A new tracheal tube for difficult intubation.
We have compared a new Portex tracheal tube with the Oxford tube in performing simulated grade 3 difficult intubations. The Portex tube was modified so that the bevel faced backwards, as in the Oxford tube. A gum elastic introducer was used with both tubes. The time taken and number of attempts needed were recorded, with changes in arterial pressure, heart rate and incidence of sore throat. Both tubes were successful in avoiding the problem of obstruction at the cords, which occurs when a standard Magill tube is used with an introducer. Thus the new tube has the merits of the Oxford tube without the disadvantages of rubber. It is suitable for both easy and difficult intubations with advantages in safety, cost and convenience. An unexpected but important finding was a clear learning effect, despite both investigators being familiar with the technique at the outset. Over the course of the study, intubation time decreased progressively (P < 0.001). This provides new evidence of the need for trainees to practise the art of intubation when the cords are not visible. Our estimate of the learning "half-life" was 15 intubations; we conclude that 30 simulated grade 3 intubations would be a reasonable objective for trainees before handling high-risk cases.