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).     

Tracheal intubation through the intubating laryngeal mask in a patient with a fixed flexed neck and deviated larynx

Insertion of the conventional laryngeal mask is more difficult or impossible when the patient's head and neck are in either the neutral or flexed position. The intubating laryngeal mask is best inserted when the patient's head is supported by a pillow, without placing the head and neck into the Magill position; therefore, insertion of this modified mask may be less difficult than the conventional mask in the patient with a flexed neck. We report a case of successful insertion of the intubating laryngeal mask and subsequent tracheal intubation through the mask using a fibre-optic bronchoscope, in a patient with a flexed neck in whom tracheal intubation using several methods had been difficult previously.     

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.     

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.     

The intubating laryngeal mask. Clinical appraisal of ventilation and blind tracheal intubation in 110 patients

This study assesses the efficacy of the intubating laryngeal mask as a ventilation device and blind intubation guide. Following induction of anaesthesia with propofol, the device was successfully inserted at the first attempt in 110/110 (100%) patients. Placement took less than 10 s in all patients. Size selection was based on nose-chin distance. Adequate ventilation was achieved in 104/110 (95%) patients. Blind tracheal intubation using an 8-mm internal diameter straight silicone cuffed tracheal tube was attempted 3 min after the administration of vecuronium. Passage of a lighted stylet through the intubating laryngeal mask was used to determine the position of the intubating laryngeal mask cuff before blind intubation. If resistance was felt during intubation, a sequence of adjusting manoeuvres was used, based on the depth at which resistance occurred. Tracheal intubation was possible in 104/104 (100%) patients. In 42 (40%) patients, no resistance was encountered and the trachea was intubated at the first attempt. Sixty-two (60%) patients required one adjusting manoeuvre. The mean (range) time taken to successful intubation, i.e. the time from disconnection of the intubating laryngeal mask from the breathing system to successful tracheal intubation, was 79 (12-315) s. Six patients with potential or known intubation problems were included in the study. The tracheas of all six patients were successfully intubated. We conclude that the intubating laryngeal mask is an effective ventilation device and intubation guide with potential for use in patients who may present difficulty in tracheal intubation.     

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.     

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.     

A comparison of two silicone-reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge-shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first-attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second-attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone-reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge-shaped bevel with a leading edge at the side.     

Efficacy of the ProSeal laryngeal mask airway during manual in-line stabilisation of the neck

The laryngeal mask airway has a potential role during cardiopulmonary resuscitation, but its placement becomes more difficult during manual in-line stabilisation of the neck, and the device cannot reliably prevent pulmonary aspiration. The ProSeal laryngeal mask airway has a theoretical advantage of reducing aspiration because of its drainage tube, but its ease of placement during stabilisation of the neck is unknown. We studied 20 patients to compare ease of placement and the sealing effect between the standard and ProSeal laryngeal mask airways. In a randomised cross-over fashion, after induction of anaesthesia and neuromuscular blockade, the standard and ProSeal laryngeal mask airways were placed in turn. Placement was significantly easier for the ProSeal laryngeal mask airway (successful at the first attempt in 16 patients and at the second attempt in the remaining four patients) than for the laryngeal mask airway (successful at the first attempt in 12 of 20 patients and at the second attempt in three patients, and failed (> two attempts) in the remaining five patients; p = 0.04). The airway pressure at which gas leaked around the device was greater for the ProSeal than the laryngeal mask airway (mean difference 5.8 cmH2O; 95% CI 2.9-8.7 cmH2O; p = 0.0008).     

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.     

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.     

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.     

An unexpected complication of the intubating laryngeal mask

Fatal oesophageal perforation occurred as a complication of elective general anaesthesia for cataract extraction in a 77-year-old female patient. Tracheal intubation had been achieved, albeit with difficulty, in the course of a clinical trial of the intubating laryngeal mask.     

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.     

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.     

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.     

Complications following the use of the Combitube, tracheal tube and laryngeal mask airway

In a prospective, randomised trial, 75 patients scheduled for routine surgery were randomly allocated to one of three groups to evaluate trauma and postoperative complications after insertion of the Combitube, tracheal tube or laryngeal mask airway. Insertion of the Combitube was associated with a higher incidence of sore throat (48% vs. 16% vs. 12% [p < 0.01]) and dysphagia (68% vs. 12% vs. 8% [p < 0.01]) compared with tracheal intubation or insertion of the laryngeal mask airway, respectively. Hoarseness was significantly less common in both the Combitube and the laryngeal mask groups (both 12%) than in the tracheal tube group (44%; p < 0.01). Haematoma occurred in 36% of the Combitube group compared with 4% in both the laryngeal mask and the tracheal tube groups (p < 0.01). The higher incidence of complications should be considered when using the Combitube.