Rapid Sequence Induction: Procedure, Medications, and Pitfalls

Rapid Sequence Induction (RSI) is considered the gold standard for emergency anesthesia induction – and at the same time one of the highest-risk procedures in acute care medicine. The combination of critically ill patients, unknown medical history, non-fasting status, and limited resources makes every emergency anesthesia a high-risk situation. While RSI in the OR setting takes place under controlled conditions, in the prehospital and emergency medicine environment, seconds and proper preparation often determine the outcome. This article examines the systematic procedure, drug selection with specific dosages, key pitfalls, and management when intubation fails.

Indications and Basic Principle

RSI is indicated whenever endotracheal intubation becomes necessary in non-fasted patients. The central goal: keep the time between loss of consciousness and secured airway as short as possible to minimize the risk of aspiration.

Typical indications include:

• Decreased level of consciousness (GCS ≤ 8) with absent protective reflexes
• Respiratory failure despite non-invasive measures
• Severe traumatic brain injury requiring controlled ventilation
• Polytrauma with hemodynamic instability and airway compromise
• Status epilepticus unresponsive to first-line therapy
• Severe burns with impending airway edema
• Agitation or states of excitement making safe treatment impossible

The basic principle of RSI consists of the rapid sequence of induction (hypnotic + neuromuscular blocking agent) without intermediate ventilation – in the classic definition. In modern practice, however, the so-called Modified RSI has become established, in which gentle intermediate ventilation with low pressures and a tight-fitting mask is accepted to extend apnea tolerance and avoid desaturation.

Preparation: The Key to Success

RSI does not begin with drug administration – it begins with structured preparation. A systematic approach demonstrably reduces complications. The "checklist principle" involving all team members has proven effective.

Team Communication and Role Assignment

A brief team briefing should take place before every RSI:

• Who intubates?
• Who administers the medications?
• Who performs cricoid pressure (if desired)?
• Who monitors vital signs?
• What is the Plan B for a difficult airway?

Airway Assessment

Every emergency anesthesia requires – albeit rapid – airway evaluation. The LEMON scheme has proven effective:

• Look externally (external abnormalities, facial hair, obesity, facial trauma)
• Evaluate 3-3-2 (mouth opening 3 finger breadths, chin-hyoid 3 finger breadths, hyoid-thyroid cartilage 2 finger breadths)
• Mallampati (often not assessable in emergencies)
• Obstruction (stridor, swelling, foreign body)
• Neck mobility (cervical spine immobilization, ankylosing spondylitis)

Equipment Check

The following equipment must be readily accessible and checked:

• Laryngoscope (video laryngoscope preferred) with functioning light source
• Endotracheal tubes in various sizes (including one size smaller)
• Stylet (bougie preferred, as it is associated with a higher first-pass intubation success rate)
• Supraglottic airway device (laryngeal mask or laryngeal tube) as backup
• Cricothyrotomy kit
• Suction – turned on and within reach
• Capnography
• Bag-valve-mask with reservoir and oxygen supply

Pre-Oxygenation: More Than Just Putting on a Mask

Pre-oxygenation is one of the most commonly underestimated measures. The goal is denitrogenation of the functional residual capacity (FRC) to maximize apnea tolerance.

Standard Procedure

• Tight-fitting mask with 15 L/min oxygen for at least 3 minutes – or alternatively 8 deep breaths when time is limited (vital capacity maneuver)
• Target: EtO₂ > 90% (where measurable) or SpO₂ of 100% as a surrogate parameter
• Head-of-bed elevation (20–30°) significantly improves FRC, especially in obese patients

Apneic Oxygenation

During the apneic phase after drug administration, a continuous oxygen flow is maintained via nasal cannula at 15 L/min O₂ or via high-flow nasal cannula (HFNC) at 50–70 L/min. This can extend the time to desaturation by several minutes and is a simple but effective safety measure.

High-Risk Populations

In the following patient groups, apnea tolerance is drastically reduced:

• Obesity (reduced FRC)
• Pregnant patients (increased O₂ consumption, reduced FRC)
• Children (higher basal metabolic rate)
• Patients with pneumonia, ARDS, or pulmonary edema

Particularly aggressive pre-oxygenation is essential here. If SpO₂ values remain below 93% despite pre-oxygenation, NIV-assisted pre-oxygenation (CPAP/BiPAP) should be considered.

Drug Selection and Dosages

The choice of induction agents depends on hemodynamics, underlying disease, and clinical context. There is no universal "standard regimen" – but there are well-established combinations.

Hypnotics

Ketamine (Esketamine)

• Dosage: 1–2 mg/kg IV (for esketamine: 0.5–1 mg/kg IV)
• Advantages: Hemodynamic stability through sympathetic stimulation, bronchodilation, preserved respiratory drive (at subclinical doses)
• Disadvantages: Increased salivation (consider atropine 0.5 mg as co-medication), increased myocardial O₂ demand
• Preferred for: Hypotension, sepsis, bronchospasm, trauma

Propofol

• Dosage: 1.5–2.5 mg/kg IV (in hemodynamically unstable patients significantly reduce: 0.5–1 mg/kg)
• Advantages: Rapid onset, good controllability, ICP reduction, antiemetic properties
• Disadvantages: Pronounced hypotension, especially in hypovolemia – frequently problematic in emergency settings
• Preferred for: Hemodynamically stable patients, status epilepticus, elevated ICP

Midazolam

• Dosage: 0.1–0.3 mg/kg IV
• Advantages: Availability, anxiolysis, amnestic potency
• Disadvantages: Slow onset, unreliable loss of consciousness as sole hypnotic, pronounced cardiovascular depression in combination
• Use: Only as a reserve agent or co-medication – not recommended as the sole hypnotic for RSI

Thiopental

• Dosage: 3–5 mg/kg IV
• Advantages: Rapid onset, ICP reduction, good controllability
• Disadvantages: Pronounced vasodilation and myocardial depression, histamine release, rarely available anymore
• Use: Plays an increasingly minor role in modern emergency medicine

Neuromuscular Blocking Agents

Rocuronium

• Dosage: 1.0–1.2 mg/kg IV (RSI dose – not the standard dose of 0.6 mg/kg!)
• Onset: 45–60 seconds at RSI dosing
• Duration: 40–70 minutes
• Advantage: Reversible with sugammadex (16 mg/kg for immediate reversal)
• Preferred neuromuscular blocking agent in modern RSI

Succinylcholine (Suxamethonium)

• Dosage: 1.0–1.5 mg/kg IV
• Onset: 30–45 seconds
• Duration: 5–10 minutes
• Disadvantages: Hyperkalemia (contraindicated in burns > 24 h, immobilization, neuromuscular diseases), malignant hyperthermia, bradycardia, fasciculations, increased intraocular pressure
• Use: Increasingly replaced by rocuronium + sugammadex; reserve option when sugammadex is not available

Adjuncts

• Fentanyl 1–2 µg/kg IV (2–3 minutes before induction): Blunting of the hemodynamic response to laryngoscopy – particularly relevant in TBI and hypertensive emergencies. Caution: additional hypotension in unstable patients.
• Lidocaine 1.5 mg/kg IV (alternative to fentanyl for ICP reduction in TBI – evidence limited, but widely used in practice)
• Atropine 0.5 mg IV: Prophylaxis for ketamine-associated hypersalivation or in children before succinylcholine

The Procedure Step by Step

A standardized procedure reduces errors. The following approach has proven effective in practice:

1. Confirm indication and brief the team (Plan A, B, C)
2. Establish monitoring: SpO₂, ECG, blood pressure, prepare capnography
3. Equipment check (laryngoscope, tube, bougie, backup airway, suction, cricothyrotomy kit)
4. Secure IV access (ideally two large-bore IVs)
5. Pre-oxygenation for 3 minutes with tight-fitting mask, head of bed elevated
6. Start apneic oxygenation (nasal cannula 15 L/min)
7. Administer adjuncts (fentanyl, lidocaine – as indicated)
8. Inject hypnotic – wait for loss of consciousness
9. Inject neuromuscular blocking agent – immediately after the hypnotic
10. Wait for full relaxation (45–60 seconds – no premature laryngoscopy!)
11. Laryngoscopy and intubation (bougie recommended as a first-line adjunct)
12. Confirm tube placement: Capnography is the gold standard – no tube is safely placed until a positive capnography waveform is confirmed
13. Secure the tube, set ventilator parameters, maintain anesthesia

Cricoid Pressure – Still Relevant?

Cricoid pressure (Sellick maneuver) is a traditional component of RSI. However, current evidence shows that:

• Actual aspiration protection has not been proven
• Incorrectly applied cricoid pressure can worsen the view of the glottis
• It often does not reliably compress the esophagus

The recommendation is therefore: Release cricoid pressure immediately if laryngoscopy is difficult. It should under no circumstances delay or impede intubation.

Difficult Airway Management

Even with optimal preparation, intubation does not always succeed on the first attempt. A structured algorithm with clear escalation steps is critical.

Can Intubate – Can Oxygenate

• Maximum 3 intubation attempts (each with optimization: positioning, blade size, bougie, BURP maneuver)
• On the second attempt: Most experienced person takes over
• Between attempts: Mask ventilation or supraglottic airway for oxygenation

Cannot Intubate – Can Oxygenate

• Insert supraglottic airway device (second-generation laryngeal mask preferred)
• Ensure oxygenation
• Decision: Allow patient to wake up (if sugammadex available) versus further airway management via supraglottic airway

Cannot Intubate – Cannot Oxygenate (CICO)

This is the absolute emergency. The decision to perform an emergency cricothyrotomy must not be delayed.

• Scalpel-bougie technique (preferred): Horizontal skin incision over the cricothyroid membrane, blunt entry, insert bougie, advance tube (6.0 mm ID) over the bougie
• Alternative: Puncture cricothyrotomy with Seldinger technique (slower, higher complication rate)

The CICO situation must be communicated loudly: "We cannot intubate and cannot oxygenate – I am now performing an emergency cricothyrotomy."

Common Pitfalls and How to Avoid Them

Inadequate pre-oxygenation: The most common preventable complication. Take the 3 minutes – they are the best investment before induction.

Underdosing the hypnotic: Out of fear of hypotension, doses are kept too low. The result: awareness, straining, laryngospasm, difficult intubation conditions. It is better to choose the correct dose and treat hypotension with vasopressors (have norepinephrine or phenylephrine boluses ready).

Underdosing the neuromuscular blocking agent: The RSI dose of rocuronium is 1.0–1.2 mg/kg – not 0.6 mg/kg. Underdosing leads to insufficient relaxation and difficult intubation.

Premature laryngoscopy: Wait at least 45–60 seconds after rocuronium administration. A common beginner mistake is premature intubation in patients who are not yet fully relaxed.

No backup strategy: Intubating without a Plan B puts patients at risk. The cricothyrotomy kit should be opened and within reach – not packed away in a drawer.

Forgetting to maintain anesthesia: After successful intubation, there is a risk of awareness if maintenance of anesthesia (e.g., propofol infusion, midazolam boluses, ketamine infusion) is not initiated immediately. This detail is frequently forgotten in the stress of the situation.

Post-intubation hypotension: The combination of positive pressure ventilation, drug effects, and relative hypovolemia frequently leads to a blood pressure drop after intubation. Have fluids and vasopressors ready early.

Special Situations

TBI and Elevated ICP

• Goal: Avoid blood pressure drops and ICP elevation
• Preferred: Esketamine + rocuronium + fentanyl to blunt the sympathoadrenal response
• Maintain MAP > 80 mmHg

Severe Sepsis / Septic Shock

• All common hypnotics can dramatically worsen existing hypotension
• Ketamine is the drug of choice, but even ketamine can cause hypotension in catecholamine-depleted patients
• Start a norepinephrine infusion before induction, have fluid boluses ready
• Drastically reduce propofol dose or avoid it entirely

Children

• Pre-oxygenation is particularly important (rapid desaturation)
• Adjust dosages according to age – weight-based calculation is mandatory
• Atropine 0.02 mg/kg (minimum 0.1 mg) before succinylcholine in children under 5 years for bradycardia prophylaxis
• Uncuffed tubes in infants and toddlers, cuffed tubes from school age onward

Practical Training

RSI is one of those procedures where theoretical knowledge alone is not sufficient. Structured preparation, team management under stress, drug selection under time pressure, and especially difficult airway management can only be internalized through regular, realistic training. In the Emergency Physician Refresher Course by Simulation Tirol, you train RSI and airway management on high-fidelity simulators in realistic scenarios – including the CICO situation and emergency cricothyrotomy. This way, you become more confident when it truly matters.

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