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Difficult airway rescue and supraglottic airways

Last post 30 Jan 2019, 11:27 AM by James Nielsen. 0 replies.
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  •  30 Jan 2019, 11:27 AM 2724

    Difficult airway rescue and supraglottic airways

    Thomsen et al. studied two key questions in difficult airway management: how often do clinicians try a supra-glottic airway, and how often does it work? In a cohort of 4,900 patients with difficult airways, one in eight had a supraglottic airway inserted, and two out of three attempts succeeded [1]. Both findings are significant. Firstly, the supraglottic airway attempt rate was low; despite recommendations in airway guidelines [2, 3], there was no recorded attempt in almost 90% of cases. Secondly, the success rate of supraglottic airway attempts was high. Recent studies have reported rates above 98% in elective cases at single institutions [4, 5], whereas success in Thomsen et al.'s study was for a secondary airway plan in a difficult cohort from multiple clinical sites. 

    The authors suggest two explanations for these findings: primary airway techniques were “difficult” but effective, or supraglottic airways were inserted, but only temporarily.  Both of these draw attention to the study inclusion criteria and to the measures of success.

    Mask ventilation was “difficult” in 30% of patients. Difficulty was defined by the Han criteria (“impossible, inadequate, unstable, or requiring two operators” [6]), which have limitations [7, 8]. “Inadequate” and “unstable” are subjective terms which were not defined by the authors, and the use of two hands reflects operator technique but not patient outcome. Mask ventilation is often better with a two-handed seal [9 - 11]. How often did that simple measure work, rendering supraglottic airway insertion unnecessary? Should those cases be classified as “difficult” - or just “well managed”?

    Finally, the study definition of supraglottic airway success was its use as the final airway. As the authors note, this did not capture temporary use, even if it was life-saving. Even an imperfectly placed supraglottic airway might rescue a hypoxic crisis. Shouldn’t that count as success rather than a failure?  


    J. R. Nielsen

    K.S. Lim

    Concord Repatriation General Hospital

    Sydney, Australia.

    Email: jamesrnielsen@gmail.com


    No external funding and no conflicts of interest declared.



    1. Thomsen JLD, N­­­­­­­­­­­­­­­­­­ørskov AK, Rosenstock CV.  Supraglottic airway devices in difficult airway management: a retrospective cohort study of 658,104 general anaesthetics registered in the Danish Anaesthesia Database. Anaesthesia 2018; 74: 151-57.
    2. Apfelbaum Jl, Hagberg CA, Caplan RA, et al. American Society of Anesthesiologists practice guidelines for management of the difficult airway.  Anesthesiology 2013; 118: 251-70.
    3. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. British Journal of Anaesthesia 2015; 115: 827-48.
    4. Saito T, Liu W, Sophia CTH, Li LK. Incidence of and risk factors for difficult ventilation via a supraglottic airway device in a population of 14 480 patients from South-East Asia. Anaesthesia 2015; 70: 1079-83.
    5. Vannucci A, Rossi IT, Prifti K, et al. Modifiable and nonmodifiable factors associated with perioperative failure of extraglottic airway devices.  Anesthesia and Analgesia 2018; 126: 1959-67.
    6. Han R, Tremper K, Kheterpal S, O’Reilly M. Grading scale for mask ventilation. Anesthesiology 2004; 101: 267.
    7. El-Orbany M, Woehlck HJ. Difficult Mask Ventilation. Anesthesia and Analgesia 2009; 108: 1870-80.
    8. Kheterpal S.  It’s about time. Anesthesiology 2017; 126: 4-5.
    9. Matioc A, Galgon R, Joffe A. Efficacy of one-handed ventilation techniques. Anaesthesia 2014; 68: 794-95.
    10. Sato S, Hasegawa M, Okuyama M, et al. Mask ventilation during induction of general anesthesia. Anesthesiology 2017; 126: 28-38.
    11. Fei M, Blair JL, Rice MJ, et al. Comparison of effectiveness of two commonly used two-handed mask ventilation techniques on unconscious apnoeic obese adults. British Journal of Anaesthesia 2017; 118: 618-24.
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