Dental strain on maxillary incisors during tracheal intubation with double-lumen tubes and different laryngoscopy techniques - a blinded manikin study

Objectives : To quantify dental forces during double-lumen tube intubations with different laryngoscopy techniques. Design : Experimental biomechanical manikin study. Setting : Two German university hospitals. Participants : 104 anaesthetists with varying levels of experience. Interventions : Participants performed a sequence of intubations on a manikin equipped with hidden forces sensors in the maxillary incisors. Different laryngoscopy techniques were evaluated under normal and difficult airway conditions. Direct laryngoscopy was compared to different videolaryngoscopy techniques: the C-MAC with a Macintosh blade, the GlideScope and the KingVision with hyperangulated blades. Measurements and Main Results : A total of 624 intubations were evaluated. In normal airway conditions, the median (IQR [range]) peak forces were significantly lower when the GlideScope (15.7 (11.3-22.0[2.1-110.5]) N) was used compared to direct laryngoscopy (21.0 (14.1-28.5[4.7-168.6]) N) (p=0.007). In difficult airways, resulting forces were reduced using hyperangulated videolaryngoscopes (GlideScope -13.7 N (p<0.001); KingVision -11.9 N (p<0.001)) compared to direct laryngoscopy, respectively. The time to intubation was prolonged with the use of the KingVision (25.5 (17.1-41.9[9.2-275.0])) s (p<0.001)) in comparison to direct laryngoscopy (20.8 (15.9-27.4[8.7-198.6]) s). The C-MAC demonstrated the shortest time to intubation. Conclusions : While hyperangulated videolaryngoscopes improve dental strain, clinicians should also consider the time to intubation, which is shortest with non-hyperangulated videoblades, when choosing a laryngoscopy technique on an individual patient basis.