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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
A randomised controlled trial comparing the McGrath Videolaryngoscope with the C-MAC Videolaryngoscope in adult patients with potential difficult airways
Scientific title
In adult patients with predicted difficult airways, which is defined as Mallampati III or IV, does the C-MAC Videolaryngoscope or the McGrath Videlaryngoscope allow a faster tracheal intubation time?
Secondary ID [1] 252673 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Patients with predicted difficult airways, defined as Mallampati grade III or IV 258135 0
Condition category
Condition code
Anaesthesiology 258379 258379 0 0

Study type
Description of intervention(s) / exposure
Patients will be anaesthetized in an area with appropriate monitoring, resuscitation equipment and assistance in accordance with the Australian and New Zealand College of the Anaesthetists’ guidelines. After pre-oxygenation with 100% oxygen to reach the end-tidal oxygen (O2) = 70%, patients will be given induction agents and neuromuscular agent of choice at the discretion of the anaesthetist involved with the patient’s overall care. Patients will be placed in the “sniffing” position with the head on a pillow and ventilated via a face-mask with 100% oxygen until complete paralysis is achieved. Patients will then be intubated with either the Miller straight blade laryngoscope or the Video Laryngoscope, according to the study allocation. The intubation will be performed by an experienced anaesthetist (> 10 years’ experience) who is familiar with the use of both devices (> 10 uses on each device) prior to the study. The McGrath Videolaryngoscope blade will be inserted along the midline of the tongue, with the introduction of a styleted endotracheal tube angulated according to the curve of the Video Laryngoscope blade, as suggested by the case series studies. If more than one attempt of intubation is required, the patient will receive bag-and-mask ventilation between attempts and various manoeuvres can be introduced, such as, external laryngeal pressure, readjustment of stylet and bougie assistance. Failed intubation is defined as failure after three attempts. An alternative airway management plan can then be resorted to at the discretion of the anaesthetist. This is a one-off treatment.
Intervention code [1] 257153 0
Treatment: Devices
Comparator / control treatment
Intubation with the C-MAC Videolaryngoscope. The tip of the C-MAC (registered trademark) Videolaryngoscope blade will be advanced towards the vallecula, in the same way it is advanced with a Macintosh blade. The position of the device will be adjusted to have the glottis in the center of the screen. This is a one-off treatment.
Control group

Primary outcome [1] 259170 0
Time for successful intubation or until alternative management selected. Alternative management will be decided after failed attempt with the allocated device. Failed attempt is defined as more than three intubation attempts.
Timepoint [1] 259170 0
During intubation - From insertion of the allocated videolaryngoscope into the participants mouth until end-tidal carbon dioxide (CO2) detected by capnography.
Secondary outcome [1] 265509 0
Comparison of the laryngoscopy view using the Cormack and Lehane grading system (Grade I to IV: Grade I is when most of glottis is seen, Grade II is when only posterior part of glottis is seen, Grade III is when only the epiglottis is seen, and Grade IV is when neither the epiglottis nor the glottis is seen.)). This is assessed by the anaesthetist performing the intubation, the view is seen during intubation.
Timepoint [1] 265509 0
During intubation, when best laryngoscopic view is obtained with the allocated device.
Secondary outcome [2] 265510 0
Proportion of successful or failed intubations in each study group
Timepoint [2] 265510 0
Recorded during the intubation attempt
Secondary outcome [3] 265511 0
Number of attempts needed for successful intubation
Timepoint [3] 265511 0
Recorded during the intubation attempt
Secondary outcome [4] 265512 0
Ease of intubation which will be surveyed using a visual analogue scale from 0-100mm. (0mm is easiest and 100mm is the most difficult). This is determined by the anaesthetist performing the intubation.
Timepoint [4] 265512 0
During intubation
Secondary outcome [5] 265513 0
Haemodynamic changes during intubation. This is assessed by the independent observer, using the patient vital record on the monitor.
Timepoint [5] 265513 0
At baseline, at induction and every minute thereafter until successful intubation.
Secondary outcome [6] 265514 0
Any complications associated with oro-tracheal intubation, such as, lips, oral mucosal and dental injury, oesophageal intubation, hypoxia with saturation of peripheral oxygen less than 90% (SpO2 < 90%) during intubation. This will be reported by the anaesthetist who performed the intubation.
Timepoint [6] 265514 0
During and after intubation

Key inclusion criteria
Mallampati III or IV
Undergoing elective surgery at Royal Melbourne Hospital
Requiring oro-tracheal intubation
American Society of Anesthesiology (ASA) Grade I, II or III
Over 18 years of age
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Non English speaking or reading
ASA Grade IV or V
Presence of any other predictors of difficult intubation

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Patient information from the Royal Melbourne Hospital pre-admission clinic is reviewed, looking for patients that fit the inclusion criteria.
If it seems that they will fall into the inclusion criteria, one of the researchers will approach the patient and explain the trial before gaining informed consent.
The patient will then be given a number unique to the trial so that their hospital identification number is not used. This allows de-identification of participants.
Using a computer program, the patient’s number will be randomly allocated into either the McGrath Videolaryngoscope group or the C-MAC Videolaryngoscope group. The randomisations will be concealed in a sealed opaque envelope.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation is by using a computer-generated block randomization method in blocks of ten.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 257605 0
Name [1] 257605 0
Royal Melbourne Hospital
Address [1] 257605 0
Grattan st, Parkville, VIC 3050
Country [1] 257605 0
Primary sponsor type
Royal Melbourne Hospital
Grattan st, Parkville, VIC 3050
Secondary sponsor category [1] 256857 0
Name [1] 256857 0
Address [1] 256857 0
Country [1] 256857 0

Ethics approval
Ethics application status
Ethics committee name [1] 259625 0
Melbourne Health Human Research Ethics Committee
Ethics committee address [1] 259625 0
PO Royal Melbourne Hospital
Parkville Victoria 3050
Ethics committee country [1] 259625 0
Date submitted for ethics approval [1] 259625 0
Approval date [1] 259625 0
Ethics approval number [1] 259625 0

Brief summary
Intubation is one of the most important skills that anaesthetists have. There are currently many different intubating devices available. Anaesthetists have to develop and maintain skills with more than one type of device, so that when faced with difficult tracheal intubation, a safe alternative technique can be used without causing complications. Both the McGrath and the C-MAC videolaryngoscopes are relatively new intubating devices, which have a high-resolution camera and light source embedded at the distal end of the blade. They allow a view of the anterior glottis without the need for a direct line of sight. Both devices claim to provide a comparable or superior glottic view when compared with direct laryngoscopy using the standard curved Macintosh blade. However, the design of the shape of the blades between the two videolarygoscopes are very different. Currently, there are no studies comparing the use of these two devices in patients with potential difficult airways, which are usually the most useful situations.

The aim of this prospective randomized controlled trial is to compare the effectiveness of using these two devices in performing endotracheal intubation in adult patients with predicted difficult airways.

The research is designed to be conducted in 130 adult patients with Mallampatti 3 or 4 (one of the predictors of difficult airways) and ASA 1-3 having oro-tracheal intubation for elective surgery . After informed consent, the patients will be randomized to having either the McGrath or C-MAC videolarygngoscopes for the intubation. The primary outcome is the timing of intubation. Secondary outcomes include the glottic view, ease of intubation, number of attempts required, haemodynamic changes and also any associated complications.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 31612 0
Address 31612 0
Country 31612 0
Phone 31612 0
Fax 31612 0
Email 31612 0
Contact person for public queries
Name 14859 0
Dr Irene Ng
Address 14859 0
Department of Anaesthesia and Pain Management
Royal Melbourne Hospital
Grattan st, Parkville, VIC 3050
Country 14859 0
Phone 14859 0
+61 3 93427540
Fax 14859 0
+61 3 93428623
Email 14859 0
Contact person for scientific queries
Name 5787 0
Dr Irene Ng
Address 5787 0
Department of Anaesthesia and Pain Management
Royal Melbourne Hospital
Grattan st, Parkville, VIC 3050
Country 5787 0
Phone 5787 0
+61 3 93427540
Fax 5787 0
+61 3 93428623
Email 5787 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary