Second Generation Supraglottic Airway (SGA) Devices

*Kriti Singh*

#### **Abstract**

Supraglottic Airways (SGAs) are an integral part of anaesthetic care. Since their introduction, several modifications, additions, and variations have been developed and are currently in clinical practice since the last 25 years. Not only are they useful for difficult ventilation during both in-hospital and out-of-hospital difficult airway management, they also act as a conduit for tracheal intubation. The newer or second-generation SGAs have been designed to provide a better seal of the airway and are relatively safer since they allow gastric aspiration. Thus, the SGAs may be the most versatile component in the airway management cart. Existing literature on SGAs tends to focus on first generation SGAs and their use in OT only. However, the scope and use of these devices is vast. Knowledge regarding specific devices and supporting data for their use is of utmost importance to patient's safety. This chapter addresses various types of commercially available novel SGAs and their use in and out of hospital settings.

**Keywords:** airway, supraglottic airway devices, laryngeal mask airway, laryngeal tubes, rescue airway

#### **1. Introduction**

In spite of tremendous advances in contemporary anaesthetic practice, advances in airway management continue to be of paramount importance to anaesthesiologists. Till some time ago, the cuffed tracheal tube was considered as the gold standard for providing a safe glottic seal [1]. The disadvantages of tracheal intubation, which involves rigid laryngoscopy, are the concomitant hemodynamic responses and damage to the oropharyngeal structures. Postoperative airway morbidity is also a serious concern. This precluded the global utility of the tracheal tube and there was a perceived need for better alternatives [2].

Dr. Archie Brain, a British anaesthesiologist, introduced the laryngeal mask airway (LMA) in 1983 for the first time, designed to be positioned around the laryngeal inlet. LMA is a supraglottic airway (SGA) device with an inflatable cuff forming a low-pressure seal around the laryngeal inlet and permitting ventilation.

Supraglottic Airways (SGAs) have revolutionised the airway management [3]. Besides serving as a rescue device in the difficult airway, and as a conduit for the endotracheal tube insertion, SGAs provide a less invasive and less traumatic means of securing the airway in surgical patients [4, 5].

Careful observations and clinical experience have led to several modifications of the LMA leading to development of newer supraglottic airway devices with better features for airway maintenance [3]. Over a period of time, new airway devices

have been added to the anaesthesiologist's armamentarium to address specific needs. A wide variety of airway devices are available today which are employed to protect the airway in both elective as well as emergency situations [6].

*2.2.3 Pregnancy*

*2.2.4 Paediatric age group*

*2.2.5 Prone position*

respiration, especially in a smaller child.

SGAs were safely used to secure the airway [26].

view and then further advanced into the trachea.

catheter and advanced into the trachea.

**2.4 Rescue airway**

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**2.3 Aiding blind and fiberoptic-guided endotracheal intubation**

Maternal morbidity from failed intubation and aspiration remains the biggest concern with general anaesthesia. SGAs can be lifesaving in caesarean deliveries where scenarios of cannot ventilate and cannot intubate is faced. Second generation

Being user-friendly, SGAs are now more commonly used in children. They obviate the use of ETTs and avoid many complications associated with endotracheal intubation [19, 20]. The LMA Classic™ and the LMA Proseal™ have established their safety and efficacy for routine as well as in emergency cases in paediatric patients [21–25]. The presence of a drain tube, which helps to empty the stomach in the Second-generation SGAs, has removed the fear of distension of the stomach with gas during controlled or spontaneous ventilation, leading to impairment of

Surgery performed in the prone position require significant OT time and necessitate additional manpower for proper positioning of the patient. Induction and device placement in the prone position avoids the displacement of OT personnel from other tasks as significantly less number of people is required in shifting the patient. Anaesthetic induction of the patient and SGA insertion can be done in prone position, unlike endotracheal intubation. A large cohort study included 1000 patients undergoing surgery under general anaesthesia in prone position where

SGAs can be used as a conduit for blind and fiberoptic-guided intubation for rescue of failed direct laryngoscopy or failed intubation [27–29]. After inserting the LMA, a well lubricated ETT with deflated cuff is passed over the fiberscope. The fiberscope is then advanced through the LMA. The ETT is advanced around 1.5 cm past the mask aperture. The tip of the ETT lifts the fiberscope away from the bowl of the mask and exposes the glottis. The fiberoptic scope is then advanced up to the distal end of the tracheal tube. The ETT is advanced until the glottis is brought into

A specific advantage of using an SGA is the ability to continue ventilating and anaesthetising the patient through the SGA until formal tracheal intubation is achieved. The Aintree catheter, a modification of the Cook's airway exchanger may be used to intubate through the SGA. It is loaded over a fiberoptic bronchoscope (FOB) and the trachea is visualised through the SGA [30, 31]. Leaving the Aintree catheter in place, the SGA is then removed. The ETT is then loaded over the

The difficult airway algorithm made by the American Society of Anesthesiologists (ASA) has a prominent place for the use of SGAs in airway rescue [32]. The Difficult Airway Society (DAS) 2015 guidelines suggests the use of SGAs as first line

SGAs have become the gadget of choice in such scenarios [16–18].

*Second Generation Supraglottic Airway (SGA) Devices DOI: http://dx.doi.org/10.5772/intechopen.93947*

In 2001, Dr. Archie Brain came up with a modification of the LMA. This device was called the Proseal-Laryngeal mask airway™ (Teleflex®, USA) [7]. This double lumen, double cuff LMA has some clear advantages over its predecessor. The double tube design separated the respiratory and alimentary tracts, providing a safe escape channel for the regurgitated fluids.

Since then, several devices that are able to accommodate nasogastric tubes have been invented. Newer features like better sealing pressures, reduced risk of pulmonary aspiration by stomach contents, single use devices, integrated bite blocks, and the ability to act as conduits for endotracheal tube (ETT) placement have rendered these devices more reliable for routine use. The last decade has seen a rapid rise in the number of clinical studies evaluating these second-generation SGAs.
