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ORIGINAL ARTICLE Table of Contents  
Ahead of print publication
Influence of different head and neck positions on oropharyngeal leak pressures and cuff positions with Ambu® AuraGainTM laryngeal airway in children


1 Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
2 Department of Anaesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
3 Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India

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Date of Submission09-Aug-2022
Date of Acceptance15-Oct-2022
Date of Web Publication07-Nov-2022
 

  Abstract 


Background: Ambu® AuraGain™ laryngeal airway is a supraglottic airway device designed to provide better airway protection and airway seal pressures. Aim of Study: To quantify oropharyngeal leak pressures (OPLPs), fibreoptic view, peak airway pressure and ventilation scoring with Ambu® AuraGain™ in children in different head and neck positions such as maximum flexion, maximum extension and lateral rotation. Patients and Methods: Sixty-eight children aged between 1 and 6 years posted for surgery were enrolled. Ambu® AuraGain™ was inserted after the induction of anaesthesia and ventilation was confirmed. OPLP, fibreoptic view, peak airway pressure and ventilation scores were noted in different head and neck positions such as maximum flexion, maximum extension and lateral rotation. Results: The OPLP significantly increased in flexion (P < 0.001) and significantly decreased in extension (P < 0.001) when compared to the neutral position. Airway pressure (Paw) increased significantly in flexion (P < 0.001) and decreased in extension (P = 0.04) when compared to the neutral position. Tidal volume delivery was comparable in all positions. There was a statistically significant decrease in ventilation scoring in the flexed position when compared to the neutral position (P = 0.005). There was a significant worsening of fibreoptic view in flexion when compared to the neutral position (P < 0.001). Fibreoptic view in the lateral position and extension was comparable with the neutral position. Conclusions: Use of Ambu® AuraGain™ laryngeal airway provides the best ventilatory parameters and Paw in children with head in the neutral and lateral position but lower OPLP with head in extension. However, flexing the head results in the worst ventilatory parameters and Paw among the positions studied.

Keywords: Ambu® AuraGain™, children, neck positions, oropharyngeal leak pressures


How to cite this URL:
Nemani S, Mishra SK, Rudingwa P, Padala SR, Senthilnathan M, Parida S. Influence of different head and neck positions on oropharyngeal leak pressures and cuff positions with Ambu® AuraGainTM laryngeal airway in children. Airway [Epub ahead of print] [cited 2022 Nov 28]. Available from: https://www.arwy.org/preprintarticle.asp?id=360523





  Introduction Top


Supraglottic airway devices (SADs) have been used in different head and neck positions in paediatric patients for various surgeries.[1] Ambu® AuraGain™ is a single use, anatomically curved, second-generation SAD which has an inbuilt gastric drainage tube to empty stomach contents.[2] It was designed to provide better airway protection and airway seal pressures.[2]

The preformed shape of the device with a slightly larger cuff size provides a good seal around the pharynx and improves the ease of insertion of the device.[3] The cuff of Ambu® AuraGain™ sits in the pharynx and forms a good seal for ventilation, thus preventing aspiration of gastric contents. Due to the changes in shape of the pharynx during head and neck movements, there is a possibility of change in the seal provided by the device. Availability of a SAD which provides good seal in different head and neck positions is the need of the hour. Ambu® AuraGain™ is reported to have higher oropharyngeal sealing pressures in different surgical procedures.[4] A shorter insertion time with better sealing pressures makes Ambu® AuraGain™ a better alternative to other SADs.[5],[6]

The aim of our study was primarily to evaluate the influence of different head and neck positions (namely neutral, maximum flexion, maximum extension and lateral rotation) on oropharyngeal leak pressure (OPLP) and fibreoptic grade using Ambu® AuraGain™ in paediatric population. Ventilation score and peak airway pressures (Paw) were also noted in all four positions.


  Patients and Methods Top


After obtaining approval of the Institutional Ethics Committee (JIP/IEC/2016/1104 dated 8th March 2017) and registering the study in the Clinical Trial Registry – India (CTRI/2017/10/009971), a total of 68 children between 1 and 6 years, belonging to American Society of Anesthesiologists (ASA) Physical Status 1 and 2, scheduled for elective surgery under general anaesthesia were enrolled. Patients with anticipated difficult airway, any pathology of the neck, upper respiratory tract or upper alimentary tract, active gastrointestinal reflux or lung disease were excluded from the study. This prospective, observational study was conducted from August 2017 to December 2018. A written informed consent was taken from the parents or guardians after the preanaesthetic evaluation and child was kept fasting as per ASA guidelines (8 h for solid, 6 h for cow's/formula milk, 4 h for breast milk and 2 h for clear fluids).

On the day of surgery, after confirmation of adequate fasting status, patients were premedicated with syrup midazolam (0.5 mg/kg orally) 30 min before shifting to the operation theatre. Monitoring included electrocardiogram, noninvasive blood pressure, pulse oximetry and capnography. All patients received standardised inhalation induction using 100% oxygen with sevoflurane increasing up to 8%. Intravenous (IV) fentanyl (1 μg/kg) and atracurium (0.5 mg/kg) were administered after securing IV access to facilitate the placement of Ambu® AuraGain™ device. The appropriate size device was selected depending on weight as per the manufacturer guidelines (size 1.5 for 5–10 kg; size 2 for 10–20 kg and size 2.5 for 20–30 kg). The device was fully deflated and water-based jelly was applied before placement. While the child's airway was maintained in 'sniffing' position, Ambu® AuraGain™ was inserted by opening the oral cavity with one hand and gently gliding the device along the hard palate till resistance was encountered. Once the device was in place, the cuff was inflated with air to keep the cuff pressure below 60 cm H2O measured using a calibrated anaeroid manometer. The device was inserted by an anaesthesiologist who had at least 3 years of clinical experience. Appropriate placement was determined by free ingress and egress of gases, appearance of a square capnograph waveform and lack of audible leak after connecting to the circle system. Anaesthesia was maintained by oxygen:air mixture in 1:1 ratio and at one minimum alveolar concentration of sevoflurane. Ventilator parameters included tidal volume of 10 mL/kg and respiratory rate was adjusted to keep end-tidal carbon dioxide in the range of 35–40 mm Hg. A lubricated gastric tube was inserted through the gastric channel and its position confirmed by epigastric auscultation.

After placing the Ambu® AuraGain™ device, the effect of various head and neck positions [Figure 1] on the device was evaluated. Neutral position was maintained by aligning the external ear canal with top of the shoulder horizontally and the ear-eye line vertically (from the external ear canal to superior orbital margin). Then the patient was repositioned in the following positions with angles being measured using a goniometer-maximal extension (45° from neutral), maximal flexion (45° from neutral) and maximal rotation to either side. Each position was switched from neutral position and depth of insertion of the device was constantly maintained as in neutral position. OPLP was determined by placing the anaesthesia circle breathing system in manual mode with adjustable pressure limiting valve closed completely and by keeping a fixed fresh gas flow of 3 L/min. The airway pressure was allowed to increase until it reached equilibrium. The equilibrating airway pressure was recorded as OPLP. The leak around the cuff was detected by any of the following methods (an audible noise while listening over the mouth and/or palpable leak around the cuff/auscultation of leak using stethoscope placed just lateral to thyroid cartilage). Peak airway pressure and expiratory tidal volume (VTexp) were noted in all positions. All ventilator parameters were assessed by Observer 1.
Figure 1: (a) Neutral position, (b) Extension, (c) Flexion, (d) Lateral rotation

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Fibreoptic views were assessed by Observer 2 by passing a fibreoptic scope through the airway tube to a point 1 cm proximal to the end of the tube and scored using the Brimacombe score (0) Vocal cords not seen and device not functioning adequately, (1) Vocal cords not seen but device functioning adequately, (2) Vocal cords plus anterior epiglottis seen, (3) Vocal cords plus posterior epiglottis seen and (4) Only vocal cords visible.[7],[8] The ventilation score was determined as 0–3 based on three criteria: No leakage with an airway pressure of 15 cm H2O, bilateral chest excursions with Paw of 20 cm H2O and a square wave capnogram, with each item scoring 0 or 1 point. Thus, if all three criteria were satisfied, then the ventilation score was 3.[9] Any adverse event that would occur with change of position decreasing the ventilation was recorded. If there was any dislodgement of the device, it was brought back to a position where there was no difficulty in ventilating the child. If ventilation still did not improve, then the device was removed and trachea was intubated with an endotracheal tube. These patients were excluded from analysis.

Based on a previous study, assuming a significant difference of 4 cm H2O between OPLPs in flexion and neutral positions at 5% level of significance and 90% power, a sample size of 68 patients was required for this study.[10]

Data were analysed using Stata 15 (StataCorp LLC, Texas, 2017). OPLP, Paw and VTexp were compared using the repeated-measures analysis of variance. Tukey's test was used for multiple comparisons. Kruskal–Wallis test and Friedman test were applied for comparing fibreoptic score and ventilation score, respectively. The remaining categorical data were analysed using the Chi-square analysis with Yate's correction/Fisher's exact test.


  Results Top


The demographic variables are summarised in [Table 1]. OPLP and Paw were significantly increased in the flexion position (P < 0.001) and significantly decreased in extension position (P < 0.001 and P = 0.04, respectively) when compared to the neutral position [Table 2]. There was no significant difference in the OPLP and Paw in lateral position when compared to neutral position [Table 2]. VTexp was comparable in all positions [Table 2]. Ventilation scoring and fibreoptic view were significantly decreased in flexion position (P = 0.005 and P = 0.001, respectively) and comparable in lateral and extension positions when compared with neutral position [Table 2] and [Table 3]. No adverse events occurred during change of positions and none of the patients required endotracheal intubation as a rescue measure in our study.
Table 1: Demographic data of children studied

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Table 2: Oropharyngeal leak pressure, ventilation score, peak airway pressure and expired tidal volumes in various head and neck positions

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Table 3: Fibreoptic view of glottis with Ambu® AuraGain™

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  Discussion Top


The results in our study showed that there is a significant increase in OPLP in flexion position when compared to the neutral position. There was also worsening of fibreoptic view and increase in Paw in the flexion position when compared to neutral positions whereas extension of the neck caused significant reduction in OPLP but fibreoptic scores were comparable to neutral position. Extension position also resulted in a significant decrease in peak airway pressure.

The increase in OPLP and Paw during flexion position in our study has been similar to other studies.[8],[10],[11],[12] The reduction in the anteroposterior diameter of pharynx with the flexion position might have increased the mucosal compression pressure exerted by the cuff of SAD. Moreover, the reduction in the tension of anterior pharyngeal muscles with flexion would have helped in forming a better seal.

We noted a significant reduction in ventilation score with increased Paw during flexion which was similar to another study indicating obstruction,[10] but unlike in their study, we did not find any significant decrease in expired tidal volumes in our study. Several studies have reported variable results regarding ventilation in flexion position using different laryngeal airways. There was reduction in ventilation with i-gel™ and improvement in ventilation with ProSeal laryngeal airways.[11],[13] Ventilation was maintained in another study using self-pressurised Air-Q laryngeal airway.[12] Variation in degree of flexion in previous studies could have been the cause for differences in ventilation quality.

The significant deterioration of fibreoptic view during flexion position in our study could be due to narrowing of pharynx and posterior displacement of epiglottis with flexion which might have led to obstruction in the view of the glottis.

Maximal extension position decreased both the OPLP and the Paw in this study similar to earlier studies.[12],[14] This reduction might be due to increase in anteroposterior diameter of the pharynx causing elevation of hyoid and laryngeal inlet during extension, resulting in poor seal of the mask over the aperture of the glottis. However, ventilation score and expired tidal volume were unaffected in our study with extension position. In another study conducted in the paediatric population with i-gel, the authors reported no change in Paw with extension when compared to neutral position.[10] They also found improved ventilation with slight extension and were of the opinion that neutral and slight extension might provide alignment of oropharyngolaryngeal axis, considering the larger occiput and cephalic position of larynx in children, helping to maintain ventilation with SAD.

In our study, lateral rotation did not have any significant changes in OPLP, Paw, ventilation and fibreoptic scores. We suggest that Ambu® AuraGain™ can be used in lateral rotation position as frequently as neutral position without compromising the ventilation. While several studies have reported similar results, few studies have mentioned that when flexible LMA was used, there was a decrease in OPLP. The reason has been ascribed to a lack of transmitted force along the airway tube.[7],[9],[10],[14]

We have certain limitations in our study. First, as we have paralysed the children in our study, our results cannot be extrapolated to spontaneously breathing children. We did not want to compromise the safety of our study population as maximal changes in head and neck positions may sometimes result in unacceptable Paw in nonparalysed patients, impeding adequate ventilation. Second, our results cannot be applied to the changes in head and neck position of milder degree as we have studied only with maximal flexion, maximal extension and maximal rotation. Third, in our study, we have used Brimacombe scoring which might be the limitation of our study as we could not find any significant improvement in extension when compared to the neutral position. Although placement of the SAD is optimal, at least a part of the epiglottis is always visible as children have large, floppy and more horizontal epiglottis. Finally, we did not compare the effect of cuff pressures in various positions and the observer could not be blinded to the position of SAD. Future studies to evaluate the effect of different degrees of head and neck positional changes on OPLP and ventilation with different types of available laryngeal mask airways would definitely add to our knowledge and safe practice of anaesthesia.


  Conclusions Top


We conclude that the use of the Ambu® AuraGain™ laryngeal airway provides best ventilatory parameters in children with the head in the neutral or lateral position. Lateral positions can be used without compromising ventilatory Paw or OPLPs. With head in the extended position, the device provides effective expiratory tidal volume with lower Paw and lower OPLP as compared to head in the neutral position and can be used with care. Placing the child in head flexed position is associated with an increase in Paw and OPLP and significant deterioration of the fibreoptic view of the glottis. Therefore, placing the head in flexed position should be avoided in children.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Jain RA, Parikh DA, Malde AD, Balasubramanium B. Current practice patterns of supraglottic airway device usage in paediatric patients amongst anaesthesiologists: A nationwide survey. Indian J Anaesth 2018;62:269-79.  Back to cited text no. 1
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2.
Behera BK, Misra S, Bellapukonda S, Sahoo AK. Impact of visually guided versus blind techniques of insertion on the incidence of malposition of Ambu® AuraGain™ in paediatric patients undergoing day care surgeries: A prospective, randomised trial. Indian J Anaesth 2020;64:937-42.  Back to cited text no. 2
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3.
Lee JH, Nam S, Jang YE, Kim EH, Kim HS, Kim JT. Clinical performance of Ambu AuraGain™ versus i-gel™ in anesthetized children: A prospective, randomized controlled trial. Anesth Pain Med (Seoul) 2020;15:173-80.  Back to cited text no. 3
    
4.
Wong DT, Ooi A, Singh KP, Dallaire A, Meliana V, Lau J, et al. Comparison of oropharyngeal leak pressure between the Ambu® AuraGain™ and the LMA® Supreme™ supraglottic airways: A randomized-controlled trial. Can J Anaesth 2018;65:797-805.  Back to cited text no. 4
    
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Joshi R, Rudingwa P, Kundra P, Panneerselvam S, Mishra SK. Comparision of Ambu AuraGain™ and LMA® ProSeal in children under controlled ventilation. Indian J Anaesth 2018;62:455-60.  Back to cited text no. 5
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Stögermüller B, Ofner S, Ziegler B, Keller C, Moser B, Gasteiger L. Ambu® Aura Gain™ versus Ambu® Aura Once™ in children: A randomized, crossover study assessing oropharyngeal leak pressure and fibreoptic position. Can J Anaesth 2019;66:57-62.  Back to cited text no. 6
    
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Keller C, Brimacombe J, Pühringer F. A fibreoptic scoring system to assess the position of laryngeal mask airway devices. Interobserver variability and a comparison between the standard, flexible and intubating laryngeal mask airways. Anasthesiol Intensivmed Notfallmed Schmerzther 2000;35:692-4.  Back to cited text no. 7
    
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Park SH, Han SH, Do SH, Kim JW, Kim JH. The influence of head and neck position on the oropharyngeal leak pressure and cuff position of three supraglottic airway devices. Anesth Analg 2009;108:112-7.  Back to cited text no. 8
    
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Sanuki T, Uda R, Sugioka S, Daigo E, Son H, Akatsuka M, et al. The influence of head and neck position on ventilation with the i-gel airway in paralysed, anaesthetised patients. Eur J Anaesthesiol 2011;28:597-9.  Back to cited text no. 9
    
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Jain D, Ghai B, Bala I, Gandhi K, Banerjee G. Evaluation of I-gel™ airway in different head and neck positions in anesthetized paralyzed children. Paediatr Anaesth 2015;25:1248-53.  Back to cited text no. 10
    
11.
Xue FS, Mao P, Liu HP, Yang QY, Li CW, He N, et al. The effects of head flexion on airway seal, quality of ventilation and orogastric tube placement using the ProSeal laryngeal mask airway. Anaesthesia 2008;63:979-85.  Back to cited text no. 11
    
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Kim HJ, Lee K, Bai S, Kim MH, Oh E, Yoo YC. Influence of head and neck position on ventilation using the air-Q® SP airway in anaesthetized paralysed patients: A prospective randomized crossover study. Br J Anaesth 2017;118:452-7.  Back to cited text no. 12
    
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Mishra SK, Nawaz M, Satyapraksh MV, Parida S, Bidkar PU, Hemavathy B, et al. Influence of head and neck position on oropharyngeal leak pressure and cuff position with the proseal laryngeal mask airway and the I-gel: A randomized clinical trial. Anesthesiol Res Pract 2015;2015:705869.  Back to cited text no. 13
    
14.
Lee JH, Jang YE, Kim EH, Kim HS, Kim JT. Flexion decreases the ventilation quality of the AMBU® Aura Gain™ laryngeal mask in paralysed patients: A prospective randomised crossover study. Acta Anaesthesiol Scand 2018;62:1080-85.  Back to cited text no. 14
    

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Correspondence Address:
Sandeep Kumar Mishra,
Department of Anaesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry - 605 006
India
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Source of Support: None, Conflict of Interest: None



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