What is rapid sequence induction (RSI) and intubation in anesthesia?

Rapid Sequence Induction and Intubation in Anesthesia

Rapid sequence induction (RSI) is a specific emergency airway management technique defined as the administration of a sedative-hypnotic agent and a fast-acting neuromuscular-blocking agent (NMBA) in rapid succession with immediate placement of an endotracheal tube before assisted ventilation. 1

Primary Indications

RSI is indicated for two critical clinical scenarios 1:

• Aspiration risk reduction in patients with full stomach, ileus, bowel obstruction, gastroesophageal reflux disease, or increased intra-abdominal pressure 1
• Optimization of intubating conditions to reduce the occurrence of difficult or failed airways, esophageal tube placement, and complications 1

Core Components of RSI

The technique consists of several sequential steps that distinguish it from standard intubation 2, 3:

Positioning

• Use semi-Fowler position (head and torso inclined) during RSI to reduce aspiration risk and potentially improve first-pass intubation success 1, 2

Preoxygenation

• High-flow nasal oxygen (HFNO) is suggested when laryngoscopy is expected to be challenging 2
• Noninvasive positive pressure ventilation (NIPPV) is recommended for patients with severe hypoxemia (PaO2/FiO2 < 150) 2
• Medication-assisted preoxygenation (delayed sequence intubation) using ketamine is suggested for agitated, delirious, or combative patients who cannot tolerate preoxygenation devices, with studies showing mean oxygen saturation increases of 8.9% 2

Pharmacologic Management

Sedative-Hypnotic Agents:

• A sedative-hypnotic induction agent must be administered when an NMBA is used for intubation 2, 4
• No significant difference exists between etomidate and other induction agents (ketamine, midazolam, propofol) with respect to mortality or hypotension 1, 2
• For hemodynamically unstable patients, etomidate (0.3 mg/kg) or ketamine (1-2 mg/kg) are recommended 4

Neuromuscular Blocking Agents:

• Administering an NMBA when a sedative-hypnotic induction agent is used is strongly recommended (strong recommendation, low quality evidence) 1, 2
• Either succinylcholine (1-1.5 mg/kg) or rocuronium (0.9-1.2 mg/kg) is suggested when no contraindications to succinylcholine exist 2, 4, 5
• Rocuronium at 0.6-1.2 mg/kg provides excellent or good intubating conditions in less than 2 minutes 5
• Sugammadex must be immediately available when rocuronium is used for potential "cannot intubate/cannot oxygenate" scenarios 4

Key Timing Considerations

The Society of Critical Care Medicine guidelines emphasize that RSI involves 1:

• Rapid succession administration of both agents without delay
• Immediate endotracheal tube placement before assisted ventilation begins
• Intubation attempted within 60-90 seconds of medication administration 5
• Maximum neuromuscular blockade achieved in less than 3 minutes with rocuronium 0.6 mg/kg 5

Historical Context and Evolution

Historically, mask ventilation was avoided during RSI to reduce regurgitation and aspiration risk; however, current evidence suggests mask ventilation may reduce critical hypoxemia risk 1. The technique has evolved from its original description, with cricoid pressure losing importance after controversial discussions in recent years 1, 6.

Target Patient Population

These guidelines apply to critically ill adult patients in the emergency department, ICU, or other locations outside the operating room requiring emergency airway management 1.

Critical Distinctions

RSI differs from standard intubation in that it specifically avoids the traditional period of mask ventilation between induction and intubation, though this practice is evolving based on hypoxemia risk 1. The technique is not recommended for rapid sequence induction in Cesarean section patients due to inadequate intubating conditions when lower thiopental doses are used 5.

Common Pitfalls

• Inadequate preoxygenation increases desaturation risk—ensure proper technique and consider medication-assisted preoxygenation for uncooperative patients 2
• Failure to have backup airway equipment immediately available can lead to "cannot intubate/cannot oxygenate" scenarios 4
• Inappropriate medication selection or dosing can cause hemodynamic instability 4
• Delayed post-intubation analgosedation when using rocuronium may increase awareness risk due to its longer duration compared to succinylcholine 2

Dosing Considerations

For obese patients, rocuronium should be dosed according to actual body weight rather than ideal body weight, as dosing by ideal body weight results in longer time to maximum block, shorter clinical duration, and inadequate intubating conditions 5.