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Year : 2018  |  Volume : 19  |  Issue : 1  |  Page : 15-21

A comparison of metal introducer and bougie-guided techniques of insertion PLMATM with respect to cuff position and air leak

Department of Anesthesiology and Critical Care, Subharti University, Meerut, Uttar Pradesh, India

Date of Submission05-Jan-2018
Date of Acceptance26-Feb-2018
Date of Web Publication22-May-2018

Correspondence Address:
Prof. Deepak Sharma
402, Mahaveer Bhawan, Subharti University, Meerut, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TheIAForum.TheIAForum_1_18

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Background: Drain tube is an integral part of proseal laryngeal mask airway (PLMA). It can lodge a sleek device such as bougie which can act as a guiding tool to advance and position the cuff. As an alternative to metal introducer tool (MIT), we compared the two techniques for ease of insertion score, various cuff positions and air leak encountered during insertion of PLMA under nonparalysed situation. Materials and Methods: Sixty anesthetized patients were divided into two groups using computer-based randomization. PLMA was inserted into either MIT or adult introducer bougie. The primary outcome was ease of insertion (Score 1–4), cuff positions defined by suprasternal notch test, gel displacement test, gastric tube passage test and air leak. Airway pressure, seal pressure, and complications encountered were the secondary outcome. Independent t-test, Fisher's exact test, and Chi-square test were used to analyze the data. P < 0.05 was considered statistically significant. Results: Ease of insertion score 4.0 was observed in 18 (60%) and 29 (96.6%) patients in MIT and AIB group, respectively. Comparing the two groups for the cuff positions, hypopharynx position was significantly higher in the AIB group (P = 0.001), whereas proximal and cuff fold positions were higher in the MIT group (P = 0.02). However, there was no difference for glottis position among the groups. The significantly higher air leak was observed in the MIT group (P = 0.01). Complications related to airway were more frequent in the MIT group. Conclusions: Bougie-guided advancement appears to be a preferred technique for inserting PLMA device in its appropriate position. With the discretionary power to provide an opportunity for effective ventilation, complications are markedly reduced with this technique.

Keywords: Adult introducer bougie, glottis and cuff fold position, hypopharynx, metal introducer tool, proseal laryngeal mask airway (proseal mask/proseal laryngeal mask airway)

How to cite this article:
Sharma D, Ahmad B, Tiwary V, K. Malhotra M M, Agarwal D, Kaur S. A comparison of metal introducer and bougie-guided techniques of insertion PLMATM with respect to cuff position and air leak. Indian Anaesth Forum 2018;19:15-21

How to cite this URL:
Sharma D, Ahmad B, Tiwary V, K. Malhotra M M, Agarwal D, Kaur S. A comparison of metal introducer and bougie-guided techniques of insertion PLMATM with respect to cuff position and air leak. Indian Anaesth Forum [serial online] 2018 [cited 2021 Jan 20];19:15-21. Available from: http://www.theiaforum.org/text.asp?2018/19/1/15/232915

  Introduction Top

The presence of double cuff in proseal laryngeal mask, a second generation supraglottic airway device gives an opportunity to effectively ventilate the lungs. The seal formed around the oropharyngeal mucosa parts the tracheobronchial tree from gastrointestinal tract which continues with the drain tube and acts as a conduit for passage of gastric tube to stomach. This separation is possible only if the proseal laryngeal mask airway (PLMA) apposite in its ideal position.

The insertion of PLMA by mounting it on metal introducer tool (MIT) is widely accepted; although, there are other techniques which involve application of guiding tool through the drain tube such as suction catheter, a gum elastic bougie, flexi-slip stylet, Foley catheter, optical stylet, and flexible bronchoscope have all been tried as an alternative.[1],[2] Coincidently, there is always a likelihood that PLMA may get malpositioned which may be responsible for ineffective ventilation. The quoted incidence of malposition is up to 15%.[3]

We believe that different cuff positions of PLMA for the two guiding tools have never been compared and thus with this knowledge in hand, this prospective randomized study was designed to ascertain and evaluate conventional metal introducer guiding tool and compared it with adult introducer bougie (AIB)-guided PLMA insertion for number of attempts, ease of insertion, airway seal pressure, airway pressures and various cuff positions of the PLMA and hemodynamic parameters in nonparalyzed patients undergoing elective surgery.

  Materials and Methods Top

After approval from the ethical committee and valid informed consent, this prospective randomized study was conducted on two groups of the American Society of Anesthesiologist (ASA) Grade I/II patients of either sex scheduled to undergo elective surgical procedures. Sixty patients were enrolled in this trial. Those with limited mouth opening (inter incisor gap <30 mm, modified mallampati class ≥3), gastric, esophageal reflux disease, prior esophagectomy, hiatus hernia, oropharyngeal pathology, and more than two failure insertion attempts were excluded from the study.

All patients were assigned to one of the two groups of thirty patients each, using a computer-generated random number assignment in a sealed opaque envelope that was opened only before entry in the study.

  • Group MIT (n = 30): PLMA insertion by conventional MIT guided technique
  • Group AIB (n = 30): PLMA insertion by AIB guided technique.

All patients enrolled in the study underwent preanesthetic check and airway examination included mallampati grading, inter incisor gap and extent of neck movement. All patients were kept nil per oral before scheduled surgery and an intravenous access was established in operation theater and were given aspiration prophylaxis with intravenous ranitidine 50 mg and metoclopramide 10 mg. Standard monitoring included heart rate, electrocardiogram, noninvasive blood pressure, end-tidal carbon dioxide (etCO2), and arterial oxygen saturation. After premedication with midazolam 0.05 mg/kg and morphine 0.1 mg/kg, induction was achieved with propofol 2.0 mg/kg and fentanyl 2.0 μg/kg. PLMA insertion was attempted. On the first failed attempt, additional dose of 25.0 mg propofol and 25.0 μg fentanyl was administered to increase the depth before the second attempt. After device insertion, mechanical ventilation was initiated with tidal volume 8.0 ml/kg, I:E ratio 1:2, & respiratory rate 12/min and anesthesia was maintained with isoflurane in air-oxygen mixture. Intraoperatively, adequate ventilation was maintained with etCO2 below 40 mmHg. At the completion of the surgical procedure, isoflurane was terminated, and proseal mask was removed when the patient was fully awake.

Insertion technique for PLMA: All insertions were attempted by an experienced investigator who was standing at the head end of the patient. A size 3 PLMA (Teleflex Medical Europe Ltd, IDA Business and Technology Park, Dublin Road, Athlone Co. Westmeath, Ireland Westmeath, Ireland) with cuff fully deflated and back surface lubricated was chosen. PLMA was mounted as per groups described, and subsequently, insertion was carried out in the following manner.

In MIT group, with head in neutral position, PLMA was advanced around the palatopharyngeal curve to position the tip of the device into the hypopharynx using a single hand technique. After positioning, MIT was removed, and the cuff was inflated with maximum recommended volume (20.0 ml) of air. In AIB group, PLMA was mounted on an introducer device which in this group was 15Fr 70 cm AIB (SunMed Largo, FL33773 USA) placed inside the drain tube such that 5-10 cm of its bent portion was left protruding from the proximal end of the drain tube. With the head in a neutral position, pharyngoscopy was performed with size 3 Macintosh laryngoscope blade and the only posterior pharyngeal wall was visualized to insert and advance distal portion of the bougie 5-10 cm into the esophagus while an assistant was holding PLMA and stabilized the bougie. Laryngoscope was removed and PLMA was railroaded into position over the tongue until firm resistance was encountered. In no case, vocal cord visualization was attempted. PLMA in both the groups were secured firmly with adhesive tape.

The following parameters were evaluated.

Insertion attempt

An attempt was counted if the insertion was such that the distal edge of the integral bite block of PLMA crossed the incisor level with either making further advancement to hypopharynx cuff position or otherwise withdrawn and exteriorized. A maximum of two attempts were permissible.

Modified ease of insertion score was defined as:[4]

  1. Insertion successful on the second attempt with tactile resistance or extra maneuvers
  2. Insertion successful on the second attempt without tactile resistance or extra maneuvers
  3. Insertion successful on the first attempt with tactile resistance or extra maneuvers
  4. Insertion successful on the first attempt without tactile resistance or extra maneuvers.

Extra maneuvers were defined as persistent head hyperextension, jaw lowering by an assistant, lateral mask rotation or incremental dose of propofol and fentanyl to increase anesthesia depth. Cuff positions of PLMA were defined by applying the following tests:

Gel displacement test (GDT)

Water soluble lubricant gel (1 ml) was placed in proximal drain tube and interpreted as either expulsion of gel from drain tube which can be either glottic placement (requiring reinsertion) or proximal position (requiring further advancement of PLMA) or no expulsion with positive pressure ventilation (PPV): gastrointestinal and respiratory system are isolated, we proceed to suprasternal notch tap test.

Suprasternal notch tap test

Gentle tapping above suprasternal notch either gives a positive result (oscillation of gel [normal PLMA tip position behind arytenoid cartilage and we continued with PPV]). A negative result was no oscillations (cuff fold over) requiring reinsertion.

Gastric tube test

Attempt insertion of 14F gastric tube through drain tube interpreted as either able to pass (continue with PPV) or unable to pass (cuff fold over, requiring reinsertion).

Airway seal pressure test

Adequate functioning of PLMA was assessed by measuring airway seal pressure by shifting to bag mode with complete closure of the adjustable pressure limiting (APL) valve, at a continuous gas flow of 5 L/min, record the airway pressure at which leak was audible. The measurement was done immediately after testing for position and at 5 min interval for 15 min.

Peak airway pressure

The measurement was done immediately after testing for cuff position and at 5 min interval for 15 min.

The primary outcome was ease of insertion (score1-4), cuff positions defined by suprasternal notch test, GDT, gastric tube passage test and air leak. Airway pressure, seal pressure, and complications encountered were the secondary outcome variables.

Study population size

The preliminary sample size was decided based on a pilot study which indicated that approximately 28 patients should be included in each group to detect type 1 error of 0.01 and power of 90% for two attempts for insertion of the PLMA. Based on this, we chose a sample size of 30 patients each in the groups. Assuming a 5% dropout rate, the final sample size was set at 63 patients for better validation of results. Continuous variables were compared using independent t-test and categorical variables were analyzed using Chi-square test or Fisher's exact test. The statistical analysis was performed using SPSS software version 20 for Windows (IBM, Armonk, NY, USA). A value of P < 0.05 was considered statistically significant.

  Results Top

Of 63 patients enrolled in the study, three patients were excluded from the study [Figure 1]. There was no difference in the parameters for demographic profile between the two groups [Table 1].
Figure 1: Study flow diagram

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Table 1: Demographic profile and inter incisor gap

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More attempts were required to successfully place the PLMA in MIT group compared to AIB group, this difference being statistically significant (P = 0.001). The two groups were observed for the ease of insertion score [Table 2].
Table 2: Ease of insertion

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Comparing the two groups for extra maneuvers required to insert PLMA, MIT group required more maneuvers with a higher incidence of tactile resistance encountered, whereas AIB group had a more smooth insertion. So was the incremental dose required as more attempts were made in the MIT group [Table 3]. Air leak around cuff detected by audible sound to positive pressure applied to airway with APL valve closed (40 cm H2O) and flow at 5 l/min, was observed to be higher in the MIT group due to inadequate seal around the cuff signifying increased incidence of malpositions in MIT group. The difference between the groups was significant since five patients in MIT group had proximal cuff position while only one patient in the AIB group had proximal cuff position (P = 0.02). One patient in the MIT group had cuff fold position detected by the inability to pass the gastric tube through the drain tube and inability to effectively ventilate.
Table 3: Tactile resistance, extra maneuvers, incremental dose and air leak detected for insertion of proseal laryngeal mask airway

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Cuff positions as per the attempt required to insert PLMA were significantly higher in AIB group for hypopharynx position on the first attempt (P = 0.001) whereas proximal position and cuff fold position were more frequently encountered in the MIT group which demanded extra maneuvers (P = 0.02) [Table 4]. In two patients of MIT group, the distal edge of the integral bite block of PLMA crossed the incisor level but could not be advanced further and thus was withdrawn and exteriorized, thereby counting as an attempt. The seal and mean airway pressures were comparable between the two groups [Figure 2] and [Figure 3].
Table 4: Comparison of cuff positions as per attempts

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Figure 2: Airway seal pressure

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Figure 3: Peak airway pressure

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Air leak was detected in 6 patients in MIT group which was significantly higher compared to AIB group (P = 0.01). Complications were observed in both the groups with more airway trauma in MIT group [Table 5].
Table 5: Complications encountered during insertion of proseal laryngeal mask airway

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  Discussion Top

A unique feature of PLMA is that it has a distinctive modified cuff that incorporates a drain tube, integral bite block and double cuff in the mask. The bulkier deflated cuff of PLMA reduces space in the mouth when the guiding tool is MIT. However, the drain tube besides acting as a conduit for passage of gastric tube offers many other advantages such as it can confirm the position of the cuff. It can also house many guiding tools, and even flexible bronchoscope can be inserted to confirm different cuff positions.

As per our study, 22 counts or 73% had first successful attempt in the MIT group while it was relatively higher 29 counts or 96.67% in the AIB group (P = 0.001). More attempts were required to successfully place the PLMA in MIT group as compared to AIB group. Madhusoodanan Pillai and Hariharan in their study included 100 patients, 50 in each group for two insertion techniques of PLMA, i.e., introducer tool guided versus bougie and observed that first attempt success rate was 98% (49 counts) in the bougie-guided technique and 86% (43 counts) in the introducer tool technique.[5] Thus, the higher success rate was achieved in the bougie guided technique. Several other studies have reported the similar outcome. Myatra et al. included 120 ASA I and II patients between 18 and 80 years under elective surgeries where PLMA was inserted using standard introducer tool in 60 patients (IT), whereas in 60 other patients, a Rusch stylet was inserted through the drain tube up to its tip (ST).[6] It was observed that first attempt success rate for insertion was higher in ST group compared to IT group (92% versus 83%). Saini et al. compared PLMA placement techniques using introducer tool and gum elastic bougie with 50 patients in each group.[7] It was observed that first attempt success rate as high as 98% in the IT group which was comparable to 100% for the bougie group. The high first attempt success rate could be due to the use of vecuronium 0.1 mg/kg, which must have eased the insertion of PLMA, whereas the use of neuromuscular blocker was not included in our study.

The ease of insertion was evaluated on a score of 1–4 with increasing score inversely related to a number of attempts to insert the PLMA. Patients in the AIB group had higher first attempt success rate compared to the MIT group. Score of 1 and 3 were those who encountered tactile resistance and various extra maneuvers which were applied during the conduct of the study. In MIT group tactile resistance was encountered, and more maneuvers were required. So was the increased incremental doses of propofol and fentanyl administered in the MIT group compared to AIB group. Chen et al. trial compared Foley airway stylet tool (FAST) with introducer assisted tool (IT) for the insertion of PLMA.[8] This evaluation included 160 patients undergoing general anesthesia for insertion conditions for the PLMA. They described these insertion conditions as smooth or no tactile resistance and as mild resistance during the insertion of PLMA and observed that smooth insertion without any tactile resistance was possible in 62 patients (89.9%) in the FAST group and 67 patients (89.4%) in IT group, however, mild resistance was reported in FAST group, i.e., 2 patients (2.9%) and 1 (1.3%) in the IT group. They also reported failed insertion in 3 patients (4.3%) in the FAST group and 1 patient (1.3%) in IT group. No variation between the groups for the ease of insertion was observed in this study which can be attributed to the use of atracurium. The use of neuromuscular blocker allows smooth insertion of PLMA without encountering much tactile resistance to facilitate the insertion of PLMA.

Mahajan et al. evaluated the ease of insertion for a laryngeal mask by including various airway maneuvers.[9] These maneuvers included chin lift, jaw thrust, head extension or flexion of the neck and categorized the insertion on a four-point scoring system. 4, 3, and 2 were first attempts without, mild and moderate tactile resistance, respectively. Score of 1 was dedicated to the 2nd attempt. Out of 62 patients, they observed ease of insertion score of 4 in 54 patients, score of 3 in 3 patients, score of 2 in two patients and score of 1 in 3 patients. Chauhan et al. also studied insertion of PLMA in 40 patients with MIT and reported the use of manipulation required for achieving effective airway as either yes or no and also other maneuvers.[4] The insertion characteristics during this study reported the use of manipulation in 17 patients (42.5%) and the application of 1 maneuver in 8 patients (20%) and 2 or more maneuvers in 9 patients (22.5%). From these above studies, it appears that various manipulations and maneuvers are required to insert laryngeal mask with introducer tool technique. However, such maneuvers are infrequently employed during mask insertion when the guiding tool is a bougie.

Various cuff positions have been described in the literature. The correct cuff position is one where tip with the distal end of the drain tube should sit at upper esophageal sphincter for an effective seal around the larynx, this being defined as hypopharynx cuff position. The hypopharynx cuff position was achieved in 22 patients (73%) on the first attempt in MIT group and 8 patients required an additional attempt to insert in this position. Whereas in the AIB group, this position was attained in first attempt in 29 patients (96.67%), however, in one patient, an additional attempt was required. Other positions have been recognized and described as malposition of the cuff such as by Sharma et al. where the incidence up to 5%–15% have been quoted.[3] The author pronounced the following malpositions; distal cuff in the laryngopharynx (7%), distal cuff in the glottic inlet (3%–6%), distal cuff fold over (3.4%), epiglottic downfolding (<0.5%), supraglottic and glottic compression (0.4%), and infolding of the cuff (0.4%). Kuppusamy and Azhar observed the lower occurrence of malposition with gum elastic bougie-guided insertion similar to that of ours where only one patient had proximal position compared to the introducer tool group.[10] Brimacombe et al. observed the failure of PLMA to advance defined as negative tap test, drain tube air leak, and gastric tube insertion in twenty patients in IT-guided technique.[11] Whereas no such incidents were stated in the bougie-guided technique. Myatra et al. also observed a high incidence of failed pharyngeal placement in four patients, malposition detected by a leak in eleven patients and failed gastric tube insertion in four patients and failed ventilation in one patient in the IT-guided technique.[6] Whereas for the stylet-guided technique, leak was detected in only three patients with no incidence of either failed gastric tube insertion, failed ventilation, and failed pharyngeal placement. Thus, higher incidence of the malpositions is associated with the metal IT-guided technique compared to bougie-guided technique. Glottic impaction of the cuff was not found in any of the patients in our study groups. However, one patient in the MIT group had cuff fold position on the first attempt which was identified and subsequently rectified into hypopharyngeal cuff position.

An effective airway seal for PLMA device is possible only with the acquisition of ideal hypopharynx cuff position. In the present study, there was no difference for the peak airway pressure and the airway seal pressure. However, air leak was detected in six patients in the MIT group due to the proximal position of LMA in five patients and cuff fold position in one patient. Whereas only one patient in the AIB group had an air leak due to the proximal position. The detection of air leak helped us to recognize malposition of the PLMA which was rectified on the second attempt. Myatra et al. detected malposition of PLMA due to leak in the IT-guided technique while in the stylet-guided technique three patients were observed to have leak.[6] Saini et al. measured the oropharyngeal leak pressure 34.84 ± 2.61 mmHg for IT technique and slightly higher 35.54 ± 2.08 mmHg for the bougie-guided group.[7] Brimacombe detected oropharyngeal leak pressure of 30 ± 9.0 mmHg for IT and 31 ± 8.0 mmHg for the bougie-guided group.[11] Maclean et al. noticed air leak in three patients of IT technique but could not detect air leak in the bougie-guided technique.[12] Thus, higher seal pressure achieved by PLMA which is essential to ventilate effectively can be influenced by the technique applied for the insertion of PLMA.

Complications were more frequent in the MIT groupas compared to AIB group. Airway trauma was the most common in MIT group, and dysphagia was the feature of AIB group. Madhusoodanan Pillai and Hariharan observed a higher incidence of complications with the IT technique compared to bougie- guided technique.[5] Blood staining on the device was seen in six patients in IT and four patients in the bougie-guided group, the sore throat was seen in fifteen patients of IT and eleven patients in the bougie-guided group. Dysphagia as a complication was exclusive to bougie-guided group. These complications were similar in incidence to that of ours. Brimacombe noticed visible blood on PLMA in four patients of IT and two patients of the bougie-guided group.[11] When the evaluation was done for the occult blood twenty-five patients in IT group while only ten patients in the bougie-guided group were found to be positive. Thus, inserting PLMA with IT invites more complications compared to the bougie-guided group.

There were a few limitations in this study. First, we did not include fibroscopic evaluation of various cuff positions, but we relied on the basic tests which were simple, safe, and effective in determining various cuff positions observed in our study. Furthermore, investigator and the assistant recording the data were not blinded to the study technique. This was inevitable because the two techniques cannot be concealed from those involved in the study. Nevertheless, those involved in data analysis were blinded from the technique.

  Conclusions Top

The drain tube is an important integral part of PLMA which is bestowed with the dual facility. Thus, it not only acts as a conduit for identifying cuff position but also permits a sleek introducer device such as bougie which can be an effective tool on which PLMA can be rail-roaded effortlessly, with an appropriate cuff position cuff position.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Lopez-Gil M, Brimacombe J, Barragan L, Keller C. Bougie-guided insertion of the proSeal laryngeal mask airway has higher first attempt success rate than the digital technique in children. Br J Anaesth 2006;96:238-41.  Back to cited text no. 1
Perilli V, Aceto P, Sacco T, Martella N, Cazzato MT, Sollazzi L, et al. Suction catheter guided insertion of proSeal laryngeal mask airway: Experience by untrained physicians. Indian J Anaesth 2014;58:25-9.  Back to cited text no. 2
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Sharma B, Sood J, Sahai C, Kumra VP. Troubleshooting proSeal LMA. Indian J Anaesth 2009;53:414-24.  Back to cited text no. 3
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Chauhan G, Nayar P, Seth A, Gupta K, Panwar M, Agrawal N, et al. Comparison of clinical performance of the I-gel with LMA proseal. J Anaesthesiol Clin Pharmacol 2013;29:56-60.  Back to cited text no. 4
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Madhusoodanan Pillai C, Hariharan S. Comparison of first attempt success rate between two insertion techniques of proseal laryngeal mask airway. J Med Sci Clin Res 2017;5:19399-406.  Back to cited text no. 5
Myatra SN, Khandale V, Pühringer F, Gupta S, Solanki SL, Divatia JV, et al. Anovel technique for insertion of proSeal™ laryngeal mask airway: Comparison of the stylet tool with the introducer tool in a prospective, randomised study. Indian J Anaesth 2017;61:475-81.  Back to cited text no. 6
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Saini S, Bala R, Kumar R, Chhabra S. Comparison of proseal laryngeal mask airway placement techniques using digital, introducer tool and gum elastic bougie in anaesthetized paralyzed patients. Int J Res Med Sci 2015;3:3703-7.  Back to cited text no. 7
Chen MK, Hsu HT, Lu IC, Shih CK, Shen YC, Tseng KY, et al. Techniques for the insertion of the proSeal laryngeal mask airway: Comparison of the foley airway stylet tool with the introducer tool in a prospective, randomized study. BMC Anesthesiol 2014;14:105.  Back to cited text no. 8
Mahajan R, Nazir R, Gulati S, Mehta A, Suri E. Ease of proseal laryngeal mask airway insertion using miller blade; A comparison with conventional digital technique. JK Science 2016;18:45-9.  Back to cited text no. 9
Kuppusamy A, Azhar N. Comparison of bougie-guided insertion of proseal laryngeal mask airway with digital technique in adults. Indian J Anaesth 2010;54:35-9.  Back to cited text no. 10
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Brimacombe J, Keller C, Judd DV. Gum elastic bougie-guided insertion of the proSeal laryngeal mask airway is superior to the digital and introducer tool techniques. Anesthesiology 2004;100:25-9.  Back to cited text no. 11
Maclean J, Tripathy D, Parthasarathy S, Ravishankar M. Comparative evaluation of gum-elastic bougie and introducer tool as aids in positioning of proSeal laryngeal mask airway in patients with simulated restricted neck mobility. Indian J Anaesth 2013;57:248-52.  Back to cited text no. 12
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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