Is the intubating laryngeal mask tube really superior to the flexometallic tracheal tube for fibreoptic nasotracheal intubation?

Abstract

We read with interest the recent article of Rai et al. [1], that concluded that the incidence of tracheal tube impingement during fibreoptic nasotracheal intubation is significantly lower with the intubating laryngeal mask (ILMA) tube than with the flexometallic tracheal tube. We believe it would be more appropriate to conclude that the ILMA tube is better only when the flexometallic tracheal tube is improperly orientated during passage. In this study, once the flexometallic tracheal tube was rotated anticlockwise by 90°, its success rate improved to 29 out of 30 patients, essentially the same as the success rate (30 out of 30) of the ILMA tube. It may be more appropriate always to start with the flexometallic tracheal tube orientated in a 90° anticlockwise direction. This technique has been used previously during awake fibreoptic orotracheal intubation, resulting in a higher success rate of intubation at the first attempt (100%) compared to the conventional approach (60%) [2]. Rotation of the bevelled tracheal tube randomly may reduce the difficulty in advancing a tracheal tube over a fibrescope, but 90° anticlockwise rotation should be effective in reducing impingement of the tracheal tube [3]. This manoeuvre was first suggested by Schwartz et al. [4]. Maktabi et al. [5] recommend 90° anticlockwise rotation as the first step to overcome difficulty in advancing the tracheal tube. Ho et al. [6] and Wheeler et al. [7] also suggested that the first attempt at railroading the tracheal tube should be done with the tracheal tube already turned in a 90° anticlockwise direction. In our practice, simple rotation of bevelled tracheal tubes anticlockwise by 90° during the first attempt has become a routine part of fibreoptic intubation [8]. This study by Rai et al. [1] should help popularise this. In the abstract, the authors conclude that compared to the ILMA tube, the incidence of laryngeal trauma from fibreoptic nasotracheal intubation may be significantly greater with the flexometallic tracheal tube, due to the higher incidence of glottic impingement. However, we find no evidence to support this in their results. This is concerning as in our experience, many readers do not read beyond the abstract of an article, and may then be misled by this statement. It may have been preferable to compare the two tubes for the severity of epistaxis, nasal pain, sore throat and dysphonia observed on the first post operative day. Both the flexometallic tracheal tube and ILMA tube lack a Ring-Adair-Elwin contour. For this reason, we feel that these tubes are not suitable choices for nasotracheal intubation for oral cavity and jaw surgery, as surgical access may be limited due to vertical protrusion of the tracheal tube from the nostrils. The absence of the distal curve of these tubes does not allow the breathing system to be positioned away from the surgical field without the use of an additional connector. The ILMA tube also requires a higher cuff pressure, which makes it less desirable, particularly in patients requiring nasotracheal intubation for a prolonged period.