Rapid Sequence Intubation (RSI)

RSI uses near-simultaneous administration of a sedative and paralytic to achieve rapid unconsciousness and muscle relaxation for endotracheal intubation.

Core Principles

• Create optimal intubating conditions quickly
• Minimize time airway is unprotected
• Reduce aspiration risk by avoiding bag-mask ventilation (when possible)
• Match drug selection to patient physiology

Indications

• Respiratory failure with intact airway reflexes
• Inability to protect airway (declining mental status, severe intoxication, TBI)
• Major trauma with high aspiration risk
• Severe sepsis/shock requiring controlled ventilation

When to Modify or Avoid Standard RSI

Profound Shock

Induction agents can precipitate arrest. Strategy: aggressive pre-RSI fluid resuscitation, start vasopressors early, use reduced drug doses, minimize apnea time.

Severe Metabolic Acidosis

Patient relies on high minute ventilation to maintain pH. Prolonged apnea worsens acidosis rapidly. Consider assisted ventilation or delayed sequence intubation (DSI).

"Can't Intubate, Can't Oxygenate" Risk

If you predict paralysis will create an unmanageable airway, consider awake intubation with topical anesthesia instead.

Airway Difficulty Prediction

Use LEMON or HEAVEN to identify difficult airways:

• Look externally: facial trauma, obesity, large tongue
• Evaluate 3-3-2: mouth opening, hyoid-mental distance, thyroid-hyoid distance
• Mallampati: tongue size relative to pharynx
• Obstruction/Obesity
• Neck mobility

Physiologic Assessment

High-risk phenotypes requiring modified approach:

• Severe hypoxemia (ARDS, pneumonia)
• Shock with tenuous BP
• Severe acidosis (pH <7.2)
• Right heart failure or massive PE

Induction Agents

Paralytics

Adjunctive Medications

• Fentanyl (1-3 mcg/kg): Blunts sympathetic surge; useful in hypertensive, tachycardic patients or those with increased ICP
• Push-dose pressors: Have phenylephrine or epinephrine ready for immediate post-induction hypotension
• Post-intubation sedation/analgesia: Fentanyl + propofol/midazolam/dexmedetomidine - titrate to BP and comfort

1. Preparation

• Assess airway and physiology
• Assemble team (laryngoscopist, airway assistant, meds, monitor)
• Prepare equipment (ETT, video laryngoscopy, bougie, SGA, surgical airway kit)
• Draw up medications and label syringes
• Verbalize Plan A, B, C

2. Preoxygenation

Goal: maximize oxygen reserve to tolerate apnea

• 3-5 minutes of high FiO₂ (non-rebreather + nasal cannula at 15 L/min, or HFNC, or CPAP/BiPAP)
• Ramped/head-up positioning (ear-to-sternal-notch)
• Apply apneic oxygenation (nasal cannula at 15 L/min during attempts)

3. Pretreatment (Selective/Optional)

• Fentanyl for hypertensive/tachycardic patients or increased ICP concerns
• Often simplified or omitted in unstable patients

4. Paralysis with Induction

• Give induction agent first
• Immediately follow with paralytic (near-simultaneous)
• Wait for full muscle relaxation (~45-60 seconds)

5. Positioning and Protection

• Maintain ramped position
• Apply C-spine precautions if trauma
• Suction if needed
• Cricoid pressure is controversial and often omitted in modern practice

6. Placement of Tube

• Perform laryngoscopy (video laryngoscopy preferred)
• Use bougie early if needed
• Visualize tube passing through cords
• Inflate cuff
• Limit each attempt to 20-30 seconds

7. Post-intubation Management

• Confirm placement: waveform capnography (gold standard)
• Secure tube
• Start mechanical ventilation
• Initiate sedation and analgesia immediately
• Reassess hemodynamics: positive pressure ventilation can drop BP - treat with fluids/pressors as needed

Modified RSI in Shock

• Aggressive pre-RSI fluid resuscitation and early vasopressors
• Reduce induction doses (ketamine 0.5-1 mg/kg, etomidate 0.2 mg/kg)
• Minimize apnea time
• Have push-dose pressors drawn and ready
• Consider gentle assisted ventilation if acidotic

Delayed Sequence Intubation (DSI)

For combative, hypoxemic patients who cannot tolerate preoxygenation:

1. Give dissociative dose of ketamine (0.5-1 mg/kg IV)
2. While patient maintains spontaneous breathing, apply high-quality preoxygenation
3. Once adequately preoxygenated, proceed with standard RSI

Rapid Sequence Airway (RSA)

Use supraglottic airway (SGA) placement after induction ± paralysis as a bridge:

• Quickly establishes oxygenation/ventilation
• Allows time to optimize patient and reattempt intubation
• Useful in prehospital or resource-limited settings

Hypotension/Cardiovascular Collapse

• Cause: Induction drugs + positive pressure ventilation reducing venous return
• Prevention: Pre-RSI fluid resuscitation, reduced drug doses, early vasopressors
• Management: Push-dose pressors, fluid boluses, vasopressor infusion

Hypoxemia/Desaturation

• Cause: Inadequate preoxygenation, prolonged attempts, difficult airway
• Prevention: Optimize preoxygenation, apneic oxygenation, limit attempt duration
• Management: Abort attempt, bag-mask ventilation or SGA, reoxygenate before re-attempting

Failed Intubation

• Management: Follow difficult airway algorithm (SGA → surgical airway if can't oxygenate)
• Call for help early
• Change devices (VL vs DL, bougie)
• Reposition patient

Drug-Specific Complications

• Succinylcholine: Hyperkalemia (cardiac arrest), malignant hyperthermia, masseter spasm
• Ketamine: Emergence reactions, laryngospasm (rare), hypotension in catecholamine depletion
• Propofol: Severe hypotension, apnea

Clinical Pearls

• Resuscitate before intubate: Optimize BP, fluids, and oxygenation before pushing drugs
• Video laryngoscopy first-line: Improves first-pass success and allows teaching
• Bougie early, bougie often: Don't wait for multiple failed attempts
• Apneic oxygenation always: Keep nasal cannula at 15 L/min during all attempts
• Three attempts maximum: After 3 attempts, declare failed airway and move to SGA/surgical airway

Common Pitfalls

• Inadequate preoxygenation: Don't rush this step - every minute of preoxygenation buys you apnea tolerance
• Choosing propofol in shock: Will crash BP - use ketamine or etomidate instead
• Forgetting post-intubation sedation: Patient is paralyzed and aware - start sedation/analgesia immediately
• Not treating post-intubation hypotension: Positive pressure + induction drugs = hypotension. Be ready with fluids/pressors
• Prolonged attempts: Limit to 20-30 seconds per attempt to avoid hypoxemia