Comparison of two Supraglottic airway devices for efficacy of ventilation in different head and neck positions in patients undergoing elective surgery under general anesthesia

Supraglottic airway devices (SADs) are widely being used for airway management in patients undergoing elective surgery for offering safer alternative in terms of more hemodynamic stability and lesser postoperative respiratory complications as compared to endotracheal intubation. Securing airway during difficult airway scenario is a vital part for patient’s oxygenation and ventilation. SADs are being progressively redesigned to improve oropharyngeal seal pressure, semblance with airway anatomy for ease of device insertion and success rate for blind endotracheal intubation.

Oropharyngeal seal pressure achieved by SADs holds due importance as it indicates the feasibility of positive pressure ventilation, the degree of airway protection from supra-cuff soiling and also relates to postoperative morbidity. Although, SADs are known to offer good seal, ventilation through SADs can be affected by change in head and neck positions required in various surgeries of head and neck for proper visualization of surgical field due to alteration of pharyngeal volume and shape.

In this study we will compare Blockbuster Laryngeal Mask Airway with I-gel for efficacy of ventilation in different head and neck positions in patients of age group 18-65 years belonging to ASAI-II undergoing elective surgery under general anesthesia.

The methodology and procedure of study will be explained to the patient and informed written consent will be taken. A computer generated random number table will be used to allocate patients in 2 groups ( group A and group B). Allocations will be concealed in sealed numbered opaque envelops, where group A represents Blockbuster LMA and group B represents i-gel.

Patients will be taken to the operation theatre, monitors attached and baseline vitals noted. After preoxygenation with 100 percent oxygen, induction with inj. Fentanyl, inj. Propofol and muscle relaxant and IPPV for 3mins, group A will be intubated with Blockbuster LMA and group B with i-gel respectively.

After confirmation of achieving effective ventilation, neutral position of head and neck will be made and parameters will be noted.

Thereafter, the position of head and neck will be changed from neutral to 20 degree flexion, maximum extension and maximum right lateral position in random order and parameters will be noted in neutral position and after 1 minute of each position change of head and neck.

Parameters to be noted are as follows

1. Number of attempts taken for successful insertion of device, time for achieving effective ventilation and ease of insertion of device

2. Oropharyngeal seal pressure (OSP), anatomical alignment of device with glottis opening (Brimacombe score), PIP, OSP-PIP, ventilation score and leak percent in neutral and different head and neck positions.