The Modified Cormack-Lehane Score for the Grading of Direct Laryngoscopy: Evaluation in the Asian Population

Abstract

The use of a modified Cormack-Lehane scoring system (MCLS) of laryngoscopic views, as previously introduced in the Western population, was investigated during direct laryngoscopy in the Asian population. We studied the distribution of the different grades of MCLS, the predictive factors and rate of difficult laryngoscopy, and the association with difficult intubation. Six hundred and five patients requiring tracheal intubation during general anaesthesia were prospectively studied. The optimal views during direct laryngoscopy were scored using the 5-grade MCLS system. The distribution of the laryngoscopy scores was 73.9% Grade 1 (full view of the vocal cords), 21.0% Grade 2A (partial view of the vocal cords), 3.3% Grade 2B (only the arytenoids and epiglottis seen), 1.6% Grade 3 (only epiglottis visible) and 0.2% Grade 4 (neither the epiglottis nor glottis seen). External laryngeal pressure was necessary in 45.3% of cases to optimize laryngoscopic views. Grade 2B was associated with significantly higher incidence of difficult intubation compared with Grade 2A (65% vs 13.4%). The rates of difficult laryngoscopy and intubation were 5.1% and 6.9% respectively. The Mallampati classification and thyromental distance were associated with low predictive value for difficult laryngoscopy. The MCLS better delineates the difficulty experienced during laryngoscopy than the original Cormack-Lehane grading.

Comparison of Mallampati test with lower jaw protrusion maneuver in predicting difficult laryngoscopy and intubation

“…The probable reasons for this may be the use of more strict criteria for difficult intubation, as described by intubation grades III and IV of Cormack and Lehane's grading rather than using only grade IV as difficult intubation or relying upon Cook's modification of Cormack and Lehane's grading. [11] Another reason for this higher incidence could be the avoidance of external pressure during intubation. Majority of intubations (82.2%) in our study were done by an anesthetist with an experience of more than four years and none by an anesthetist with less than two years experience.…”

“…[10] Cormack and Lehane defined the grade of laryngoscopic view and they are widely used to label the difficulty of tracheal intubation. [1112]…”

The causes of difficult tracheal intubation and preoperative assessments in different age groups

“…In addition, head and neck movement, thyromental distance, interincisor gap, dentition, and Mallampati score were investigated as airway assessment factors prior to the induction of anesthesia [2,4,7,9]. …”

“…The interincisor gap is the distance between the incisors of the maxilla and the mandible when the mouth is opened to the maximum extent. To determine dental status, the existence of irregular dentition and lost or protruding maxilla incisors and canines were investigated, following the suggestion of Koh et al [7]. A dental condition with normal dentition and total anodontia was classified as grade 1; grade 2 indicated the existence of one of the dental conditions listed above; and grade 3 indicated the existence of two of the dental conditions listed above.…”

Transventricular Chondroplastic Laryngotomy—A New Surgical Technique for the Endolarynx

“…In addition, endoscopic approaches may not be possible in some patients, [7][8][9][10][11] making surgical exposure challenging. In contrast, external approaches may result in damage to the anterior insertion of the vocal folds as in thyrotomy.…”