Laryngeal Tube vs Laryngeal Mask Airway
Condition: Cardiac Arrest
MeSH terms: Heart Arrest
Study type: Interventional

Summary: 
      Introduction: The laryngeal mask airway (LMA) is used as the primary airway by paramedics in
      Singapore Civil Defense Force's Emergency Ambulance Service (SCDF's EAS) in the management of
      out-of-hospital cardiac arrest, because endotracheal intubation requires skilled and
      experienced personnel, and local paramedics are not trained to this level of skill and
      competency. However, self-reported insertion success rates by paramedics in the field are
      currently only about 50-87%. Devices like the laryngeal tube have been shown to have higher
      placement success rates and fewer complications.

      Aim: Investigators aim to evaluate the efficacy and safety of a new device, the Laryngeal
      Tube (LT), compared to the LMA. They hypothesize that the LT is superior to the LMA in terms
      of placement success rates by paramedics in SCDF's EAS, and is associated with fewer adverse
      events.

      Methodology: Investigators propose to conduct a prospective, longitudinal multi-centre
      randomized trial comparing LMA and LT in patients with cardiac arrest (medical or traumatic)
      managed by SCDF EAS. The trial will recruit 1,015 eligible patients presenting to SCDF
      irrespective of destination hospital over a period of 1 year to detect an expected 15%
      difference in placement success rate. Currently the LMA is used as standard of care by SCDF's
      EAS in patients with cardiac arrest.

      Results: Besides the primary outcome, the secondary outcomes of dislodgment rates, time to
      placement, number of attempts and adverse events will be analyzed and will be useful in
      guiding future SCDF cardiac arrest protocols.
    

Detailed description: 
      Endotracheal intubation (ETI) is considered the gold standard of airway management as it a
      definitive airway providing ventilation and prevention of aspiration in a patient unable to
      protect his airway. However, it can only be used by skilled, experienced personnel and can be
      difficult in the pre-hospital setting. It may also result in unrecognized oesophageal
      intubation. Currently ETI is not recommended for Singapore Civil Defence Force (SCDF)
      ambulances by MHA (Medical Advisory Committee) and local paramedics were not trained to this
      level of skill and competency. Furthermore, there has been reduced emphasis on early tracheal
      intubation unless achieved by highly skilled individuals to minimise interruption to chest
      compressions according to the 2010 resuscitation guidelines.

      In view of the above reasons, ETI is not recommended by the Ministry of Home Affair's Medical
      Advisory Committee (MAC). Instead, the disposable laryngeal mask airway (LMA) has been used
      as the primary airway by paramedics in SCDF's Emergency Ambulance Service (EAS) in the
      management of both medical and traumatic cardiac arrest patients and is approved by the MAC
      for use in both adults and children.

      However there can still be complications with the LMA such as incomplete seal and partial
      airway obstruction from mask misplacement or kinking. In addition, SCDF's self-reported
      success rate of LMA is only 50-87% .Hence there was a need to explore other alternatives to
      the LMA. The American Heart Association (AHA) recommends advanced airway adjuncts such as the
      Laryngeal Tube (LT) and Oesophageal-tracheal tube (Combitube) for alternative airway
      strategies. Other devices include the pharyngeaotracheal lumen airway and the oesophageal
      obdurator airway - oesophageal gastric tube airway (EOA-EGTA).

      Investigators have chosen the LT as an alternative adjunct because it has a higher insertion
      success rate than LMA. It also has low complication such as regurgitation, vomiting and
      dislodgement and comes in sizes to accommodate both paediatric and adult. Method of use is
      quite simple as it can be inserted blindly into the oropharynx and pushed in until resistance
      is felt or device is fully inserted as denoted by the markings on the device.

      Our long term objective is to improve existing EAS's cardiac arrest protocol and placement
      success rate and to lower complications and adverse events rates in out of hospital cardiac
      arrest. The result of the study will be reviewed by SCDF's Medical Advisory Committee (MAC).
      The results can also determine the choice of rescue airways used in the hospitals eg
      operating theatres, emergency departments, endoscopy rooms.

      Primary objectives:

      Investigators aim to evaluate the efficacy of the Laryngeal Tube (LT) as a primary airway in
      the management of cardiac arrest patients by comparing placement success rates of LT to that
      of LMA (Laryngeal Mask Airway) in Out-of-Hospital Cardiac Arrest managed by Singapore Civil
      Defence Force ambulances

      Secondary Objective:

      To compare the safety of the two airway devices by comparing the following outcomes:

        1. Number of placement attempts required,

        2. Dislodgement rates and

        3. Time to successful placement of airway device.

      Hypothesis:

      The LT is more efficacious than the LMA as a primary airway device in the prehospital
      management of cardiac arrest by SCDF's EAS done by paramedics in Singapore Civil Defence
      Force's Emergency Ambulance Service (SCDF's EAS).

      Investigators propose to conduct a prospective longitudinal multi-centre (fire stations)
      randomised study comparing the laryngeal mask airway (LMA) and laryngeal tube (LT ).The trial
      will recruit 1,015 eligible patients over 1 year. They will randomise all Emergency Ambulance
      Service (EAS) ambulance stations managed by SCDF into two trial groups using a longitudinal
      multi-centre randomised trial design. Group 1 will use new laryngeal tube (LT) protocol for
      12 months and group 2 will continue laryngeal mask airway (LMA) protocol for 12 months.
      Investigators will record expertise/experience/training variables for each paramedic, so
      adjustment can be made in analysis.

      Singapore General Hospital (SGH) will be submitting an ethics application to Centralised
      Institutional Review Board (CIRB) on behalf of SCDF to recruit all cases presenting to SCDF,
      irrespective of destination hospital. This is because SCDF does not have its own IRB. All the
      enrolled patients will be followed up by a review of their Emergency Department and hospital
      records for any medical related adverse effects.

      The local self-reported LMA insertion success rate is 50-87%, based on a survey done as part
      of a larger analysis of cardiac arrest figures during the period of July 2012 to June 2013.
      Results from European and American airway trials involving paramedics report varying LT
      insertion success rates of up to 100%.

      Most cardiac arrest cases occurs out-of-hospital, and most of them are conveyed by SCDF EAS.
      Patients will be given the treatment if all eligibility criteria are met and treatment is
      indicated by protocol. No written consent will be sought as this will be part of routine
      clinical care.

      Half of the 30 SCDF ambulances will use the LT (after half day training on usage) and another
      half will continue with the LMA for 12 months. The treatment that each ambulance station will
      be providing will be randomised. Stratified randomisation with 3 strata will be carried out.
      The 1st strata, 2nd and 3rd stratum consist of ambulances coming from fire posts equipped
      with 1 ambulance, 2 ambulances and 3 ambulances respectively. Block randomisation within each
      stratum will be carried out to randomise the ambulances to administer LMA or LT.

      Sample size calculation is based on a test for 2 proportions in a repeated measurements
      design. Assuming a sample size of 35 paramedics in each arm to achieve 80% power to detect an
      increase in successful insertion rate to 0.95 in the LT arm with 10 patient measurements per
      paramedic, having a Compound Symmetry covariance structure when the successful insertion
      proportion from the LMA arm is 0.800, the correlation between observations on the same
      subject is 0.5, and the alpha level is 0.05. The number of SCDF paramedics is estimated at
      70, thus expect a total sample of 700 patients. Assuming a dropout rate of 45%, the
      investigators would need to enrol a total of 1,015 patients. This number of patients
      corresponds to the number of patients with out of hospital cardiac arrest (OHCA) needing
      intubation expected during the study period.

      Frequency tables and descriptive statistics with 95% confidence intervals for all outcome
      variables listed above will be calculated. Associations between treatment groups and all
      endpoints will be analysed using the t-test/ Mann-Whitney and chi-square tests with odds
      ratios presented where applicable. Multivariate logistic regression will be used to adjust
      for relevant covariates in the analysis of primary end point of success (Y/N) of insertion.

      In the control arm, the LMA will be inserted as per current SCDF protocols. The LMA can be
      inserted with the curved portion of the tube and the flat side of the cuff facing the
      patient. The patient's mouth needs to be opened and head tilted backward (except in suspected
      neck injury). By keeping the leading edge flat at the time of insertion, direct the cuff
      against the hard palate and maintain constant pressure down through the oropharynx in a
      smooth, continuous motion until resistance is encountered. For the intervention arm, the LT
      is inserted blindly into the oropharynx and pushed in until resistance is felt or device is
      fully inserted as denoted by the second black line. The LT has two cuffs, one at the distal
      and the other in the middle part of tube. The cuffs are simultaneously inflated with one
      syringe. The distal cuff obstructs the oesophagus and the proximal cuff occludes the pharynx.
      In the right position, the distal aperture should face the glottis aperture.
    

Intervention name(s): Laryngeal Mask Airway (LMA); Laryngeal Tube (LT)
Intervention type(s): Device; Device
Intervention description(s): Laryngeal Mask Airway (LMA) for Control group; Laryngeal Tube (LT) for Intervention group
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Investigator)
Primary purpose: Treatment
Keywords: Intubation; Ventilation; Cardiac arrest; prehospital; Laryngeal Masks; Laryngeal Tube; airway management