Tracheal intubation through the intubating laryngeal mask in patients with unstable necks

BACKGROUND: In patients with unstable necks, the neck should be stabilized during induction of anaesthesia, but this may make tracheal intubation difficult. Awake intubation may produce straining, which could be detrimental to the unstable neck. METHODS: We studied 20 patients with unstable necks to examine the efficacy of insertion of the intubating laryngeal mask under conscious sedation (to minimize the possibility of losing a patent airway and to facilitate fibrescope-aided intubation) followed by tracheal intubation through the laryngeal mask after induction of anaesthesia (to reduce stress response to intubation). After the patient had been sedated with midazolam (up to 5 mg) and fentanyl (up to 100 microg), the intubating laryngeal mask was inserted. General anaesthesia was then induced with sevoflurane and tracheal intubation attempted. RESULTS: In all patients, tracheal intubation through the laryngeal mask succeeded without airway obstruction. Neither insertion of the mask under conscious sedation nor tracheal intubation after induction of anaesthesia caused straining, and only two patients moved upper extremities at intubation. Insertion of the laryngeal mask did not significantly alter blood pressure or heart rate. Tracheal intubation significantly increased blood pressure and heart rate, but the increase was considered to be small. CONCLUSIONS: In the patient with an unstable neck with a low risk of pulmonary aspiration, insertion of the intubating laryngeal mask while the patient is sedated may minimize difficulty in obtaining a patent airway before tracheal intubation and may facilitate a fibrescope-aided tracheal intubation; subsequent induction of anaesthesia before tracheal intubation may minimize stress response to intubation.     

Ease of tracheal intubation through the intubating laryngeal mask during manual in-line head and neck stabilisation

We studied 40 anaesthetised and paralysed patients, in a randomised manner, to compare the ease of tracheal intubation either using a Macintosh laryngoscope and gum elastic bougie (group C) with the ease of tracheal intubation through the intubating laryngeal mask using a fibreoptic bronchoscope (group L), during manual in-line stabilisation of the patient's head and neck. In both groups, a maximum of 120 s was allowed for attempts at tracheal intubation. The ease of placement of the intubating laryngeal mask or tracheal intubation was assessed using a 100-mm visual analogue scale (VAS). In patients in whom tracheal intubation succeeded, time for intubation was measured. The intubating laryngeal mask was placed successfully in 19 of 20 patients, with the median VAS of 18 mm (95% CI: 13-32 mm). The success rate of tracheal intubation in group L (17 patients) was significantly higher than in group C (nine patients) (p < 0.01), tracheal intubation in group L was significantly easier than intubation in group C (p < 0.001; 95% CI for difference in VAS: 18-68 mm) and time taken for tracheal intubation was significantly shorter in group L than in group C (95% CI for difference: 8-50 s).     

The intubating laryngeal mask Use in failed and difficult intubation

The use of the intubating laryngeal mask in three patients is described. In two patients for whom tracheal intubation using traditional techniques had failed, the intubating laryngeal mask was used to achieve successful tracheal intubation. The trachea of one of these patients was subsequently re-intubated for a second procedure using the same technique. A third patient with a cervical spine fracture whose trachea was electively intubated using the intubating laryngeal mask is also presented.     

Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask

Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.     

A comparison of the intubating laryngeal mask tracheal tube with a standard tracheal tube for fibreoptic intubation

We conducted a prospective randomised study to compare the intubating laryngeal mask tracheal tube with a standard tube, for ease of tracheal intubation over a fibrescope. Thirty-six patients were investigated, using a sequential analysis technique. Ease of intubation was improved when the intubating laryngeal mask tracheal tube was used compared with the standard tube (p = 0.0009). Median (interquartile range [range]) intubation times (time from the tube's tip being level with the patient's teeth to successful placement) were 1.5 (1-2.3 [1-3]) s when the intubating laryngeal mask tracheal tube was used and 5 (3-7.3 [3-13]) s when the standard tube was used (p < 0.0001).     

The use of cricoid pressure with the intubating laryngeal mask

Unexpected difficulty with tracheal intubation contributes to anaesthetic morbidity and mortality. The intubating laryngeal mask is effective in facilitating blind intubation. We have evaluated the effect of cricoid pressure on the ability to insert an intubating laryngeal mask, and to pass a tracheal tube through it. Insertion and intubation through the mask were attempted in 50 patients, Mallampati grade 1-3, randomly allocated to cricoid and noncricoid pressure groups. Tracheal intubation was successful in 21 (84%) of the noncricoid group and 13 (52%) of the cricoid group (p = 0.03). Cricoid pressure may have to be released to allow correct placement and intubation through the intubating laryngeal mask.     

Effect of the size of a tracheal tube and the efficacy of the use of the laryngeal mask for fibrescope-aided tracheal intubation

We randomly allocated 60 patients with normal airways into three groups to compare the ease of fibrescope-aided tracheal intubation using 8.0-mm internal diameter (group F₈) and 6.0-mm (group F₆) reinforced tracheal tubes and to evaluate the efficacy of the laryngeal mask as an aid for fibreoptic tracheal intubation (group L). In group F₈ tracheal intubation was optimal in 2 of 20 patients and in two patients in whom intubation over the fibrescope was difficult the attempts resulted in inadvertent oesophageal intubation. In group F₆ intubation was always successful and significantly easier than in group F₈ (p < 0.005; 95% confidence interval for the difference in the proportion of the optimal intubation grade: 20–70%). In group L tracheal intubation was optimal in 18 of 20 patients and easier than in group F₆ (p = 0.014; 95% confidence interval for difference: 10–60%). In both groups F₆ and L tracheal intubation was completed within less than about 1 min. We conclude that conventional fibrescope-aided tracheal intubation with a 6.0-mm tracheal tube is easier than with an 8.0-mm tube and that the laryngeal mask facilitates fibrescope-aided tracheal intubation.     

The cardiovascular response to insertion of the intubating laryngeal mask airway

Sixty-one patients received a standardised anaesthetic and were randomly assigned to three groups: tracheal intubation via direct laryngoscopy, tracheal intubation via an intubating laryngeal mask airway with immediate removal of the device, and tracheal intubation via an intubating laryngeal mask airway with delayed removal. The cardiovascular response to intubation was of a similar magnitude in all groups, although delayed removal of the intubating laryngeal mask airway was associated with a second pressor response. Norepinephrine changed significantly over time following direct laryngoscopy and following immediate removal of the intubating laryngeal mask airway, but not after delayed removal. The findings of this study do not support using the intubating laryngeal mask instead of direct laryngoscopy purely to decrease the response to intubation.     

Nasal fibreoptic tracheal intubation in anaesthetised patients breathing via a modified laryngeal mask airway

A modified laryngeal mask airway was used to facilitate nasotracheal intubation with a fibreoptic laryngoscope. A size 4 laryngeal mask airway was modified by creating a defect at the base of the stem and removing the bars to allow passage of the fibreoptic laryngoscope from the nasopharynx to the larynx. The laryngeal mask airway cuff was split and the cut edges were sealed with silicone. This design allowed the cuff to function normally and allowed removal of the split laryngeal mask airway after the tracheal tube had been 'railroaded' into place. Thirty-four patients were studied. The split laryngeal mask airway was easily inserted with satisfactory airway maintenance in 32 patients. Nasal airway endoscopy and laryngoscopy were successfully achieved with the split laryngeal mask airway in place in 31 of 32 patients. Railroading the tracheal tube over the fibreoptic laryngoscope with the split laryngeal mask airway in place was successful in all 31 of these patients. This prototype split laryngeal mask airway allows good airway maintenance while fibreoptic nasotracheal intubation is performed.     

Awake tracheal intubation with the intubating laryngeal mask in a patient with diffuse idiopathic skeletal hyperostosis

Diffuse idiopathic skeletal hyperostosis, otherwise known as Forestier's disease or ankylosing hyperostosis, is a relatively common condition that is distinguished from ankylosing spondylitis by the relative preservation of spinal function and the characteristic 'candle flame' lipping of the vertebrae. We report a patient with this condition and a well-recorded history of impossible intubation who presented for emergency laparotomy. The patient was intubated awake using the intubating laryngeal mask and sedation and anaesthesia were provided by a target-controlled infusion of propofol.     

The Brain laryngeal mask airway An alternative to emergency tracheal intubation

The laryngeal mask airway was used to resuscitate a patient in whom direct and fibreoptic laryngoscopy were impossible because of cervical pathology and pulmonary oedema. The laryngeal mask airway may be an alternative to tracheal intubation in emergency resuscitation.     

Intubation through the laryngeal mask

Unexpected difficulty with tracheal intubation contributes to anaesthetic mortality. The laryngeal mask can almost always be placed satisfactorily and its position should facilitate blind intubation. A 6-mm cuffed tube will pass through both adult sizes of the mask and this study tested the feasibility of intubation through the mask. The effect of the application of cricoid pressure on the technique was also investigated. Intubation via the laryngeal mask was attempted in 100 routine patients: of the first 50 (group 1, no cricoid pressure), 45 (90%) were successfully intubated. Maintenance of cricoid pressure throughout the manoeuvre (group 2) reduced the success rate significantly to 56% (p less than 0.05). Despite the possibility that cricoid pressure may have to be interrupted momentarily, the ease with which the technique can be learnt, and the immediate availability of the necessary apparatus suggest that it should be considered for inclusion in failed intubation drill.     

A ventilation-exchange bougie for fibreoptic intubations with the laryngeal mask airway

The ventilation-exchange bougie is a new airway device which can be mounted on a fibreoptic laryngoscope for passage through the larynx into the trachea via a laryngeal mask airway. Subsequent removal of the fibreoptic laryngoscope and laryngeal mask airway allows a tracheal tube to be railroaded into position over the ventilation-exchange bougie. This study described the use of this technique for elective tracheal intubation in two groups of 12 subjects in whom difficulty with intubation was not expected. All the subjects were successfully intubated by one of two anaesthetists, one experienced and the other inexperienced with fibreoptic intubation techniques. Neither had had prior experience with the ventilation-exchange bougie. Because ventilation was maintained throughout the procedure, intubation did not need to be hurried. Cusum analysis confirmed the impression of a learning curve and the technique could be considered learnt after four and six intubations for the experienced and inexperienced fibreoptic larvngoscopists respectively. No difficulty was found either in intubating the larynx with the fibreoptic laryngoscope and ventilation-exchange bougie or when railroading the tracheal tube over the ventilation-exchange bougie. It is suggested that this new device could have an important role in teaching fibreoptic techniques, management of the difficult airway and failed intubations.     

Use of the laryngeal mask for fibrescope–aided tracheal intubation in an awake patient with a deviated larynx

I report a case in which fibrescope–aided awake tracheal intubation was achieved using a laryngeal mask, in a patient with a mediastinal goitre in whom tracheal intubation with both a laryngoscope and a fibreoptic bronchoscope had failed. The tumour extended to the upper part of the mediastinum. The larynx and the upper segment of the trachea were displaced by the tumour. Awake tracheal intubation with both a laryngoscope and a fibreoptic bronchoscope failed. The laryngeal mask was then inserted without difficulty. After a fibreoptic bronchoscope had been covered by a plastic tube, the combination was passed through the laryngeal mask into the trachea. The fibreoptic bronchoscope and the laryngeal mask were removed, and a reinforced endotracheal tube was then inserted over the plastic tube into the trachea. The time for tracheal intubation was about 70 s. The laryngeal mask may allow easier location of the laryngeal inlet with a fibreoptic bronchoscope, and this technique is a useful alternative to the conventional technique of tracheal intubation in the patient with a deviated larynx.     

A comparison of blind and lightwand-guided tracheal intubation through the intubating laryngeal mask

We have tested the hypothesis that intubation success rates, haemodynamic changes, airway complications and postoperative pharyngolaryngeal morbidity differ between blind and lightwand-guided intubation through the intubating laryngeal mask airway. One hundred and twenty paralysed anasthetised adult patients (ASA I-II, no known or predicted difficult airways) were assigned in a random manner to one of two equal-sized groups. In the blind group, patients were intubated blindly through the intubating laryngeal mask airway. In the lightwand group, patients were intubated through the intubating laryngeal mask airway assisted by transillumination of the neck with a lightwand. A standard sequence of adjusting manoeuvres was followed if resistance occurred during intubation or if transillumination was incorrect. The number of adjusting manoeuvres, time to intubation, intubation success rates, haemodynamic changes (pre-induction, pre-intubation, postintubation), oesophageal intubation, mucosal trauma (blood detected), hypoxia (oxygen saturation < 95%) and postoperative pharyngolaryngeal morbidity (double-blinded) were documented. Overall intubation success was similar (blind, 93%; lightwand, 100%), but time to successful intubation was significantly shorter (67 vs. 46 s, p = 0. 027) and the number of adjusting manoeuvres was significantly fewer (p = 0.024) in the lightwand group. There were no significant differences in blood pressure or heart rate between the groups at any time. Oesophageal intubation occurred more frequently in the blind group (18 vs. 0%, p = 0.002). The incidence and severity of mucosal injury, sore throat and hoarseness were similar between the groups. We conclude that lightwand-guided intubation through the intubating laryngeal mask is superior to the blind technique.