Head Elevated Position and Hyper-angulated Video-laryngoscope Guided Intubation

January 28, 2026 updated by: Jun joohyun, Hallym University Kangnam Sacred Heart Hospital

Effect of Head Elevated Position on Ease of Tracheal Intubation Using Hyper-angulated Video-laryngoscope in Patients With Simulated Difficult Airway

Cervical immobilization with manual in-line stabilization (MILS) is recommended to prevent further neurologic injury during intubation in patients with known or suspected cervical spine injuries. However, MILS is associated with increased rates of failed tracheal intubation using direct laryngoscopy, because the restriction of neck flexion and head extension may prevent adequate alignment of the oral, pharyngeal, and tracheal axes, hence adversely affecting laryngeal visualization during direct laryngoscopy.

The GlideScope® (Verathon, Bothell, WA, USA) is a videolaryngoscope with an hyer-angulated blade (HA-VL), which is characterized by a sharper curvature than the Macintosh blade. The large curvature of the HA-VL allows seeing 'round the corner', which can provide indirect laryngeal visualization even with restricted neck movements . However, the HA-VL also prevents direct visualization of larynx, which make it difficult to guide the tracheal tube (TT) towards the glottis despite obtaining a good laryngeal view. Thus, the good view of the laryngeal inlet provided by videolaryngoscopes does not always lead to an easy or successful intubation. There are numerous reports in the literature of devices managing to achieve an improvement in view but still being unable to pass an TT to laryngeal inlet. Thus, the key to a successful tracheal intubation using HA-VL lies not in the laryngeal view obtained but in the ease of inserting the TT. Recent meta studies comparing alternative intubation devices with the standard Macintosh laryngoscope in subjects with cervical spine immobilization reported that GlideScope® was associated with improved glottis visualization but no statistically significant differences in intubation failure or time to intubation compared with direct laryngoscopy.

The sniffing position recommended for direct laryngoscopy has been reported to interfere with successful tracheal intubation with HA-VL because flexion of the neck narrows the angle between the sternum and the chin, making it more difficult to insert the HA-VL blade into mouth. In contrast, placing the patient in a 'neutral' or 'back-up head-elevated (BUHE)' position was not associated with a higher incidence of difficult laryngoscope with HA-VL. Given that the 'BUHE' position, when compared with the regular supine position, extend the safe apnoea time during direct laryngoscopy, this position seems better suited for HA-VL than neutral position. However, there is currently insufficient evidence to recommend a specific patient position for the use of HA-VL.

Previous studies using magnetic resonance imaging (MRI) suggests that head elevation until the external auditory meatus and sternal notch (AM-S) are in the horizonal plane leads to better anatomic alignment of the pharyngeal and laryngeal axes. Investigators therefore hypothesized that BUHE position (to align the AM-S in horizontal plane), compared with neutral position, would allow a relatively straight passage which makes it easier to guide the TT into the laryngeal inlet (facilitates insertion of TT into the laryngeal entrance) during HA-VL guided intubation. To compare the effect of the BUHE position and the neutral position on the ease of tracheal intubation using a HA-VL (GlideScope®), MILS was applied to patients without any known or suspected neck pathology as a way of simulating a difficult airway. The primary outcome was the tracheal intubation time with both positions. Secondary outcomes examined included rates of successful tracheal intubation and intubation success rate, number of intubation attempts, heart rate responses during intubation, and handling of the Glidesope VL after alignment of the EAM and sternal notch.

Study Overview

Status

Status

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Completed

Conditions

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Interventional

Enrollment (Actual)

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182

Phase

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  • Not Applicable

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Study Locations

  • South Korea
      • Seoul, South Korea
        • Hallym University Kangnam Sacred Heart Hospital

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Ages Eligible for Study

18 years to 80 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • patients of ASA physical status 1-2 who were scheduled for elective surgery under general anaesthesia requiring tracheal intubation.

Exclusion Criteria:

  • if they required rapid sequence induction;
  • history of previous difficult direct laryngoscopy
  • unwilling to provide informed consent
  • uncontrolled hypertension
  • history of ischaemic heart disease without optimal control of symptoms
  • history of acute or recent stroke or myocardial infarction
  • cervical spine instability or cervical myelopathy
  • symptomatic asthma or reactive airway disease requiring daily pharmacological treatment for control of symptoms
  • history of gastric reflux.

Study Plan

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How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

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Intervention / Treatment

Intervention / Treatment

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Placebo Comparator: neutral position
intubation was performed in the neutral position
Procedure: neutral position
The patient was then placed in the netural position
Experimental: back-up head elevated position
he trachea was intubated in the back-up head elevated position
Procedure: back-up head elevated position
The patient was then placed in the back-up head elevated position to align the external auditory meatus and sternal notch, which was achieved by breaking the operating table

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
ease of tracheal intubation (easy/modified/unachievable)
Time Frame: The time from the insertion of laryngoscope into oral cavity until tracheal intubation over 1minute period
the need for optimization procedure to facilitate laryngeal visualization and tracheal intubation easy: no need for optimization procedure. modified: need for optimization procedure unachievable: unable to insert tracheal tube even after optimzation procedure
The time from the insertion of laryngoscope into oral cavity until tracheal intubation over 1minute period

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
intubation time
Time Frame: : The time from the insertion of laryngoscope into oral cavity until its removal over 1 minute period
time required for intubation
: The time from the insertion of laryngoscope into oral cavity until its removal over 1 minute period
percentage of glottic opening (POGO) score (0-100%)
Time Frame: During laryngeal visualization by laryngoscope over 1 minute period
percentage of glottic opening (0 - 100) 0%: visualization of none of the glottis 100%: visualization of the whole glottis
During laryngeal visualization by laryngoscope over 1 minute period

Collaborators and Investigators

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Sponsor

Sponsor

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Hallym University Kangnam Sacred Heart Hospital

Publications and helpful links

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General Publications

Study record dates

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Study Major Dates

Study Start (Actual)

Study Start

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January 16, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 31, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 31, 2023

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 3, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 3, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 5, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 29, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 28, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2022-11-010-001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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