Comparison of Various Measures for Anticipating Difficult Laryngoscopy
Condition: Difficult Laryngoscopy
Study type: Observational

Summary: 
      Demographic features and eight diagnostic variables were evaluated for difficult laryngoscopy
      (DL) predictivity. These were retrognathia, presence of buck teeth, modified Mallampati test
      (MMT), upper lip bite test (ULBT), sternomental distance (SMD), interincisor distance (IID),
      thyromental distance, and neck circumference. DL was identified by Grade III-IV view during
      laryngoscopy according to the Cormack-Lehane (CL) classification.
    

Detailed description: 
      Creating a regression model among selected bedside tests for predicting difficult
      laryngoscopy )defined as Grade III or IV view during laryngoscopy according to Cormack-Lehane
      classification) is the primary objective. Recruiting of 145 ASA I-II adult patients who would
      have an elective surgery under general anesthesia were planned.

      Criteria for exclusion were: a history of craniofacial surgery or restriction of cervical
      mobility, edentulous patients, pregnant women, patients who did not have a proper mouth
      opening (< 3 cm), and those who might require awake intubation or rapid sequence induction,
      cancellation of the surgery or change in the anesthetic strategy.

      The selected tests and clinical situations were:

      The presence of retrognathia (reduced temporomandibular joint-incisor distance) Buck teeth
      Modified Mallampati test (MMT) in the sitting position without phonation. A scale ranging
      between 1 and 4 points is used and scores of 3 or 4 are considered as predictors of DL. Upper
      lip bite test (ULBT) performed in a neutral position. ULBT is graded as 1-3 according to the
      extension ability of lower incisors.

      Sternomental distance - The distance between the mentum and upper border of the manubrium
      sterni when the head is fully extended and the mouth is closed.

      Thyromental distance (TMD) - The distance between mentum and the thyroid notch when the head
      is fully extended.

      Interincisor distance (IID) - The distance between upper and lower incisors when the mouth is
      fully opened.

      Neck circumference (NC) - It was measured at the level of the cricoid cartilage,
      perpendicular to the cervical axis.

      The patients are premedicated with 0.03 mg/kg and oxygenated with the help of a bag-mask.
      Anesthesia is induced by consequent administration of 2 mcg/kg fentanyl, 1 mg/kg lidocaine, 2
      mg/kg propofol, and 0.7 mg/kg rocuronium bromide thereafter. Two minutes after induction, the
      laryngoscopy is performed
    

Intervention name(s): Laryngoscopy
Intervention type(s): Diagnostic Test
Intervention description(s): The laryngoscopy is performed with the help of an appropriate size Macintosh blade. The patient's head is held in the sniffing position. External manipulation is not used for improving the view in this investigation.
Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Consecutive patients attending the anesthesiology out-patient clinic for preoperative
        evaluation in Kanuni Sultan Suleyman Ed. ad Research Hospital. The planned anesthetic
        method should be general anesthesia.
      
Keywords: Cephalometry; Endotracheal intubation; Ethnicity; Laryngoscopy