A 48-year-old man with a history of hypertension (on amlodipine) presents with acute peritonitis secondary to perforated peptic ulcer. He is hemodynamically unstable: BP 95/58 mmHg, HR 118/min, RR 22/min, SpO₂ 94% on room air. He last ate 4 hours ago. The surgical team requests urgent intubation for airway protection before transfer to the operating room. Which of the following is the MOST appropriate sequence of actions during rapid sequence induction in this patient?

Explanation

## RSI Sequence in Hemodynamically Unstable Patient with Aspiration Risk ### Clinical Assessment This patient has **multiple critical factors**: - **Hemodynamic instability:** BP 95/58, HR 118 → hypovolemia, sepsis risk - **Aspiration risk:** Unfasted (4 hours), acute peritonitis, altered mental status risk - **Respiratory compromise:** RR 22, SpO₂ 94% → marginal oxygenation reserve ### The Correct RSI Sequence **Key Point:** RSI has a strict, evidence-based sequence: **Preoxygenation → Induction → Paralysis → Intubation → Cricoid Pressure (EPIC)**. ```mermaid flowchart TD A["Patient preparation (IV access, monitors)"]:::action --> B["Preoxygenation 100% O₂ × 3 min OR 8 vital capacity breaths"]:::action B --> C{"Hemodynamic status?"}:::decision C -->|"Stable"| D["Propofol or Thiopental"]:::outcome C -->|"Unstable"| E["Etomidate 0.2-0.3 mg/kg"]:::action E --> F["Succinylcholine 1.5 mg/kg OR Rocuronium 1.2 mg/kg"]:::action F --> G["Apply cricoid pressure (Sellick maneuver)"]:::action G --> H["Intubate with cuffed tube"]:::action H --> I["Confirm tube position (auscultation, ETCO₂)"]:::outcome ``` ### Detailed Breakdown of Correct Answer #### 1. **Preoxygenation: 3 minutes with 100% O₂** **High-Yield:** Preoxygenation is **MANDATORY** in RSI, even with aspiration risk. - **Goal:** Denitrogenate lungs and build oxygen reservoir in FRC - **Duration:** 3 minutes continuous OR 8 vital capacity breaths (faster alternative) - **Benefit:** Extends apnea tolerance from ~30 seconds to 8–10 minutes in normal patients - **Critical in this case:** RR 22 and SpO₂ 94% indicate marginal oxygenation — preoxygenation is life-saving **Warning:** Never omit preoxygenation in RSI. Aspiration risk does NOT contraindicate it; instead, it makes it MORE essential because you must intubate quickly. #### 2. **Induction: Etomidate 0.2 mg/kg IV** **Clinical Pearl:** Hemodynamic instability (BP 95/58) mandates etomidate over propofol. | Factor | Etomidate | Propofol | |--------|-----------|----------| | **BP effect** | Minimal (maintains MAP) | ↓↓ (drops 20–30%) | | **HR effect** | Minimal | Reflex tachycardia | | **Airway reflexes** | Preserved | Suppressed | | **In sepsis/hypovolemia** | ✓ Safe | ✗ Contraindicated | - **Dose:** 0.2–0.3 mg/kg IV (reduced to 0.1–0.15 mg/kg if severely shocked) - **Onset:** 15–30 seconds - **Adrenal suppression:** Single-dose etomidate does NOT cause clinical adrenal crisis in RSI #### 3. **Paralysis: Succinylcholine 1.5 mg/kg IV** **High-Yield:** Succinylcholine is preferred in RSI because: - **Rapid onset:** 30–60 seconds - **Rapid offset:** 5–10 minutes (allows rapid reversal if intubation fails) - **Depolarizing mechanism:** Reliable in emergency **Alternative:** Rocuronium 1.2 mg/kg if succinylcholine contraindicated (pseudocholinesterase deficiency, malignant hyperthermia risk, hyperkalemia risk). #### 4. **Cricoid Pressure (Sellick Maneuver)** **Key Point:** Apply cricoid pressure **AFTER** induction agent given, **BEFORE** paralytic onset, and maintain until tube cuff is inflated and position confirmed. - **Mechanism:** Compresses esophagus against cervical spine, preventing passive regurgitation - **Pressure:** 10 N awake → 30 N after loss of consciousness - **Timing:** Critical in aspiration-risk patients ### Why Other Answers Fail #### Option 1 (Correct) ✓ Follows standard RSI sequence with appropriate agent selection for hemodynamic instability. #### Option 2 (Propofol) ✗ - **Fatal flaw:** Propofol causes severe hypotension in this already-hypotensive patient (BP 95/58) - **Expected outcome:** Cardiovascular collapse, cardiac arrest - **Extended preoxygenation (8 min):** Unnecessary and delays critical intubation #### Option 3 (Omit preoxygenation) ✗ - **Dangerous misconception:** Aspiration risk does NOT contraindicate preoxygenation - **Consequence:** Rapid desaturation during apnea, hypoxic cardiac arrest - **Reduced doses:** Etomidate 0.1 mg/kg and succinylcholine 0.5 mg/kg are inadequate for reliable induction/paralysis #### Option 4 (Ketamine) ✗ - **Ketamine 1 mg/kg:** While ketamine preserves airway reflexes and BP, it is **NOT first-line in RSI** due to: - Risk of emergence delirium (contraindicated in acute peritonitis with possible sepsis) - Increased intracranial pressure (not relevant here, but less ideal) - Etomidate remains superior in hemodynamic instability - **Acceptable alternative:** Ketamine 0.5–1 mg/kg can be used if etomidate unavailable, but etomidate is preferred ### Mnemonic: RSI Sequence **EPIC-RSI:** - **E** — Evaluate & Prepare (IV access, monitors, equipment check) - **P** — Preoxygenate (3 min, 100% O₂) - **I** — Induction (agent choice based on hemodynamics) - **C** — Cricoid pressure (apply after induction) - **R** — Rapid paralysis (succinylcholine or rocuronium) - **S** — Secure airway (intubate) - **I** — Identify tube position (auscultation, ETCO₂) [cite:Morgan & Mikhail's Clinical Anesthesiology 6e Ch 13; Stoelting's Pharmacology and Physiology in Anesthetic Practice 5e Ch 4]