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. 2018 Mar 30;5(1):22-28.
doi: 10.15441/ceem.16.185. eCollection 2018 Mar.

Cervical collar makes difficult airway: a simulation study using the LEMON criteria

Moonsu Yuk  1 , Woonhyung Yeo  1 , Kangeui Lee  1 , Jungin Ko  2 , Taejin Park  1
Affiliations

Cervical collar makes difficult airway: a simulation study using the LEMON criteria

Moonsu Yuk et al. Clin Exp Emerg Med. .

Abstract

Objective: Endotracheal intubation is extremely difficult to perform in patients wearing a cervical collar for a head and neck injury. Therefore, we analyzed actual measurements using the look externally, evaluate 3-3-2, Mallampati score, obstruction, and neck mobility (LEMON) criteria before and after cervical collar application to investigate the causes of a difficult airway.

Methods: This simulation study was performed in 76 healthy volunteers. We measured the mouth opening, modified Mallampati classification, and neck extension before and after cervical collar application.

Results: The mean inter-incisor distance significantly decreased from 4.3 to 2.6 cm (P<0.001). Fifty-seven participants classified as I and II were newly classified as III and IV according to the modified Mallampati classification after cervical collar application (16% to 91%). The angles of neck extension significantly decreased from 44° to 22° after cervical collar application (P<0.001). Before cervical collar application, our simulations predicted that 14 of 76 participants (18%) would have a difficult airway, whereas after cervical collar application, 76 of 76 (100%) were predicted to have a difficult airway.

Conclusion: All values for the LEMON criteria (mouth opening, modified Mallampati classification, and neck extension) worsened significantly after cervical collar application. Additionally, a difficult airway was predicted in all participants after cervical collar application.

Keywords: Airway management; Cervical collar; Difficult airway; LEMON criteria.

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Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1.
Fig. 1.
Study enrollment and methods. TMJ, temporomandibular joint; BMI, body mass index.
Fig. 2.
Fig. 2.
Measurement methods for mouth opening, Mallampati score, and degree of neck extension with and without the cervical collar. (A) Measurement methods for evaluating mouth opening and Mallampati score without the cervical collar. (B) Measurement methods for evaluating mouth opening and Mallampati score with the cervical collar. (C) Measurement method for evaluating degree of neck extension with and without the cervical collar.
Fig. 3.
Fig. 3.
Inter-incisor distance before and after cervical collar application.
Fig. 4.
Fig. 4.
Mallampati score before and after cervical collar application.
Fig. 5.
Fig. 5.
Angle of neck extension before and after cervical collar application.
See this image and copyright information in PMC

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