Objective: To compare the ability of UK paramedics to intubate a simulated difficult airway using a Mackintosh laryngoscope versus an intubating laryngeal mask airway (ILMA).
Method/Design: A randomised controlled trial.
Results: 100% of the paramedics were able to intubate a simulated difficult airway using the ILMA versus 0% of those using the Mackintosh laryngoscope.
Conclusions: This study has demonstrated the ability of paramedics to use the ILMA when faced with a difficult intubation. However, further evaluation of this potential role for the ILMA is required.
- ILMA, intubating laryngeal mask airway
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This is a prospective randomised controlled trial of the ability of UK paramedics to use the ILMA in a simulated difficult intubation in a hospital environment.
Local ethical committee approval was gained before commencement of the study.
Paramedics involved in this trial were based at the Three Shires Ambulance Service and had no previous exposure to the ILMA.
All candidates received a tutorial on the ILMA, consisting of a short lecture and instructions on its insertion. Demonstration of ILMA removal after intubation (leaving the endotracheal tube in situ) was not performed.
The Mannequin used for both scenarios was the ALS 4000 (Laerdal), which was adapted by placing padding underneath the tongue to simulate a difficult airway. The best view at laryngoscopy obtained by the authors was grade 3 (epiglottis visible, no vocal cords visible).8 Bag–mask ventilation was not assessed as the Mannequin was unable to simulate both a failed bag–mask ventilation and a failed intubation concurrently.
Candidates were informed that this was a simulated difficult intubation scenario.
Each candidate was randomly allocated to perform scenarios A and B in differing orders to prevent learning. In scenario A, candidates attempted intubation using the Mackintosh laryngoscope. In scenario B, candidates attempted insertion, ventilation and intubation using the ILMA (table 1).
A bougie was not made available to the paramedics as it is not part of their standard equipment.
One hundred percent of the paramedics were able to intubate a simulated difficult airway using the ILMA versus 0% of those using the Mackintosh laryngoscope.
In this study, the ILMA was superior to the Mackintosh laryngoscope for intubation. The authors were not trying to validate ILMA use in the unanticipated difficult intubation, but the ability of paramedics to master this airway device. This study has shown that paramedics are able to ventilate and intubate successfully with the ILMA even when unable to intubate with a laryngoscope. In an out-of-hospital environment where intubation is more difficult, we believe that if an ILMA is inserted successfully to maintain an airway and the patient’s airway reflexes are obtunded, the paramedics can then more successfully proceed to secure that airway to reduce the risk of aspiration.
The ILMA does have a learning curve. The results from this study reflect this, with some candidates taking longer to achieve ventilation and successful intubation.
Despite the authors’ best efforts, however, there do remain some elements of bias. All candidates were aware that the scenarios involved a difficult intubation, which may have affected their efforts with the laryngoscope.
This study has successfully established the ability of paramedics to use the ILMA if a difficult intubation is encountered in a hospital setting. Further out-of-hospital assessment of the ILMA’s performance is required.
Until recently, only reusable ILMAs have been available. Disposable ILMAs are currently under trial and therefore this current financial and practical obstacle (ie, cleaning and tracing) for use by paramedics should be resolved.
We thank Mr John Careless (the Three Shires Ambulance Service) and Drs Jill Mollison and Ros Weatherall (Oxford Centre for Statistics in Medicine) for their help in the completion of this study.
Competing interests: None declared.
One of the intubating laryngeal masks used for this study was donated by Intavent.