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 Table of Contents  
Year : 2021  |  Volume : 4  |  Issue : 1  |  Page : 35-40

Comparison of clinical performance of Ambu Aura40 laryngeal mask airway with Classic laryngeal mask airway for spontaneous ventilation during elective surgeries under general anaesthesia

Department of Anaesthesia, Bangalore Baptist Hospital, Bengaluru, Karnataka, India

Date of Submission16-Dec-2020
Date of Acceptance02-Mar-2021
Date of Web Publication29-Apr-2021

Correspondence Address:
Dr. Reena R Kadni
Department of Anaesthesia, Bangalore Baptist Hospital, Bellary Road, Hebbal, Bengaluru - 560 024, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/arwy.arwy_64_20

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Background: Introduction of the laryngeal mask airway (LMA) has revolutionised the practice of anaesthesia. This study compares the clinical performance of Ambu Aura40 LMA with Classic LMA in anaesthetised spontaneously breathing patients in terms of its ease of use and side effects. Patients and Methods: In this prospective randomised controlled study, 176 patients were allocated to either the Classic LMA or Ambu Aura40 LMA group according to a pregenerated block randomisation number sequence with concealment method. The allocated LMA was placed under general anaesthesia without muscle relaxant. The time and ease of insertion were noted in addition to any adverse events. Results: It was observed that Ambu Aura40 LMA and the Classic LMA were positioned successfully in the first attempt in 94% and 81% of patients respectively. The Ambu Aura40 LMA was placed in <12 s in 52% of patients, whereas only 2% of patients in the Classic LMA group could have the device placed within 12 s. Ninety-four percent of Classic LMA and 48% of Ambu Aura40 LMA were placed between 12 and 16 s, respectively. Statistically, a significant difference was noted with time and ease of insertion in between the groups. Conclusion: Ambu Aura40 LMA is better in terms of ease of insertion, with reduced time for insertion and lesser incidence of postoperative sore throat in comparison with Classic LMA.

Keywords: Ambu Aura40 laryngeal mask airway, classic laryngeal mask airway, spontaneous ventilation

How to cite this article:
Raj A, Kadni RR, Zachariah VK. Comparison of clinical performance of Ambu Aura40 laryngeal mask airway with Classic laryngeal mask airway for spontaneous ventilation during elective surgeries under general anaesthesia. Airway 2021;4:35-40

How to cite this URL:
Raj A, Kadni RR, Zachariah VK. Comparison of clinical performance of Ambu Aura40 laryngeal mask airway with Classic laryngeal mask airway for spontaneous ventilation during elective surgeries under general anaesthesia. Airway [serial online] 2021 [cited 2021 Jun 20];4:35-40. Available from: https://www.arwy.org/text.asp?2021/4/1/35/315169

  Introduction Top

The increased use of the laryngeal mask airway (LMA) in anaesthesia practice is because of the ease of use, safety and increased incidence of day-care surgeries. The use of LMA dates back to 1988 with the introduction of a reusable supraglottic airway device, the Classic LMA, by Dr Archie Brain. This device has proven to be safe and effective in airway management ever since.[1] The LMA represents a moulded device resulting from a combination of the face mask and the endotracheal tube in terms of both the anatomical position and degree of invasiveness.[2] The Classic LMA is a first-generation LMA and is associated with certain concerns related to skill, positioning and trauma. Ambu LMA was first introduced in 2004. The Ambu LMA is known to fit better in the airway due to the curved shaft at an angle of almost 90° which is similar to the natural anatomy of the oropharyngeal cavity. This results in easy insertion in a shorter period of time.[1],[3] Our study compared the clinical performance of Ambu Aura40 LMA with Classic LMA in anaesthetised spontaneously breathing patients. The primary objectives were ease of insertion, time of insertion, intraoperative respiratory complications, the incidence of trauma, dysphonia and sore throat. Haemodynamic variables were also noted as a secondary objective.

  Patients and Methods Top

This study was conducted between March and November 2017 after obtaining approval of the Institutional Review Board (reference EC/ANA/160/2017 dated 21 March 2017). This study, which adheres to the applicable CONSORT guidelines [Figure 1], is a prospective randomised controlled trial including 176 patients. The sample size was calculated based on the success of the first attempt insertion.[1] Written informed consent was obtained during the preanaesthetic visit.
Figure 1: Consort diagram showing flow of patient recruitment and study

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Patients undergoing peripheral orthopaedic procedures, plastic surgery, urological surgery or breast surgery of moderate duration were considered appropriate for recruitment. Patients belonging to the American Society of Anesthesiologists (ASA) physical status 1 and 2 aged between 18 and 60 years and weighing between 30 and 70 kg scheduled to undergo elective surgeries in the supine position were included in the study. Those who had a predicted difficult airway, cervical spine disease, mouth opening <2.5 cm, full-stomach and pregnant patients, reflux gastro-oesophageal disease, weight >70 kg, failure of proper placement of LMA (persistent leak) and surgery involving the head-and-neck region were excluded from the study.

Patients were designated to either the Classic LMA or Ambu Aura40 LMA group by a computer-generated block randomisation number sequence which was concealed in a sealed opaque envelope. The envelope was opened before the induction of anaesthesia and patients remained blinded to their group allocation. Weight-based sizing of the airway devices was used (size 3: 30–50 kg; size 4: 50–70 kg and size 5 >70 kg). Routine preinsertion checks were performed for the LMA. Standard monitoring included electrocardiogram, noninvasive blood pressure and pulse oximetry. Following preoxygenation, anaesthesia was induced with intravenous fentanyl 2 μg/kg and propofol 2 mg/kg. Patients were ventilated with 100% oxygen and isoflurane. After the loss of eyelash reflex and decreased jaw tone with adequate depth of anaesthesia, the allotted LMA device was placed and secured.

The cuff was filled with the recommended volume of air (20 mL for size 3, 30 mL for size 4 and 40 mL for size 5) and the intracuff pressure was measured to keep the cuff pressure between 40 and 60 cm H2O. Anaesthesia with spontaneous ventilation was maintained with an air-oxygen mixture 50:50 and isoflurane to maintain a minimal alveolar concentration of 1. To avoid bias in grading the ease of insertion of LMA, it was decided that only two consultants with at least 5 years of experience in the field of anaesthesia were involved in placing the device.

The time from picking up of the LMA until the appearance of the first square wave capnogram on the monitor was recorded as insertion time.[4] The ease of insertion of LMA was graded as follows: Grade 1 – no manipulation, Grade 2 – minimal manipulation (deflating or readjustment), Grade 3 – major manipulation (removing and reinsertion) and Grade 4 – change of LMA.[5],[6] Inability to place the LMA after 3 attempts was considered a failure. The airway was considered adequate if the minimal expired tidal volume was 6 mL/kg, peripheral oxygen saturation ≥95%, ETCO2 ≤45 mm Hg with a respiratory rate of 12–14/min and a fresh gas flow of 3 L/min without an oropharyngeal leak or gastric insufflation. Systemic arterial hypotension was treated with intravenous ephedrine. Titrated boluses of fentanyl/morphine provided additional analgesic requirements. Parameters such as heart rate, mean arterial blood pressure, SpO2, ETCO2, presence of a square wave capnograph, peak airway pressures and expiratory tidal volume were documented every 5 min. At the end of surgery, the anaesthetic was terminated and the LMA removed after the return of airway reflexes. The patient was transferred to the recovery room. Any adverse events (i.e., aspiration/regurgitation, bronchospasm and airway obstruction) and corresponding interventions were recorded. Any respiratory complications such as desaturation or bronchospasm, blood staining on the device or trauma to the tongue, lips or teeth were recorded. Postoperative follow-up was performed 12–24 h after the procedure. Patients were followed up for the presence or absence of sore throat, dysphonia or dysphagia.[2],[6]

Data entry and analysis were done using the statistical software SPSS Inc. Released 2009. PASW Statistics for Windows, Version 18.0. Chicago, IL: SPSS Inc., and R Core Team (2013) R; A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna (Available from: http://www.R-project.org/). Microsoft Word and Microsoft Excel were used to generate the graphs and tables. Descriptive and inferential statistical analyses were carried out for the study. Results on continuous measurements were presented as mean ± standard deviation (range) and categorical measurements were presented as numbers (%). Significance was assessed at a 5% level. Student t-test (two-tailed, independent) was used to evaluate the significance of study parameters on a continuous scale between the two groups. Levene's test was performed to assess the homogeneity of variance. Chi-square/Fisher exact test was used to assess the significance of study parameters on a categorical scale between the two groups, the non-parametric setting for qualitative data analysis. P < 0.05 was considered to be statistically significant.

  Results Top

The two groups were demographically well matched with no statistical significance in terms of age, ASA Physical Status and weight [Table 1]. It was observed that Ambu Aura40 LMA and Classic LMA were positioned successfully in the first attempt in 94% and 81% of patients respectively. Six percent of patients in the Ambu Aura40 LMA group and 15% of patients in the Classic LMA group needed minimal manipulation. Five percent of patients in the Classic LMA group and none in the Ambu Aura40 LMA group needed major manipulation. The ease of insertion was in favour of the Ambu Aura40 LMA (statistically significant with P = 0.01) [Table 2]. Time of insertion for Ambu Aura40 LMA was <12 s in 52% of the patients whereas only 2% of the Classic LMA could be placed within 12 s. Ninety-four percent of Classic LMA and 48% of Ambu Aura40 LMA were placed between 12 and 16 s. Three percent of Classic LMA required more than 16 s for insertion. The P value for the same was 0.001 which was statistically significant [Table 3].
Table 1: Weight of patients in study groups and incidence of complications

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Table 2: Ease of insertion of laryngeal mask airway

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Table 3: Time for insertion of laryngeal mask airway

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Sore throat and dysphonia were observed in 9/88 and 2/88 patients, respectively, in the Classic LMA and Ambu Aura40 LMA groups, respectively (P = 0.029). Blood staining on device at extubation was observed in 9/88 and 3/88 patients respectively in Classic LMA and Ambu Aura40 LMA groups, respectively (P = 0.119). None of the patients in either group desaturated to <95% intraoperatively [Table 1]. One patient in the Classic LMA group developed bronchospasm intraoperatively; the Classic LMA was replaced with an endotracheal tube and managed accordingly. No such events occurred in the Ambu Aura40 LMA group. The heart rate, blood pressure and mean arterial pressure were comparable between the groups.

  Discussion Top

The introduction of the LMA into clinical practice has radically changed airway management. The LMA is a semi-invasive method of airway management requiring minimum skills for insertion in elective and emergency scenarios. We compared the clinical efficacy of Ambu Aura40 LMA with Classic LMA in anaesthetised spontaneously breathing patients. In our study, the Ambu Aura40 LMA had a higher first-attempt success rate as compared to the Classic LMA. Four patients needed the Classic LMA to be removed and reinserted. The 90° preformed shape of the shaft of Ambu Aura40 LMA provides a sturdy grip during insertion. As it follows the shape of the natural airway, the insertion is simplified. These findings are similar to a study conducted by Sudhir et al. who compared Ambu AuraOnce LMA and Classic LMA in ASA 1 and 2 patients and concluded that the Ambu AuraOnce LMA was easier to insert.[7] Another study conducted by Siddharam et al. also had a similar conclusion.[8] In both these studies, assessment of the performance of the respective LMA was done in spontaneously breathing patients as we had done in our study.

In their study comparing Ambu LMA with Classic LMA, Lopez et al. found that Ambu LMA was easier to insert by inexperienced postgraduates (P = 0.03).[9] In 1999, before the advent of Ambu LMA, Yodfat had modified the Brain technique of LMA insertion by inserting a rigid stylet into a partially inflated LMA and creating a 90° angulation close to the bowl of the LMA. He stated that this modification significantly increased the rate of first-attempt success. Due to this 90° curvature, only a simple wrist motion is sufficient to insert the LMA instead of applying downward force.[10],[11]

Time taken for insertion of the AmbuAura40 LMA was significantly shorter (P = 0.001). This could be because of ease of insertion due to the rigid curvature of the shaft facilitating faster insertion as compared to the softer shaft of the Classic LMA.[12],[13] In a study by Suzanna et al. that included 118 paralysed anaesthetised patients, the P value for the time of insertion was 0.008. They found that Ambu AuraOnce LMA was faster to insert than Classic LMA. The time taken to insert the LMAs in their study was from the time the anatomical face mask was removed until the point when the LMA device was securely positioned. The recorded time of insertion was 40 s for Classic LMA and 35 s for Ambu AuraOnce LMA.[1] We observed in our study that Ambu Aura40 LMA took <16 s to insert without paralysing the patients and our endpoint was the appearance of the ETCO2 waveform. In a meta-analysis, Baidya et al. concluded that Ambu AuraOnce LMA could be placed faster (P = 0.001). The faster insertion of Ambu AuraOnce LMA makes it a desirable choice in emergent situations where rapid airway control might be required.[14]

None of the patients in either of our study groups had episodes of desaturation intraoperatively.[2] One patient in the Classic LMA group had intraoperative bronchospasm which was dealt with by replacing the LMA with an endotracheal tube. Bronchospasm can be a possibility with the LMA because of airway irritation from pooled secretions or sudden painful stimuli during surgery initiating a parasympathetic response. None of the patients in the Ambu Aura40 LMA group had intraoperative bronchospasm. This was similar to the observations in other studies that were reviewed.

At extubation, three patients in the Ambu Aura40 LMA group and nine patients in the Classic LMA group had blood stain on the device. Although the difference between the two groups was not statistically different, it was clinically significant. The number of attempts and the volume of air used could result in tissue distortion and venous compression leading to this concern. Literature has reported that the incidence of blood staining at extubation is similar in both the devices.[4],[6]

On follow-up within 24 h of extubation, nine patients in the Classic LMA group and two patients in the Ambu Aura40 LMA group complained of sore throat and the difference was statistically significant (P = 0.029). Similar results were reported by Ng et al. and Siddharam et al.[2],[8] In both these studies, the assessment of LMA performance was done in spontaneously breathing patients.

Our study has a few limitations. We conducted our study in patients with the normal airway. The ventilator parameters and parameters related to ease and time of insertion, number of attempts and intraoperative and postoperative complications could be different in patients with a difficult airway. Had the depth of anaesthesia during insertion of LMA been assessed, we could have given a better baseline parameter for insertion techniques.

  Conclusion Top

We conclude that Ambu Aura40 LMA is better than the Classic LMA in terms of ease of insertion, requiring less time for insertion and creating a lower incidence of postoperative sore throat. Ambu Aura40 LMA can be a superior substitute for LMA Classic for rapid airway control scenarios and day-care surgeries.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Suzanna AB, Liu CY, Rozaidi SW, Ooi JS. Comparison between LMA-Classic and AMBU AuraOnce laryngeal mask airway in patients undergoing elective general anaesthesia with positive pressure ventilation. Med J Malaysia 2011;66:304-7.  Back to cited text no. 1
Ng SY, Teoh WH, Lim Y, Cheong VG. Comparison of the AMBU® laryngeal mask and the LMA Classic in anaesthetised, spontaneously breathing patients. Anaesth Intensive Care 2007;35:57-61.  Back to cited text no. 2
Yahaya Z, Teoh WH, Dintan NA, Agrawal R. The AMBU® Aura-i™ Laryngeal Mask and LMA Supreme™: A Randomized Trial of Clinical Performance and Fibreoptic Positioning in Unparalysed, Anaesthetised Patients by Novices. Anesthesiol Res Pract 2016;2016:4717061. doi: 10.1155/2016/4717061. Epub 2016 Oct 25. PMID: 27847515; PMCID: PMC5099491.  Back to cited text no. 3
Shariffuddin II, Wang CY. Randomised crossover comparison of the Ambu® AuraOnceTM laryngeal mask with the LMA ClassicTM laryngeal mask airway in paralysed anaesthetised patients. Anaesthesia 2008;63:82-5.  Back to cited text no. 4
Nirmala BC. A comparative study for ease of insertion of laryngeal mask airway with propofol and thiopentone sodium. IOSR-JDMS 2014;13:64-9.  Back to cited text no. 5
Asai T, Neil J, Stacey M. Ease of placement of the laryngeal mask during manual in-line neck stabilization. Br J Anaesth 1998;80:617-20.  Back to cited text no. 6
Sudhir G, Redfern D, Hall JE, Wilkes AR, Cann C. A comparison of the disposable Ambu® AuraOnceTM laryngeal mask with the reusable LMA ClassicTM laryngeal mask airway. Anaesthesia 2007;62:719-22.  Back to cited text no. 7
Siddharam J, Liyakhath A, Manjunath M. A prospective randomized study comparing the efficacy of the LMA Classic, the Ambu Aura40 laryngeal mask and the i-gel using fiberoptic bronchoscope in spontaneously breathing anesthetized patients. IAIM 2015;2:105-15.  Back to cited text no. 8
López AM, Valero R, Bovaira P, Pons M, Sala-Blanch X, Anglada T. A clinical evaluation of four disposable laryngeal masks in adult patients. J Clin Anesth 2008;20:514-20.  Back to cited text no. 9
Yodfat UA. Modified technique for laryngeal mask airway insertion. Anesth Analg 1999;89:1327.  Back to cited text no. 10
Jaffe RA, Brock-Utne JG. A modification of the Yodfat laryngeal mask airway insertion technique. J Clin Anesth 2002;14:462-3.  Back to cited text no. 11
Francksen H, Bein B, Cavus E, Renner J, Scholz J, Steinfath M. Comparison of LMA Unique, Ambu laryngeal mask and Soft Seal laryngeal mask during routine surgical procedures. Eur J Anaesthesiology 2007;24:134-40.  Back to cited text no. 12
Andrews DT, Williams DL, Alexander KD, Lie Y. Randomised comparison of the Classic laryngeal mask airway with the cobra perilaryngeal Airway during anaesthesia in spontaneously breathing adult patients. Anaesth Intensive Care 2009;37:85-92.  Back to cited text no. 13
Baidya DK, Chandralekha, Darlong V, Pandey R, Maitra S, Khanna P. Comparative efficacy and safety of the Ambu(®) AuraOnce(™) laryngeal mask airway during general anaesthesia in adults: A systematic review and meta-analysis. Anaesthesia 2014;69:1023-32. doi: 10.1111/anae.12682. Epub 2014 May 7. PMID: 24801012.  Back to cited text no. 14


  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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