Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12609000688280
Ethics application status
Approved
Date submitted
7/04/2009
Date registered
12/08/2009
Date last updated
15/09/2010
Type of registration
Prospectively registered

Titles & IDs
Public title
Comparing two intubation devices (videolaryngoscope vs straight blade laryngoscope) in intubating patients with potential difficult airways.
Scientific title
A randomized controlled trial comparing the McGrath (Registered Trademark) Video Laryngoscope with the Miller straight blade laryngoscope in intubating adult patients with predicted difficult airways.
Secondary ID [1] 252707 0
McGrath vs Henderson
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Patients with potential difficult airways 4573 0
Condition category
Condition code
Anaesthesiology 4865 4865 0 0
Anaesthetics

Intervention/exposure
Study type
Interventional
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 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. A direct laryngoscopy assessment will be performed with the allocated intubating device. The Video Laryngoscope 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.
Intervention code [1] 4335 0
Treatment: Devices
Comparator / control treatment
Intubation with the Miller straight blade laryngoscope. The Miller straight blade will be inserted using the paraglossal technique as described by Henderson. It will be a one-off treatment.
Control group
Active

Outcomes
Primary outcome [1] 5719 0
Comparison of the laryngoscopy view using the Cormack and Lehane grading system (Grade I to IV) between the Miller straight blade laryngoscope and the McGrath Video Laryngoscope in patients with Mallampati grade III or IV.
Timepoint [1] 5719 0
At the time of intubation
Secondary outcome [1] 241640 0
The time taken for successful tracheal intubation, which is measured from the time the allocated intubating device is inserted in the patient's mouth until end-tidal carbon dioxide is detected. If failed intubation is encountered, the time taken to resort to an alternative airway management is measured instead.
Timepoint [1] 241640 0
At the time of intubation
Secondary outcome [2] 257173 0
The proportion of successful and failed intubation in each of the study group. Failed intubation is defined as failure after 3 attempts.
Timepoint [2] 257173 0
At time of intubation
Secondary outcome [3] 257174 0
The number of attempts needed for successful tracheal intubation.
Timepoint [3] 257174 0
At time of intubation
Secondary outcome [4] 257175 0
The ease of intubation which will be surveyed using a visual analogue scale from 0-100mm.
Timepoint [4] 257175 0
At time of intubation
Secondary outcome [5] 257176 0
Any complications associated with oro-tracheal intubation will be recorded, such as, lips, oral mucosal and dental injury, oesophageal intubation, hypoxia (SpO2 < 90%) during intubation.
Timepoint [5] 257176 0
At time of intubation

Eligibility
Key inclusion criteria
Adult patients with American Society of Anesthesiologists (ASA) physical status classification system I, II or III and Mallampati III or IV (assessed with patients sitting upright with head in neutral position. Patients open the mouth maximally, protruding the tongue without phonation; class 3: soft and hard palate and base of the uvula are visible, class 4: only hard palate visible), who are scheduled for elective surgery requiring oro-tracheal intubation at the Royal Melbourne Hospital will be recruited for this study.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Exclusion criteria include patients who are < 18 years of age, non-English speaking, ASA Grade IV or V, presence of any other predictors of difficult intubation, including small mouth opening (< 4cm), short thyromental distance (< 6cm) and reduced neck extension (< 80o), patients at risk of regurgitation and aspiration (defined as history of oesophageal reflux, known hiatus hernia and not fasted), or patients with cervical spine instability.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation s concealed by sealed opaque envelopes.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Potential candidates for this study will be reviewed at the pre-admission clinic of the Royal Melbourne Hospital. Eligible patients will then be approached if they meet the inclusion criteria. Interested individuals will be seen by either the principal investigator or one of the co-investigator in order to explain the research study in detail. Written informed consent will be obtained before commencement of the study. After informed consent, patients will be assigned, by using a computer-generated block randomization method in blocks of eight, to either having intubation with the Miller straight laryngoscope using a size 3 or 4 blade or intubation with the Video Laryngoscope (McGrath).
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
27/09/2009
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
80
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 4760 0
Hospital
Name [1] 4760 0
Royal Melbourne Hospital
Country [1] 4760 0
Australia
Primary sponsor type
Hospital
Name
Royal Melbourne Hospital
Address
Grattan street, Parkville, Vic. 3050
Country
Australia
Secondary sponsor category [1] 4298 0
None
Name [1] 4298 0
Address [1] 4298 0
Country [1] 4298 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 6803 0
Melbourne Health Human Research Ethics Committee
Ethics committee address [1] 6803 0
Office for Research
Level 6 East, Main Building
Grattan Street
The Royal Melbourne Hospital VIC 3050
Ethics committee country [1] 6803 0
Australia
Date submitted for ethics approval [1] 6803 0
Approval date [1] 6803 0
12/11/2008
Ethics approval number [1] 6803 0
2008.163

Summary
Brief summary
When patients are having general anaesthesia for an operation, most of them will need an oro-tracheal intubation, which is a procedure where a breathing tube is inserted through the mouth down into the trachea (the breathing pipe). This enables the anaesthetist to assist the patient’s ventilation (breathing) under general anaesthesia. The procedure of inserting the tube into the trachea is performed after the patient is sedated and is asleep. The breathing tube is inserted with the help of a laryngoscope, an instrument that permits the anaesthetist to see the upper portion of the trachea (the breathing pipe), just below the vocal cords (the voice box). It is one of the most important skills in anaesthetics practice.

Some patients may have what we call difficult airways because of the physical structure of the area, for example, small mouth opening, large tongue, and poor neck mobility. This makes the insertion of the breathing tube more complicated. There are different techniques and intubating equipment available for anaesthetists to deal with difficult airways. Anaesthetists use their knowledge and previous experience to decide which type of laryngoscope to use in these cases.

The purpose of this project is to compare the effectiveness of two laryngoscopes, the Video Laryngoscope (McGrath) and the Miller straight blade laryngoscope. Previous studies have demonstrated that both the Video Laryngoscope and the Miller straight blade laryngoscope provide a better view of the vocal cords (the voice box) compared with the standard laryngoscope, when used in patients with potentially difficult airways. However, there are no studies comparing these two devices. We wish to know whether one device is better than the other to use in these cases.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 29471 0
Address 29471 0
Country 29471 0
Phone 29471 0
Fax 29471 0
Email 29471 0
Contact person for public queries
Name 12718 0
Irene Ng
Address 12718 0
Department of Anaesthesia and Pain Management
The Royal Melbourne Hospital
Grattan Street, Parkville, Vic. 3050
Country 12718 0
Australia
Phone 12718 0
+61-3-93427540
Fax 12718 0
+61-3-93428623
Email 12718 0
Irene.Ng@mh.org.au
Contact person for scientific queries
Name 3646 0
Irene Ng
Address 3646 0
Department of Anaesthesia and Pain Management
The Royal Melbourne Hospital
Grattan Street, Parkville, Vic. 3050
Country 3646 0
Australia
Phone 3646 0
+61-3-93427540
Fax 3646 0
+61-3-93428623
Email 3646 0
Irene.Ng@mh.org.au

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