Measurement of Forces Applied Using a Macintosh Direct Laryngoscope Compared to GlideScope Video Laryngoscope

Measurement of Forces Applied Using a Macintosh Direct Laryngoscope Compared to GlideScope Video Laryngoscope in Patients With at Least One Difficult Intubation Risk Factor

During Anesthesia many patients require that a breathing be inserted into their windpipe. This is usually achieved using a direct laryngoscope, consisting of a retraction blade with a light near its end. When achieving a direct line-of-sight to the windpipe is difficult, more force is often applied, resulting in greater patient stress. A GlideScope video laryngoscope uses a camera and light source to see the windpipe. This enables the user to see objects that may not be in the direct line-of-sight. This likely results in less force being required, reducing patient stress. Because such stresses are often confounded by patient variables, we are comparing the forces required by the direct and video laryngoscopes on patients with at least one risk factor for difficulty, by directly measuring these with special sensors attached to the laryngoscope blades.

Study Overview

• Status: Completed
• Conditions: Moderately Difficult to Intubate
• Intervention / Treatment: Device: Intubation with GlideScope Video Laryngoscope or Macintosh Direct Laryngoscope

• Study Type: Interventional
• Enrollment (Actual): 44
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M8X 1W4
      • Toronto General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• age > 18years
• elective surgery
• single lumen endotracheal intubation required
• signed informed consent
• one risk factor for a difficult laryngoscopy ( Mallampati score >3, inter-incisor gap < 3.5cm, thyromental distance < 6.5cm, sternomental distance < 12.5cm, reduced neck extension and flexion)

Exclusion Criteria:

• lack of patient consent
• anesthesiologist declines to consent
• contraindication to neuromuscular blockade
• ASA 4
• rapid sequence intubation
• previous failed intubation
• other method of intubation indicated eg fiberoptic intubation, awake tracheostomy
• symptomatic gastro-esophageal reflux
• cervical spine instability
• unstable hypertension and symptomatic coronary artery disease
• cerebrovascular disease or raised intracranial pressure
• oral/pharyngeal/laryngeal carcinoma
• loose teeth/poor dentition

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Macintosh Direct Laryngoscope; 2 main forces - a 'lifting' force to elevate the structures not in the line of sight and a force exerted by the user's wrist to counterbalance the torque effect of the tongue tissues on the blade	Device: Intubation with GlideScope Video Laryngoscope or Macintosh Direct Laryngoscope
Active Comparator: GlideScope Video Laryngoscope; The GlideScope has a 60º angulation anteriorly at the distal portion of the blade, allowing an anterior view of the larynx.	Device: Intubation with GlideScope Video Laryngoscope or Macintosh Direct Laryngoscope

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak forces during intubation	Peak forces generated during the laryngoscopy and intubation process using both laryngoscopes.	Intraoperatively

Collaborators and Investigators

• Sponsor: University Health Network, Toronto

Publications and helpful links

General Publications

• Cordovani D, Russell T, Wee W, Suen A, Cooper RM. Measurement of forces applied using a Macintosh direct laryngoscope compared with a Glidescope video laryngoscope in patients with predictors of difficult laryngoscopy: A randomised controlled trial. Eur J Anaesthesiol. 2019 Mar;36(3):221-226. doi: 10.1097/EJA.0000000000000901.

Study record dates

Study Major Dates

• Study Start: July 1, 2011
• Primary Completion (Actual): June 1, 2012
• Study Completion (Actual): June 1, 2012

Study Registration Dates

• First Submitted: March 15, 2013
• First Submitted That Met QC Criteria: March 15, 2013
• First Posted (Estimate): March 19, 2013

Study Record Updates

• Last Update Posted (Estimate): December 7, 2016
• Last Update Submitted That Met QC Criteria: December 6, 2016
• Last Verified: March 1, 2013

More Information

Terms related to this study

• Other Study ID Numbers: 11-0229-B