Effects of cardiopulmonary resuscitation on direct versus video laryngoscopy using a mannequin model

During the last decade, guidelines for cardiopulmonary resuscitation has shifted, placing chest compressions and defibrillation first and airway management second. Physicians are being forced to intubate simultaneously with uninterrupted, high quality chest compressions. Using a mannequin model, this study examines the differences between direct and video laryngoscopy, comparing their performance with and without simultaneous chest compressions.

Fifty emergency medicine physicians were randomly assigned to intubate a mannequin six times, using direct laryngoscopy (DL) and with two video laryngoscopy (VL) systems, a C-MAC traditional Macintosh blade and a GlideScope hyperangulated blade, with and without simultaneous chest compressions. A total of 300 intubations were completed and variables including intubation times, accuracy, difficulty, success rates and glottic views were recorded.

The C-MAC VL system resulted in quicker intubations compared to DL (p = 0.007) and the GlideScope VL system (p = 0.039) during active chest compressions. Compared to DL, intubations were rated easier for both the C-MAC (p < 0.0001) and the GlideScope (p < 0.0001). Intubation failure rates were also higher when DL was used compared to either the C-MAC or GlideScope (p = 0.029). VL devices provided a superior overall Cormack-Lehane grade view compared to DL (p < 0.0001). The presence of chest compressions significantly impaired Cormack-Lehane views during direct laryngoscopy (p = 0.007). Chest compressions made the intubation more difficult under DL (p = 0.002) and when using the C-MAC (p = 0.031). Chest compressions also made ETT placement less accurate when using DL (p = 0.004).

Using a mannequin model, the C-MAC conventional VL blade resulted in decrease intubation times compared with DL or the GlideScope hyperangulated VL blade system. Overall, VL out performed DL in terms of providing a superior glottic view, minimizing failed attempts, and improving physician's overall perception of intubation difficulty. Chest compressions resulted in worse Cormack-Lehane views and higher rates of inaccurate endotracheal tube placement with DL, compared to VL.