Fiberoptisch unterstützte endotracheale Intubation durch die Larynxmaske im Kindesalter

Fibre optic-assisted tracheal intubation through the laryngeal mask airway is a simple and safe procedure for securing the airway in the paediatric patient with unexpected and known difficult tracheal intubation. Therefore, fibre optic-assisted tracheal intubation through the laryngeal mask airway represents a standard airway technique and must be part of clinical education and also regular training. However, the removal of the laryngeal mask airway over the tracheal tube is impaired by the short length of the tracheal tube, easily resulting in tube dislocation from the trachea. Among several techniques to overcome this problem, the Cook airway exchange catheter offers a reliable method not only for safe removal of the laryngeal mask over the tracheal tube but also for insertion of an adequate tracheal tube, particularly in paediatric patients. This is particularly important for cuffed tubes as the pilot balloon of the cuffed tube is too large to pass through laryngeal mask airway tubes size 2.5 and smaller. This presentation demonstrates fibre optic-assisted tracheal intubation through the laryngeal mask airway in children step-by-step and discusses its clinical implications. A list with compatible sizes of laryngeal mask airways, tracheal tubes and airway exchange catheters is also provided.     

Resistance and additional inspiratory work imposed by the laryngeal mask airway

Laryngeal mask airways and tracheal tubes were studied to determine both their resistance to constant gas flows and additional inspiratory work during simulated inspiration. Laryngeal mask airways imposed less resistance and required lower additional inspiratory work compared with the corresponding sized tracheal tubes. If inspiratory loading during anaesthesia is an important consideration, then the laryngeal mask airway may be preferable to a tracheal tube.     

The reinforced laryngeal mask airway (RLMA) protects the airway in patients undergoing nasal surgery — an observational study of 200 patients

PURPOSE: The laryngeal mask airway (LMA) is used in nasal surgery but there is some concern of tracheal or laryngeal contamination with blood and secretions. We have evaluated the ability of the LMA to prevent airway contamination until full emergence from anesthesia. METHODS: Two hundred adults, ASA I-III patients, undergoing nasal surgery under general anesthesia were included in a prospective observational study. A reinforced LMA, sizes 3-5, was used during surgery and removed with its cuff inflated, in recovery, when the patients awoke. The LMA was examined on its laryngeal aspect for contamination of blood and secretions and scored (0-3) independently by two observers according to soiling (score of 0 = no blood; score of 1 = staining on the cuff; score of 2 = staining on the inside of mask; score of 3 = blood in the tube). RESULTS: The contamination scores were [n (%)]: 0 =174 (87%); 1 = 22 (11%); 2 = 4 (2%); 3 = 0 (0%). CONCLUSION: Ninety-eight percent of patients had no or minimal contamination of the LMA. The 2% incidence of grade 2 LMA soiling is low and probably acceptable, since it did not result in symptoms of airway contamination. We suggest that the use of the LMA for nasal surgery may be appropriate.     

An investigation into the quantity of secretions removed by inflated and deflated laryngeal mask airways

It has been suggested that removal of a laryngeal mask airway with the cuff inflated may remove more secretions than with the cuff deflated. We performed a study to determine whether this suggestion is correct. Patients were randomly allocated to removal of the laryngeal mask airway with the cuff deflated (n = 75) or inflated (n = 74). The laryngeal mask airways were weighed before insertion and after removal, the difference in these two weights being taken to be the mass of secretions adherent to the airways on removal. The mean (SD) increase in laryngeal mask airway weight was 2.45 (1.47) g with the cuff deflated and 3.03 (1.76) g with the cuff inflated (p = 0.03). We conclude that removal of the laryngeal mask airway with the cuff inflated removes approximately 0.5 g more secretions than with the cuff deflated.     

Surgeons' exposure to sevoflurane during paediatric adenoidectomy: a comparison of three airway devices

Although sevoflurane is commonly used in anaesthesia, a threshold value for maximum exposure to personnel does not exist and although anaesthetists are aware of the problem, surgeons rarely focus on it. We used a photo‐acoustic infrared device to measure the exposure of surgeons to sevoflurane during paediatric adenoidectomies. Sixty children were randomly allocated to laryngeal mask, cuffed tracheal tube or uncuffed tracheal tube. The average mean (maximum) sevoflurane concentrations within the surgeons' operating area were 1.05 (10.05) ppm in the laryngeal mask group, 0.33 (1.44) ppm in the cuffed tracheal tube group and 1.79 (18.02) ppm in the uncuffed tracheal tube group, (p < 0.001), laryngeal mask and cuffed tracheal tube groups vs. uncuffed tube group. The presence of sevoflurane was noticed by surgeons in 20% of cases but there were no differences between the groups (p = 0.193). Surgical and anaesthetic complications were similar in all three groups. We conclude that sevoflurane can be safely used during adenoidectomies with all three airway devices, but in order to minimise sevoflurane peak concentrations, cuffed tracheal tubes are preferred.     

Tracheal intubation and sore throat: a mechanical explanation

Although tracheal intubation remains a valuable tool, it may result in pressure trauma and sore throat. The evidence for an association between these sequelae is not conclusive and sore throat may be caused at the time of intubation. This hypothesis was tested in a mechanical model and the results from tracheal intubation compared with those from insertion of a laryngeal mask airway, which is associated with a lower incidence of sore throat. Use of the model suggests that the tracheal tube and laryngeal mask airway impinge on the pharyngeal wall in different manners and involve different mechanisms for their conformation to the upper airway, but that in a static situation, the forces exerted on the pharyngeal wall are low with both devices. It also suggests that the incidence of sore throat should be lower for softer and smaller tracheal tubes and that the standard 'Magill' curve (radius of curvature 140 +/- 20 mm) is about optimum for the average airway.     

Paediatric airway management

The first part of this article describes the anatomical and physiological features of the upper airway and the respiratory system in paediatric patients relevant to airway management. This is followed by a section on airway evaluation, which outlines elements of the patient's history and examination that should alert medical and nursing staff to potential airway problems. Subsequent sections deal with practical airway management, including the indications for tracheal intubation, and the use of cuffed tracheal tubes and laryngeal mask airways in children. The review concludes with a brief outline of the principles of managing the child with a potentially difficult airway.     

The LMA CTrach in airway resuscitation: six case reports

We report six patients with unexpected difficult airways who underwent tracheal intubation using the Laryngeal Mask Airway CTrach. All these patients had failed orotracheal intubation using direct laryngoscopy and gum elastic bougie placement. Fibreoptic bronchoscopy failed in two of these patients due to blood and secretions in the airway. This report describes the successful use of this new intubating laryngeal mask in these cases, all of whom were intubated on the first attempt with this new device.     

Laryngeal mask airway and tracheal tube cuff pressures in children: are clinical endpoints valuable for guiding inflation?

We prospectively assessed common clinical endpoints for their usefulness in avoiding hyperinflation of the cuffs of laryngeal mask airways (slight outward movement) and tracheal tubes (disappearance of an audible leak around the cuff during manual ventilation < 20 cmH₂O) in 640 children. Cuff pressures were measured at induction and immediately before emergence from anaesthesia. With the laryngeal mask airway (sizes 1–4), the median cuff pressures ranged from 90 to > 120 cmH₂O at induction and 105 to > 120 cmH₂O before emergence. With tracheal tubes (sizes 3–7 mm), median cuff pressures were 40–60 cmH₂O at induction and 45–70 cmH₂O at emergence. With the use of nitrous oxide a consistent rise in cuff pressure was observed between the first and second readings whereas cuff pressures remained constant when nitrous oxide was not used. The use of clinical endpoints alone was associated with significant hyperinflation of cuffs with both devices in almost all patients, with an exacerbation when nitrous oxide was used. In order to avoid unnecessary cuff hyperinflation in laryngeal mask airways and tracheal tubes, the routine use of cuff manometers is mandatory in children.     

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.     

High concentration potassium permanganate eliminates protein and particle contamination of the reusable Classic laryngeal mask airway

In this three-stage study, we test the hypothesis that supplementary cleaning with potassium permanganate > or =4 mg.l(-1) eliminates protein and particle contamination from the reusable Classic laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 x 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l(-1) and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l(-1). The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l(-1) or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p < 0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 x 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density of > or =1 mum surface particles was lower in the potassium permanganate 8 mg.l(-1) than the control group (21 vs. 121 .cm(-2), p < 0.0001) and was similar to brand new laryngeal mask airways (24 .cm(-2)). We conclude that supplementary cleaning with potassium permanganate 8 mg.l(-1) eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.     

Fibreoptic views through the laryngeal mask and the intubating laryngeal mask.

BACKGROUND AND OBJECTIVE: The intubating laryngeal mask (intubating laryngeal mask airway) was designed to facilitate blind intubation. Its value as an adjunct to fibreoptic laryngoscopy has not been evaluated. This study compares the intubating laryngeal mask airway with the standard laryngeal mask airway as conduits for fibreoptic laryngoscopy. METHODS: The fibreoptic view of the laryngeal inlet was graded via both devices in 60 anaesthetized patients. The fibreoptic view through the intubating laryngeal mask airway was assessed after the central epiglottic elevator bar had been lifted out of the field of vision by an 8-mm Euromedical tracheal tube, which was inserted to a depth of 18 cm. The fibreoptic view from the aperture bars of the laryngeal mask was recorded. RESULTS: The vocal cords were viewed less frequently through the intubating laryngeal mask airway (52%) than through the laryngeal mask airway (92%) [difference = 40% (95% CI = 26% to 54%), P < 0.0001]. CONCLUSION: The view of the laryngeal inlet is better through the laryngeal mask airway than through a tracheal tube inserted to 18 cm in the intubating laryngeal mask.     

The effect of introducing fibreoptic bronchoscopes on gas flow in laryngeal masks and tracheal tubes

The laryngeal mask airway, reinforced laryngeal mask airway and tracheal tube were studied to determine (1) flow resistance during simulated inspiration and (2) the maximum size of fibreoptic scope which can he passed down the lumen at clinically useful ventilatory settings. In addition, the flow resistance imposed by the mask aperature bars was quantified. The laryngeal mask airway can accommodate a larger fibrescope than the corresponding sizes of reinforced laryngeal mask airway or tracheal tube. Mean (range)flow resistance was 2.3 (1.7-35) times higher with the reinforced laryngeal mask airway compared to the laryngeal mask airway, 2.1 (1.2-4.2) times higher with the tracheal tube compared with the laryngeal mask airway and 1.2 (0.7-1.8) times lower with the tracheal compared with the reinforced laryngeal mask airway. Removal of the mask aperture bars resulted in a mean decrease in flow resistance of 3.6%. Our data have shown that the laryngeal mask airway can accommodate a larger fibrescope than either the reinforced laryngeal mask airway or tracheal tube at clinically useful ventilatory settings and that the current recommendations for maximum size of fibrescope should be revised.     

异丙酚抑制老年患者术毕喉罩替换气管导管时机体反应的药效学

目的 探讨异丙酚抑制老年患者术毕喉罩替换气管导管时机体反应的药效学.方法 择期腹腔镜下拟行胆囊切除术的老年患者20例,ASA Ⅰ或Ⅱ级,年龄65～70岁.术毕行喉罩替换气管导管时,根据是否诱发机体反应,采用序贯法调节异丙酚血浆靶浓度,采用概率单位法得出异丙酚抑制喉罩替换气管导管时机体反应的半数有效血浆靶浓度(EC_(50))和95%有效血浆靶浓度(EC_(95))及其95%可信区间(95%CI).结果 异丙酚抑制喉罩替换气管导管时机体反应的EC_(50)(95%CI)为2.79(2.44～3.04)μg/ml;EC_(95)(95%CI)为3.61(3.27～4.78)μg/ml.结论 老年患者术毕靶控输注异丙酚血浆靶浓度3.61 μg/ml可满足喉罩平稳替换气管导管.     

The anatomical position of three extraglottic airway devices in patients with clear airways

We tested the hypothesis that, in patients with clear airways, the anatomical position of three single-use extraglottic airway devices is similar. The airways studied were: the laryngeal mask airway unique (LMA-U), the Softseal laryngeal mask airway (SS-LM) and the Cobra perilaryngeal airway (Cobra-PLA). Three hundred spontaneously breathing patients were randomly allocated to have their airway managed using one of these three supraglottic airway devices. A rigid endoscope was passed down the airway tube and the following anatomical assessments were made: position of the epiglottis; position of the glottis; and position of the cuff. The epiglottis was more frequently visible with the LMA-U than with the SS-LM (76 vs 57%, p = 0.006) and with the LMA-U than with the Cobra-PLA (76 vs 46%, p < 0.0001). The epiglottis was in contact with the mask aperture bars in 25% of patients, and in 34% of these, the epiglottis was seen to be herniated through the aperture bars. Herniation of the epiglottis through the mask aperture bars occurred more frequently with the Cobra-PLA than the LMA-U (8 vs 3%, p = 0.008). The vocal cords and arytenoids were more frequently visible with the LMA-U and SS-LM than with the Cobra-PLA (both p < 0.006). Herniation of the arytenoids through the mask aperture bars was more frequently seen with the Cobra-PLA than with the LMA-U (8 vs 0%, p = 0.004). The position of the cuff was optimal for the LMA-U and SS-LM in 90% and 93% of patients, respectively. The cuff was more frequently in the midline with the LMA-U than with the SS-LM (p = 0.002). We conclude that the anatomical position of the LMA-U and SS-LMA is superior to that of the Cobra-PLA in patients with clear airways. The mask aperture bars probably have no anatomical utility and predispose to herniation of the pharyngeal structures.     

Protein cross-contamination during batch cleaning and autoclaving of the ProSeal laryngeal mask airway

We tested the hypothesis that protein cross-contamination occurs during batch cleaning and autoclaving of a reusable extraglottic airway device, the ProSeal laryngeal mask airway. At the end of each day for 10 days, nine laryngeal mask airways that had been used for non-intra-oral surgery were cleaned and autoclaved alongside a new unused laryngeal mask airway. In addition, a new unused laryngeal mask airway underwent the same cleaning and autoclaving procedures in isolation. Protein staining was more frequently detected on the unused laryngeal mask airways that were processed by batch rather than in isolation (p < 0.01). Protein staining was detected on all unused laryngeal mask airways that were processed by batch, but none on those processed in isolation. Protein staining was more severe with the used compared with the unused laryngeal mask airways (p < 0.001). We conclude that protein cross-contamination of the laryngeal mask airway occurs during batch cleaning and autoclaving and recommend that reusable airway devices are cleaned in isolation.     

A French survey of paediatric airway management use in tonsillectomy and appendicectomy

BACKGROUND: There are no epidemiological data describing tracheal intubation and laryngeal mask airway (LMATM) use in paediatric anaesthesia. This analysis focused on the factors leading to the indication for an airway management procedure, i.e. tracheal intubation and laryngeal mask airway vs face mask during general anaesthesia for tonsillectomy and appendicectomy. METHODS: The data were recorded in the French survey of Practical Anaesthesia performed in 1996. Two main types of surgical procedures were selected: tonsillectomy and appendicectomy because of the number of patients and the need to use an invasive airway management technique. RESULTS: During a 1-year period, 627 anaesthetics for appendicectomy and 653 anaesthetics for tonsillectomy were recorded in the sample under consideration. Tracheal intubation or laryngeal mask airway was undertaken in 66% of tonsillectomies and 84% of appendicectomies. Univariate analysis showed that tracheal intubation/laryngeal mask were used significantly more often in older children, with long duration of anaesthesia, in nonambulatory procedures and in procedures performed at an academic centre. When these variables were included in a multivariate analysis, the duration of anaesthesia over 30 min was a factor linked to the use of tracheal intubation/laryngeal mask airway for the two types of surgery (P < 0.0001). For tonsillectomy, inpatients were 2.9 times more likely to be intubated (or have an laryngeal mask airway) than were outpatients. For appendicectomy, older children were 3.4 times more likely to be intubated (or have an laryngeal mask airway) than younger children. CONCLUSIONS: This large French survey shows that the use of tracheal intubation/laryngeal mask airway in this country is primarily related to a predicted long duration of anaesthesia.     

Comparison of the GlideScope video laryngoscope vs. the intubating laryngeal mask for females with normal airways

BACKGROUND AND OBJECTIVE: In this randomized clinical study, we compared the intubation success rates of the intubating laryngeal mask airway with the GlideScope in patients with normal airways. The primary hypothesis was that the intubating laryngeal mask airway was equally effective as the GlideScope in terms of successful intubation times. METHODS: Sixty ASA I and II adult patients undergoing elective gynaecological surgery were randomly allocated into either the intubating laryngeal mask airway group or the GlideScope group. After a standard anaesthetic intravenous induction, orotracheal intubation was performed. Time taken for successful tracheal intubation, ease of device insertion, difficulty of tracheal intubation, manoeuvres needed to aid tracheal intubation, number of intubation attempts, haemodynamic changes every 2.5 min interval for 5 min and complications during tracheal intubation were recorded. RESULTS: Time to successful intubation was longer (mean 68.4 s +/- 23.5 vs. 35.7 s +/- 10.7; P < 0.05), mean difficulty score was higher (mean 16.7 +/- 16.3 vs. 7.3 +/- 13.1; P < 0.05) and more intubation attempts were required in the intubating laryngeal mask airway group. CONCLUSION: The GlideScope improved intubation time and difficulty score for tracheal intubation when compared with the intubating laryngeal mask airway in our patients. Blind intubation through the intubating laryngeal mask airway offers no advantages over the GlideScope in patients with normal airways. Despite its limitations, the intubating laryngeal mask airway is a valuable adjunct, especially in cases of difficult airway management when it can provide ventilation in between intubation attempts.     

Airway equipment and its maintenance for a non difficult adult airway management (endotracheal intubation and its alternative: face mask,laryngeal mask airway,laryngeal tube)

The airway equipment for a non difficult adult airway management are described: endotracheal tubes with a specific discussion on how to inflate the balloon, laryngoscopes and blades, stylets and intubation guides, oral airways, face masks, laryngeal mask airways and laryngeal tubes. Cleaning and disinfections with the maintenance are also discussed for each type of airway management.     

Anaesthetic management of a patient with relapsing polychondritis undergoing laparoscopic surgery

We describe the anaesthetic management of a patient with relapsing polychondritis who underwent laparoscopic cholecystectomy. We failed to secure a patent airway with a ProSeal laryngeal mask airway, probably because of the deformity of the larynx. The glottis was small and it was only possible to pass a 5.5 mm cuffed endotracheal tube into the trachea. Positive pressure ventilation with 5 cm H2O positive end-expiratory pressure and surgery were safely performed. In relapsing polychondritis, recurrent inflammation and destruction of laryngeal and tracheobronchial cartilage causes airway obstruction, and various sizes of tracheal tubes and other airway manipulation devices should be prepared.