Comparison of Various Measures for Anticipating Difficult Laryngoscopy

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.