Tracheal intubation using the mobile C-MAC video laryngoscope or direct laryngoscopy for patients with a simulated difficult airway

Abstract

Background: Several studies have shown that video laryngoscopy enhances the laryngeal view in patients with apparently normal and anticipated difficult airways. The utility of the novel, portable, battery-powered C-MAC video laryngoscope is unproven, but its design makes it potentially useful for emergency situations. We hypothesized that, in patients with a simulated difficult airway created by means of a rigid cervical immobilization collar, the rate of glottic views considered "failed" under direct laryngoscopy could be significantly reduced with the C-MAC video laryngoscope.

Methods: Following power analysis and ethical approval, 43 adults undergoing surgery under general anesthesia were studied. First, direct laryngoscopy was performed with the naked eye with and without applying external laryngeal pressure (BURP maneuver). The best-obtained view was graded by the laryngoscopist without looking at the video monitor. A second anesthesiologist, who was blinded to the laryngeal view obtained under direct laryngoscopy, graded the laryngeal view on the video monitor. A difficult airway was then created and the laryngoscopy sequence repeated. Endotracheal intubation was then attempted under video-aided visualization.

Results: In patients with a normal airway, the glottic view was considered as "good" in the vast majority of patients (40-43/43; 93-100%) regardless of the laryngoscopy technique used. When a difficult airway was created, the glottic view was graded as "failed" in 30/43 (70%) and 16/43 (37%) of patients under direct laryngoscopy without and with the BURP maneuver, respectively (P=0.0047). Using video laryngoscopy, significantly fewer laryngoscopic views were graded as "failed" without (14%, P<0.0001) and with the BURP maneuver (5%, P=0.0003) compared to direct laryngoscopy. Endotracheal tube placement was successful in 88% of patients with a difficult airway.

Conclusion: The C-MAC video laryngoscope effectively enhanced the laryngeal view in patients with limited inter-incisor distance and eliminated cervical spine clearance. However, endotracheal tube placement failed in 5/43 patients despite a mostly good laryngeal view.