Laryngeal Masks (LMA) & Supraglottic Airways – Revolutionising Ventilation
One of the most critical decisions that an emergency medicine physician, Anesthesiologist and emergency technician has to make is – how to successfully and safely manage the airway of a patient during anesthesia, unconsciousness and critical care. During such situations, a device that was invented in the early 1980s helps medical professionals secure airways.
Laryngeal masks are a type of supraglottic airway which keep a patient’s airway open during the state of unconsciousness and when the patient is under anesthesia. When the laryngeal mask is correctly placed, it sits above the glottis in the hypopharynx region.
Dr. Archi Brain, the inventor of the Laryngeal mask was inspired by the Goldman dental mask to create the prototype of the present day laryngeal mask as the anatomy surrounding larynx was of similar proportions. Initially, the commercial interest and the trust of other anesthesiologists was lacking when it came to this newly invented device, but after six months of its launch – almost 50% of the National Health Service (NHS) hospitals in United Kingdom had it. Now, Laryngeal Masks are widely used for airway management worldwide. In fact, anesthesiologists consider the development of LMA to be one of the most important developments in the past 50 years with regards to airway management. One of the main advantages that a LMA offers is that it does not require muscle relaxation for insertion, laryngoscopy is not needed, and hemodynamic changes are minimized. The insertion technique to safely and correctly insert LMA is easy to learn and most physicians and emergency technicians are familiar with it.
With advancements and better understanding of anatomical structures of the region Laryngeal mask airways are now available in a variety of configurations;
- LMA Classic
- LMA Flexible
- LMA Fastrach
- LMA C Trach
- LMA Unique
- LMA Proseal
- LMA Supreme
LMA Classic is the original design which is reusable. Laryngeal masks Airway Classic consist of three main components:
- Airway Tube –The airway tube is curved in order to match the anatomy of the oropharynx. It is usually semi-transparent and semi rigid so that it’s easy to handle and the regurgitated and condensed material is clearly visible. The distal end of the airway tube opens into an inflatable mask protected by rubber mask aperture bars which prevents the epiglottis from entering the airway.
- Inflatable Mask– The inflatable mask of the laryngeal mask is usually oval shaped and has a round and broad proximal end. It is attached to the outer rim of the back plate of the inflatable mask. The inflatable mask has an inflatable cuff and a concave back plate.
- Mask Inflation Line– The mask inflation line is attached to the proximal portion of the cuff. It consists of the long narrow inflation line, pilot balloon, syringe port and a metallic valve.
The laryngeal mask comes in various sizes making it suitable for neonates to adults. Anatomically, the mask presses against several anatomical structures after placement.
The LMA classic is indicated to be used during elective short surgical procedures under general anesthesia, difficult airway management and cardiopulmonary resuscitation. The contraindications to the use of LMA classic include poor lung compliance, non-fasting patients and inadequate opening of the mouth.
There are some complications that can arise in patients while placement of Laryngeal mask –
- The mask might fold on itself leading to device being pushed into glottis opening due to pressure.
- The epiglottis might get trapped in the laryngeal inlet of mask.
- The tip of epiglottis may fold into the vocal cord triggering coughing or laryngospasm.
- Excessive lubricant can leak into trachea trigging laryngospasm and coughing
Flexible laryngeal mask airway was developed by Dr. Brain in 1992. Flexible LMA improves surgical access and prevents cuff displacement and tube occlusion. The wire reinforcement in Flexible LMA prevents kinking and the increased diameter provides more mouth room.
The intubating LMA fastrach eliminates the need of anatomical distortion and manipulation of head and neck. It consists of three parts – the intubating Laryngeal Mask Airway, a stabilizing rod and a tracheal tube. With appropriate lubrication the insertion of LMA fastrach is easy as the rigid tube follows the curve of palate. LMA Fastrach allows for blind insertion with a single hand without having to move the head and neck.
LMA C Trach
This LMA is integrated with a fiber-optic camera offering a clear view of the larynx. It provides real time visualization with its two fiber-optic channels – a light guide that illuminates the larynx and 10,000-pixel image guide to transfer the image. It consists of a modified elevating bar that optimizes the light source.
This disposable LMA is manufactured using medical grade polyvinyl chloride. It is sterile and is suitable only for a single time use. LMA Unique can be used for a wide range of applications in the which range from use during general anesthesia, emergency device and resuscitation. It is ideal for emergency and pre-hospital settings.
LMA Proseal is equipped with an additional channel that allows for the suctioning of gastric contents. It was designed keeping in mind the importance of improved ventilation and protection against regurgitation and gastric insufflation. This LMA is a double mask forming two junctions – one with the respiratory tract and one with gastrointestinal tract. It is manufactured using medical grade silicone. The gastric drain tube reduces the likelihood of aspiration. The LMA proseal is a highly versatile Laryngeal Mask Airway as it enables ventilation for a long time with minimum posterior pharyngeal wall damage.
LMA Supreme has a design similar to LMA Proseal but comes equipped with a bite block. It is an advanced LMA with an anatomical curve that aids easy insertion. LMA Supreme can be inserted within a matter of seconds by any technician familiar to the technique. The LMA supreme provides airway stability and fixation tabs to help secure the airway. LMA Supreme is often considered as the most safe and reliable LMA combining the best features of all other LMAs.
There are many supraglottic airways which have superior performance and are trusted by anesthesiologists and emergency physicians worldwide. One such innovative second generation supraglottic airway is the Intersurgical Igel.
Intersurgical Igel is often considered to have transformed the field of airway management. It was launched in 2007 and has since been used widely across the globe. The Igel airway has a soft non-inflatable cuff which provides an anatomical impression fit. The perilaryngeal anatomy is mimicked by the shape, softness and contours of the Intersurgical Igel. The speed and ease of insertion reduces the trauma induced commonly associated during insertion of the laryngeal masks. Other features such as superior seal pressure, gastric access and the integral bite block make this product a great choice for airway management.
Choosing the correct airway management device is a crucial decision that has to be taken by emergency physicians, anesthesiologists and emergency medicine technicians. What was invented close to 30 years back by experimenting with Goldman Masks and cadaveric casts has been developed, innovated and used over 300 million times worldwide. LMAs of superior quality sourced from authorized vendors should be the only choice when purchasing Laryngeal Mask Airways. The innovations in LMA have provided anesthesiologists, emergency physicians, and patients an option to make airway management less stressful and more uncomplicated improving the quality of patient care.