Prehospital standardization of medical airway management: incidence and risk factors of difficult airway

Acad Emerg Med. 2006 Aug;13(8):828-34. doi: 10.1197/j.aem.2006.02.016. Epub 2006 Jun 28.


Objectives: The rate of difficult intubation in prehospital emergency medicine varies greatly among studies already published and depends on several factors. The authors' objective was to determine the rate of difficult intubations and to determine factors associated with prehospital difficult airways when a standard protocol for sedation and intubation was applied.

Methods: This 30-month clinical, observational, prospective study was performed in a suburb of Paris, France (Val de Marne, population 1,300,000) by a prehospital emergency medical unit. Airway management for patients who needed tracheal intubation was standardized. The pharmacological procedure recommended rapid sequence intubation for patients with spontaneous cardiac activity. In cases of difficult, laryngoscopy-assisted intubation, a predefined algorithm was proposed. The Intubation Difficulty Score (IDS) was calculated for all patients requiring tracheal intubation, and factors associated with difficult intubation, defined by IDS of >5, were identified by using multivariate statistical analysis.

Results: During the study period, 1,442 patients were included; 640 (44%) were in cardiorespiratory arrest, and 802 had a spontaneous cardiac activity. Deviation from the pharmacological and airway management procedures occurred in 1% of cases. When the predefined difficult airway management algorithm was followed, failure to intubate was encountered twice (0.1%). One hundred six (7.4%) patients had an IDS of >5, and 60 (4.1%) required first (n = 56) then second (n = 4) alternative techniques for tracheal intubation. Semirigid leaders allowed tracheal access in 93% of difficult-intubation patients. One patient required a prehospital cricothyroidotomy. Factors associated with difficult intubation were the following: a history of ear, nose, or throat neoplasia or surgery; obesity; facial trauma; the operator's status; and the operator's position.

Conclusions: If prehospital medical airway management is standardized and performed by trained operators, failure to intubate is rare (0.1%), and the incidence of difficult tracheal intubation is 7.4%, independent of cardiorespiratory status.

Publication types

  • Evaluation Study

MeSH terms

  • Airway Obstruction / epidemiology
  • Airway Obstruction / therapy*
  • Clinical Protocols*
  • Emergency Medical Services / methods
  • Emergency Medical Services / standards*
  • Emergency Medical Services / statistics & numerical data*
  • Female
  • France / epidemiology
  • Humans
  • Hypnotics and Sedatives / therapeutic use
  • Incidence
  • Intubation, Intratracheal / standards*
  • Intubation, Intratracheal / statistics & numerical data*
  • Logistic Models
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Prospective Studies
  • Risk Factors
  • Treatment Failure


  • Hypnotics and Sedatives