Elsevier

Resuscitation

Volume 82, Issue 12, December 2011, Pages 1519-1524
Resuscitation

Clinical paper
Difficult prehospital endotracheal intubation – predisposing factors in a physician based EMS☆

https://doi.org/10.1016/j.resuscitation.2011.06.028Get rights and content

Abstract

Objectives

For experienced personnel endotracheal intubation (ETI) is the gold standard to secure the airway in prehospital emergency medicine. Nevertheless, substantial procedural difficulties have been reported with a significant potential to compromise patients’ outcomes. Systematic evaluation of ETI in paramedic operated emergency medical systems (EMS) and in a mixed physician/anaesthetic nurse EMS showed divergent results. In our study we systematically assessed factors associated with difficult ETI in an EMS exclusively operating with physicians.

Methods

Over a 1-year period we prospectively collected data on the specific conditions of all ETIs of two physician staffed EMS vehicles. Difficult ETI was defined by more than 3 attempts or a difficult visualisation of the larynx (Cormack and Lehane grade 3, or worse). For each patient ETI conditions, biophysical characteristics and factors of the surrounding scene were assessed. Additionally, physicians were asked whether they had expected difficult ETI in advance.

Results

Out of 3979 treated patients 305 (7.7%) received ETI. For 276 patients complete data sets were available. The incidence of difficult ETI was 13.0%. In 4 cases (1.4%) ETI was impossible, but no patient was unable to be ventilated sufficiently. Predicting conditions for difficult intubation were limited surrounding space on scene (p < 0.01), short neck (p < 0.01), obesity (p < 0.01), face and neck injuries (p < 0.01), mouth opening < 3 cm (p < 0.01) and known ankylosing spondylitis (p < 0.01). ETI on the floor or with C-spine immobilisation in situ were of no significant influence. The incidence of unexpected difficult ETI was 5.0%.

Conclusions

In a physician staffed EMS difficult prehospital ETI occurred in 13% of cases. Predisposing factors were limited surrounding space on scene and certain biophysical conditions of the patient (short neck, obesity, face and neck injuries, and anatomical restrictions). Unexpected difficult ETI occurred in 5% of the cases.

Section snippets

Background

According to the 2010 guidelines on resuscitation endotracheal intubation (ETI) is still regarded to be the gold standard to secure the airway in prehospital emergency medicine.1 The procedure will continue to be advocated, trained and used, although definite proof for a positive effect on patient outcome is lacking.2 Even worse, ETI might pose additional risks onto the patient, ranging from tracheal lesions,3 or unintended hyperventilation4 to unrecognised oesophageal intubation (with an

Comparability of studies

If looking at previous studies, many relevant factors greatly vary. At first no uniform definition of difficult ETI exists.16, 17 The Task Force on Management of the Difficult Airway of the American Society of Anesthesiologists (ASA) defined difficult ETI as impossibility to intubate within 3 attempts or a procedure time of more than 10 min.17 A French group introduced an intubation difficulty score (IDS)18 based on a combination of the number of attempts and the visualisation of the vocal cords

Methods

From May, 13th 2004 to May, 12th 2005 we prospectively analysed all ETIs performed by the emergency physicians of the mobile intensive care unit (MICU) and the helicopter emergency medical system (HEMS) based at a university hospital (Benjamin Franklin Medical Center, Berlin, Germany). Both vehicles together serve a metropolitan area of approximately 400,000 inhabitants. They are part of a two-tiered EMS system which (at the time of the study) operated with 95 BLS and 15 ALS vehicles for 3.5

Results

Within the observation period 3979 patients were treated. 305 of these received ETI (7.7%). 5 cases had to be excluded from analysis because they had not been intubated by physicians from the study site, and 24 cases had to be excluded because of incomplete data sets. Finally 276 ETIs could be analysed (92% of eligible cases). The median number of prehospital ETIs for each participating physician was 15 per year (range 3–45).

Discussion

The first aim of the study was to determine the incidence of difficult prehospital ETI for emergency physicians in a typical unselected patient population. The patient cohort in our study showed a respective distribution of underlying conditions (cardiac arrest 63.8%, medical non cardiac arrest 23.5%, and trauma 12.6%) which was similar to a large American registry on more than 4 million EMS activations.21

Our difficult ETI incidence of 13.0% lies within the upper range of published data for EMS

Conclusion

The incidence of difficult prehospital ETI conditions for emergency physicians of different specialty backgrounds in an unselected patient population was 13.0%. The incidence of unexpected difficult ETI was 5.0%.

Main predisposing factors were limited space on scene, obesity, and short neck. Other significant conditions were anatomical obstacles of the upper airways. For cervical spine immobilisation, ETI on the floor, and secretions obstructing the airway no influence could be demonstrated. A

Contributors

SK collected data and performed statistical analysis, BB and LS collected data and made intellectual contributions. HM, HRA made important intellectual contributions to the study design and the manuscript. JB designed the study, evaluated the results and prepared the manuscript.

Conflict of interest statement

None.

References (31)

  • M.E. Jemmett et al.

    Unrecognized misplacement of endotracheal tubes in a mixed urban to rural EMS setting

    Acad Emerg Med

    (2003)
  • J.H. Jones et al.

    Emergency physician-verified out-of-hospital intubation: miss rates by paramedics

    Acad Emerg Med

    (2004)
  • R.M. Lyon et al.

    Field intubation of cardiac arrest patients: a dying art?

    Emerg Med J

    (2010)
  • A. Timmermann et al.

    The out-of-hospital esophageal and endobronchial intubations performed by emergency physicians

    Anesth Analg

    (2007)
  • H.E. Wang et al.

    Mulitvariate predictors of failed prehospital endotracheal intubation

    Acad Emerg Med

    (2003)

    • Cited by (0)

    ☆

    A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.06.028.

    View full text
    Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.