Comparison of glottic visualisation and ease of intubation with different laryngoscope blades.

CONTEXT: Literature suggests glottic view is better with straight blades while tracheal intubation is easier with curved blades.

AIMS: To compare glottic view and ease of intubation with Macintosh, Miller, McCoy blades and the Trueview(®) laryngoscope.

SETTINGS AND DESIGN: This prospective randomised study was undertaken in operation theatres of a 550 bedded tertiary referral cancer centre after approval from the Institutional Review Board.

METHODS: We compared the Macintosh, Miller, McCoy blades and the Trueview(®) laryngoscope for glottic visualisation and ease of tracheal intubation; in 120 patients undergoing elective cancer surgery; randomly divided into four groups. After induction of anaesthesia laryngoscopy was performed and trachea intubated. We recorded: Visualisation of glottis (Cormack Lehane grade), ease of intubation, number of attempts; need to change the blade and need for external laryngeal manipulation.

STATISTICAL ANALYSIS: Demographic data, Mallampati classification were compared using the Chi-square test. A P<0.05 was considered significant.

RESULTS: Grade 1 view was obtained most often (87% patients) with Trueview(®) laryngoscope. Intubation was easier (Grade 1) with Trueview(®) and McCoy blades (93% each). Seven patients needed two attempts; one patient in Miller group needed three attempts. No patient in McCoy and Trueview(®) Groups required external laryngeal manipulation.

CONCLUSIONS: We found that in patients with normal airway glottis was best visualised with Miller blade and Trueview(®) laryngoscope however, the trachea was more easily intubated with McCoy and Macintosh blades and Trueview(®) laryngoscope.