What are the differences between rapid sequence intubation (RSI) and delayed sequence intubation (DSI) in airway management?

Rapid Sequence Intubation vs Delayed Sequence Intubation: Key Differences in Airway Management

Delayed sequence intubation (DSI) significantly reduces peri-intubation hypoxia compared to rapid sequence intubation (RSI) in critically injured patients who are agitated or delirious and unable to tolerate optimal preoxygenation. 1

Definitions and Core Concepts

• Rapid Sequence Intubation (RSI): Administration of a sedative-hypnotic agent and a neuromuscular-blocking agent (NMBA) in rapid succession with immediate placement of an endotracheal tube before assisted ventilation 2

• Delayed Sequence Intubation (DSI): Administration of a dissociative dose of sedative (typically ketamine) followed by a period of preoxygenation (typically 3 minutes) before administering a paralytic agent for intubation 1

Key Differences Between RSI and DSI

Medication Administration Sequence

• RSI: Sedative and paralytic agents administered in rapid succession, followed immediately by intubation 2

• DSI: Sedative agent administered first, followed by a deliberate preoxygenation period (typically 3 minutes), and then paralytic administration before intubation 1

Preoxygenation Phase

• RSI: Preoxygenation occurs before any medications are given, which can be challenging in agitated or delirious patients 1

• DSI: Preoxygenation occurs after sedation but before paralysis, allowing for better patient compliance with preoxygenation in agitated patients 1

Clinical Indications

• RSI: Standard approach for most emergency intubations; particularly indicated for patients at risk of aspiration (full stomach, ileus, bowel obstruction, GERD, increased intra-abdominal pressure) 2

• DSI: Specifically beneficial for agitated, delirious, or combative patients who cannot tolerate preoxygenation masks or devices 2, 1

Comparative Effectiveness

Oxygenation Outcomes

• DSI demonstrates significantly lower rates of peri-intubation hypoxia (8%) compared to RSI (35%) in critically injured trauma patients who are agitated or delirious 1

• DSI shows significant improvement in mean oxygen saturation levels from baseline, while RSI does not show this improvement in the same patient population 1

Intubation Success Rates

• DSI shows higher first-attempt success rates (83%) compared to RSI (69%) in critically injured trauma patients 1

• In general ED settings, RSI has higher first-attempt success rates (73%) compared to non-RSI approaches (63%) 3

Complication Rates

• No significant difference in airway-related adverse events between DSI and RSI in trauma patients 1

• No significant difference in complication rates between RSI and non-RSI approaches in general ED settings (12% vs. 13%) 3

Clinical Decision Algorithm

1. Assess patient's mental status and ability to cooperate with preoxygenation:

   • If patient is cooperative → Consider standard RSI
   • If patient is agitated, delirious, or combative → Consider DSI 2, 1

2. Evaluate aspiration risk:

   • High aspiration risk (full stomach, ileus, etc.) → RSI preferred unless patient cannot tolerate preoxygenation 2
   • Consider nasogastric tube decompression in high-risk patients 2

3. Assess oxygenation status:

   • Severe hypoxemia (PaO2/FiO2 < 150) → Consider DSI with NIPPV for preoxygenation 2
   • Anticipated difficult laryngoscopy → Consider DSI with HFNO for preoxygenation 2

4. Select appropriate positioning:

   • Head and torso inclined (semi-Fowler) position is suggested during intubation 2

Pitfalls and Caveats

• Awareness during paralysis: Ensure adequate sedation is achieved before administering paralytic agents, especially in DSI where there is a time gap between sedation and paralysis 4

• Hemodynamic instability: Both RSI and DSI can cause hemodynamic changes; select appropriate induction agents based on patient's cardiovascular status 4

• Medication selection: Choice between etomidate and ketamine should be based on patient-specific factors; retrospective evidence suggests etomidate may produce less hypotension than ketamine in patients with shock or sepsis 4

• Paralytic selection: Choice between succinylcholine and rocuronium should be based on patient-specific factors, considering half-life and adverse effect profiles 4

• Non-RSI approaches: Intubation without paralysis is associated with significantly higher rates of complications including aspiration (15%), airway trauma (28%), and death (3%) compared to RSI 5