title: Predictive factors of difficult airway with known assessment scales.
abstract: BACKGROUND
  difficult intubation is defined as the need for more than three attempts for intubation or more than 10 min to accomplish it, a situation that occurs in 1.5-8% of general anesthetic procedures. The aim of this study was to evaluate the predictive factors of difficult airway with known assessment scales.
  
  
  METHODS
  in a cross-sectional study conducted in 184 patients during the pre-anesthetic evaluation, we assessed the oral opening, viewing pharyngeal structures (Mallampati scale), condition of teeth, anatomic chin and neck, head extension and neck flexion (normal or limited), thyromental distance (Patil-Aldreti test) and the presence of obesity. We performed a calculation of sensitivity (S), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) using contingency tables.
  
  
  RESULTS
  we found that grades III and IV Mallapati (84%) and limited extension and flexion of the head and neck (99%) showed a high specificity for predicting difficult intubation. Other factors associated with difficult intubation were related to micrognathia, limited mouth opening and teeth with anatomic abnormalities.
  
  
  CONCLUSIONS
  it is essential to take the necessary time to assess the airway with the greatest number of criteria predictive of difficult intubation for the person performing the procedure in order to take the necessary steps to face difficulties in this technique.
authors.affiliation: Departamento de Anestesiología, Hospital Universitario "Dr. Ángel Leaño," Universidad Autónoma de Guadalajara, Guadalajara, Jalisco, México. jmoapat@yahoo.com.mx.
authors.forename: Elida
authors.initials: E
authors.lastname: Orozco-Díaz
authors.forename: Juan Jorge
authors.initials: JJ
authors.lastname: Alvarez-Ríos
authors.forename: José Luis
authors.initials: JL
authors.lastname: Arceo-Díaz
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Ornelas-Aguirre
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058109:Airway Management; D003430:Cross-Sectional Studies; D005260:Female; D005544:Forecasting; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055815:Young Adult