Postoperative sore throat - know where your airway is positioned.

Abstract

It was interesting to read the review article by El-Boghdadly et al. 1 on the incidence of postoperative sore throat following insertion of tracheal tubes (TT) and supraglottic airway devices (SAD) in patients undergoing anaesthesia. An astonishing 62% of postoperative patients report a sore throat, which is often neglected by medical and nursing staff and is not routinely investigated. We should focus on further improving our techniques to reduce this high incidence of complications, mainly as a direct consequence of the instrumentation of the patient's airway. We compliment the authors on the analysis they performed within this systematic review. Several techniques to reduce the incidence were listed, with most interventions not able to demonstrate major improvements. Comparing results using different devices is difficult as one fundamental item is lacking: how well are airway devices positioned in patients? If we want to compare apples with apples, we need to be absolutely sure that the airway device is positioned correctly in the trachea (TT) or the hypopharynx (SAD). Down-folding of the epiglottis can occur during laryngoscopy and tracheal intubation, which can go unnoticed by the laryngoscopist/intubator 2, 3. Ideally, a correctly-sized SAD should be positioned in the hypopharynx with the distal cuff located at the entrance of the oesophagus, blocking the latter, and the epiglottis resting on the outside of the proximal cuff, with the tip of the epiglottis aligned with the rim of the proximal cuff. As such, the SAD tube opening opposes the glottic opening and the entrance to the trachea, allowing for spontaneous breathing and mechanical ventilation. Imaging studies (MRI, radiography and fibreoscopy) have revealed that a variety of malpositioning of SADs occurs in up to 80% of all insertions, with the epiglottis often posteriorly deflected, resulting in partial epiglottis down-folding in the bowl of the airway device in 80% and complete down-folding of the epiglottis in 10% 4-9. In some instances, this may cause partial or even complete obstruction of the airway, and trauma (oedema, ischemia) to the epiglottis, in particular if the malposition is not detected during long operations, with a sore throat as a likely outcome. There are many reasons why malpositioning of SADs occurs, including initial down-folding of the epiglottis during insertion of the SAD, sideways folding of the epiglottis, distal cuff folding over backwards, distal cuff sitting between the vocal cords, malalignment between the tip of the epiglottis and the rim of the proximal cuff (due to the use of an incorrect size or incorrectly inflated cuff), down-folding of the epiglottis in the bowl of the device (potentially leading to air leaks or airway obstruction), and material used (PVC cuffs show foldings, contrary to silicone cuffs) 10. The anaesthetist can only be sure about optimal position if the device is inserted with a direct view, using either classic laryngoscopy or videolaryngoscopy. This allows the use of visually-guided manoeuvres to direct the SAD into a final optimal position. Furthermore, El-Boghdadly et al. 1 described themselves, in their review article, that the use of laryngoscope-guided SAD insertion offered the greatest reduction of the incidence of sore throat postoperatively. Until we are able to correctly place devices in the accurate position, we cannot judge whether one particular insertion technique or brand of device is better than the other. Every effort should be made to avoid prolonged times whereby the down-folded epiglottis is trapped between the pharynx and the device (SAD) as well as between the tracheal wall and the tube (TT). If down-folding of the epiglottis is not corrected, the major issue of sore throat after anaesthesia will continue to remain a problem.