Indications for Rapid Sequence Intubation

Rapid sequence intubation (RSI) is a life-saving technique used for emergency airway management and manifestation. It is essential when a patient is at risk of pulmonary aspiration, such as when they are undergoing an emergent procedure without time to fast beforehand. The goal of RSI is to minimize the time in which a patient’s airway is unprotected. During RSI, the patient is intubated without typical breathing aids such as bag valve masks (Stollings et al., 2014). An inducer and muscle relaxant are administered simultaneously, followed by endotracheal intubation. The physical endotracheal procedure is the same, but the use of sedating and paralyzing medications in RSI requires in-depth pharmacology knowledge (Stollings et al., 2014). Two or three health care professionals are required to successfully manage a patient for RSI, and RSI is often managed by anesthesiologists and emergency department physicians (Schrader & Urits, 2021). 

Though RSI technique has evolved over time, the indications have remained unchanged (Avery et al., 2021). Rapid sequence intubation is generally indicated for patients in acute respiratory failure or patients who cannot protect their airway, such as acute burn or trauma patients (Schrader & Urits, 2021). Patients who are at risk of aspiration of gastric contents, for example due to upper GI bleeding, are also indicated for RSI (Avery et al., 2021). Before beginning, many clinicians use the LEMON mnemonic to determine if an airway can be intubated: (Schrader & Urits, 2021) 

  • L: Look externally 
  • E: Evaluate 3-2-2  
    • 3 fingers between the incisors? 
    • 3 fingers between mentum and hyoid bone? 
    • 2 fingers from mandible to top of thyroid cartilage?  
  • M: Mallampati score  
    • Assesses structure of oropharynx  
  • O: Obstruction or Obesity 
  • N: Neck Mobility 

However, the LEMON criteria list has been criticized for not including physiological factors in combination with anatomical factors. Compared to the LEMON criteria, the HEAVEN criteria list is potentially more relevant and practical in predicting success of RSI. Meeting individual and total HEAVEN criteria is associated with a decrease in intubation success (Nausheen et al., 2019):  

  • H: Hypoxemia 
  • E: Extremes of size 
  • A: Anatomic challenge 
  • V: Vomit/blood fluid 
  • E: Exsanguination 
  • N: Neck mobility issues 

During a 4-year retrospective study in a Colombian emergency department, researchers found that the main indication for RSI was a Glasgow Coma Scale of less than 8, with hypoxemia next. Other indications for RSI were neurological impairment, traumatic brain injury, and induced unconsciousness. Considering that an indication for RSI is risk of aspiration, this may be related to the association with a decreased Glasgow score (Muñoz et al., 2021).  

RSI, for which there are few absolute contraindications, is contraindicated during situations in which there is complete upper airway obstruction or loss of important anatomical landmarks (Schrader & Urits, 2021). Furthermore, in some situations, the administration of an induction agent and muscle relaxant may be harmful to patients who have abnormal airway anatomy, severe hypoxia, acidemia, or hypotension. These patients may not handle the pharmacological agents involved in RSI well. Ketamine is a potential alternative in these situations to facilitate endotracheal intubation. It will allow airway preparation and preoxygenation in these patients as the patient continues to breathe spontaneously (Merelman et al., 2019). 

Ultimately, RSI is a life-saving procedure that requires skilled clinicians and pharmacological knowledge. General indications are acute respiratory failure or high risk of pulmonary aspiration. Future work to assess when RSI should be performed should compare the usefulness of indication tools such as the LEMON and HEAVEN criteria lists. New technologies such as video laryngoscopy also offer alternatives to traditional RSI tactics and potentially expand the indications of patients that can undergo RSI (Merelman et al., 2019). 

References 

Avery P, Morton S, Raitt J, Lossius HM, Lockey D. Rapid sequence induction: where did the consensus go?. Scand J Trauma Resusc Emerg Med. 2021;29(1):64. Published 2021 May 13. doi:10.1186/s13049-021-00883-5 

Merelman AH, Perlmutter MC, Strayer RJ. Alternatives to Rapid Sequence Intubation: Contemporary Airway Management with Ketamine. West J Emerg Med. 2019;20(3):466-471. doi:10.5811/westjem.2019.4.42753 

Muñoz ÁM, Estrada M, Quintero JA, Umaña M. Rapid Intubation Sequence: 4-Year Experience in an Emergency Department. Open Access Emerg Med. 2021;13:449-455. Published 2021 Oct 14. doi:10.2147/OAEM.S321365 

Nausheen F, Niknafs NP, MacLean DJ, et al. The HEAVEN criteria predict laryngoscopic view and intubation success for both direct and video laryngoscopy: a cohort analysis. Scand J Trauma Resusc Emerg Med. 2019;27(1):50. Published 2019 Apr 24. doi:10.1186/s13049-019-0614-6 

Schrader M, Urits I. Tracheal Rapid Sequence Intubation. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 16, 2021. 

Stollings JL, Diedrich DA, Oyen LJ, Brown DR. Rapid-Sequence Intubation: A Review of the Process and Considerations When Choosing Medications. Annals of Pharmacotherapy. 2014;48(1):62-76. doi:10.1177/1060028013510488