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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 4  |  Issue : 3  |  Page : 179-184

The usefulness of laryngeal tube in airway maintenance and intermittent positive pressure ventilation for paramedics: A manikin-based study


1 Department of Anaesthesiology and Critical Care, KS Hegde Medical Academy, Deralakatte, Mangaluru, Karnataka, India
2 Department of Anaesthesia and Operation Theatre Technology, KS Hegde Medical Academy, Deralakatte, Mangaluru, Karnataka, India

Date of Submission20-Jul-2021
Date of Acceptance18-Sep-2021
Date of Web Publication13-Nov-2021

Correspondence Address:
Dr. Netravati V Kurahatti
Department of Anaesthesiology and Critical Care, KS Hegde Medical Academy, Deralakatte, Mangaluru, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/arwy.arwy_42_21

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  Abstract 


Background: Supraglottic airway devices (SADs) are used to keep the upper airway open and to provide unobstructed ventilation. The recent addition to SADs is the laryngeal tube (LT). It can be inserted blindly past the oropharynx into the hypopharynx to provide a patent airway and mechanical ventilation during emergency conditions and cardiopulmonary resuscitation. Aim: To evaluate the success rate and usefulness of LT insertion for airway maintenance and intermittent positive pressure ventilation on manikins by paramedical personnel. Methods: The technique of LT insertion was explained to 200 paramedical personnel, all of whom attempted its insertion three times; the maximum time allowed for 3 attempts was 3 min. The success rate in terms of ease of insertion, adequacy of ventilation and the audible leak was assessed. The average time taken for insertion and success rate in the first, second and third attempts was assessed. Confirmation was done by ventilation with a self-inflating bag and adequate lung inflation. Results: Average time taken for insertion of LT was 14.66 ± 4.96 s. With progressive attempts, the success rate improved to 86.5%, adequacy of ventilation to 96.5% and only a minimal leak was appreciated in all. Conclusion: The LT could be a reliable device for airway management in emergencies by paramedical personnel as all participants successfully placed it within three attempts with a very good success rate.

Keywords: Intermittent positive pressure ventilation, laryngeal tube, manikin study, paramedics, supraglottic airway device


How to cite this article:
Bangera A, Kurahatti NV, Herakal GI, Murali KV. The usefulness of laryngeal tube in airway maintenance and intermittent positive pressure ventilation for paramedics: A manikin-based study. Airway 2021;4:179-84

How to cite this URL:
Bangera A, Kurahatti NV, Herakal GI, Murali KV. The usefulness of laryngeal tube in airway maintenance and intermittent positive pressure ventilation for paramedics: A manikin-based study. Airway [serial online] 2021 [cited 2022 Aug 11];4:179-84. Available from: https://www.arwy.org/text.asp?2021/4/3/179/330383




  Introduction Top


Maintenance of a patent airway and assisting ventilation is a primary component of treating any patient in the emergency room, critical care unit and operating room. The most common cause of airway obstruction is falling back of the tongue in an unconscious patient. Although there are various techniques of relieving airway obstruction, the simplest method of relieving it is using the triple airway manoeuvre.[1],[2] However, this manoeuvre alone may not relieve airway obstruction, necessitating the use of airway gadgets such as the oropharyngeal airway, nasopharyngeal airway or the recently popularised supraglottic airway devices (SADs). SADs also referred to as extraglottic airway devices, are used to provide a patent airway in an unconscious patient including under general anaesthesia with intermittent positive pressure ventilation. In addition, they may provide some degree of protection against aspiration of gastric contents.

Over the last 40 years, the invention of the laryngeal mask airway (LMA) has been the most impactful advancement in the field of airway management. Owing to their versatility and ease of insertion, these SADs rapidly replaced endotracheal intubation and face mask ventilation in more than 40% of general anaesthetics. SADs are also lifesaving devices in a “cannot intubate-cannot oxygenate” situation. The laryngeal tube (LT) is a relatively new SAD designed to secure a patent airway during either spontaneous breathing or controlled ventilation.[3] In the year 1999, a German company (VBM Medizintechnik GmbH) developed a LT and introduced it into the European market. This device could be inserted blindly past the oropharynx into the hypopharynx to provide a patent airway and effective mechanical ventilation. The LT is also recommended for medical personnel not experienced in tracheal intubation and as a rescue device during failed intubation in adults. We felt the need to study the use of LTs for airway maintenance by paramedical staff as it is logical to train paramedical personal to maintain airway patency in manikins before they handle airway emergencies in real life. Training on manikins for paramedical personnel is particularly important as they may not, unlike medical personnel, be exposed to manage many of these emergencies.

As there are not many studies describing the use of the LT by paramedics in India, this study was planned to evaluate the usefulness of LT insertion for airway maintenance and positive pressure ventilation by this group of professionals.


  Methodology Top


This prospective study was done in the Simulation Department of a tertiary care medical institution between April 2019 to March 2020. It involved anaesthesia technicians, operation theatre technicians, emergency room technicians and endoscopy technicians. The study was performed on adult manikins by 200 paramedical staff. The sample size was calculated using the following formula

n = 4 pq ÷ l2

n = Number of total participants

p = Number who placed device successfully

q = (100-p)

l = Allowable error

Written informed consent was obtained from all the participants. As the study was performed on manikins, there were no ethical considerations. Unwilling participants and candidates who failed to understand the technique were excluded from the study. The technique of LT insertion was explained to all participants with the help of a video. Three attempts were allowed for each participant with a maximum time limit of 3 min.

The manikin was placed on a table with the head in a neutral position. A size #4 LT was selected, cuff inflated fully and checked for any leak before every insertion. The cuff was deflated fully and held like a pen in the area of the 3 black lines. The lubricant was applied to the distal tip and posterior wall of the tube, the mouth was opened to around 3 cm with the thumb and index finger of the free left hand and the chin was lifted. The LT was introduced in the midline and passed along the hard palate behind the upper incisors and pushed down till the teeth mark was reached indicating its final position [Figure 1] and [Figure 2]. During insertion, care was taken to not use force to insert the tube because it could lead to cuff damage or damage to the manikin in a simulated environment. After proper insertion, the cuff was inflated with 70 mL of air using the inflating syringe. The proper placement was confirmed using ventilation with a self-inflating bag and adequate lung inflation was ensured by observing bilateral chest rise.
Figure 1: Position of the laryngeal tube[4]

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Figure 2: Placement of laryngeal tube in the manikin[5]

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Recorded data were entered in Microsoft Excel and analysed using IBM SPSS Statistics for Windows, version 26.0 (IBM Corp., Armonk, NY, USA). Parameters recorded included time taken for insertion, success rate, adequacy of ventilation and the amount of audible leak. Collected data were analysed using descriptive statistics such as frequency, percentage, mean, median, standard deviation and interquartile range. Inferential statistics were analysed using the Kruskal–Wallis test and Mann–Whitney U test as appropriate.


  Results Top


The average time taken for placement of the LT in the first, second and third attempts was 17.0 ± 5.72 s, 15 + 4.99 s and 12 + 4.18 s respectively. The majority of the operators had straight forward success rate during the study, i.e., 48%, 65% and 86.5% progressively according to the attempts. There were incidences of significant difficulty of 10%, 4% and 1% respectively with the progression of the attempts. Details of the success rate in different attempts are presented in [Table 1].
Table 1: Ease of insertion and success rate (n=200)

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The majority of operators achieved adequate ventilation during the study, i.e., 82%, 86% and 96.5% respectively with the progressive number of attempts [Table 2]. The incidences of inadequate ventilation decreased with progressive attempts (7%, 3.5% and 0.5%).
Table 2: Adequacy of ventilation (n=200)

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The majority of the operators were able to ventilate with a minimal leak during the study, i.e., 93%, 95.5% and 100% progressively according to the number of attempts. There was a considerable leak in only 7%, 4.5% and 0% with the progression of attempts.

The Kruskal–Wallis test was used to compare the time taken for insertion according to success rate (P < 0.001). Hence, there was a very significant difference in the time taken for insertion according to the success rate.

The Kruskal–Wallis test was used to compare the time taken for insertion according to the adequacy of ventilation (P < 0.001). Hence, there was a very significant difference in the time taken to obtain adequate ventilation.


  Discussion Top


Face mask ventilation is the basic technique that any medical or paramedical person is expected to master. However, on many occasions, it fails to ventilate and oxygenate the patient adequately. Endotracheal intubation is the gold standard for airway maintenance and positive pressure ventilation, but it requires more intensive training to master the technique. To overcome this, many SADs have been devised that have the advantage of ease of insertion, especially for paramedical personnel. One such device introduced recently is the LT which is thought to have many benefits. This study was done on manikins by including 200 paramedical staff to evaluate the usefulness of the LT in airway maintenance and positive pressure ventilation by personnel with this professional background.

The LT is made up of latex-free silicone material and can thus be autoclaved and reused up to 50 times. The inflation of the distal cuff seals the oesophagus and reduces the possibility of gastric insufflation while the proximal cuff stabilises the tube and seals the nasopharynx and oropharynx. When properly positioned, the distal aperture of the LT directly faces the glottis.[6]

Our study observed ease of insertion (straight forward, moderate difficulty or significant difficulty), adequacy of ventilation (adequate, partially adequate or inadequate ventilation), and the amount of audible leak (considerable or minimal leak). A maximum of 3 attempts was allowed for each participant. In our study, all 200 participants attempted three times, and the success rate in terms of ease of insertion, adequacy of ventilation and the audible leak was assessed. The average time taken for insertion in the first attempt was 17.0 ± 5.72 s with a 48% success rate, 82% adequacy of ventilation and a considerable leak in only 7% of subjects. The average time taken for insertion in the second attempt was 15 ± 4.99 s with a 65% success rate, 86% adequacy of ventilation and a considerable leak in only 4.5% of subjects. In the third attempt, the average time taken for insertion was 12 ± 4.18 s with an 86.5% success rate, 96.5% adequacy of ventilation and only a minimal leak in all patients [Table 1], [Table 2], [Table 3], [Table 4].
Table 3: Time taken for insertion (seconds) with progressive attempts (n=200)

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Table 4: Comparison of time taken (seconds) to obtain adequate ventilation with progressive attempts (n=200)

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Bahathiq et al. conducted a prospective randomised controlled trial that included 100 paramedic students where the Macintosh direct laryngoscope (DL), intubating LMA (ILMA) and GlideScope videolaryngoscope (GVL) were tested in both normal and difficult airway scenarios.[7] GVL and ILMA required less time to intubate, with a greater success rate of intubation, reduced number of attempts and optimisation manoeuvres and reduced severity of dental trauma compared to Macintosh DL in both normal and difficult airway scenarios. The success of intubation was 80% using DL, 95% using ILMA and 94% using GVL. Kannaujia et al. conducted a similar study on i-gel to determine the ease of insertion and the time taken to achieve effective airway and oropharyngeal seal pressure.[8] They found a 90% success rate at the first attempt with an insertion time of 11 s, while the remaining 10% of patients needed a second attempt. Our findings are similar to their study.

In a study using LMA Fastrach®, i-gel® and conventional endotracheal tube, Kapoor et al. found an overall 100% success rate in placement with adequate ventilation at first attempt with the average time of 19.40 ± 3.32 s with the i-gel® which is comparable to our study.[9] They also found a 100% successful insertion with adequate ventilation at the first attempt with an average time taken for placement of 38.96 ± 4.41 s with the LMA-Fastrach®. Mihai et al. found a 73% success rate of insertion and adequate ventilation in the first attempt and a 95% success rate of insertion with adequate ventilation in the 2nd attempt.[10] Cook et al. compared ProSeal-LMA (PLMA) with LT during anaesthesia with controlled ventilation.[11] Their study including 32 patients revealed a 100% ease of insertion with good ventilation in 15 patients and failure in 1 patient. The time taken for insertion of PLMA was less than the LT. Placement of the LT failed in 2 patients out of 32. Adequacy of ventilation was good in 9, fair in 6 and failed in only one patient.

Genzwuerker et al. studied all cardiac arrest situations during 2 years (2006-2008) in which the LT-D had been applied according to the ERC guidelines (2005). Out of 92 resuscitation attempts, the LT-D was successfully inserted in more than 90% of all cases in the first attempt.[12] In 95% of cases, ventilation was possible without any problems. Bernhard et al. reviewed first-pass insertion (FPI) and overall-pass insertion (OPI) success of LT by emergency medical services and in-hospital providers performing airway management for emergencies as well as for scheduled surgery.[13] This cumulative analysis of 53 studies (n = 3,600) revealed FPI and OPI success of 80.1% and 92.6%, respectively. The results of 26 studies (n = 2,159) comparing the LT with the LMA demonstrated an FPI success of 77% versus 78.7% and an OPI success of 92.2% versus 97.7%. In a manikin-based study comparing Combitube, LMA and endotracheal intubation among experienced and inexperienced medical staff, Saeedi et al. found a success rate of insertion of 100% with Combitube, 73% with endotracheal intubation and 98.3% with LMA.[14] In a meta-analysis comparing i-gel with other SADs in adult manikins, An et al. found that experienced volunteers placed the i-gel more rapidly compared to other SADs such as Classic-LMA, ProSeal-LMA, LMA-Fastrach, LT, Combitube and Easy Tube.[15] On the contrary, the time taken for i-gel insertion was more compared with that for Supreme-LMA, Air-Q and Aura-I.

Bein et al. evaluated Classic-LMA, ProSeal LMA, LT, LTS and the oesophageal Combitube. They found that LT and LTS are primarily intended as emergency airway devices for controlled ventilation in adults.[16] Howes et al. studied LMA Supreme insertion by airway novices in a manikin without any complications. Fifty airway novices inserted the LMA Supreme in anaesthetised patients undergoing elective surgery. The first insertion success rate was 86% and the overall insertion success rate was 100%. Mechanical ventilation was successful in all cases.[6]

Länkimäki et al. conducted a prospective, observational study with 300 first responders (FRs) as volunteers.[17] These volunteers were given a 30-minute lecture on the LT followed by hands-on manikin training. In 46 cases (71.9%), the LT was placed in the first attempt, in 13 cases (20.31%) in the second attempt and in 4 cases (6.3%) in the third attempt. Only 1 case required more than four attempts to place the LT. The adequacy of ventilation was confirmed by capnometry and out of all these cases, regurgitation occurred in 8 cases. This study showed that manikin training was quite useful as the FRs inserted the LT and also performed adequate ventilation with a rational success rate and insertion time. Schmutz et al. conducted a study on 2 airway manikins (TruCorp AirSim® and Laerdal Resusci Anne® Airway Trainer™) involving 80 experienced anaesthesia providers. Five different second-generation SADs (LMA® Supreme™, Ambu® AuraGain™, i-gel®, KOO™-SGA and LTS-D™) were studied and ventilation was feasible on the manikin with all SADs. An oropharyngeal leak pressure (OLP) exceeding 10 cm H2O was reached with most of the SADs in the TruCorp AirSim® but only with the LTS-D™ in the Laerdal Resusci Anne® Airway Trainer™.[18]

In our study, the majority of participants successfully inserted the LT and adequately ventilated with a minimal audible leak. Their experience improved with progressive attempts. We concluded that only a reasonable degree of practice is needed for paramedical staff to learn this lifesaving skill. With the routinely advised technique of bag and mask ventilation for paramedical personnel, the amount of air leak is more because of the improper seal with the mask. But with the LT, we found that the adequacy of ventilation is quite good with only a minimal amount of air leak. Thus, we believe that the LT could be a reliable gadget to maintain the patency of the airway and for assisting ventilation in an emergency. We found from our study that the LT is useful in maintaining a patent airway during emergency conditions as the majority of paramedical personnel could insert the LT successfully within three attempts and achieve adequate ventilation with a minimal leak.

Our study has the limitation that we did not compare the LT with other SADs and also did not accurately measure the amount of tidal volume delivered. Further studies focusing on these areas may provide useful information for the future.


  Conclusion Top


The LT is a reliable device in airway management for use in an emergency by paramedical personnel as all participants in this study successfully inserted the device within three attempts and achieved adequate ventilation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Howes BW, Wharton NM, Gibbison B, Cook TM. LMA Supreme insertion by novices in manikins and patients. Anaesthesia 2010;65:343-7.  Back to cited text no. 6
    
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Genzwuerker HV, Finteis T, Slabschi D, Groeschel J, Ellinger K. Assessment of the use of the laryngeal tube for cardiopulmonary resuscitation in a manikin. Resuscitation 2001;51:291-6.  Back to cited text no. 12
    
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Saeedi M, Hajiseyedjavadi H, Seyedhosseini J, Eslami V, Sheikhmotaharvahedi H. Comparison of endotracheal intubation, combitube, and laryngeal mask airway between inexperienced and experienced emergency medical staff: A manikin study. Int J Crit Illn Inj Sci 2014;4:303-8.  Back to cited text no. 14
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Schmutz A, Bohn E, Spaeth J, Heinrich S. Comprehensive evaluation of manikin-based airway training with second generation supraglottic airway devices. Ther Clin Risk Manag 2019;15:367-76.  Back to cited text no. 18
    


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