency + **E**xcellent hemodynamics - **P**ropofol = **P**rohibited (in shock) - **T**hiopental = **T**oxic (to BP) ### RSI Protocol in This Patient ```mermaid flowchart TD A[Hemodynamically unstable<br/>Full stomach<br/>GI bleed]:::outcome --> B[Confirm RSI indication]:::decision B -->|Yes| C[Preoxygenation 3 min]:::action C --> D[Etomidate 0.2 mg/kg IV]:::action D --> E[Succinylcholine 1.5 mg/kg IV]:::action E --> F[Cricoid pressure applied]:::action F --> G[Intubate with cuffed tube]:::action G --> H[Confirm placement]:::action H --> I[Proceed to endoscopy]:::outcome ``` **Warning:** Do NOT use propofol or thiopental in this patient — both will cause profound hypotension and potential cardiac arrest in the setting of hemorrhagic shock.