COMPARATIVE EVALUATION OF EFFECT OF DIFFERENT ANGLES OF RAMPED POSITION ON VIDEOLARYNGOSCOPIC GLOTTIC VIEWS FOR TRACHEAL INTUBATION IN INDIAN NON-OBESE ADULT PATIENTS- A PILOT STUDY

Airway management during anaesthesia is an important determinant of morbidity and mortality despite progress in identifying factors that can predict difficult mask ventilation and endotracheal intubation (ETI). of the prerequisites described for successful laryngoscopy and ETI is optimal patient positioning. ‘Sniffing’ position (SP) which involves neck flexion at chest and head extension at atlanto-occipital (AO) joint is conventionally considered ideal for direct laryngoscopy (DL) as it is believed to align oro-pharyngeal and laryngeal axes of the patient for allowing the line of vision of the operator to fall directly on the laryngeal inlet.2 In view of the importance of positioning for laryngoscopy and ETI, many studies have been conducted to establish optimal patient positioning but their results and recommendations are dissimilar.3 Some of these include changing the pillow height,4 utilizing ramped position,5 using maximum head extension or no head extension,6 head-elevated-laryngoscopy position5 and back-up position5 etc.

Ramped position, also referred to as back-up or head-elevated position involves flexion of the patient at hips and was introduced to offer better laryngeal exposure during DL in morbidly obese patients than the patients in the sniffing position7and has been said to facilitate better alignment of the pharyngeal, laryngeal and oral axis of the airway during difficult laryngoscopy, especially in the large patients.8 Some studies found this position usefulin non-obese conditions also.Various techniques have been used to achieve the elevation for ramping, viz., stack of pillows, towels, blankets, specially designed commercially available foam pillows and adjustment of head end of the operating table.10Hospital pillows, towels or blankets are most frequently used for making ramps during airway management but have many disadvantages like more time-consumption11,difficulties in arranging appropriate linen in sufficient quantities for making ramp, requirement of lifting the patient during positioning12 and alignment of External Auditory Meatus - Sternal Notch (EAM-SN) line vs. horizontal, difficulty of removing the blankets after the procedure, inability to quantify the ramp angle, difficulties in changing the angle of ramp if required, difficulties in achieving the targeted height of the head of patient for laryngoscopy and intubation and almost no possibility to replace the blankets in order to realign the patient for the best position for airway management after tracheal extubation.12 Commercially available foam pillow ramps have not become popular because of their cost factor11 and use of operating table ramp has also proven difficult and with no specific guidelines.Though a few studies have recommended 25° ramp for favourable conditions for DL in obese patients,14 degree of elevation required for appropriate ramping is still a big question and achieving different angles of ramp with the existing ramping methods is very difficult. Moreover, any simple ramping device which can offer variable angles of ramp according to requirements is also not available.A recommendation of an endpoint of horizontal alignment of the patient’s EAM with SN line during ramping has also been suggested7 as a good end-point for DL in both obese as well as non-obese patients, as it is said to provide a closer alignment of pharyngeal, laryngeal and oral axes.15Video-laryngoscopy (VL) has been found to provide a better laryngeal view, reduced rate of oesophageal intubation, higher first-attempt intubations as compared to DL in general population suggesting that VL is an excellent alternative to DL in many normal as well as difficult airway scenarios.16However, the present guidelines for ramping for DL may not apply to VL because of the difference in geometric design of the two types of laryngoscopes in terms of angle of the blade and difference in the mechanics of visualization of glottis and the required line-of-vision in view of location of a camera only a few millimetres before the vocal cords in video-laryngoscopes and provision of the image of glottis on an external monitor.17 Similarly, due to different mechanics of obtaining the glottic views in the two techniques, results of correlations of different angles of EAM-SN line vs. horizontal in the videoscopic image obtained with video-laryngoscope may be different than that of DL. Lacunae in the existing knowledgeExtensive search of literature reveal that there are no studies which recommend any specific ramping positions for achieving most favourable glottic views and best intubating conditions during VL. Moreover, no studies have recommended any specific angle of ramp for use of ramped position to achieve best results in terms of laryngoscopic views and intubation with VL. Likewise, there are no studies to provide any information on the relationship of angle of EAM-SN line vs. horizontal axis while utilizing different angles in the ramp during video-laryngoscopy and no recommendations are also available on this subject. In view of the above and importance of ramp position for laryngoscopy and ETI, difficulties associated with the use of existing methods for making the ramp  and a real need to search the best angle of ramp suitable to provide best glottic views and intubating conditions during VL, a simple, self-fabricated, portable ramping device made up of acrylic polystyrene which is strong enough to hold the weight of the patient and which can provide an adjustable ramp angle of 15°, 20° and 25° without physically lifting the patient during use, was designed for the present study. This device henceforth would be called as Sethi’s Ramp Positioner (SRP). Therefore, the present randomized pilot study was designed to evaluate and compare the glottic views according to Percentage of Glottic Opening (POGO) score and modified Cormack and Lehane (MCL) grade, ease of insertion of the blade of video-laryngoscope, need of optimization manoeuvres for facilitating ease of intubation, intubation difficulty score (IDS), time to successful intubation, number of Intubation attempts, incidence of failure to intubate using VL and correlation of angles of ‘EAM-SN line vs. horizontal’ using head-flat position and 15°, 20° and 25° angles of ramped position using SRP in Indian non-obese adult patients and to recommend, if possible, the most optimal angles of ramp during VL for best outcomes.