INTRODUCTION

In the recent times, Supraglottic airway devices (SADs) have become a Quintessential part of difficult airway management. 

Societal guidelines for difficult airway management have recommended the use of SADs as a conduit for ventilation and subsequent intubation in the “CANNOT INTUBATE CANNOT VENTILATE” step of unanticipated difficult airway algorithm. 

 Since the time of classic Laryngeal mask airway (LMA) was introduced, there are several SADS (mostly II generation SADs) that are introduced with unique design characteristics to improve ventilation and intubation. 

 Blockbuster LMA was introduced in 2012 as a new multi-functional intubation LMA It has a short and wide shaft attached to the cuff at an angle >95° to match oropharyngeal curve. 

It is used as a guidance device that directs specially designed silicon tipped Parker flextube at an angle of 30° to improve successful glottic entry. It Has a small antero-posterior diameter with a large transverse diameter and this creates a large inner lumen reducing the ventilation resistance. It also reduces the (6-8 mm ID) intubation resistance. 

 Ambu auragain  has ttOriginal anatomical curve and fast insertion time. 

Ambu auragain LMA was introduced in 2013 and has the highest oropharyngeal seal pressure among all SADs it also has a wide shaft attached to the cuff at an angle of 90°. 

 Blockbuster LMA and Ambu auragain LMA are used in routine anaesthesia, difficult airway, failed intubation, as a conduit for intubation. Can pass upto 8.0 size ET tube. 

 * In our study, we intend to compare the fibreoptic glottic score (brimacombe berry score) and successful first pass fibreoptic guided intubation through Blockbuster LMA and Ambu auragain LMA in adult patients with simulated restriction of neck movement using a cervical collar. 

 This study would help us to develop a protocol for the department and the right LMA can be standardised for usage in unanticipated difficult airway situation.

NEED FOR STUDY 

Societal guidelines do not recommend any specific SAD for intubation. With more than a dozen second generation SADs in market, it is crucial to use the one which is best suited for a quick and successful intubation in an emergency difficult airway situation. 

* The device should be easy to insert and should allow easy and successful fist pass Intubation. A large number of studies are available comparing successful intubation through various SADs with varying success rate(58-91%). 

* However 90% of the studies have compared blind intubation which is not recommended by AIDAA 2018/DAS 2015 guidelines. Very few studies have compared fibreoptic guided intubation through LMAs. 

* There are no studies that have included the clinical performances in a simulated difficult airway setting which is more relatable in real time. Hence, we are comparing Blockbuster LMA and Ambu Auragain LMA use as a conduit for fibreoptic scope guided intubation in a simulated difficult airway setting. 

METHODOLOGY

 * hundred adult patients aged between 18-59 yrs,Of either sex, belonging to ASA physical status I and II, requiring endotracheal intubation for general anesthesia,Undergoing elective surgeries will be recruited for the study. 

     A written informed consent will be taken from patients. Patients will be allocated into either Ambu Auragain group or Blockbuster LMA group using computer generated randomization method.  

* An appropriate size SAD will be chosen based on patient’s weight and the tube size as per manufacturer guidelines. The LMA placement and intubation will be done in the guidance of an anesthesiologist with 5yrs of experience.  

*In the Operation room, standard monitors will be connected and appropriate size Philadelphia collar will be applied. Patients are kept in neutral position and preoxygenated with 100% 02. Patients are induced according to standard general anesthesia protocol. 

* After complete muscle paralysis, the allocated SAD is inserted and cuff is inflated as per manufacturer guidelines, an effective supraglottic airway placement is assessed by adequate chest rise, presence of end tidal CO2 waveform and movement of reservoir bag during ventilation. When more than one insertion attempt is required, the patient will receive bag and mask ventilation between attempts. 

* Failed attempt at insertion of LMA is defined as complete withdrawal of LMA and reinsertion. 

*Failed SAD placement is declared when 2 attempts at insertion fails. Further management is as per the decision taken by attending consultant. 

*After achieving satisfactory ventilation via the allocated SAD, fibreoptic guided tracheal intubation will commence. A fibreoptic scope loaded with a pre lubricated Parker flex tube will be inserted through the LMA once the scope tip reaches the glottic opening, the fibreoptic scoring of glottic view will be assessed using a standardized Brimacombe berry scoring system. 

*The scope will be inserted into the Trachea, the ETT is railroaded into the trachea and the fibreoptic scope is then removed. Proper placement of ETT is confirmed clinically and by presence of end tidal CO2 trace. The SAD is then removed. 

*A maximum of two attempts is allowed with yhi guided intubation.an alternative airway management plan could be instituted at the discretion of anaesthetist if failed intubation was encountered after two attempts with the allocated device. 

PARAMETERS ASSESED IN THE STUDY 

1.     Glottic visualisation by brimacombe berry score 

2.     Percentage of first pass successful intubation in each group 

3.     Proportion of failed SGD placement in each group 

4.     Proportion of failed intubation in each group. 

                5.  Complications like sore throat and hoarseness of voice in each group.