Table 2.
Characteristics of the Operator and Intubation Procedure.
| Characteristic | Video Laryngoscope (N = 705) | Direct Laryngoscope (N = 712) |
|---|---|---|
| Operator * | ||
| Clinical specialty — no. (%) | ||
| Emergency medicine | 496 (70.4) | 497 (69.8) |
| Critical care medicine | 177 (25.1) | 182 (25.6) |
| Anesthesiology | 18 (2.6) | 25 (3.5) |
| Other† | 14 (2.0) | 8 (1.1) |
| Level of training — no. (%) | ||
| Resident physician | 513 (72.8) | 502 (70.5) |
| Fellow physician | 164 (23.3) | 173 (24.3) |
| Attending physician | 9 (1.3) | 18 (2.5) |
| Other clinician‡ | 19 (2.7) | 19 (2.7) |
| Median no. of previous intubations performed (IQR) | 50 (25–90) | 50 (26–99) |
| Proportion of previous intubations performed with a video laryngoscope — no./total no. (%)§ | ||
| <0.25 | 44/704 (6.2) | 34/711 (4.8) |
| 0.25 to 0.75 | 398/704 (56.5) | 429/711 (60.3) |
| >0.75 | 262/704 (37.2) | 248/711 (34.9) |
| Intubation Procedure | ||
| Preoxygenation received — no. (%) | 702 (99.6) | 711 (99.9) |
| Median oxygen saturation at induction (IQR)¶ | 100 (97–100) | 100 (98–100) |
| Median systolic blood pressure at induction (IQR) — mm Hg∥ | 130 (111–150) | 129 (110–148) |
| Sedative medication administered for induction — no./total no. (%) | 668/695 (96.1) | 676/705 (95.9) |
| Neuromuscular blocking medication administered — no./total no. (%) | 668/696 (96.0) | 677/706 (95.9) |
| Laryngoscope — no. (%) | ||
| Direct** | 0 | 704 (98.9) |
| Video†† | 705 (100) | 8 (1.1) |
| Standard geometry blade | 607 | 5 |
| Hyperangulated blade | 98 | 3 |
| Cormack–Lehane grade of view — no. (%)‡‡ | ||
| 1 | 538 (76.3) | 318 (44.7) |
| 2 | 141 (20.0) | 244 (34.3) |
| 3 | 19 (2.7) | 97 (13.6) |
| 4 | 7 (1.0) | 53 (7.4) |
| Instrument used on first laryngoscopy attempt — no. (%) | ||
| Endotracheal tube with stylet | 389 (55.2) | 339 (47.6) |
| Bougie | 297 (42.1) | 335 (47.1) |
| No attempt to intubate on first laryngoscopy attempt§§ | 19 (2.7) | 37 (5.2) |
| Not reported | 0 | 1 (0.1) |
A total of 387 unique operators performed an intubation during the trial, with each operator performing a median of 2 intubations (IQR, 1 to 4).
The other specialty category included internal medicine, combined emergency medicine and internal medicine, pediatric emergency medicine, and paramedicine.
The other clinician category included certified registered nurse anesthetists, physician assistants, and nurse practitioners.
The proportion of previous intubations performed with a video laryngoscope was calculated by dividing the number of intubations the operator had performed with a video laryngoscope by the total number of intubations the operator had performed with either a video laryngoscope or a direct laryngoscope. Values range from 0.0 (all previous intubations were performed with a direct laryngoscope) to 1.0 (all previous intubations were performed with a video laryngoscope).
Data on oxygen saturation at the time of induction of anesthesia were missing for 121 patients (8.5%): 57 in the video-laryngoscope group and 64 in the direct-laryngoscope group.
Data on systolic blood pressure at induction were missing for 208 patients (14.7%): 108 in the video-laryngoscope group and 100 in the direct-laryngoscope group.
Among the 704 patients who underwent intubation with a direct laryngoscope, 696 (98.9%) underwent procedures that were performed with a Macintosh blade and 8 (1.1%) underwent procedures that were performed with a Miller blade.
Video laryngoscopes with a standard geometry blade included Storz C-MAC (used in 428 patients), McGrath MAC (in 96 patients), and GlideScope MAC (in 88 patients). Video laryngoscopes with a hyperangulated geometry blade included GlideScope LoPro (used in 61 patients), GlideScope GVL (in 14 patients), Storz C-MAC D-blade (in 23 patients), and McGrath X blade (in 3 patients). No video laryngoscopes with channeled blades were used.
The operator assessed the view of the larynx on the first laryngoscopy attempt with the use of the Cormack–Lehane grading scale; grades range from 1 (view of most of the vocal cords) to 4 (epiglottis not visible).
Cases in which neither a stylet nor a bougie was used on the first laryngoscopy attempt are cases in which the laryngoscope blade was removed from the mouth without any attempt to intubate the trachea.