Abstract
Background and Objectives: Video laryngoscopy has been proven useful under difficult airway scenarios, but it is unclear whether anticipated improvement of visualization is related to specific difficult intubation prognostic factors. The present study evaluated the change in laryngoscopic view between conventional and C-MAC® laryngoscopy and the presence of multiple difficult intubation risk factors. Materials and Methods: Patients scheduled for elective surgery with >2 difficult intubation factors, (Mallampati, thyromental distance (TMD), interinscisor gap, buck teeth, upper lip bite test, cervical motility, body mass index (BMI)) were eligible. Patients underwent direct laryngoscopy (DL) followed by C-MAC™ laryngoscopy (VL) and intubation. Change of view between DL and VL, time for best view, intubation difficulty scale (IDS) and correlation between prognostic factors, laryngoscopic view improvement, and IDS were measured. Results: One-hundred and seventy-six patients completed the study. VL lead to fewer Cormarck–Lehane (C/L) III-IV, compared to DL (13.6% versus 54.6%, p < 0.001). The time to best view was also shorter (VL: 10.82 s, DL: 12.08 s, p = 0.19). Mallampati III-IV and TMD ≤ 6 cm were related to improvement of C/L between DL and VL. Logistic regression showed these two factors to be a significant risk factor of the glottis view change (p = 0.006, AUC-ROC = 0.57, 95% CI: 0.47–0.66). 175/176 patients were intubated with VL. 108/176 were graded as 0 < IDS ≤ 5 and 12/176 as IDS > 5. IDS was only correlated to the VL view (p < 0.0001). Conclusion: VL improved laryngoscopic view in patients with multiple factors of difficult intubation. Mallampati and TMD were related to the improved view. However, intubation difficulty was only related to the VL view and not to prognostic factors.
Highlights
While direct laryngoscopy (DL) with the conventional Macintosh laryngoscope still remains the most common technique for endotracheal intubation, the introduction of video-assisted laryngoscopy (VL) during recent years has changed that practice
The aim of the present study was to compare the use of the Storz® C-MACTM video laryngoscope with conventional direct laryngoscopy in patients with known risk factors for difficult intubation during routine induction of anesthesia
4 cm, the presence of buck teeth more than 0.5 cm, upper lip bite test (ULBT) grade III and IV and > 15◦ reduction of cervical motility were considered as risk factors for difficult intubation
Summary
While direct laryngoscopy (DL) with the conventional Macintosh laryngoscope still remains the most common technique for endotracheal intubation, the introduction of video-assisted laryngoscopy (VL) during recent years has changed that practice. The role of VL in difficult intubation scenarios, has recently been recognized in both ASA and DAS guidelines [2,3]. Video laryngoscopy has been proven useful under difficult airway scenarios, but it is unclear whether anticipated improvement of visualization is related to specific difficult intubation prognostic factors. The present study evaluated the change in laryngoscopic view between conventional and C-MAC® laryngoscopy and the presence of multiple difficult intubation risk factors. Change of view between DL and VL, time for best view, intubation difficulty scale (IDS) and correlation between prognostic factors, laryngoscopic view improvement, and IDS were measured. VL lead to fewer Cormarck–Lehane (C/L) III-IV, compared to DL
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