BJA Advance Access published online on September 14, 2007
British Journal of Anaesthesia, doi:10.1093/bja/aem260
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Evaluation of the revised laryngeal tube suction: the laryngeal tube suction II in 100 patients
Department of Anaesthesia, Royal United Hospital, Bath, UK
* Corresponding author. E-mail: timcook007{at}googlemail.com
Accepted for publication July 2, 2007.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
Background: We prospectively assessed the performance of the laryngeal tube suction mark II (LTS II).
Methods: LTS II was assessed during controlled and spontaneous ventilation during total i.v. anaesthesia. Ventilation adequacy, functional and anatomical positioning and airway seal were evaluated.
Results: One hundred healthy patients (30F:70M) aged 18–85-yr-old were studied. Insertion of the LTS II was successful in 71 at first attempt, in 24 at second attempt and in five at third/fourth attempt. Median insertion time was 15 s (range 5–120 s). Temporary obstruction occurred in six patients. A median of one manipulation per patient was required to establish an airway (range 0–5). During maintenance, temporary airway obstruction occurred in eight patients. Use of the device was abandoned once during insertion, once during maintenance and once because of complications unrelated to the study. The airway was clear in 89 of 97 patients during maintenance and partially obstructed in eight. Median seal pressure was 29.5 (range 15–85) cm H2O. A gastric tube was passed via the posterior channel in 97 of 99 patients. The glottis was visible using a fibrescope passed via the device in 51% of patients. Via the drain tube the upper oesophagus was visible in 22% and this was open in 50%. Blood was visible on the device after removal in 12 patients. After the operation 14 patients reported mild sore throat.
Discussion: The LTS II appears to be an improvement on its predecessor and merits further investigation comparing it with its competitors during use for anaesthesia and emergency airway management.
Keywords: airway, patency, complications; equipment masks, anaesthesia
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
The laryngeal tube suction (LTS, VBM Medizintechnik GmbH, Sulz, Germany) is a supraglottic airway, which has a gastric port designed to increase the safety of the device. Three randomized trials1–3 have reported similar performance of the LTS and the Proseal laryngeal mask airway (PLMA) (Intavent Orthofix, Maidenhead, UK) during routine surgical procedures, even under conditions of elevated intra-abdominal pressure. In contrast, one study strongly favoured the PLMA.4 Notwithstanding these results, in late 2005 the LTS was replaced by the LTS mark II (LTS II). The LTS is no longer available.
Like the LTS, LTS II is designed for maintaining the patency of the airway during anaesthesia and in emergency airway management. It consists of a translucent double lumen silicone tube with two inflatable balloons (Fig. 1). A larger proximal balloon stabilizes the tube and blocks the oral and nasopharynx. The smaller distal balloon blocks the oesophageal inlet and is designed to reduce the likelihood of gastric ventilation. Anterior ventilation holes lie between the balloons. Both balloons are inflated through a single pilot tube and balloon through which the cuff pressure can be monitored. A posteriorly placed drainage tube is designed for passage of a gastric tube up to size Ch16. Compared with the LTS, the LTS II is considerably longer and has a markedly modified, smaller tip, and a redesigned distal balloon, which is more ovoid in shape (Fig. 2A and B). The LTS II also incorporates minor changes to the airway orifices and to the pilot balloon.
|
|
The LTS II is designed for blind insertion without laryngoscopy. The airway tube has a 25 mm connector (colour coded for different sizes) and has a ‘dental line’ mark to indicate correct depth of insertion. There are three sizes: size 3 for children/small adults (<155 cm height), size 4 for medium adults (155–180 cm height), and size 5 for large adults (>180 cm height). The LTS II is intended for use for controlled or spontaneous ventilation during anaesthesia.
There are no published studies evaluating the performance of the LTS II. This study evaluates the performance of the LTS II in a cohort of 100 consecutive unselected patients undergoing elective surgery.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
Approval of the Local Ethics Committee was obtained for the study. Patients attending for elective surgery, who were ASA I–III, were considered for inclusion in the study. Patients were excluded if they had respiratory or cardiovascular disease and also if they had any pathology of the neck, upper respiratory, or upper alimentary tract or were at risk of regurgitation, or pulmonary aspiration of gastric contents.
Patients were given written and verbal information by the anaesthetist before signing a consent form. All three anaesthetists participating in the study had at least 5 yr experience of airway management. Before recruiting patients into the study, each anaesthetist was instructed in the use of the LTS II and used the LTS II to manage the airway of 10 patients; these data were not recorded.
The Samsoon and Young modification5 of the Mallampatti classification6 was used to assess the airway of all patients. Anaesthetic monitoring conformed to the minimum standard recommended by the Association of Anaesthetists of Great Britain and Ireland. Anaesthesia consisted of induction with fentanyl 1 µg kg–1 and propofol 1% delivered by target-controlled infusion (target 4–7 µg ml–1). Neuromuscular block was not used. Target levels of propofol were increased if there were difficulties in mouth opening, coughing, and gagging or if body movement occurred during the insertion of LTS II. Maintenance of anaesthesia was with a target-controlled infusion of propofol 1%. Anaesthesia was considered adequate for device insertion when the patient was unresponsive, had lost their eye lash reflex and did not respond to anterior jaw thrust and the effect site concentration exceeded 2 µg ml–1.7
Before insertion both balloons of the LTS II were deflated and a water-soluble lubricant was applied. The LTS II was inserted blindly according to the manufacturer's instructions, placing the flat edge of the LTS tip on the hard palate and sliding it along the palate in the midline of the mouth down into the hypopharynx until resistance was felt or horizontal depth marker on the LTS II tube was levelled with the upper teeth. Cuff pressure was measured with an aneroid barometer (VBM, Sulz, Germany): as recommended by the manufacturer the balloons were initially inflated to a pressure of 90 cm H2O then this was reduced to 60 cm H2O. The number of attempts at insertion, time for successful insertion, and the number of airway manipulations to establish the airway were recorded. Complications during insertion (defined before the study), the quality of the airway obtained, and the ability to ventilate through the device were recorded.
Ease of insertion was (subjectively) classified as easy/slightly difficult/very difficult/not possible and the quality of airway was classified as excellent/good/fair/inadequate. The volume of air inserted in the device was recorded in millilitres.
Gentle manual ventilation of the patient's lungs was attempted before formal evaluation. Successful ventilation was defined as visible chest movement, square wave capnogram, stable oxygenation >95% and the ability to achieve an expired tidal volume of 7 ml kg–1 (with an initial tidal volume of 7 ml kg–1 increased if necessary up to a maximum of 10 ml kg–1). If it was not possible to ventilate the lungs, the following adjustments were allowed: neck extension or flexion, chin lift, jaw thrust, gentle pushing, or pulling of the device. Adequacy of ventilation was reassessed and, if it was not possible ventilate through the LTS II, further attempts at insertion of the device were allowed to a maximum of four. If insertion failed the use of the LTS II was abandoned and the airway maintained as clinically indicated. The LTS II was used as the primary airway throughout anaesthesia unless complications necessitated its removal.
The anatomical position of the LTS II was assessed by fibreoscopy through both lumens of the device. Via the airway tube the best view of the airway (i.e. the best view obtained via either airway orifice) was scored as follows: Grade 1, perfect view of the vocal cords; Grade 2, partial view of the vocal cords or a view of the arytenoids only; Grade 3, view of the epiglottis only; Grade 4, view of the cuff of the device or the pharynx or oesophageal sphincter.8 The view down the drain tube was recorded as mucosa/closed upper oesophageal sphincter or oesophagus/open upper oesophageal sphincter or oesophagus/larynx.
The circuit was then closed to atmosphere to assess airway leak pressure: ventilation stopped momentarily and using a fresh gas flow of 5 litre min–1 the pressure in the airway circuit was recorded until an audible leak occurred or airway pressure plateaued. Airway pressure was not allowed to exceed 40 cm H2O.
The ability to pass a lubricated gastric tube though the drain tube was recorded with only one attempt allowed.
During the maintenance of anaesthesia any complications of airway management or manipulations required were recorded. Overall airway quality, ease of hands-free anaesthesia, and usefulness of the device were each assessed, by the anaesthetist, using a five-point subjective scale (excellent/good/fair/poor/inadequate).
The use of the LTS II was initially evaluated during controlled ventilation. However, during maintenance, as neuromuscular blocking drugs were not used, the patients were able to resume spontaneous ventilation. This occurred at the varying stages of maintenance and occupied a variable proportion of the case as a result of widely varying durations of surgery. However, the methodology allowed evaluation of the LTS II during both controlled and spontaneous ventilation, which we considered important because previous versions of laryngeal tubes have performed poorly particularly during spontaneous ventilation.9
On emergence from anaesthesia the device was removed by recovery staff, with both balloons completely deflated when the patient was able to mouth-open to command. During emergence and removal, airway complications and the presence or absence of blood or troublesome secretions were recorded.
Patients underwent a structured interview before leaving the recovery area and again at 24 h to elicit the presence of sore throat, neck, jaw or ear pain, alteration in tongue sensation, oral swelling, or nausea. All positive responses were rated by the patient as mild, moderate, or severe.
Data were analysed using the statistical software ‘Analyse-it’ (Leeds University, UK) and Excel Spreadsheet (Microsoft, USA).
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
We studied 70 males and 30 females, with a median age of 44 yr (range 18–85 yr), median weight of 80 kg (range 55–107 kg), and median BMI 26 kg m–2 (range 18–37 kg m–2). The modified Mallampati classification was recorded in 96 patients and was Class 1 (n=50), Class 2 (n=42), and Class 3 (n=4). The surgical speciality was orthopaedics in 45 patients, general surgery in 40, and urology in 15. The median duration of procedures was 45 min (range 10–200).
A size 4 LTS II was used in 67 patients and size 5 in 33 patients. Insertion was possible in 99 patients. Insertion was successful for 98.5% (66/67) of size 4 and 100% (33/33) of size 5 devices, respectively. Extra boluses of propofol were required during insertion in 17 patients.
After successful insertion the airway was clear in 87 patients, partially obstructed in nine and obstructed in one. These data were not recorded for two patients. Insertion and ventilation were possible on the first attempt in 73 patients, on second attempt in a further 22 patients, and five patients needed three or four attempts. Fifty-seven patients required a total of 82 manipulations (median 1, range 0–5) to establish a patent airway.
One patient had a total of five manipulations but the airway could still not be established. A classic LMA (Intavent Orthofix) was passed. A second patient started vomiting soon after a successful insertion of the LTS II and was deemed to require tracheal intubation. There was no evidence of aspiration. The first case was regarded as a failed insertion, the second was not.
Securing an effective airway took <30 s in 74 patients, with an overall median duration of 15 s (range 5–120 s). In 82 patients, the airway was established uneventfully (no complications), whereas 18 had at least one complication. Excluding failure to establish an airway in one patient, there were 26 complications during insertion in 18 patients (Table 1). Insertion was rated as easy (n=71), slightly difficult (n=21), or difficult (n=8).
|
Fibreoptic inspection of position was performed in 77 patients. The glottis was visible via airway tube 51% of patients. The upper oesophagus was visible via the drain tube in 22% and this was open in 50%. The fibreoptic view down the airway tube and drain tubes are detailed in Table 2.
|
In one patient, airway obstruction soon developed during maintenance: this did not improve with manipulation so the LTS II was removed and anaesthesia was continued with face mask ventilation.
Overall adequate ventilation was possible in 97 patients. Median seal pressure was 29.5 cm H2O and was >20 cm H2O in 78 patients. We found no correlation with functional or anatomical position and airway seal (quality of airway vs airway seal: kendall rank correlation 
=0.04, 2-tailed P=0.66, fibreoptic view of airway vs airway seal: kendall rank correlation =–0.09, 2-tailed P=0.31). The median volume of air inserted in the pharyngeal cuff to achieve an intracuff pressure of 60 cm H2O was 68 ml (range 30–100 ml).
The LTS II was used throughout maintenance in 97 patients. The airway was clear in 89 patients and partially obstructed in eight patients. The airway became completely obstructed requiring removal of the LTS II in one patient. Seven patients required a total of 20 manipulations of the airway during maintenance (0.2 manipulations per patient). Arterial oxygen saturation remained >90% in all patients and >95% in 94 patients.
The quality of the airway was considered excellent in 49 patients, good in 40, fair in eight, and poor in one. Ease of hands-free anaesthesia and overall usefulness of the device was excellent in 59 patients, good in 28, fair in five, and poor in six.
A gastric tube was successfully passed at first attempt in 97 of the 99 (98%) patients in whom it was attempted.
The LTS II was generally tolerated well during emergence from anaesthesia (data from 89 patients), with blood being visible on the device in 12 (13%) patients, and secretions being troublesome in five (6%) patients. Poor tolerance of the device in 10 (11%) patients led recovery nurses to remove it in the recovery unit before the patient was able to open their mouth to command (i.e. earlier than desirable), however this did not lead to important complications in any patient.
Complications occurring at the time of device removal are recorded in Table 3. After the operation mild sore throat was reported by 13 patients in recovery and 14 patients at 24 h.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
In this study, insertion and ventilation via the LTS II is successful on first attempt in 73% and within two attempts in 95% of patients. These are lower than reported for the LMA,10 but are likely to be acceptable in many circumstances. We found it to be an effective airway for anaesthesia in the majority of patients during both controlled-ventilation and spontaneous breathing. In this small study, no major complications arose. Airway obstruction occurred in ~10% of patients. This was readily corrected in most, but necessitated removal of the device in two patients.
Overall results in this cohort of 100 patients are considerably better than those previously observed by us in a group of 32 ventilated patients in whom the former version of the LTS was used.4 In that report, we had a 42% first time failure rate and 18% overall failure rate. In this study, these failures reduced to 27 and 2%, respectively. Manipulations required to establish the airway remain high: in our previous randomized-controlled trial of the LTS we reported 0.6 manipulations per patient required during insertion compared with 0.8 for the LTS II in this paper.4
The LTS II was easy to insert and requires minimal mouth opening. There was one clear failure at insertion and one case of airway obstruction shortly after insertion. When an airway was established, ventilation was usually easy. On removal of the LTS II blood was seen in 13% of cases and 14% of patients complained of sore throat in the recovery room or at 24 h. Comparative figures for the LMA are 12–1511 12 and 12–28%,13 14 respectively.
The LTS II generally provided a good airway seal (median seal pressure 29.5 cm H2O, >25 cm H2O in 63 patients). This is higher than the classic LMA15 or laryngeal tube16 and of a similar level to the ProSeal.17 This combined with the ability to reliably access the gastrointestinal tract via the drain tube offers the possibility of increased protection against gastric distension, regurgitation, and pulmonary aspiration compared with supraglottic airways that are simple ‘airway tubes’.
We were only able to view the glottis via the device in 51% of patients, (though we made no efforts to optimize this view). This and the relatively small airway orifices of the device make the LTS II less obvious as a device for use for difficult airway management when access to the trachea is required. Current evidence and experiences suggest the classic, intubating, and ProSeal laryngeal masks are likely to be more suitable for such uses.18–20
There are several limitations of this study. Firstly, we studied only low-risk patients who have normal airways and were not obese. We cannot extrapolate from these data to performance in other groups. Secondly, we did not compare performance with likely competitors of the LTS II. This study can be regarded as a feasibility study and clearly randomized-controlled studies comparing performance are required. Thirdly, this study has not examined the performance of the LTS II in unstarved patients or those who may have a full stomach. The results do not show that the use of the LTS II in such groups would be appropriate. Finally, this study is relatively small and while it shows that the LTS II appears to be fairly efficacious, it offers almost no useful evidence of the safety of the LTS II, which requires data from a considerably larger cohort in routine practice.
This study gives better results for the LTS II than have been obtained in previous studies of the LTS. In particular, problems such as difficult insertion and axial rotation appear to have been largely overcome by redesign. Potentially, the LTS II combines some of the advantages of laryngeal masks (easy handling), the Combitube (aspiration protection), and the PLMA (good airway seal and good access to the gastrointestinal tract via the drain tube). These features point towards potential roles in anaesthesia, airway rescue after failed intubation and perhaps airway management during cardiopulmonary resuscitation.
Further studies comparing the LTS II with its likely clinical competitors, including the PLMA, i-gel (Intersurgical, Wokingham, UK), and Supreme airway (Intavent Orthofix) during anaesthesia and in other situations such as airway rescue or during cardiac arrest are now indicated. Studies determining whether the LTS II can successfully be placed by inexperienced users and studying protection against aspiration would also be useful.
In conclusion, the laryngeal tube LTS II was inserted easily in the majority of patients without injury to the oropharynx, providing a patent airway during anaesthesia and was well tolerated during emergence. Further specific studies are now required to establish its roles in airway management both within and outside anaesthesia.
|
Acknowledgements |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
The LTS IIs used in this study were provided free by the manufacturers, VBM GmbH, Sulz, Germany. This was the company's only involvement in this study. T.C. has received free or reduced price equipment for research from a number of manufacturers of airway equipment and has been paid by Intavent Orthofix and the LMA company for lecturing.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionAcknowledgementsReferences |
|---|
1 Bein B, Carstensen S, Gleim M, et al. A comparison of the Proseal laryngeal mask airway, the laryngeal tube S and the oesophageal-tracheal combitube during routine surgical procedures. Eur J Anaesthesiol (2005) 22:341–6.[CrossRef][Web of Science][Medline]
2 Roth H, Genzwuerker HV, Rothhaas A, Finteis T, Schmeck J. The ProSeal laryngeal mask airway and the laryngeal tube suction for ventilation in gynaecological patients undergoing laparoscopic surgery. Eur J Anaesthesiol (2005) 22:117–22.[CrossRef][Web of Science][Medline]
3 Gaitini LA, Vaida SJ, Somri M, Yanovski B, Ben-David B, Hagberg CA. A randomized controlled trial comparing the ProSeal laryngeal mask airway with the laryngeal tube suction in mechanically ventilated patients. Anesthesiology (2004) 101:316–20.[CrossRef][Web of Science][Medline]
4 Cook TM, Cranshaw J. Randomized crossover comparison of ProSeal laryngeal mask airway with laryngeal tube sonda during anaesthesia with controlled ventilation. Br J Anaesth (2005) 95:261–6.
5 Samsoon GLT, Young JRB. Difficult tracheal intubation: a retrospective study. Anaesthesia (1987) 42:487–90.[Web of Science][Medline]
6 Mallampati SR, Gatt SP, Gugiona LD, et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J (1985) 32:429–34.[Web of Science][Medline]
7 Drage MP, Nunez J, Vaughan RS, Asai T. Jaw thrusting as a clinical test to assess the adequate depth of anaesthesia for insertion of the laryngeal mask. Anaesthesia (1996) 51:1167–70.[Web of Science][Medline]
8 Verghese C, Berlet J, Kapila A, Pollard R. Clinical assessment of the single use laryngeal mask airway—the LMA-Unique. Br J Anaesth (1998) 80:677–9.
9 Miller DM, Youkahana I, Pearce AC. The laryngeal mask and VBM laryngeal tube compared during spontaneous ventilation. A pilot study. Eur J Anaesthesiol (2001) 18:593–8.[CrossRef][Web of Science][Medline]
10 Brimacombe J. Laryngeal Mask Anaesthesia. Principles and Practice. (2004) London: WB Saunders. 198–220.
11 Parker MR, Day CJ. Visible and occult blood contamination of laryngeal mask airways and tracheal tubes used in adult anaesthesia. Anaesthesia (2000) 55:388–90.[CrossRef][Web of Science][Medline]
12 Greenberg RS, Brimacombe J, Berry A, Couze V, Piantadosi S, Dake EM. A randomised controlled trial comparing the cuffed oropharyngeal airway in spontaneously breathing anaesthetised adults. Anesthesiology (1998) 86:970–7.
13 Figuerdo E, Vivar-Diago M, Munoz-Blanco F. Laryngo-pharyngeal complaints after use of the laryngeal mask airway. Can J Anesth (1999) 46:220–5.[Web of Science][Medline]
14 Oczenski W, Krenn H, Dahaba AA, et al. Complications following the use of the Combitube, tracheal tube and laryngeal mask airway. Anaesthesia (1999) 54:1161–5.[CrossRef][Web of Science][Medline]
15 Brimacombe JR, Brain AIJ, Berry AM. The Laryngeal Mask Airway Instruction Manual. (1997) Berkshire, UK: Intavent Research Limited.
16 Cook TM, McKinstry C, Hardy R, Twigg S. Randomised controlled crossover trial of the laryngeal mask airway Proseal with the laryngeal tube during anaesthesia with controlled ventilation ventilation. Br J Anaesth (2003) 91:678–83.
17 Cook TM, Lee G, Nolan JP. The ProSealTM laryngeal mask airway: a review of the literature. Can J Anesth (2005) 52:739–60.[Web of Science][Medline]
18 Brimacombe J. Laryngeal Mask Anaesthesia. Principles and Practice. (2005) 2nd Edn. London: WB Saunders. 305–55.
19 Caponas G. The intubating laryngeal mask airway. Anaesth Intensive Care (2002) 30:551–69.[Web of Science][Medline]
20 Cook TM, Silsby J, Simpson TP. Airway rescue in acute upper airway obstruction using a ProSealTM laryngeal mask airway and an aintree catheterTM—a review of the ProSealTM laryngeal mask airway in the management of the difficult airway. Anaesthesia (2005) 60:1129–36.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||