Comparative evaluation of laryngeal view and intubating conditions in two laryngoscopy positions-attained by conventional 7 cm head raise and that attained by horizontal alignment of external auditory meatus - sternal notch line - using an inflatable pillow - A prospective randomised cross-over trial

A comparative evaluation of the sniffing, the simple head extension and the head hyperextension positions for laryngoscopic view and intubation difficulty in adults undergoing direct laryngoscopy

OBJECTIVE

This work aimed to compare between the laryngoscopy positions; sniffing, simple head extension and head hyperextension positions to assess whether the laryngeal view, intubation time and intubation difficulty could improve with one of these positions than the others.

DESIGN

Prospective randomized three arms clinical trial.

SETTING

Operation room, the phoniatrics unit [removed for blind peer review].

PARTICIPANTS

The study included 75 cases with 25 cases in each group. Group "A" with head in the sniffing position, Group "B" with the head in simple extension position, Group "C" with head in hyperextension position.

RESULTS

The three groups were compared regarding intubation time and laryngoscopic view time. Intubation time showed statistically significant difference between the three groups. Mean of sniffing group (No. = 25) was 13.19 s (± 3.35). Mean of simple extension group (No. = 25) was 11.29 s (± 3.14). Mean of Hyperextension group (No. = 25) was 14.39 s (± 4.14). Laryngoscopic view time showed statistically highly significant difference between the three groups. Mean of sniffing group (No. = 25) was 17.19 s (± 7.27). Mean of simple group (No. = 25) was 12.18 s (± 4.46). Mean of hyperextension group (No. = 25) was 17.08 s (± 6.51).

CONCLUSION

Comparing the sniffing, the simple extension and the hyperextension positions, the simple extension position showed the best time regarding intubation time and laryngoscopic view time.

Effects of head-elevated position on tracheal intubation using a McGrath MAC videolaryngoscope in patients with a simulated difficult airway: a prospective randomized crossover study

Background

The head-elevated laryngoscopy position has been described to be optimal for intubation, particularly in obese patients and those with anticipated difficult airways. Horizontal alignment of the external auditory meatus and sternal notch (AM-S) can be used as endpoints for optimal positioning. Thus, we aligned the head-elevated position with the AM-S in the horizontal plane and evaluated its effect on laryngeal visualization and ease of intubation using a McGrath MAC videolaryngoscope in patients with a simulated difficult airway.

Methods

Sixty-four patients were included in this prospective, crossover, randomized controlled trial. A cervical collar was used to restrict neck movement and mouth opening. The head-elevated position was achieved by raising the back section of the operation room table and ensuring that the end point was horizontally aligned with the AM-S (table-ramp method). The laryngeal view was randomly assessed in both head-flat and head-elevated positions based on the percentage of glottic opening (POGO) score and modified Cormack–Lehane (MCL) grade. External laryngeal manipulation was not permitted when laryngeal visualization was scored. The trachea was intubated only once (in the second position). The ease of intubation was assessed based on the need for optimization maneuvers, intubation difficulty scale (IDS) scores and time to intubation.

Results

The mean table-ramp angle required to achieve the horizontal alignment of AM-S was 17.5 ± 4.1°. The mean POGO score improved significantly in the head-elevated position (59.4 ± 23.8%) when compared with the head-flat position (37.5 ± 24%) (P <  0.0001). MCL grade 1 or 2a was achieved in 56 (85.9%) and 28 (43.7%) of patients in the head-elevated and head-flat positions, respectively (P <  0.0001). Optimization maneuvers for intubation were required in 7 (21.9%) and 17 (53.1%) patients in the head-elevated and head-flat positions, respectively (P <  0.0001). The IDS scores and time to intubation did not differ significantly between the two positions.

Conclusion

In the head-elevated position, aligning the AM-S in the horizontal plane consistently improved laryngeal visualization without worsening the view when the McGrath MAC videolaryngoscope was used in patients with simulated difficult airways. It also improved the ease of intubation, which reduced the need for optimization maneuvers.

Trial registration

This trial was registered with www.clinicaltrials.gov, NCT04716218, on 20/01/2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01706-5.