Rapid sequence induction
Editor-in-Chief: Santosh Patel M.D., FRCA 
Synonyms and keywords: Rapid sequence intubation; RSI
Rapid sequence induction , when performed in an Emergency Department or pre-hospital setting is an advanced medical protocol which permits the intubation of conscious patients who require advanced airway support. Having evolved from procedures used to "induce" a coma-state in preparation for surgery, RSI is now often used in emergency settings also.
Commonly used medications during a rapid sequence induction:
- Atropine — For patients where bradycardia is a concern
- Metaraminol or ephedrine, where hypotension (low blood pressure) may occur secondary to the sedating drugs
Rapid sequence intubation refers to the pharmacologically induced sedation and neuromuscular paralysis prior to intubation of the trachea. The technique is a quicker form of the process normally used to induce general anesthesia. With standard intravenous induction of general anesthesia, the patient typically receives an opioid, such as fentanyl, and then a drug to induce unconsciousness (commonly propofol). Generally a person undergoing will be manually ventilated for a short period of time before a neuromuscular blocking agent (for example succinylcholine or rocuronium) is administered and the patient is intubated. During rapid sequence induction, the person still receives an IV opioid. However, the difference lies in the fact that the induction drug and blocking agent are administered in rapid succession with no time allowed for manual ventilation. In either case, the endotracheal tube is placed shortly after onset of action of the blocking agent. Medications are utilized to allow rapid placement of an endotracheal tube between the vocal cords, while the cords are being visualized with the aid of a laryngoscope. Once the endotracheal tube has been passed between the vocal cords, a cuff is inflated around the tube in the trachea and the patient can then be artificially ventilated.
This procedure involves preoxygenating the lungs with a tightly-fitting oxygen mask, followed by the sequential intravenous administration of predetermined doses of a sleep-inducing drug and a rapid-acting neuromuscular blocking agent. Commonly used hypnotics include thiopental, propofol and etomidate. Commonly used neuromuscular blocking agents used include succinylcholine and rocuronium. The neuromuscular blocking agents paralyze all of the skeletal muscles, most notably and importantly in the oropharynx, larynx, and diaphragm. Opioids such as fentanyl may be given to attenuate the responses to the intubation process (accelerated heart rate and increased intracranial pressure). This is supposed to have advantages in patients with ischemic heart disease and those with brain injury (e.g. after traumatic brain injury or stroke). Lidocaine is also theorized to blunt a rise in intracranial pressure during laryngoscopy, although this remains controversial and its use varies greatly. Atropine may be used to prevent a reflex bradycardia from vagal stimulation during laryngoscopy, especially in young children and infants. Despite their common use, such adjunctive medications have not been demonstrated to improve outcomes.
One important difference between RSI and routine tracheal intubation is that the practitioner does not typically manually assist the ventilation of the lungs after the onset of general anesthesia and cessation of breathing, until the trachea has been intubated and the cuff has been inflated. RSI involves the use of a sedative/hypnotic medication to relax the patient followed by administration of a rapid-acting neuromuscular blocker (a paralytic) to disable the patient's involuntary reflex to fight the intubation. Sedatives typically used include thiopental, propofol, versed, or etomidate. Neuromuscular-blocking drugs typically used include succinylcholine or rocuronium. The combination enables the insertion of an endotracheal tube to ventilate patients requiring this type of advanced airway measure. Often, lidocaine is given as well if increased intracranial pressure is suspected (although there is controversy about effectiveness) and atropine is given in patients less than 2 years old to block reflex bradycardia. Sometimes fentanyl may also be used to sedate and block any pain response.
This procedure can be performed by paramedics in certain settings, especially aero-medical paramedics.
Age can play a role in whether or not the procedure is warranted, and is commonly needed in younger persons. The clinician that performs RSI must be skilled in tracheal intubation and also in bag valve mask ventilation. Alternative airway management devices must be immediately available, in the event the trachea cannot be intubated using conventional techniques. Such devices include the combitube and the laryngeal mask airway. Invasive techniques such as cricothyrotomy must also be available in the event of inability to intubate the trachea by more conventional techniques.
Since the introduction of RSI, there has been controversy regarding virtually every aspect of this technique, including:
- Choice of intravenous hypnotic agents as well as their dosage and timing of administration
- Dosage and timing of administration of neuromuscular blocking agents
- Avoidance of manual ventilation before tracheal intubation
- Optimal position and whether the head-up, head-down, or horizontal supine position is the safest for induction of anesthesia in full-stomach patients
- Application of cricoid pressure, which is also referred to as the Sellick maneuver
Pharmacologically Assisted Intubation
A similar procedure known as "pharmacologically assisted intubation" utilizes the sedative and hypnotic medications without the use of paralytics. This procedure is highly controversial and is usually performed where full RSI procedures are not legally allowed. RSI is the preferred procedure because it maximizes the chance of a successful intubation and reduces the chance of developing harmful increased intracranial pressure or other injuries during intubation.
- ↑ Suresh MS, Munnur U and Wali A (2007). "Chapter 32: The patient with a full stomach". In Benumof, JL. Benumof's Airway Management: Principles and Practice (2nd ed.). Philadelphia: Mosby-Elsevier. pp. 752–82. ISBN 978-0-323-02233-0.
- ↑ Pousman, RM (2000). "Rapid Sequence Induction for Prehospital Providers". The Internet Journal of Emergency and Intensive Care Medicine. 4 (1).
- ↑ Neilipovitz, DT; Crosby, ET (2007). "No evidence for decreased incidence of aspiration after rapid sequence intubation". Canadian Journal of Anesthesia. 54 (9): 748–64. doi:10.1007/BF03026872. PMID 17766743.
- ↑ Stone DJ and Gal TJ (2000). "Airway management". In Miller, RD. Anesthesia, Volume 1 (5th ed.). Philadelphia: Churchill Livingstone. pp. 1414–51. ISBN 978-0-443-07995-5.
- ↑ Warner KJ, Sharar SR, Copass MK, Bulger EM (2009). "Prehospital management of the difficult airway: a prospective cohort study". The Journal of Emergency Medicine. 36 (3): 257–65. doi:10.1016/j.jemermed.2007.10.058. PMID 18439793. Retrieved 2012-06-28. Unknown parameter
- ↑ El-Orbany, MI; Connolly, LA (2010). "Rapid Sequence Induction and Intubation: Current Controversy" (PDF). Anesthesia & Analgesia. 110 (5): 1318–25. doi:10.1213/ANE.0b013e3181d5ae47.