Comparison of two Macintosh laryngoscope blades in 300 patients

Background. There are two forms of Macintosh laryngoscope blade. Compared with the standard blade, the English blade is longer, its curve is more continuous across the entire length of the blade, the ¯ange of the blade continues much closer to the blade tip, and the height of the ¯ange is shorter. Method. We studied 300 patients to compare the ease of laryngoscopy with each type of Macintosh laryngoscope blade. In a random crossover design, after induction of anaesthesia and neuromuscular block, the two blades were inserted in turn, and the views of the glottis at lar-yngoscopy (Cormack and Lehane scores) were compared. Results. There was a difference in the view of the glottis in 80 patients. Among these patients, the view was better for the English blade for 63 patients and the standard blade was better for 17 patients. Laryngoscopy was dif®cult (grade 3 or 4) for at least one blade in 42 of 300 patients (14%). In these 42 patients, there was a difference in the score between the blades in 28 patients; the view was better for the English blade in 25 patients (60%) and for the standard blade in three patients (7%). The view was signi®cantly better for the English blade than for the standard blade (P<0.001; 95 % con®dence interval 45±74%). Conclusions. In patients in whom laryngoscopy was unexpectedly dif®cult, the English blade provided a better glottic view signi®cantly more frequently than the standard blade