Letters to the Editor: Letters & Announcements
To the Editor:
We have read the article by Kundra et al. (1) describing the use of various tracheal tubes for blind intubation via the intubating laryngeal mask airway (ILMA) with great interest. The authors have done an excellent job determining success rates with both conventional PVC and armored tracheal tubes.
Although we originally reported the use of PVC tracheal tubes with the ILMA (2–4), we feel that our previous conclusion and the conclusion of Kundra et al. do not adequately address the safety concerns of using non-silicone tracheal tubes with the ILMA. We may have performed a disservice to the public by discussing the use of PVC tracheal tubes for blind intubation via the ILMA. There has already been a reported death (with the silicone tracheal tube) with blind tracheal intubation via the ILMA (5). We have since shown in an in vitro model that room temperature PVC, warmed PVC, and armored tubes exert much greater forces on distal objects on exiting the ILMA compared with silicone tracheal tubes (6). Also, the silicone tracheal tubes collapse on impact, resulting in a larger surface area of contact and less overall pressure being exerted. The maximal pressure that can be exerted by a PVC tracheal tube is 7 to 10 times that of silicone tracheal tubes.
At our institution, we have advocated the cessation of blind tracheal intubations with PVC tubes. We still use exclusively PVC tracheal tubes; however, a fiberoptic bronchoscope is used in conjunction so that trauma is avoided and success rates are improved.
Finally, one should seriously consider the legal ramifications of using a non-silicone tube for blind intubation via the ILMA. If legal actions are brought as a result of trauma to the airway or esophageal structures, it may be difficult to defend a practice that is unconventional and shown in an in vitro model to be associated with the possibility of trauma. One should assume that the manufacturers and distributors of the ILMA will be quick to defer any and all legal liability to the person using the PVC or armored tracheal tube.
Hwan Joo, MD
Viren Naik, MD
St. Michael’s Hospital
University of Toronto
1. Kundra P, Sujata N, Ravishankar M. Conventional tracheal tubes for intubation through the intubating laryngeal mask airway. Anesth Analg 2005;100:284–8.
2. Joo H, Rose K. Fastrach: a new intubating laryngeal mask airway: successful use in patients with difficult airways. Can J Anaesth 1998;45:253–6.
3. Joo HS, Rose DK. The intubating laryngeal mask airway with and without fiberoptic guidance. Anesth Analg 1999;88:662–6.
4. Joo HS, Kapoor S, Rose DK, Naik VN. The intubating laryngeal mask airway after induction of general anesthesia versus awake fiberoptic intubation in patients with difficult airways. Anesth Analg 2001;92:1342–6.
5. Branthwaite MA. An unexpected complication of the intubating laryngeal mask. Anaesthesia 1999;54:166–7.
6. Joo HS, Kataoka MT, Chen RJ, et al. PVC tracheal tubes exert forces and pressures seven to ten times higher than silicone or armoured tracheal tubes: an in vitro
study. Can J Anaesth 2002;49:986–9.