A predictive test for difficult intubation in laryngeal microsurgery. Validation study

Abstract

Background: In 2003 a simple test to detect difficult intubation (DI) in patients underwent laryngeal microsurgery was described. The present study was conducted to validate the test.

Methods: Patients with laryngeal disease scheduled for laryngeal microsurgery were included. The variables evaluated were eleven parameters: Mallampati Score ≥III, thyromental distance <6.5cm, mouth opening <40mm, limitation of the temporomandibular joint, pathological dentition, arched paladet, maxillary deficiency, neck mobility <90°, body mass index, symptoms of laryngeal dysfunction, and tumour of supraglottic region. A rapid examination of the airway by an expert anaesthesiologist was carried out just before induction. DI was defined by a Cormack laryngeal view gradeiii-iv and/or if auxiliary equipment was required to achieve orotracheal intubation. A comparison of ROC curves was conducted to estimate the best predicting cut-off, as well as differences between the index described in 2003 and the rapid assessment by an expert anaesthesiologist.

Results: One hundred and five patients were included in the study. The incidence of DI according to the predefined criteria was 45% (47 patients). The score at the cut-off of 5 provides a sensitivity of 89% and a specificity of 55%. The fast-evaluation by an expert anaesthesiologist obtained similar sensitivity (89%) and better specificity (81%). Area under curve (AUC) was 0.87, similar to a fast evaluation (AUC: 0.85; P=.71).

Conclusion: The index was validated at a cut-off of ≥5, being a useful and reliable test to predict DI in patients with laryngeal diseases and it is a useful tool for anaesthesiologists with conventional training.

Keywords: Airway management; Difficult intubation; Intubación difícil; Laryngeal microsurgery; Manejo vía aérea; Microcirugía laringe.