What is Rapid Sequence Induction (RSI) and Intubation in anesthesia?

Rapid Sequence Induction and Intubation in Anesthesia

Rapid sequence induction and intubation (RSI) is a specialized anesthetic technique designed to rapidly secure a definitive airway while minimizing the risk of pulmonary aspiration of gastric contents in patients at increased aspiration risk. 1

Core Principles and Indications

RSI is indicated for patients who cannot safely fast or have conditions that increase aspiration risk, including: 2

• Patients with less than 2 hours liquid fasting or 6 hours solid food fasting 2
• Acute vomiting, sub-ileus, or ileus 2
• Absent protective airway reflexes 2
• Gastrointestinal passage disorders 2
• Pregnant women after the third trimester and during labor 2
• Emergency situations where fasting status is unknown 1

The technique aims to create ideal intubating conditions rapidly, attenuate pathophysiologic reflex responses to laryngoscopy, and reduce pulmonary aspiration risk. 3

Essential Components of RSI

Pre-oxygenation

Administer 100% oxygen (FiO₂ 1.0) with oxygen flow >10 L/min using a completely sealing face mask for 3-5 minutes, targeting an end-tidal oxygen concentration >0.9. 2 Capnography should be used during pre-oxygenation to confirm mask seal. 2

Patient Positioning

Position the patient with optimal upper body elevation to reduce aspiration risk and improve intubating conditions. 2

Pharmacologic Agents

For rapid sequence induction, administer a combination of opioid, hypnotic, and muscle relaxant to achieve rapid deep anesthesia and prevent coughing or choking. 2

Muscle Relaxants

The European Society of Anaesthesiology and Intensive Care strongly recommends using fast-acting muscle relaxants: either succinylcholine 1-2 mg/kg or rocuronium 0.9-1.2 mg/kg for RSI. 1

• Rocuronium 0.6-1.2 mg/kg provides excellent or good intubating conditions in most patients within 2 minutes 4
• Succinylcholine 1.0 mg/kg remains an alternative when no contraindications exist 5, 2
• The availability of sugammadex makes rocuronium the preferred choice in many settings 2

Hypnotic Agents

Acceptable hypnotics include: 2

• Propofol (most commonly used)
• Thiopental
• Etomidate
• Ketamine

An opioid of choice should be co-administered with the hypnotic agent. 2

Modified RSI Techniques

Pediatric/Controlled RSI

In pediatric patients, current French guidelines recommend a "controlled" or "modified" RSI approach that includes gentle bag-mask ventilation to prevent hypoxemia, which poses greater risk than aspiration in children. 1

Key modifications for pediatric RSI include: 1

• Preoxygenation with FiO₂ 0.8
• Deep anesthesia with opioid and hypnotic
• Non-depolarizing muscle relaxant
• Gentle bag-mask ventilation with peak inspiratory pressure <15 cmH₂O (just enough to raise chest wall) when SpO₂ drops below 95%

This approach decreases hypoxemia, hemodynamic complications, and difficult intubation compared to classic RSI, with no observed aspiration events in retrospective studies. 1

Cricoid Pressure Controversy

The role of cricoid pressure has become controversial and is no longer universally recommended. 1

• Some guidelines no longer include cricoid pressure for pediatric aspiration-risk patients 1
• If cricoid pressure is applied and direct laryngoscopy proves difficult, it should be released 1
• Practice varies internationally, and clinicians should follow their country's current standards 1

Critical Safety Considerations

Equipment and Personnel

RSI must only be performed by experienced clinicians or trained individuals under supervision, with immediate availability of: 4

• Facilities for intubation and mechanical ventilation 4
• Oxygen therapy 4
• Reversal agents (particularly sugammadex for rocuronium) 4
• Difficult airway equipment 2

Medication Error Prevention

Accidental administration of neuromuscular blocking agents can be fatal; store rocuronium with cap and ferrule intact to minimize wrong-drug selection. 4

Failed Intubation Plan

In cases of unexpected difficult airway during RSI, a second-generation supraglottic airway device should be immediately available and used. 2 All practitioners must have a pre-planned strategy for the unanticipated difficult airway. 3

Special Populations

Obstetric Patients

Rocuronium is NOT recommended for rapid sequence induction in Cesarean section patients, as intubating conditions were poor or inadequate in a significant proportion of patients when lower doses of thiopental were used. 4

Obese Patients

Dose rocuronium based on actual body weight, not ideal body weight, as dosing by ideal body weight results in longer time to maximum block, shorter clinical duration, and inferior intubating conditions. 4

COVID-19 Patients

For COVID-positive or highly suspicious patients, follow strict barrier precautions during RSI: 1

• Limit personnel in the operating room
• Avoid mask ventilation during pre-oxygenation
• Stop oxygen before removing the bag-valve mask
• Use video laryngoscopy by the most experienced clinician
• Connect ventilator only after inflating the endotracheal tube cuff

Post-Intubation Monitoring

Use peripheral nerve stimulation to monitor neuromuscular blockade, determine need for additional doses, assess recovery adequacy, and guide reversal. 4 This decreases complications from overdosage if additional doses are required. 4