We evaluated blind intubation through an ILMA in patients wearing a rigid Philadelphia collar. Adequate or possible ventilation was established via the ILMA in 45 of 50 patients (90%) within two insertion attempts. Our overall success rate of 96% for blind intubation in this patient population did not differ significantly from our control patients who were intubated without a collar.
This is not the first report describing the use of an ILMA to facilitate intubation in patients wearing a cervical collar;5–7
however, previous studies remain controversial. Ferson et al.5
reported 100% success rate of blind intubation via the ILMA in 68 patients wearing a rigid Philadelphia collar within two attempts. However, their study was retrospective. Furthermore, the investigators cut out the chin portion of the collar to facilitate access to the patient’s mouth, a manoeuvre that surely reduced efficacy of the collar and would ease ILMA insertion.
Moller et al.6
reported 100% success rate of blind intubation via the ILMA in 17 patients wearing a stiff neck collar (Stiffneck Sellect; Laerdal Medical Corp, Wappinger’s Falls, NY). However, using same type of collar with application of cricoid pressure, Wakeling and Nightingale7
succeeded in blindly intubating only 2 of 10 patients. The success rate of ventilation and blind intubation via the ILMA in this study7
might have been exacerbated by application of cricoid pressure as observed in patients with normal airway.8
We did not find any differences in the intubation success rate, number of intubation attempts, or types of adjusting manoeuvres applied between our two study groups. It thus appears that when positioned properly, the rigid Philadelphia collar does not greatly alter upper airway anatomy. However, we did find that ILMA insertion time was longer, more insertion attempts were required, and that ventilation through the ILMA was worse in rigidly immobilized patients. Although there are statistically significant differences in inter-incisor distance between our groups, this small difference seems clinically unimportant. The more likely explanation for the difficulty in insertion of the ILMA in the collared patients is that the collar prevented small movement of the head and neck that might have facilitated insertion of the device.
Our protocol has several limitations. First, we only studied patients undergoing elective surgery without an unstable cervical spine. Oesophageal intubation occurred in 14% of the patients, and 34% of patients required multiple intubation attempts. Significant Prolonged intubation time may not be acceptable in an emergency situation with a patient with gastric paresis, or respiratory or cardiac insufficiency. Furthermore, the ILMA exerts considerable pressure against cervical vertebrae,9
and possible neurological deterioration must be considered before using the ILMA in patients with an unstable cervical spine.
A second limitation of our study was that we did not have a positive control (i.e. comparison of the ILMA with another intubation technique in the presence of a collar). Although there is no gold standard technique for emergent airway management of a patient with possible cervical spine injury, several techniques can be used in this scenario. Blind nasal intubation is successful in more than 90% of patients, but it requires multiple attempts in 67–90% of patients.10–12
Thus, it may be slower and cause trauma to the nose or pharynx. There are also objections to the use of the nasal route as it is dangerous in the presence of basal skull fracture.13
The fibreoptic technique in awake patients allows intubation under direct vision and has success rate near 100% in skilled hands.14
However, successful fibreoptic tracheal intubation requires a cooperative patient and a secretion-free and blood-free airway.
Direct laryngoscopy with the aid of a gum elastic bougie is successful in more than 90% of patients whose neck movements are restricted, although 20% of the patients require multiple attempts.15,16
Due to blind insertion of a bougie into the trachea, oesophageal intubation may occur in some patients. Prism laryngoscope improves laryngoscopic view compared to the Macintosh blade;17,18
however the use of a prism significantly increases the difficulty of intubation as it interferes with passage of the endotracheal tube,17
prolongs intubation time, and produces more failed intubation attempts than does the Macintosh blade.19,20
From these results, the prism laryngoscope may not be recommended in this scenario.
The Bullard laryngoscope was used in real and simulated cervical spine injury patients with a success rate of 85–100% and intubation time of ~40 seconds.21–23
The device can be used in awake patients or under general anaesthesia, and the time required for intubation is reasonable. However, blood and secretion in the airway compromise the success rate of this technique as in the case of the fibreoptic technique. Compared to above-mentioned techniques, the ILMA does not need a secretion-free and blood-free airway, and even when the intubation is not possible, the ILMA acts as ventilation device with high success rate.
In conclusion, blind intubation through an ILMA is thus a reasonable strategy for controlling the airway in patients who are immobilized with a rigid cervical collar, especially when urgency precludes a fiberoptic approach.