Study of effect of head elevation in PROSEAL laryngeal mask airway insertion at a tertiary hospital.

Background &Aims: Proseal Laryngeal Mask Airway (PLMA) is a supra-glottic airway device that prevents gastric insufflation and pulmonary aspiration. In the present study, we intend to determine the effect of head elevation in PLMA insertion. Methodology: The present study was a single-center, comparative, interventional study, conducted in patients of 18-60 years of age, either gender, American Society of Anaesthesiologists (ASA) grade I-II, patients posted for elective surgical procedures under general anaesthesia. 123 adult patients were randomized into three groups using a random number table. Group C: No head elevation (No pillow), Group LP: 4 cm head elevation (4 cm pillow), and Group HP: 8 cm head elevation (8 cm pillow). Results: PLMA insertion at first attempt was successful in 30 patients (73.17%) in Group C, 40 patients (97.56%) in Group LP & 22 patients (53.66 %) in Group HP, the difference was statistically significant (P <0.001). The mean insertion time of LMA in Group C, Group LP, and Group HP was found to be 21.90 ± 4.48s, 16.12 ± 5.35s, and 25.14 ± 8.79s respectively


Introduction
Endotracheal intubation is the gold standard of securing the airway during general anaesthesia (GA) to maintain adequate oxygenation and ventilation. 1However when there is difficult airway, supraglottic airway devices are used to maintain adequate oxygenation and ventilation. 2These devices overcome many of the disadvantages of endotracheal intubation such as oesophageal intubation, endobronchial intubation, pressor response of laryngoscopy, and sore throat. 3oseal Laryngeal Mask Airway (PLMA) is a supra-glottic airway device which has a posterior cuff to improve the seal around the glottis and a channel for gastric tube placement which prevents gastric insufflation and pulmonary aspiration. 3The sniffing position has been shown to be effective for facemask ventilation and intubation. 4This 'sniffing position' is optimal for direct laryngoscopy and intubation, as it aligns the laryngeal, pharyngeal, and oral axes and is influenced by pillow height. 5r PLMA insertion also, a sniffing position has been recommended and is effective. 3,6 ever the appropriate degrees of neck flexion is not clear.The superiority of the sniffing position over head extension (without a pillow) for PLMA insertion has been questioned.Hence in the present study, we intend to determine the effect of head elevation in PLMA insertion and whether the sniffing position (4cm or 8cm pillow) results Head elevation in PLMA insertion | 161 in a higher success rate of PLMA insertion as compared to simple extension of the head without a pillow.previous study conducted by Mi-Jung Yun et al 6 in which the success rate was found to be 87% for head elevation by 3 cm versus 60% for head elevation by 6 cm.In the present study, the sample size was calculated assuming an equivalence margin of 50%, considering the power of 80% and α-error of 5%; which was estimated to be 41 patients in each group.After obtaining informed consent 123 adult patients were randomized into three groups using a random number table which was concealed in a sealed envelope until the start of anaesthesia.

General characteristics were comparable
(Table 1 Analyzing radiologically, the sniffing position provides greater occipital-Atlanta axial extension compared to simple head extension and hence provides a better view of the glottis. 13There are other studies 14, 15 as well where the sniffing position was better compared to a simple head extension.
However, there have been only a few studies conducted for PLMA insertion without a pillow, in easy and difficult airways. 6The 'sniff' position increases the submandibular space and facilitates vertical alignment of the mandible, tongue base, and larynx.
In our study, on comparing 4cm with 8cm pillow, the 4 cm pillow had a higher first attempt success rate (97.56% vs 53.662% respectively).This result correlates with the study done by Mi Jung Yun et al., 6 where they found that the first attempt success rate was higher in 3cm (87%) than in 6cm (60%).
The influence of head elevation for sniffing position for ETT insertion is different from that of PLMA insertion.In a clinical study done to find the optimal pillow height between 3cm, 6cm, and 9cm, they recommend a 9cm pillow for improved laryngeal view during endotracheal intubation. 8 The overall success rate of PLMA insertion after 3 attempts was 100% in all the 3 groups.Similar results were seen in the study conducted by Jun et al., 16 where he compared the ease of PLMA insertion with head in neutral position and head in sniffing position of height of 8cm.This was also similar to the result of Brimacombe et al., 17 and Figueredo et al. 18 In our study, on comparing 8cm with 4 cm pillow, the number of 2 nd attempt and

Conclusion
The first attempt success rate of PLMA was higher and insertion time was faster with a 4 cm pillow than with an 8 cm pillow and no head elevation.The incidence of postoperative complications like blood stains on PLMA and sore throat was lesser with a 4cm head elevation than with an 8cm head elevation.Hence, a head elevation by a pillow of height of 4 cm was effective for PLMA insertion in adult patients when compared with an 8 cm pillow.

Conflicts of interest Nil
obtaining institutional ethical clearance and clinical trial registration in India (CTRI/2018/04/013484), this comparative interventional study, was conducted in the Department of Anaesthesiology, at M S Ramaiah Medical College & Hospital, Bangalore, India.Patients 18-60 years of age, either gender, American Society of Anaesthesiologists (ASA) grade I-II, posted for elective surgical procedures under GA using PLMA, were included in the study.Patients with predicted difficult airway (such as mouth opening < 2.5cm, upper airway anomalies, morbid obesity, edentulous patients), risk of aspiration like pregnancy, gastro-oesophageal reflux disease, nonfasted, recent sore throat were excluded.The sample size was calculated based on a Fig 1: Group C Fig 2: Group LP Fig 3: Group HP

Table 1 :
General characteristics to vocal cords and sore throat are worrisome to the anesthesiologist.7Thisled to the use of

Table 2
Attempt for LMA insertion among groups.
P value less than 0.05 was considered as statistically significant

Table 3
Insertion time, blood stain and sore throat in various groups.