European Journal of Cardiovascular Medicine

Laryngeal mask airway (LMA), after its introduction in 1981 by Dr. Archie Brain¹, plays a pivotal role in management of Difficult Airway^2-5. However, the standard method of LMA insertion described by Brain⁶, though relatively easy, has a variable success rate (from 75% to 96%^7,8). In this technique intraoral manipulation can put the operator at risk of finger trauma and infection⁹. So, from its very inception many alternative techniques have been devised for LMA introduction^1,3,10-17.

LMA, being a reliable airway device, minimises the iatrogenic injury to patients and is associated with low airway morbidity. But with classical technique airway complications namely transient glottic closure, laryngospasm, coughing, nausea, vomiting, dysphonia, dysphagia, bleeding and sore throat are as high as 42%¹⁸.

Brimacombe J et al¹⁴ described different alternate methods of LMA insertion. Among these techniques most popular and commonly used are Rotational technique (back to front like Guedel airway) and triple airway manoeuvre technique (mouth opening, head extension and jaw thrust). For both these techniques there is no need to insert finger into oropharynx. And they are reliable and acceptable alternative to classical method according to previous studies^9,14-17.

Hu LQ et al¹⁹ in 2017 described a novel technique of LMA introduction i.e. External larynx lift with pre-inflated cuff. They found it to be associated with lower incidence of trauma to upper airway during insertion with comparable success rate with classical technique due to proper alignment of airway structure.

Alignment of airway structures properly during introduction of LMA may decrease time and attempt required for its placement minimise pharyngolaryngeal adverse events. So, we want to compare this new technique with three other established techniques namely Classical technique described by Brain⁶, Rotational technique and Triple airway manoeuvre described by Brimacombe J¹⁴ in a randomised control trial to evaluate the ease and adequacy of LMA placement and associated pharyngolaryngeal complications.

After institutional ethics board approval 104 consenting adult patients of ASA 1-2, aged 18- 60 years undergoing routine surgical procedures in which the use of the LMA was applicable, were enrolled into this study. Patients were excluded if they had a known difficult airway, Mallampati grading III and IV, mouth opening <2.5 cm, body mass index>35 kg/ m², presence of lung co-morbidities and at risk of aspiration.

All patients followed the fasting guideline and received Inj. Ranitidine 50mg IV and Inj. Metoclopramide 10mg IV 30 minutes before the procedure. On receiving the patient in the operation theatre, they were asked to choose among sealed envelopes containing computer generated random numbers. This decided the group (Group-C for classical technique, Group- R for rotational technique, Group-T for triple airway manoeuvre technique and Group-E for external laryngeal lift with partially pre inflated cuff technique) to which patient belonged.

Pre-medications were given with i.v. Midazolam (2 mg), i.v. Glycopyrrolate (200μg) and i.v. Fentanyl 2 μg/kg 5 minutes before induction. After pre-oxygenation induction was done with Propofol (1.5-2.5mg/kg). The LMA was inserted following loss of response to trapezius squeeze using one of the four randomly selected techniques by two anaesthesiologist proficient in the technique every time to maintain uniformity. LMA was selected based on the recommendation of the LMA manual: size 3 for adult 30 to 50 kg, size 4 for adult 50 to 70 kg and size 5 for adult 70 to 100 kg.

In group C the classical insertion technique as recommended by Brain⁶ in the instruction manual was followed. Insertion was conducted with the cuff fully deflated and lubricated with water soluble gel and then it was firmly applied against the hard palate and advanced  into the hypopharynx with the gloved index finger, the deflated rim was at the posterior and we were using the posterior approach.

In group R LMA was inserted by rotational technique first described by Briamacomb¹⁵. The LMA was inserted with the cuff fully deflated but back to front, like a Guedel airway. First LMA was held in middle third of the tube between the index finger and thumb of the dominant hand and inserted back to front and rotated anticlockwise through 180^o as it was pushed into hypopharynx. When index finger and thumb reaches the mouth the position of the index finger was adjusted so that it pulls upward on the inferior surface of the tube then LMA was pushed into the final position holding the shaft.

In group T LMA was inserted with the Triple airway manoeuvre technique described by Brimaombe and Keller ¹⁴ with cuff fully deflated. First LMA was held in the middle third of the tube between the index finger and thumb of the dominant hand after that “triple airway manoeuvre”, the combination of head extension, mouth opening and jaw thrust was performed. In this process only jaw thrust was done by another anaesthesiologist. Then LMA was directed against the hard palate and pushing it along the posterior palatopharyngeal curve using the index finger and thumb. When the index finger and thumb reached the mouth, the position of the index finger was adjusted so that it pulls upward on the inferior surface of the tube. Then LMA was pushed into its final position holding the shaft.

In group E LMA was inserted with the External laryngeal lift technique with partially pre- inflated cuff described by Hu LQ et al¹⁹, in pre-inflated cuff air volume was 22 ml, 17.5 ml and 12.5 ml for No.5, No.4 and No.3 LMA respectevly¹⁵. In this technique the LMA was inserted by placing the thumb and middle finger of one hand on either side of the larynx. The larynx was lifted in an upward direction, against gravity, to the neutral position while the LMA was inserted above the tongue with continued lifting of the larynx until there was loss of resistance to the advancement of the airway. As the larynx was lifted, correct alignment of the tip of the airway with the oesophagus had to felt by the fingers of the lifting hand as the airway was advanced.

After the insertion of the LMA, its cuff was inflated using a 20-ml syringe and the volume adjusted to a minimal intra-cuff pressure of 20cm of H₂O and maintained throughout the procedure. Anaesthesia was maintained with oxygen in N₂O and isoflurane. Once the bowl of the LMA placed in the mouth 10sec was allowed to push it into hypopharynx if not done it was regarded as failure. After failure same technique was tried but after third attempt it was considered as total failure and it was excluded from further analysis except the success rate. Functional status of the LMA was assessed by movement of the bag or by gentle ventilation and capnogrphic wave form.

Patient’s heart rates, mean arterial pressure (MAP) were recorded just before insertion of the device and at 1, 3 and 5 min after the insertion of the LMA and duration of the LMA at larynx also noted. Any adverse events including desaturation (SpO₂<92%), laryngospasm or transient glottic closure, airway trauma (presence of blood on removal of LMA) dysphonia, dysphagia, coughing and nausea and vomiting was noted. After successful insertion fibre optic evaluation was done through LMA lumen. The fibre optic grading of larynx was assessed and noted for proper placement of LMA on a four point scale²⁰, 4: only vocal cords are visible, 3: cords and posterior epiglottis are visible 2: cords and anterior epiglottis are visible, 1: vocal cord not seen. After LMA removal coughing and sore throat was assessed on ten point scale at recovery room and over 24 hours.

A total of 104 patients were assessed initially among them 4 patients declined to participate in the study and 95 patients completed the study. Patient characteristics, success rate, number of attempt and failure among study groups are shown in Table 1.

There was no difference of duration of LMA in the larynx, fibreoptic grading among the study groups. Regarding adverse events the incidence of desaturation (SpO₂<92%) laryngospasm or transient glottic closure, dysphonia, dysphagia, coughing, nausea and vomiting were similar among the four groups (p>0.05) but while assessing sore throat, 13 (56.5%) patients complained about that out of 23 patients in Group-C it is significantly higher (p=0.047) than other groups (Table 2).

Intensity of Sore throat measured on 10 point scale was significantly higher in Group-C (3.26±3.12) compared than other groups (Group-R; 1.96±2.91, Group-T; 1.38±2.58 and Group-E; 1.04±2.2, p=0.009 (Table 2). And incidence of blood staining on LMA after removal was significantly lower in group-E (8.4%) compared than other groups (group-C 56.5%, group-R 29.2% and group-T 20.8%, p=0.025) (Table 2).

Success of insertion at first attempt was highest in External larynx lift technique (92%) followed by triple airway manoeuvre technique (76%), classical technique (72%) and rotational technique (72%). However, the difference may not be meaningful in routine practice, it can be worthwhile in emergency airway management. Similar result was observed by Eglen et al⁹ after comparison among classical technique (first attempt success 88.3%), rotational (78.3%) and triple airway manoeuvre technique (88.3%). Hu LQ et al¹⁹ also has similar result in first attempt success with classical (83%) and external larynx lift technique (91%).

The LMA was designed based on extensive studies on anatomy of adult pharynx²¹. After correct placement, the tip of LMA lies over the upper oesophageal sphincter, the sides facing the pyriform fossae and the upper surface behind the base of the tongue with the epiglottis pointing upwards. Fibreoptic scoring to evaluate proper LMA placement was first described by Briamacombe j et al²⁰. In our study the “ideal position” (grade-4) was achieved in higher number of patients in external larynx lift technique (79.2%) compared to triple airway manoeuvre technique (75%), classical technique (73.9%) and rotational technique (70.8%), though it was not statistically significant (p=0.866). Similar but significant (p<0.05) result was found out in Triple airway manoeuvre technique compared to classical technique in a study by Kazuyoshi A et al¹⁶. This is due to the downward compression of epiglottis by the LMA during insertion by classical technique. Triple airway manoeuvre provides a wider pharyngeal space facilitating proper LMA placement. In the study of Brimacombe J and Berry A¹⁵ rotational technique with deflated cuff was found to have similar fibreoptic and functional result compared to classical technique. However in some cases rotation was incomplete in coronal plane. We found no such difference among the techniques in regard to fibreoptic result.

Presence of blood on LMA has a strong association with the incidence and severity of sore throat. Objective of this study was to find out a suitable technique that increases the success of insertion with least incidence of iatrogenic injury to improve patient safety and satisfaction. In this study classical technique was associated with a highest incidence of pharyngolaryngeal morbidity (blood staining of the LMA and sore throat). In external larynx lift technique 91.7% patients had no blood staining compared to 79.2% patients in triple airway manoeuvre technique, 70.8% patients in rotational technique and 43.5% in classical technique (p=0.025). Similar observation was made by Hu LQ et al¹⁹ (Classical 82% vs external larynx lift 91%, p=0.05). It suggests that use of external larynx lift is most effective in decreasing the trauma due to collision to oropharyngeal structures during LMA insertion by aligning the pharyngeal and laryngeal axis. Insertion of LMA with cuff inflated was found to reduce the incidence of airway trauma due to a smoother surface against the palate¹⁹, but it has been implicated in causing down-folding of epiglottis¹⁴ causing decreased fibreoptic view. It has also been observed that there has been a lower incidence of sore throat in External larynx lift technique (20.8%%) compared with classical technique (56.5%) and also with other two groups (Rotational,33.3% and Triple airway manoeuvre, 25%) and the difference has been found to be significant (p= 0.047). Similarly, intensity of sore throat also higher in classical group (3.26±2.12) measured in 10 point sale than other groups (Rotational 1.96±2.91, Triple airway manoeuvre 1.38±2.58 and external larynx lift 1.04±2.20, p=0.009). In terms of other pharyngolaryngeal morbidities (desaturation p=0.493, laryngospasm or transient glottic closure p=0.859, dysphonia p=0.859, dysphagia p=0.793, coughing p=0.944 and nausea and vomiting p=0.958) there was no significant difference among the four groups. Apart from insertion time and technique the factors has been implicated the pharyngolaryngeal complications are using LMA with deflated cuff, inappropriate size, experience of the operator, oropharyngeal suctioning, intra cuff pressure and duration of surgery¹⁸.

In our study size of LMA was determined from body weight as per manufacture guideline, intracuff pressure was kept constant at 20 cm of H₂O pressure and duration of surgery was comparable in the groups. So, lower incidence of airway morbidities and non-significant but higher first attempt success rate in case of external larynx lift technique has a potential advantage than other techniques.

1. Brain AIJ. The laryngeal mask–a new concept in airway management. Br J Anaesth 1983;55(8):801-5.
2. Apfelbaum JL, Hagberg CA, Caplan RA, Blitt CD, Connis RT, Nickinovich DG, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013;118:251–70.
3. Brain AIJ, McGhee TD, McAteer EJ, Thomas A, AbuSaad MAW, Bushman JA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 40:356-61.
4. Brodrik PM, Webster NR, Nunn JF. The laryngeal mask airway. A study of 100 patients during spontaneous breathing. Anaesthesia 1989;44:238-41.
5. Maltby JR, Loken RG, Watson NC. The laryngeal mask airway: clinical appraisal in 250 patients. Can J Anaesth 1990;37:509-13.
6. Brain AIJ. The Intavent laryngeal mask instruction manual. 2nd ed. Henlley-on Thames, England: Intavent International SA;1991.
7. John RE, Hill S, Hughes TJ. Airway protection by laryngeal mask airway. A barrier today placed in the pharynx. Anaesthesia 1991;46:366-7.
8. McCrirrick A, Ramage DTO, Pracilio IA, Hickman IA. Experience with the laryngeal mask airway in two hundred patients. Anaesth Intens Care 1991;19:256-60.
9. Merih E, Bahar K, Ferim G, Sule O, Semih K, Ebru P. Comparison of three different insertion techniques with LMA-UniqueTM in adults: results of randomized trial. Rev Bras Anestesiol 2017;67(5):521-6.
10. Nalini KB, Shivkumr S, Archana S, Rani DCS, Mohan CVR. Comparison of three insertion techniques of ProSeal laryngeal mask airway: A randomized clinical trial. J Anaesthesiol Clin Pharmacol 2016;32:510-4.
11. Young TM. The laryngeal mask in dental anaesthesia. Eur J Anaesth 1991;4:53-9.
12. Mason DG, Bingham RM. The laryngeal mask airway in children. Anaesthesia 1990;45:760-3.
13. Chow BFM, Lewis M, Jones SEF. Laryngeal mask airway in children: insertion technique. Anaesthesia 1991;46:590-1.
14. Brimacombe J, Keller C. Insertion of the LMA Unique TM with and without digital intraoral manipulation by inexperienced personel after mankin-only training. J Emerg Med 2004;26:1-5.
15. Brimacombe J, Berry A. Insertion of the laryngeal mask airway- A prospective study of four techniques. Anaesth Intensive Care 1993;21:89-92.
16. Aoyama K, Takenaka I, Sata T, Shigematsu A. The triple airway manoeuvre for insertion of the laryngeal mask airway in paralyzed patient. Can J Anaesth 1995;42(11)1010-6.
17. Kuvaki B, Kucukguclu S, Lyilikci L, Tuncali BE, Cinar O. Soft Seal disposable laryngeal mask airway in adults: comparison of two insertion technique without intra-oral manipulation. Anaesthesia 2008;63:1131-4.
18. Seet E, Yousaf F, Gupta S, Subramanyam R, Wong DT, Chung F. Use of manometry for laryngeal mask airway reduces postoperative pharyngolaryngeal adverse events: a prospective, randomized trial. Anesthesiology 2010;112:652–7.
19. Hu LQ, Leavitt OS, Malwitz C, Kim H, Doty RA, McCarthy RJ. Comparison of laryngeal mask airway insertion methods, including the external larynx lift with pre-inflated cuff, on postoperative pharyngolaryngeal complications: A randomised clinical trial. Eur J Anaesthesiol 2017;34(7):448-55.
20. Brimacombe J, Berry A. A proposed fiber-optic scoring system to standardize the assessment of laryngeal mask placement. Anesth Analg 1993;76:457.
21. Brain AIJ. The development of the Laryngeal Mask–a brief history of the invention, early clinical studies and experimental work from which the Laryngeal Mask evolved. Eur J Anaesthesiol Suppl 1991; 4:5-17.
22. Dingley J, Asai T. Insertion methods of the laryngeal maskairway. A survey of current practice in Wales. Anaesthesia.1996;51:596-9.