Use of the intubating laryngeal mask in children: an evaluation using video-endoscopic monitoring

BACKGROUND AND OBJECTIVE: The intubating laryngeal mask is designed to act as a ventilatory device and as an aid to blind tracheal intubation in adults. The aim of this study was to evaluate the efficacy of the intubating laryngeal mask for ventilation of the lungs and tracheal intubation in children using video-endoscopic control. METHODS: The handling and efficacy of the size 3 intubating laryngeal mask for tracheal intubation in 80 children weighing > or = 25 kg were assessed under video-endoscopic control. Ease of intubating laryngeal mask insertion, adequacy of lung ventilation through the intubating laryngeal mask and airway sealing pressures were recorded. Tracheal intubation was performed blindly by the intubator, while the supervisor observed the procedure on the video display. If blind intubation failed at the first attempt, the monitor view was used to guide the tracheal tube into the trachea. The success rate and time required for successfully placing the tracheal tube were recorded. RESULTS: Insertion of the intubating laryngeal mask was easy in all children. Lung ventilation through the intubating laryngeal mask was uniformly excellent. Blind tracheal intubation at the first attempt was successful in 53 children (66%) within 18.8 +/- 4.1 s. Twenty-four of the 27 failed blind intubation attempts were successfully intubated with video-endoscopic guidance within 28.6 +/- 9.4 s. Two children required replacing the intubating laryngeal mask, one child had to be intubated conventionally. CONCLUSIONS: The size 3 intubating laryngeal mask provides an airway that is easy to establish in children > or = 25 kg with excellent ventilation conditions and allows blind tracheal intubation at the first attempt with a high success rate. Endoscopic monitoring improves its safety and intubation success rate.     

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.     

Laryngeal mask and anaesthetic waste gas exposure

In recent years there has been a growing awareness of the possible hazards caused by anaesthetic gases in operating theatres. The laryngeal mask airway provides an alternative both to tracheal intubation and the face mask although the implications for operating theatre contamination have not been quantified. This paper describes the incidence and magnitude of exposure of theatre personnel to waste anaesthetic gases during laryngeal mask airway anaesthesia. The leakage of anaesthetic gases to the anaesthetist's breathing zone was monitored using a Bruel & Kjaer Multi Gas Monitor, Type 1302 during 50 general anaesthetics employing either spontaneous (n = 24) or controlled (n = 26) ventilation. All patients were anaesthetised with propofol, alfentanil and nitrous oxide. There was no statistically significant association between the amount of anaesthetic gas leakage and ventilation method. The laryngeal mask airway meets occupational safety requirements on nitrous oxide concentrations in the operating theatre environment.     

Electroencephalographic arousal response during tracheal intubation and laryngeal mask airway insertion after induction of anaesthesia with propofol

Laryngoscopy and tracheal intubation, or insertion of a laryngeal mask airway may lead to an arousal response on the electroencephalogram. We studied whether more intense stimulation (laryngoscopy and tracheal intubation) causes a greater arousal response than less intense stimulation (laryngeal mask airway insertion). Thirty-four patients (ASA I-II) were anaesthetised with propofol 3 mg.kg-1, followed by vecuronium 0.15 mg.kg-1 and a propofol infusion of 10 mg.kg-1.h-1. Three minutes after induction of anaesthesia, either laryngoscopy and tracheal intubation (n = 18), or laryngeal mask airway insertion (n = 16) was performed. Laryngoscopy and tracheal intubation caused a significantly greater increase in blood pressure (but not heart rate) than laryngeal mask airway insertion (p < 0.05). Electroencephalogram responses were not different. More intense stimulation does not cause a greater arousal response during propofol anaesthesia.     

Inhalational induction of anaesthesia with 8% sevoflurane in children: conditions for endotracheal intubation and side-effects

BACKGROUND AND OBJECTIVE: This study was designed to assess the conditions for endotracheal intubation or insertion of a laryngeal mask airway following an inhalational induction using 8% sevoflurane and nitrous oxide without the use of muscle relaxants or opioids. METHODS: There were two groups: 30 children had endotracheal intubation and 30 children had a laryngeal mask airway inserted. Induction of anaesthesia was accomplished using an inspiratory concentration of sevoflurane 8% in a nitrous oxide and oxygen mixture. After an end-expiratory concentration of sevoflurane of at least 4% had been reached, when the pupils were miotic and centred, the trachea was intubated or a laryngeal mask inserted. The time to loss of consciousness and successful airway management was recorded. Jaw relaxation, movements, visibility, and position of the vocal cords and vital parameters were monitored. RESULTS: Jaw relaxation was complete in all children. The vocal cords were completely visible in all patients of the tracheal intubation group, whereas vocal cord relaxation was incomplete in five children. Nevertheless, all children had an atraumatic intubation or insertion of the laryngeal mask without the use of a muscle relaxant. Vital signs were stable in both groups. There were no cases of restlessness and/or postoperative shivering. Four patients in the endotracheal group (13.3%) were nauseous and three (10%) vomited, while two children (6.6%) in the laryngeal mask group experienced nausea and vomiting. CONCLUSIONS: Induction with sevoflurane in nitrous oxide and oxygen leads to fast loss of consciousness and provides ideal conditions for managing the airway without supplemental opioids or muscle relaxants. Furthermore, sevoflurane using this technique was very well tolerated, indicated by high haemodynamic stability and a reduced rate of postoperative restlessness, shivering, nausea and vomiting.     

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.     

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.     

Use of a larynyngeal mask airway during aortic valve replacement

We report the elective use of a laryngeal mask airway during cardiac surgery for congenital tracheal stenosis. A 53-year-old woman with severe aortic valve stenosis was scheduled for aortic valve replacement. During anesthesia induction, the anesthesiologists attempted conventional intubation but failed. Fiberoptic tracheal examination and computed tomography showed a tracheal stenosis with 5 mm minimal diameter. A laryngeal mask airway was used at the patient's rescheduled surgery. The laryngeal mask airway use did not lead any surgical complication. We concluded that the laryngeal mask airway may be considered as an alternative to conventional intubation in patients with tracheal stenosis.     

Use of a larynyngeal mask airway during aortic valve replacement

We report the elective use of a laryngeal mask airway during cardiac surgery for congenital tracheal stenosis. A 53-year-old woman with severe aortic valve stenosis was scheduled for aortic valve replacement. During anesthesia induction, the anesthesiologists attempted conventional intubation but failed. Fiberoptic tracheal examination and computed tomography showed a tracheal stenosis with 5 mm minimal diameter. A laryngeal mask airway was used at the patient's rescheduled surgery. The laryngeal mask airway use did not lead any surgical complication. We concluded that the laryngeal mask airway may be considered as an alternative to conventional intubation in patients with tracheal stenosis.     

Use of an illuminated flexible catheter for light-guided tracheal intubation through the intubating laryngeal mask by nurses

We evaluated the ability of inexperienced personnel in using a prototype illuminated flexible catheter to assist tracheal intubation through the intubating laryngeal mask in anaesthetised, paralysed patients. The device consists of a completely flexible thin plastic catheter, a bulb attached to its distal end and a 15-mm concentric adapter at its proximal end. The illuminated catheter is placed into a straight silicone tracheal tube in such a way that the bulb is placed at the distal end of the tracheal tube. Six nurses inexperienced in tracheal intubation followed a 2-hr training program by using the device through the intubating laryngeal mask in a mannequin and then intubated 10 patients each, with instruction from an anaesthetist. All patients (n=60) were ASA 1-2, scheduled to undergo general anaesthesia for elective surgery. After fentanyl/propofol induction the intubating laryngeal mask was inserted. When an adequate airway was established, patients received atracurium and the endotracheal tube preloaded with the device was inserted through the intubating laryngeal mask and by observing the glow in the neck was advanced into the trachea. The final outcome and the duration of the procedure were recorded. The intubating laryngeal mask was inserted successfully in all patients. The success rate of intubation was 57/60 (95%); 38 patients at first attempt and 19 after two or three attempts. The mean (+/-SD) duration of the procedure in the first five patients in the series of each nurse was 74+/-40 s while in the last five patients it was diminished to 52+/-23 s (P=0.01). We conclude that the described methodology has the potential for more widespread use of tracheal intubation through the intubating laryngeal mask even by inexperienced personnel.     

Difficult airway management in the neonate: a simple method of intubating through a laryngeal mask airway

Tracheal intubation through a laryngeal mask airway is one option for securing an airway in the patient with a difficult airway. A variety of techniques and equipment have been used to stabilize the position of the tracheal tube while removing the laryngeal mask airway. We have shown that if a fibreoptic bronchoscope is used to place an tracheal tube through a laryngeal mask in neonates, additional equipment is not needed to remove the laryngeal mask airway without endangering tracheal tube placement. This is possible even in small neonates.     

The laryngeal mask airway: its features,effects and role

The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anaesthetic practice. Numerous articles and letters about the device have been published in the last decade, but few large controlled trials have been performed. Despite widespread use, the definitive role of the laryngeal mask has yet to be established. In some situations, such as after failed tracheal intubation or in anaesthesia for patients undergoing laparoscopic or oral surgery, its use is controversial. There are a number of unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoid pressure prevents placement of the mask. We review the techniques of insertion, details of misplacement, and complications associated with the use of the laryngeal mask. We discuss the features and physiological effects of the device, including the changes in intra-cuff pressure during anaesthesia and effects on blood pressure, heart rate and intra-ocular pressure. We then attempt to clarify the role of the laryngeal mask in airway management during anaesthesia, based on the current knowledge, by discussing the advantages and disadvantages as well as the indications and contraindications of its use. Lastly we describe the use of the laryngeal mask in circumstances other than airway maintenance during anaesthesia: fibreoptic bronchoscopy, tracheal intubation through the mask and its use in cardiopulmonary resuscitation.     

Laryngeal mask airway for Caesarean section

The use of a laryngeal mask airway is described in a patient for emergency Caesarean section, when tracheal intubation was not possible. Provision of the laryngeal mask airway for use in the Maternity Unit is discussed.     

Intubating laryngeal mask for airway management in lateral decubitus state: comparative study of right and left lateral positions

Background. The intubating laryngeal mask has been used forthe emergency management of the airway in patients placed inthe lateral decubitus position. We have conducted this prospectivestudy to compare the feasibility of placement of an intubatinglaryngeal mask and blind tracheal intubation guided by the intubatinglaryngeal mask in patients placed in the right and the leftlateral positions. Methods. A total of 82 adults of both sexes with normal airways,scheduled for cholecystectomy, were allocated randomly to beplaced in either the right (n=41) or left (n=41) lateral positionfor the insertion of an intubating laryngeal mask and blindtracheal intubation guided by the intubating laryngeal maskunder balanced general anaesthesia. A sequence of standard manoeuvreswas performed after each failed attempt at intubating laryngealmask placement and intubation. Results. The intubating laryngeal mask was placed in all patientsat the first attempt. Ventilation of the lungs through the intubatinglaryngeal mask was possible in 40 patients (97.5%) from eachgroup after the first attempt at insertion (P=1). Followingadjustments, adequate ventilation could be achieved in all patients.The first attempt success rates of blind tracheal intubationwere 85.3% (35/41) and 87.8% (36/41) in the right and left lateralgroups, respectively (P=1). The remaining patients from bothgroups (except for one patient in the left lateral group whohad a failed intubation) were intubated at the second attempt. Conclusion. Insertion of the intubating laryngeal mask and blindtracheal intubation through it in the lateral position is feasiblein patients with normal airways. These procedures have a highand comparable success rate when patients are placed in theright and left lateral positions.     

Proseal喉罩与支纤镜联合Aintree导管用于颈椎不稳患者气管插管的临床研究

目的 通过与清醒经鼻支纤镜插管对比,研究Proseal喉罩与支纤镜联合Aintree导管用于颈椎不稳患者气管插管的有效性和安全性。方法 因颈椎骨折或严重颈椎间盘突出拟行颈椎减压内固定手术的患者40例,随机分配至以下两组：A组20例,清醒表麻后行经鼻支纤镜引导插管,然后麻醉诱导;B组20例,常规麻醉诱导后置入Proseal喉罩,沿喉罩在支纤镜引导下将Aintree导管插入气管内,退出喉罩后经Aintree导管置入气管插管。监测插管前（T0）、开始插管（T1）、插管成功时（T2）、插管成功后1min（T3）、插管成功后3min（T4）的平均动脉压（MAP）和心率（HR）;记录支纤镜插管时间、插管总时间（表麻时间或置喉罩时间加支纤镜插管时间）和插管相关并发症。结果 A组有1例因不能配合改为诱导后支纤镜插管,B组所有病例插管成功。T2和T3两时点,A组HR（92±17次/分,95±18次/分）显著高于B组（78±13次/分,83±17次/分）;T3时点A组MAP（93±28mmHg）显著高于B组（80±24mmHg）（P<0.05）;A组在T2、T3两时点的HR、MAP均显著高于各自的T0时点基础值（P<0.05）。插管的总时间两组相当（A组184±55s,B组179±27s,P>0.1）,而B组支纤镜插管时间较短（A组62±32s,B组39±18s,P<0.05）。两组患者术后无任何插管相关并发症。结论 Proseal喉罩与支纤镜联合Aintree导管用于颈椎不稳患者气管插管与传统支纤镜清醒插管效果相当,但血流动力学更平稳,是安全有效的困难气道处理新技术。     

A comparison of laryngeal mask airway with tracheal tube for intra-ocular ophthalmic surgery

The use of the laryngeal mask was compared with tracheal intubation in 30 patients who underwent intra-ocular ophthalmic surgery and who received intravenous anaesthesia with propofol. Changes in intra-ocular pressure, heart rate and mean arterial pressure after the insertion of the laryngeal mask airway or the tracheal tube were not significantly different. However, at the end of the procedure, a significantly higher percentage of patients with a tracheal tube coughed, reacted to head movement and suffered breath-holding. In addition, significantly more patients in this group complained of a sore throat (p less than 0.05). During intravenous propofol anaesthesia, the laryngeal mask airway does not offer any advantage over tracheal intubation in the control of intra-ocular pressure for intra-ocular ophthalmic surgery. However, there were fewer complications immediately following surgery in the laryngeal mask group.     

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.     

Postal survey of the anaesthetic techniques used for paediatric tonsillectomy surgery.

A postal survey of anaesthetic techniques used for tonsillectomy surgery in children (age 3-16 years) was performed with particular reference to the use of the reinforced laryngeal mask airway and the use of suxamethonium. From 110 questionnaires despatched, replies were obtained from 88 consultant anaesthetists with commitments to otolaryngologic (ENT) anaesthesia (response rate 80%). In paediatric practice, the reinforced laryngeal mask airway was routinely used by 14 (16%) respondents from the 88 who replied. Thirteen (33%) respondents out of 39 respondents who replied saying that they had used the reinforced laryngeal mask airway at some point, reported problems with its use. Suxamethonium was used routinely by 40 consultants (45%) for tonsillectomy surgery. Severe problems with its use had been encountered by 26 (30%) respondents     

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.