Weread with interest the recent case report by Greif et al, [1] describingtracheal intubation using the SensaScope^TM (Acutronic MedicalSystems AG, Hirzel, Switzerland), in thirteen sedated patients with ananticipated difficult airway. Whilst we acknowledge that the authors haveconsiderable experience using this device, and that anaesthetic techniques mayvary internationally, we would like to make the following comments.

Followingthe administration of intravenous sedation and local anaesthesia (bothtopically and by trans-cricoid injection), the authors routinely practiced anawake intubation technique, which required the insertion of a warmed Macintoshlaryngoscope (size 3 or 4) in order to clear the airway. Following thedisplacement of the tongue off the palate, the SensaScope could be advancedthrough the glottis and the tracheal tube railroaded over the device and intothe trachea.

Areduced interincisor distance or mouth opening may in certain patients severelyrestrict the use of a laryngoscope blade in this way [2], so we were surprisedto read that this technique was successful in patients with mouth opening of1.7 and 1.5 cm (patients 4 and 6 respectively). Alternative methods of clearingthe airway exist, which may have fewer restrictions than inserting alaryngoscope blade. In our practice, we either ask the awake patient toprotrude their tongue, or perform gentle lingual traction using Duval's forceps[3].

Thepresence of saliva restricted the view during the SensaScope intubation in twopatients (number 3 and 4), and potentially may have been a problem in thepatient with Down's syndrome (number 11), as excessive salivation and droolingare often encountered in Down's patients, due to decreased ability to swallow orkeep saliva in the mouth.

Inour experience, airway instrumentation in awake and sedated patients mayfrequently result in an increase in salivation. Consequently, an intravenousantisialogogue, e.g. glycopyrronium may be administered to reduce, slow orprevent the flow of saliva [4], and thus topical local anaesthesia may be moreeffective when applied to a relatively dry mucous membrane. However, the authorsreport that they do not commonly use glycopyrronium, but rely instead on‘blowing away' the saliva and blood contamination with high flow oxygen. The latter is delivered through the tracheal tube via an adapter on the SensaScope. As asuction channel is unavailable on the SensaScope, we believe that anantisialogogue should routinely be administered before the use of theSensascope, as this may improve the view during intubation. It remainsunclear what happens to the saliva and blood contamination after it is blownaway by the oxygen, but nonetheless, this is less favourable than removing saliva using a suction catheter.

DD Keene

JL Tong

The Royal Centre forDefence Medicine, Birmingham.

References

1. Greif R,Klein-Brueggeney M, Theiler L. Awake tracheal intubation using the  

    Sensascope^TM in 13 patients with an anticipated difficultairway. Anaesthesia 2010; 65:   

    525-8.

2. Aiello G, MetcalfI. Anaesthetic implications of temporomandibular joint disease.

    Canadian Journal of Anaesthesia 1992; 39:610-6.

3. Durga VK, MillnsJP, Smith JE. Manoeuvres used to clear the airway during fibreoptic

    intubation. British Journal of Anaesthesia2001; 87: 207-11.

4. Malik JA, Gupta D,Agarwal An, et al. Anticholinergic premedication for flexible

   bronchoscopy: a randomized, double-blind, placebo-controlledstudy of atropine and  

   glycopyrrolate. Chest 2009; 136: 347-54.