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Trial registered on ANZCTR


Registration number
ACTRN12607000346471
Ethics application status
Not yet submitted
Date submitted
25/06/2007
Date registered
27/06/2007
Date last updated
27/06/2007
Type of registration
Prospectively registered

Titles & IDs
Public title
A randomised, blinded, controlled trial of silicone disposable laryngeal masks during anaesthesia in spontaneously breathing adult patients
Scientific title
A randomised, single blind, controlled trial to assess the efficacy of disposable silicone disposable laryngeal masks versus the Classic Larygeal mask (control) as a supralaryngeal airway during anaesthesia in spontaneously breathing adult patients
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Supralaryngeal device in spontaneuosly breathing patients 1897 0
Condition category
Condition code
Other 1992 1992 0 0

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The intervention groups will receive either the Meditech Systems Limited (MSL) or ProAct (PA) L aryngeal Mask Airway (LMA) for airway maintenance. We hypothesise that there will be no difference (equivalence) between the three silicone laryngeal masks studied. The ease of insertion, time to achieve effective airway, success rate on first or subsequent attempts, cuff seal pressure, and incidence of oro-pharyngeal trauma will be measured and we believe they will be similar in all groups.
The laryngeal mask airway is a reusable supraglottic airway device that has been available since 1998 and is widely used during elective general anaesthesia where endotracheal intubation is not thought necessary. Newer single-use disposable supraglottic airway devices are now available, which potentially reduce the risk of infection transfer.
The laryngeal mask is the most commonly used supraglottic device; its silicone construction ensures that it is easy to insert and minimises airway trauma. The Therapeutics Goods Administration in Australia has recently assessed a number of silicone disposable LMAs, and they are now available for use in Australia. The LMAC is easy to insert, creates an effective airway seal but provides only limited protection against aspiration. The LMAC is predominantly silicone construction with a PVC cuff. The major differences between the LMAC and the disposable devices are that the MSL and PA LMA have no aperture bars on the inferior surface of the laryngeal cuff.
Anaesthetic technique
Routine anaesthetic monitoring, as per Australian and New Zealand College of Anaesthetists guidelines for general anaesthesia, will be instituted [6]. A standardised general anaesthetic technique will be employed. Patients will not be pre-medicated. Induction of anaesthesia will utilise propofol 1-2 mg/kg, fentanyl (1-3 mg/kg), and midazolam (0.025-0.05 mg/kg), at the discretion of the anaesthetist concerned, to produce a loss of lash reflex. Following induction of anaesthesia patients undergo controlled ventilation using an anaesthetic facemask and 100% oxygen with sevoflurane (end tidal concentration at discretion of the anaesthetist). Following insertion of supraglottic airway device and return of spontaneous ventilation, maintenance of anaesthesia is to be achieved using sevoflurane (end tidal concentration at discretion of the anaesthetist) and a fresh gas flow with an inspired oxygen concentration of 70-100%. No nitrous oxide will be used. Small doses of metaraminol or phenylephrine can be administered to control systemic arterial blood pressure. Maintenance of general anaesthesia will be with sevoflurane in an oxygen:air mixture to achieve an inspired oxygen level of 70-100%.

Insertion of supraglottic airway device
A practitioner experienced in the use of LMA devices will carry out insertion. Routine recommended preinsertion tests of the control and study device will be performed [7]. The airway device will be inserted when loss of lash reflex and jaw tone allows. Successful device placement will be confirmed by:
· resistance to further downward movement of the device
· cuff inflation with the appropriate volume of gas to achieve an intracuff pressure of 60cmH20.
· effective ventilation as defined by assisted ventilation with chest wall movement, observance of a square wave capnograph trace and assisted ventilation without a leak at airway pressure of at least 10cmH20.
At the conclusion of surgery the anaesthetic gases will be replaced by 100% oxygen to allow patient recovery. When protective reflexes are noted to have returned to normal, the airway device will be removed after deflation of the cuff. The device will be inspected for secretions and blood.
Intervention code [1] 1848 0
Treatment: Devices
Comparator / control treatment
The control group will receive the LMA Classic (LMAC).
Control group
Active

Outcomes
Primary outcome [1] 2815 0
Airway pressure leading to cuff leakage immediately after induction of general anesthesia and placement of LMA, measured in cmH20. The LMAC sealing pressures are between 20-25cmH20. No study to date has directly compared the sealing pressures between the LMAC and other silicone based LMAs. This may have important consequences with the use of these devices in patients where it is considered difficult to maintain a patient airway during general anaesthesia. A standardised amount of air will be injected to achieve cuff inflation pressure of 60cmH20. A manometric stability test (to a maximum pressure of 35 cm H20) will be performed to determine LMA leak pressure.
Timepoint [1] 2815 0
Immediatley after induction of general anesthesia
Secondary outcome [1] 4741 0
1.Failure to establish an adequate airway (maximum of three attempts, intra-op)
Timepoint [1] 4741 0
Secondary outcome [2] 4742 0
2.First attempt insertion (intra-operative).
Timepoint [2] 4742 0
Based on observation intraoperatively.
Secondary outcome [3] 4743 0
3.Ease of insertion (intra-operative).
Timepoint [3] 4743 0
Assessed and reported by the Clinician at the end of the intervention period.
Secondary outcome [4] 4744 0
4.Time to achieve effective airway (intra-operative from induction of anaesthesia to time to achieve effective ventilation)
Timepoint [4] 4744 0
Secondary outcome [5] 4745 0
5.Laryngeal (anatomical) alignment as assessed by fibre-optic examination (intra-operative).
Timepoint [5] 4745 0
Assessed at a single point intraoperatively during General anaesthesia.
Secondary outcome [6] 4746 0
6.Intra-cuff volume at standardized pressure or maximum intracuff pressure (intra-operative).
Timepoint [6] 4746 0
Measured at time of inflation of laryngeal mask.
Secondary outcome [7] 4747 0
7.Post-anaesthesia sore throat, hoarse voice and dysphagia in recovery (PACU).
Timepoint [7] 4747 0
Measured in recovery when the patient is awake and orientated and at 24 hours through question over telephone at 24 hours post-operatively.

Eligibility
Key inclusion criteria
Adult undergoing spontaneous ventilation general anaesthesia in whom a supraglottic airway device would have been chosen for maintenance of airway patency by the Anaesthetist responsible for the individual patient.
Minimum age
18 Years
Maximum age
Not stated
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Individuals undergoing general anaesthesia in whom it would not have been appropriate to insert a supraglottic airway device for airway patency as determined by the anaesthetist responsible for that patient will be excluded. Such patients include:· Patients with morbid obesity (Body Mass Index 35 kg/m2)· Risk of aspiration· Limited interincisor distance (2.5 cm)· Known difficult airway.Patients who are unable to communicate in English, because of a language barrier, cognitive deficit or intellectual disability will not be approached.

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)
Randomisation results will be concealed in opaque envelopes until after patient consent has been obtained.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Patients will be allocated into three equal groups of forty patients according to a computer generated random sequence.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Blinding: subjects, data analyst. Un-blinded: Anaesthetist and assessor.
Phase
Phase 4
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
23/07/2007
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
120
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 2133 0
Hospital
Name [1] 2133 0
Royal Melbourne Hospital
Country [1] 2133 0
Australia
Primary sponsor type
Individual
Name
Investigator initiated (Dr. Daryl Williams)
Address
Country
Secondary sponsor category [1] 1939 0
None
Name [1] 1939 0
None
Address [1] 1939 0
Country [1] 1939 0

Ethics approval
Ethics application status
Not yet submitted
Ethics committee name [1] 3930 0
Royal Melbourne Hospital
Ethics committee address [1] 3930 0
Ethics committee country [1] 3930 0
Australia
Date submitted for ethics approval [1] 3930 0
Approval date [1] 3930 0
Ethics approval number [1] 3930 0

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 27662 0
Address 27662 0
Country 27662 0
Phone 27662 0
Fax 27662 0
Email 27662 0
Contact person for public queries
Name 11037 0
Dr. Daryl Williams
Address 11037 0
Department of Anaesthesia
Royal Melbourne Hospital
Parkville VIC 3050
Country 11037 0
Australia
Phone 11037 0
+61 3 93427540
Fax 11037 0
+61 3 93428623
Email 11037 0
daryl.williams@mh.org.au
Contact person for scientific queries
Name 1965 0
Dr. Daryl Williams
Address 1965 0
Department of Anaesthesia
Royal Melbourne Hospital
Parkville VIC 3050
Country 1965 0
Australia
Phone 1965 0
+61 3 93427540
Fax 1965 0
+61 3 93428623
Email 1965 0
daryl.williams@mh.org.au

No information has been provided regarding IPD availability


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
TypeIs Peer Reviewed?DOICitations or Other DetailsAttachment
Plain language summaryNo We hypothesised that two new silicone disposable l... [More Details]
Study results articleYes Anaesthesia & Intensive Care Volume 37 Issue 6 pa... [More Details]

Documents added automatically
No additional documents have been identified.