Observational Study of the LMA Protector

There is a lack of research data on regarding the use of the LMA Protector. There is no regulatory requirement to collect or publish patient data on any device, either before CE marking or after. These devices are freely purchased and used.

There is, however, a professional duty to know that a device conforms to established norms for use. These norms are not official standards but rather, reference data against which a device can be clinically judged. Therefore, a device that is easy to insert but has a low 'leak pressure' (see above) is different from one that is more difficult to insert but as a high leak pressure. It is not that one is 'better' than the other, but rather that the data help create a 'usability profile' of the device which can be useful when making a clinical selection for the device.

Preoperative assessment:

During the preoperative visit, patient information leaflet will be given to the patients meeting the eligibility criteria.

Wherever possible, suitable patients will be identified in the preoperative assessment clinic and the information leaflet given. The patients will be given adequate time to read this information and any queries will be answered before being asked to sign a consent form. A detailed airway assessment will be performed by one of the investigators and documented on the study proforma.

Induction of anaesthesia:

On arrival in the anaesthetic room patients will be monitored with pulse oximetry, electrocardiography and invasive or non-invasive blood pressure measurements. After intravenous access is secured and the pre-surgical checklist completed, all patients will be pre-oxygenated using a facemask to achieve end tidal oxygen concentration of at least 80%. A 'sniffing' position of the head and neck and a 20 degree head-up bed tilt will be used for pre-oxygenation. General anaesthesia will be induced intravenously. After induction of anaesthesia, facemask ventilation will be commenced and anaesthesia maintained with an inhalational anaesthetic agent in oxygen or with total intravenous anaesthesia. The volatile agent's (anesthetic gases) concentration of 1 MAC adjusted for the patient's age will be achieved and maintained. This is normal process of anaesthesia applicable for all patients irrespective of participation in the study.

Supraglottic airway device (SAD) insertion:

Once deep plane of anaesthesia is confirmed, with the absence of movement to jaw thrust stimulation the SAD (LMA protector) will be inserted. The size of the device will be based on the manufacturer's recommendations for the body weight. The breathing system will be connected to the device. Ventilation of the lungs will be then confirmed by observing adequate bilateral chest inflation and square end-tidal capnogram wave with positive pressure ventilation. Adequate ventilation will be recorded if three tests are passed: 1) adequate chest movement, 2) an expired tidal volume of at least 7 ml/kg and 3) stable oxygenation. Time would continue until LMA® ProtectorTM inserted successfully. If it is not possible to insert the device or ventilate through it, two more attempts at placement of the device will be allowed. If placement has failed after two further attempts, the study will be abandoned and the other device will be used. If this fails on first attempt a different LMA or tracheal tube will be used as appropriate.

Maintenance of anaesthesia and recovery

The main interventions refer to the insertion of the airway device into the patient to obtain a airway and allow the conduct of the anaesthetic and therefore the surgery. However, if there are problems with the device and the airway obtained is suboptimal then the below interventions are allowed (which will be noted in the data collection form):

1. Neck extension - move patient's neck upward
2. Neck flexion - move patient's neck downward
3. Chin lift - manoeuvre to open the airway
4. Jaw thrust - manoeuvre to open the airway
5. Reposition of the device At the end of operation, anaesthetic agents will be discontinued while the device is left in place. The device will be removed after the patient has regained consciousness, and has responded to verbal command to open the mouth. Any complications that occur during the use of the device will be recorded.

Postoperative assessment Postoperatively in recovery or on the ward, the investigators will visit each patient and determine whether the following airway complications are present after surgery: sore throat (constant pain, independent of swallowing), dysphagia (difficulty in, or pain provoked by, swallowing), sore jaw, dysphonia (difficulty in, or pain on, speaking), numbness of the tongue or the oropharynx, ear pain, neck or mouth ache, hearing changes. Each complication will be graded as none, mild, moderate or severe. The same questions will be asked 24-48 hours later.

First visit During the first visit by the anaesthetist to the participant, at the anaesthetist's earliest opportunity, either in the recovery area or on the ward, the participants will be asked about the following complications, which will be graded as none, mild, moderate or severe.

1. Vomiting
2. Lip or tongue swelling
3. Hearing changes
4. Ear pain
5. Sore throat
6. Pain on swallowing
7. Jaw pain
8. Neck or mouth ache
9. Pain on speaking
10. Numbness of the tongue

Second visit (or telephone consultation) During the second visit 24-48 hours post-operatively on the ward or via telephone the participants will be asked about the following complications, which will be graded as none, mild, moderate or severe.

1. Vomiting
2. Lip or tongue swelling
3. Hearing changes
4. Ear pain
5. Sore throat
6. Pain on swallowing
7. Jaw pain
8. Neck or mouth ache
9. Pain on speaking
10. Numbness of the tongue