Rapid Sequence Intubation

Definition and Core Principles

• Rapid Sequence Intubation (RSI) is an advanced airway management technique that produces immediate unresponsiveness and profound muscular relaxation.
• It represents the fastest and most effective means of securing and controlling the emergency pediatric airway.
• The technique relies on the rapid, sequential administration of a sedative-hypnotic induction agent followed immediately by a neuromuscular blocking agent.
• Forceful bag-mask ventilation is strictly minimized during the apneic pause to prevent gastric distention and aspiration of gastric contents.

Indications for Rapid Sequence Intubation

• Impending respiratory failure or profound, refractory hypoxemia.
• Severe hypercarbia associated with an altered mental status or apnea.
• Loss of protective airway reflexes (gag and cough).
• A Glasgow Coma Scale (GCS) score of 8 or less, frequently observed in severe traumatic brain injury or status epilepticus.
• Cardiovascular signs of profound hypoxia, including marked tachycardia, severe bradycardia, or uncompensated shock.
• The presence of a life-threatening injury requiring immediate airway control in a patient with an intact gag reflex and a full stomach.
• Clinical signs of inhalation injury, such as facial burns, stridor, or carbonaceous sputum.

Contraindications

• Anatomically or pathologically difficult airways, such as congenital upper airway deformities or traumatic laryngeal fractures.
• Clinical scenarios where an emergency surgical airway (cricothyrotomy) is anatomically impossible, such as massive anterior neck trauma or obstructing tumors.
• Specific neuromuscular blocking agents carry absolute contraindications.
• Succinylcholine is strictly contraindicated in patients with denervating neuromuscular disease, malignant hyperthermia, severe hyperkalemia, recent massive burns, or major crush injuries.

Precautions and Clinical Nuances

• Attempting endotracheal intubation in a child with cardiogenic or septic shock carries substantial hemodynamic risks.
• Sedation and analgesia can dangerously blunt endogenous catecholamine release and increase systemic venous capacitance.
• This leads to severe venous pooling, decreased right ventricular preload, and subsequent peri-intubation cardiac arrest.
• Pre-medication with small boluses of epinephrine may be required to maintain coronary perfusion pressure during induction.
• In patients with suspected raised intracranial pressure (ICP), a targeted cerebroprotective RSI approach is preferred.
• Pharmacological adjuncts like intravenous lidocaine or fentanyl are utilized to blunt the reflex spike in ICP triggered by laryngoscopy.
• Prolonged or multiple intubation attempts must be avoided strictly to prevent secondary brain injury from hypoxia and ischemia.

The Seven P's of Rapid Sequence Intubation

Preparation

• Identify high-risk patient factors that impact medication choices, including cardiovascular status, raised ICP, bronchospasm, or genetic syndromes.
• Assess for a difficult airway utilizing the LEMON mnemonic:
  • Look externally,
  • Evaluate the 3-3-2 rule, (interincisor 3 finger, mentohyoid 3 finger, thyrohyoid 2 finger)
  • Mallampati scale,
  • Obstruction, and
  • Neck mobility.
• Assemble and verify all equipment using the SOAPME checklist: Suction, Oxygen, Airway equipment (ETT, stylet, blades), Pre-oxygenation tools, Monitoring/Medications, and End-tidal CO2 detectors.

Preoxygenation

• Provide 100% oxygen via a tightly fitting non-rebreather mask or face mask for a minimum of 3 minutes.
• This process establishes an adequate alveolar oxygen reservoir by replacing alveolar nitrogen (denitrogenation).
• Effective preoxygenation extends the duration of safe apnea, preventing critical desaturation during the intubation attempt.
• Apneic oxygenation should be provided simultaneously via a nasal cannula set at high flow rates.
• A head and torso inclined (semi-Fowler) position is recommended to increase functional residual capacity and optimize preoxygenation.

Pretreatment

• Administer pharmacological agents approximately 3 minutes prior to induction to mitigate adverse physiological responses.
• Atropine (an anticholinergic) is not routinely recommended for all children, but is utilized to prevent reflex bradycardia in infants under one year of age.
• Fentanyl provides excellent analgesia and blunts the sympathetic response in patients with elevated ICP or cardiovascular instability.

Paralysis and Induction

• Administer a potent sedative-hypnotic induction agent by rapid intravenous push to produce immediate unconsciousness.
• Follow this immediately with an intubating dose of a rapidly acting neuromuscular blocking agent (NMBA).
• Do not provide bag-mask ventilation during the onset of paralysis unless it is absolutely necessary to rescue the patient from severe hypoxia.

Positioning and Protection

• Position the patient optimally as they lose consciousness.
• For older children, utilize the sniffing position (neck flexion and head extension) if there are no cervical spine injury concerns.
• For infants, place a small towel roll under the shoulders to achieve a neutral airway axis.
• The application of cricoid pressure (Sellick maneuver) to occlude the esophagus and prevent aspiration remains highly controversial.
• Cricoid pressure must be discontinued immediately if it impedes ventilation or obstructs the laryngoscopic view.
• Backward, Upward, Rightward Pressure (BURP) can be applied to the thyroid cartilage to manipulate and improve the view of the glottis.

Placement and Proof

• Insert the laryngoscope blade and visualize the vocal cords once sufficient muscle relaxation has occurred (typically 45 to 60 seconds).
• Place the endotracheal tube under direct vision.
• Verify successful placement immediately using a quantitative end-tidal carbon dioxide (EtCO2) detector.
• Perform a secondary clinical confirmation by auscultating for equal, bilateral breath sounds and ensuring absent breath sounds over the epigastrium.

Post-Intubation Management

• Secure the endotracheal tube firmly utilizing waterproof tape or a commercial securing device.
• Connect the patient to the mechanical ventilator and initiate appropriate respiratory support settings.
• Initiate continuous intravenous sedation and analgesia (e.g., midazolam or fentanyl infusions) to ensure ongoing patient comfort and prevent spontaneous extubation.
• Obtain an urgent bedside chest radiograph to definitively confirm the anatomical depth of the endotracheal tube tip.

Pharmacological Agents for RSI