From its inception, the clinical specialty of anaesthesia has been utterly dependent on medical devices in order to deliver care to the patient. Be it devices for the administration of anaesthesia drugs to the patient in order to achieve anaesthesia, or devices to maintain or protect the airway, it is impossible to practice the specialty in the absence of devices of one sort or another. Anaesthetists have themselves been at the forefront of the task of devising this equipment, and on occasion some have helped the specialty make quantal changes in the practice of anesthesia. One such physician is Dr Archie Brain,1 the British anaesthetist who invented the laryngeal mask airway, a type of supraglottic airway, in the early 1980s. Many imitations and copies have followed over the ensuing decades, but the supraglottic airway has come to dominate the arenas of both routine and emergency airway management, to the extent that it is used in up to, and in some countries more than, half of all general anaesthesia cases.2,3 One criticism, however, of the manner in which such devices are currently introduced into clinical practice is that they are often introduced with little or no clinical evidence having been established as to either their safety or their efficacy.4–6
Airway management and patient care
As the practice of medicine has matured around the world, various societies have developed to foster the scientific advancement of care to the patient. These exist across specialties for the wider interests of the medical community but also within specialties, addressing the specific needs and concerns of individual patient groups and disease states or those of particular areas of clinical practice. Within the specialty of anaesthesia, particular attention is directed towards the management of the patient’s airway, with national societies dedicated to the scientific advancement of patient care in this domain. In the UK, it is the Difficult Airway Society (DAS) that is widely acknowledged as the standard-bearer in this task.
It is one of the largest specialist societies in the UK, with around 3000 members and its guidelines for the management of the airway are acknowledged and adopted around the world. It was the DAS, in light of what it saw as the introduction of an ever-increasing number of airway devices with little or no clinical evidence as to their safety and efficacy, which published an article calling for a minimum level of evidence to be required for an airway device to be introduced into clinical practice.7 Their Airway Device Evaluation Project Team (ADEPT) produced guidance in 2011 for anaesthesia departments to be able to seek a minimum of level 3b evidence for the safety and efficacy of a medical device before purchasing it for use. However, over the following five years, no airway management devices were specifically evaluated in accordance with ADEPT guidance.
In February 2016, the DAS announced the launch of the first project grant directed to ADEPT guidance, funded by way of an unrestricted direct research grant supplied by Teleflex Medical Incorporated, a leading global provider of medical technologies for critical care and surgery, and administered by the DAS. The DAS project grant was made available for a trial to evaluate the LMA® ProtectorTM Airway from Teleflex (Figure 1) and met the pre-defined ADEPT guidance criteria, including the need for multi-centre sites. The proposed study is planned to examine the safety and efficacy of a dedicated second-generation sterile single-use supraglottic airway management device across at least four distinct National Health Service (NHS) Trusts in England or Wales.
Figure 1: LMA® Protector™ Airway (image courtesy of Teleflex; ©2017 Teleflex Incorporated)
The research team will include a clinician (not specifically an MD) with a doctorate (PhD/DPhil) and a non-clinician with a degree of Doctor of Philosophy (PhD). All investigators are recognised as accomplished investigators in anaesthesia and/or airway management, and all named clinical investigators have substantive NHS consultant appointments in anaesthesia (with or without association with a host university). All results and discoveries resulting from work supported at least in part by DAS are to be made available to the public and scientific community through scientific and/or public policy channels such as national meetings and peer-reviewed publications. One award was made with the allocation of the grant being independent of Teleflex.
The LMA® Protector™ Airway
The device in question, the LMA® Protector™ Airway,8 is a second generation supraglottic airway. The LMA® Protector™ Airway shares common features9–13 with previous LMA® devices, such as the LMA® ProSeal™ Airway (high oropharyngeal leak pressure, gastric access, and bite block), the LMA® Fastrach™ Airway (fixed-curved tube and guiding handle), the LMA® Unique™ Airway (single use), and the LMA® Supreme™ Airway, incorporates a drain tube within its lumen to separate the respiratory and gastrointestinal tracts. The LMA® Protector™ Airway is made with medical-grade silicone, which makes it a more flexible and potentially a less traumatic device than the LMA® Supreme™ Airway, which is made of polyvinyl chloride. The LMA® Protector™ Airway provides access to, and functional separation of, the respiratory and digestive tracts, with the presence of two drainage channels, which emerge proximally as separate ports and enter a chamber, located behind the cuff bowl.
Removal of gastric fluid through the upper oesophageal sphincter can be performed by attaching suction to the male suction port or by insertion of a gastric tube through the female drainage port to the stomach. The LMA® Protector™ Airway also has Cuff Pilot technology, an integrated cuff pressure indicator for single use airway management devices that enables continuous cuff pressure monitoring at a glance and facilitates easy, accurate adjustment when necessary.14
The LMA® Protector™ Airway is the most advanced second-generation airway from Teleflex. It is the only laryngeal mask that combines a pharyngeal chamber and dual gastric drainage channels, designed specifically to channel gastric content away from the airway.
Because anaesthetists are faced with a multitude of different SADs being introduced to their clinical practice, the problem is that many lack the evidence of efficacy and safety to inform evidence-based decision-making regarding which devices to adopt. In order to introduce new devices into clinical practice or develop an appropriate clinical trial, detailed knowledge of the physical characteristics and potential application is essential. Only through careful analysis of the design of new devices, with appropriate preclinical research and development followed by preclinical testing, can specific hypotheses be generated that are amenable to clinical testing. It is only by the medical device industry working in partnership with the specialist medical societies that the safety and efficacy of medical devices can be established. It is by adopting ADEPT that we can safeguard patient care.
1 Van Zundert TCRV et al. Archie Brain: celebrating 30 years of development in laryngeal mask airways. Anaesthesia 2012;67:1375–85.
2 Fourth National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society. Major complications of airway management in the United Kingdom. Report and Findings. March 2011. ISBN 978-1-9000936-03-3 Royal College of Anaesthetists.
3 O’Sullivan E, Laffey J, Pandit JJ. A rude awakening after our fourth ‘NAP’: lessons for airway management. Anaesthesia 2011;66:331–4.
4 Cook TM. Novel airway devices: spoilt for choice? Anaesthesia 2003;58:107–10.
5 Pandit JJ, Yentis SM. All that glisters…How to assess the ‘value’ of a scientific paper. Anaesthesia 2005;60:373–83.
7 Pandit JJ et al. The Difficult Airway Society ‘ADEPT’ Guidance on selecting airway devices: the basis of a strategy for equipment evaluation. Anaesthesia 2011;66:726–37.
8 Van Zundert AA et al. Value of knowing physical characteristics of the airway device before using it. BrJ Anaesthesia 2016;117(1):12–16.
9 Van Zundert A, Brimacombe J. The LMA Supreme™ – a pilot study. Anaesthesia 2008;63:209–10.
10 Seet E et al. Safety and efficacy of laryngeal mask airway Supreme versus laryngeal mask airway ProSeal: a randomized controlled trial. Eur J Anaesthesiol 2010;27:602–7.
11 Maitra S, Khanna P, Baidya DK. Comparison of laryngeal mask airway Supreme and laryngeal mask airway Pro-Seal for controlled ventilation during general anaesthesia in adult patients. Eur J Anaesthesiol 2014;31:266–73.
12 Gaitini L, Vaida S. Is the newly designed distal tip of the LMA Supreme an advantage or a disadvantage? J Clin Anesth 2015;27:181–2.
13 Wong DT, Yang JJ, Jagannathan N. Brief review: the LMA Supreme™ supraglottic airway. Can J Anesth 2012;59:483–93.
14 Bick E et al. Editorial: Fewer sore throats and a better seal: why routine manometry for laryngeal mask airways must become the standard of care. Anaesthesia 2014;69:1299–313.