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.

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

Inclusion Criteria:

• ASA I-II
• Candidate for elective surgery under general anesthesia

Exclusion Criteria:

• History of craniofacial surgery or restriction of cervical mobility,
• Edentulous patients
• Pregnancy
• Patients who do not have a proper mouth opening (< 3 cm)
• Patients who might require awake intubation or rapid sequence induction.

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.