A MRI study of the sniffing, neutral and extended head positions
Research type
Research Study
Full title
Changes in the angle between tracheal and laryngeal axes in sniffing, neutral and head extended positions by magnetic resonance imaging.
IRAS ID
282078
Contact name
Cyprian Mendonca
Contact email
Sponsor organisation
University Hospitals Coventry and Warwickshire NHS Trust
Duration of Study in the UK
0 years, 11 months, 30 days
Research summary
Videolaryngoscopes (a piece of equipment with a video screen used to place breathing tubes when patient’s go to sleep for operations) are increasingly used. However, the breathing tube getting caught on the front part of the windpipe when trying to advance it (anterior impingement) is a recognised problem with some videolaryngoscopes. In a previous study, the sniffing position has been shown to increase the chance of difficulty in placing the tube. Therefore, poor patient positioning could result in an unsuccessful attempt and further repeated attempts can be associated with poor outcomes.
Although the geometrical axes within the oral cavity for direct laryngoscopy have been studied previously, we are not aware of any study looking at the angle between tracheal (windpipe) and laryngeal (opening to the wind pipe, at the vocal cords) axes for videolaryngoscopy. We aim to measure the alpha (α) angle (the angle between the tracheal axis and laryngeal axis) using MRI in 20 volunteers in three different positions (neutral, sniffing and extension) and hypothesise the position that brings the alpha angle closest to 180 degrees would reduce the incidence of anterior impingement.
Healthy volunteers, aged > 18 years, NHS staff, medically able and willing to undertake MRI scanning will be invited to take part on voluntary basis.
Primary outcome is α angle between the tracheal axis (TA) and laryngeal axes (LA). Secondary endpoints include β angle (between laryngeal and pharyngeal axes) and δ angle (between pharyngeal and oral axes). Based on previous volunteer studies using MRI scan, we plan to recruit 20 volunteers. Data will be analysed using ANOVA or appropriate test and p value less than 0.05 was considered statistically significant.
The findings of this study will help the anaesthetist to choose a head and neck position during videolaryngoscopy that is likely to improve the success rate of placing the breathing tube in the windpipe.
REC name
West Midlands - Solihull Research Ethics Committee
REC reference
21/WM/0140
Date of REC Opinion
6 Jul 2021
REC opinion
Further Information Favourable Opinion