Discussion
The best method of securing the airway in patients who
have suffered blunt trauma, head injury and who may have
potential cervical spine injury has been extensively debated
[2,7-91. In the UK, the usual management involves
orotracheal intubation following a rapid sequence induction
with manual in-line stabilisation of the head and neck
and the application of cricoid pressure. The aim of manual
in-line stabilisation is to balance the forces of the intubator
and minimise movement of the cervical spine. Manual
in-line stabilisation will reduce movement of the cervical
spine by about 60% [lo].
Laryngoscopy is more likely to be difficult with the
patient's head and neck in the neutral position [3,4]. The
anaesthetist when faced with a grade 3 view during direct
laryngoscopy with a Macintosh blade may try to improve
the view by two methods: either by levering the blade
against the upper incisor teeth, or by using excessive
traction with the laryngoscope. This may result in
dangerous movement of the cervical spine or damaged
teeth. The gum elastic bougie has been recommended as a
simple way of achieving rapid intubation without moving
the cervical spine, especially for grade 3 views of the larynx
(31. Orotracheal intubation using the gum elastic bougie
takes longer than direct visual intubation [I I] and has the
potential to cause additional trauma to the airway [12].
The aim of this study was to confirm McCoy and
Mirakhur's assertion that the McCoy blade would improve
the laryngoscopic view in patients with anatomically
immobile cervical spines [5]. Manual in-line stabilisation
artificially immobilises the cervical spine. An improved
laryngoscopic view would reduce the need for the gum
elastic bougie and enable direct visual intubation to be
performed more readily. The difficult laryngoscopic views in
our study seemed to be caused by an overhanging epiglottis.
The view of the larynx was improved by one or more grades
when the tip of the McCoy blade was elevated in the
vallecula pulling the epiglottis more anteriorly.
There were seven patients with a grade 2 view with both
laryngoscopes. In a proportion, elevating the tip of the
McCoy produced an improved view, but not enough to
classify them as grade I , just a better grade 2. There were
Table 1. Grade of view at laryngoscopy (YOi)n the neutral, manual
in-line stabilisation position with the McCoy and Macintosh
laryngoscopes.
Macintosh grades
Total (%)
McCoy grades 1 2 3 McCoy
1 70 34 13 117 (70)
2 0 7 35 42 (25)
Total (YO) 70 (42) 41 (24.5) 56 (33.5) 167 (100)
Macintosh
3 0 0 8 8 (5)
eight patients who were grade 3 with both laryngoscopes.
In half of them we would normally have elected to use a size
4 blade. The tip of the McCoy blade simply did not reach
into the vallecula in these patients. A size 4 McCoy may
have converted these grade 3 views to a better grade.
This study has not formally compared the forces required
by either laryngoscope during laryngoscopy nor measured
cervical spine movement during laryngoscopy. It is our
impression that no more force is required with the McCoy
compared with the Macintosh laryngoscope to obtain the
best view of the larynx.
The laryngoscopic view is an important determinant for
ease of orotracheal intubation. We found a 33.5% incidence
of difficult laryngoscopy with the Macintosh blade
compared with only 5% with the McCoy. We consider there
is still a place for the gum elastic bougie when using the
McCoy laryngoscope for these grade 3 views. We
recommend that the McCoy laryngoscope be used in
preference to the Macintosh when direct laryngoscopy is
performed in patients with a suspected cervical spine injury
and a full stomach.