We read with interest the letters of Drs. Rajan and Heidegger. Dr. Rajan asks if our study was a validation or an invalidation of the Airway Management Algorithm. Clearly, our study was designed to assess a  difficult Airway Management Algorithm and not The  Airway Management Algorithm because we do not think that there is only one way to manage the unanticipated airway.1 

We do not agree with Dr. Rajan that the 16 patients who experienced transient hypoxemia prove the inefficiency of the algorithm assessed. Indeed, most of these patients experienced arterial desaturation at the end of gum elastic bougie challenge only a few seconds before effective tracheal intubation. On the other hand, the Intubating Laryngeal Mask Airway ™ (LMA North America, Inc., San Diego, CA) was used as a first step alternative technique in patients demonstrating a difficult ventilation scenario whenever arterial desaturation occurred. We agree with Dr. Rajan that several factors must be taken into account before defining the different steps of the algorithm. Obviously, in our algorithm, difficulties with face mask ventilation and oxygenation have been taken into account. Last, our study was not a comparative study assessing different management strategies of unanticipated difficult airway, but we are convinced of the great interest of such studies. It is possible that, as stated by Dr. Rajan, a broad-based protocol taking into account several factors could be the most prudent and effective approach in case of unanticipated difficult airway. Nevertheless, to our knowledge, large, prospective or retrospective, descriptive or comparative studies assessing the efficiency of such kind of protocol are still lacking.

To answer Dr. Heidegger, among our 100 patients with unanticipated difficult airway, 15 were anesthetized in emergency situations and considered at risk of pulmonary aspiration. We agree with Dr. Heidegger that difficult intubation distribution is not the same across surgical disciplines. Nevertheless, in our experience the difficulties of airway management encountered in the Ear, Nose, and Throat department are most often expected and strategies other than the one proposed in our study are applied.

In our study, we have considered that difficult airway was unanticipated when occurring in a patient who was considered to have normal preanesthetics evaluation of the airway (thyromental distance ≥60 mm, mouth opening ≥30 mm, Mallampati classification less than III, free from any history of difficult airway management in the past, unknown of ear, nose, and throat pathology, and with a body mass index <35 kg/m2).

During the study period, 253 patients with anticipated difficult airway were managed in our institution. Ninety-nine underwent primary fiberoptic intubation under topical and locoregional anesthesia. For the other patients, general anesthesia was induced using short-acting anesthetic agents and succinylcholine. With difficult face mask ventilation or class III-IV Cormack laryngeal view, gum elastic bougie was used as first alternative technique (n = 42) and Intubating Laryngeal Mask Airway ™ as a second step in case of gum elastic bougie failure (n = 3).

* Hôpital Henri Mondor, Creteil, France. xavier.combes@hmn.aphp.fr

Combes X, Le Roux B, Suen P, Dumerat M, Motamed C, Sauvat S, Duvaldestin P, Dhonneur G: Unanticipated difficult airway in anesthetized patients: prospective validation of a management algorithm. Anesthesiology 2004; 100:1146–50