Effect of stylet angulation and endotracheal tube camber on time to intubation with the GlideScope®

  • Philip M. JonesEmail author
  • Timothy P. Turkstra
  • Kevin P. Armstrong
  • Paidrig M. Armstrong
  • Richard A. Cherry
  • Jason Hoogstra
  • Christopher C. Harle
Reports of Original Investigations



The GlideScope® videolaryngoscope usually provides excellent glottic visualization, but directing an endotracheal tube (ETT) through the vocal cords is sometimes difficult. The goal of the study was to determine which of two ETT angles (60°vs 90°) and cambers (forwardvs reverse) was better, as determined by time to intubation (TTI).


Tw o hundred patients requiring orotracheal intubation for elective surgery were randomly allocated to one of four groups: A) 90° angle, forward camber; B) 90° angle, reverse camber; C) 60° angle, forward camber; D) 60° angle, reverse camber. Time to intubation was assessed by a blinded observer. Operators were blinded until the point of intubation. A visual analogue scale (VAS) assessed the ease of intubation. The number of intubation attempts, number of failures, glottic grades, and use of external laryngeal manipulation were recorded.


The angle of the ETT had an impact on TTI but camber did not. The 90° angle demonstrated a 13% faster TTI than the 60° angle (47.1 ± 21.2 secvs 54.4 ± 28.2 sec,P = 0.042), and it resulted in easier intubation (VAS 16.4 ± 14.2 mmvs 27.3 ± 23.5 mm,P = 0.0001). The overall incidence of a grade 1 or 2 Cormack-Lehane glottic view was 99%.


In a heterogeneous group of operators and patients intubated with the GlideScope®, a 90° ETT angle provided the best result and should be the initial configuration. The camber of the ETT does not affect the time to intubation.


Visual Analogue Scale Intubation Attempt Video Laryngoscope Macintosh Laryngoscope Difficult Tracheal Intubation 
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Effet de l’angulation du mandrin et de la cambrure de la sonde endotrachéale sur le temps requis pour l’intubation avec le GlideScope®



Le vidéo-laryngoscope GlideScope® offre en général une excellente visualisation glottique; toutefois, il est parfois difficile d’orienter la sonde endotrachéale (SET) entre les cordes vocales. Le but de cette étude était de déterminer lequel de deux angles de SET (60° vs 90°) et quelle cambrure (avant vs arrière) étaient les meilleurs, déterminés selon le temps requis pour l’intubation (TRI).


Deux cents patients nécessitant une intubation oro-trachéale pour une chirurgie réglée ont été répartis en quatre groupes de façon aléatoire: a) angulation de 90°, cambrure avant; b) angulation de 90°, cambrure arrière; c) angulation de 60°, cambrure avant; d) angulation de 60°, cambrure arrière. Le temps requis pour l’intubation était estimé par un observateur ignorant le groupe d’allocation. Les opérateurs ont été tenus ignorants du groupe d’allocation jusqu’à l’intubation. Une échelle visuelle analogique (VAS) permettait d’estimer la facilité d’intubation. Le nombre de tentatives d’intubation, d’échecs, les grades glottiques ainsi que l’utilisation de manipulation laryngée externe étaient notés.


L’angulation de la SET a eu un impact sur le TRI mais pas la cambrure. Avec une angulation de 90°, le TRI était de 13% plus rapide qu’avec une angulation de 60° (47,1 ± 21,2 sec vs 54,4 ± 28,2 sec, P = 0,042), et l’ intubation était plus facile (VAS 16,4 ± 14,2 mm vs 27,3 ± 23,5 mm, P = 0,0001). L’incidence globale d’une visualisation glottique Cormack-Lehane de grade I ou 2 a été de 99 %.


Dans un groupe hétérogène d’opérateurs et de patients intubés avec le GlideScope®, une angulation de la SET de 90° offre le meilleur résultat et devrait être la configuration initiale. La cambrure de la SET n’affecte pas le temps requis pour l’intubation.


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Copyright information

© Canadian Anesthesiologists 2007

Authors and Affiliations

  • Philip M. Jones
    • 1
    Email author
  • Timothy P. Turkstra
    • 1
  • Kevin P. Armstrong
    • 1
  • Paidrig M. Armstrong
    • 1
  • Richard A. Cherry
    • 1
  • Jason Hoogstra
    • 1
  • Christopher C. Harle
    • 1
  1. 1.Department of Anesthesia & Perioperative MedicineUniversity of Western OntarioLondonCanada

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