The i-view™ video laryngoscope – key considerations

i-view

Video laryngoscopy represents one of the most significant advances in airway management in recent years. With the increased emphasis placed on ensuring the first attempt at intubation is the best attempt, the role of video laryngoscopy in airway management seems secure, at least for the foreseeable future.

Video laryngoscopes utilise the latest video and camera technology to provide an optimal (indirect) view of the larynx during the process to insert an endotracheal tube in to the patient’s trachea. There are many video laryngoscopes available, but the i-view™ from Intersurgical is the first single use and totally disposable adult video laryngoscope with a Macintosh type blade. i-view™ provides the option of video laryngoscopy, wherever and whenever the clinician may need to intubate, whether in the emergency room on a patient with respiratory failure, or in the intensive care unit on a patient with a difficult airway.

Where availability of a video laryngoscope may be limited due to the cost implications of purchasing reusable devices for multiple sites, i-view™ provides a cost effective solution, by combining all the advantages of a fully integrated video laryngoscope in a single use, disposable product. As i-view incorporates a Macintosh blade, it can be used for direct as well as video laryngoscopy, making it ideal for use in the emergency sector, where there may be a greater potential for the airway to become soiled with blood or other fluids, obscuring the view on the screen. In such circumstances, the operator can immediately switch from indirect to direct laryngoscopy.

As with all medical devices, whether single use or reusable, deciding on the most appropriate video laryngoscope to use is not straightforward, and consideration may need to be given to a number of factors. These may include evaluation of financial, environmental and infection control related issues, as well as the clinical requirements, evidence and preferences. It is important to recognise this assessment may change according to where, when and how often the device is to be used.

Financial

Whilst a single use video laryngoscope may not initially appear to be the optimal choice from a financial perspective, in circumstances where it is not used frequently, it may prove to be the most economic option.

8008-000_i-View_press

Infection control

In their safety guideline booklet (2008), ‘Infection Control in Anaesthesia 2’, The Association of Anaesthetists of Great Britain and Ireland (AAGBI), confirmed that, in relation to standard laryngoscopes, ‘Current practices for decontamination and disinfection between patients are frequently ineffective, leaving residual contamination that has been implicated as a source of cross-infection.’ They went on to note that, ‘Blades are also regularly contaminated with blood, indicating penetration of mucous membranes, which places these items in to a high risk category.’ They concluded that the use of single use blades was ‘to be encouraged’.

Laryngoscope handles may also become contaminated. The AAGBI’s recommendation in relation to laryngoscope handles is that they should be, ‘washed/disinfected and, if suitable, sterilised by SSDs after every use.’ There is no reason to believe the same considerations and arguments that apply to standard laryngoscope blades & handles regarding infection control, would not also apply to video laryngoscopes, since all laryngoscopes, whether direct or indirect, incorporate some form of blade and handle.

I understand new infection prevention and control guidelines from the AAGBI are in the final draft stage, and after comments from members have been reviewed, a final version is to be presented to the Associations Board for approval.

The UK Difficult Airway Society (DAS) were due to launch ‘The Decontamination of Video Laryngoscope Guidelines’ in November 2017, following two years of discussion by the DAS Decontamination Work Group. To my knowledge, this guidance has still not been published. However, an update on DAS projects in the DAS Summer 2017 Newsletter confirmed that, ‘Ideally, sterile single use VL would be the way forward’, and that the VL of the future is likely to be single use, and any reusable components would need to be ‘amenable to automated cleaning to the highest level of decontamination’.

8008-000_i-view_light_camera_side

Environmental

Environmental considerations are more complex and less easily assessed. Whilst it is appropriate for healthcare professionals, as well as anyone else with environmental concerns, to consider the implications of using single use devices in relation to product disposal, any assessment of the environmental impact of any medical device, whether single use or reusable, needs to consider a number of factors. This should include disposal of single use devices, and reprocessing or decontamination of reusable devices, in the context of a complete Life Cycle Assessment (LCA). The considerations of an LCA may vary depending on the type of product being assessed, the range and type of information and data available and the objective of the assessment. However, typically, an LCA will usually consider the following areas:

  • Raw material acquisition
  • Processing & manufacturing
  • Distribution & transportation
  • Use, reuse and maintenance
  • Recycling
  • Waste management

Assessing just one element of an LCA, such as waste management, may result in misleading conclusions as to the overall environmental impact of a device. A decision also needs to be taken as to what impact factors are to be assessed and how much weight is to be given to each. Is the focus primarily on climate change and water use, or is there an interest in assessing other or additional factors, such as, ecotoxicity, eutrophication, ozone depletion or urban and natural land transformation?

A number of LCA’s have been conducted for anaesthetic and airway devices. Their conclusions vary, and the complexity of any such assessment means the LCA usually needs to be considered as hospital or organisation specific, as any variation in reprocessing practices, such as the volume of water used during manual washing, the electricity consumption of different types of washer/disinfection unit, or the type of packaging material used for repacking after reprocessing, will all have an effect on the overall environmental impact. Decisions also need to be taken as to what to include and exclude. For example, should energy recovery from waste incineration or the environmental impact of Personal Protective Equipment (PPE) used by healthcare workers involved in reprocessing be included?

On the larger scale, a key factor to consider when looking at the environmental impact of a device from one country to another is how electricity is generated, since the impact will be different for a country that still relies primarily on fossil fuels for electricity generation compared to one which uses more renewables, such as wind. As well as the CO2 emissions associated with different types of electricity generation, how is the extraction method for coal and/or natural gas to be assessed from an environmental perspective? Should this also be included or excluded from the assessment? Inevitably, not everything can be considered and some assumptions will need to be made. As a result, any assessment of the results of an LCA needs to ensure the limitations are acknowledged and considered appropriately.

Of course, all products have an impact on the environment, but it is important to ensure the environmental assessment is considered alongside other key factors, such as infection control considerations and the clinical benefits offered by the device.

For example, the weight given to the clinical benefit of having a single use video laryngoscope available in a life threatening road-side emergency, perhaps when this might be the only viable VL option economically, might be quite different than the assessment made for regular routine use in the operating theatre.

8008-000_i-View_side_by_side_render

In an interesting paper published in the British Journal of Anaesthesia, entitled, ‘A national survey of videolaryngoscopy in the United Kingdom’, Cook & Kelly reported on the results of an electronic survey sent to all UK National Health Service Hospitals. With regard to availability of video laryngoscopy (VL) by clinical area, 91% of operating theatres reported availability of VL. In contrast, only 55% of Obstetric departments, 54% of Intensive Care Units and 35% of Emergency departments reported availability of VL. The authors noted that, ‘The distribution of availability is notable because the incidence of difficult or failed intubation increases in those places where videolaryngoscopy is less available; in order, main theatres, obstetric, ICU, and the ED.

It is not known why VL was less available in these areas, but it is possible that with less frequent use than in the OR, the financial implications of purchasing a reusable VL may have been a factor. If so, availability of a single use device might provide a more economically viable option due to its lower unit cost, which as discussed earlier, may be more economic when use is infrequent.

In summary, the i-view video laryngoscope from Intersurgical is the first single use and totally disposable adult video laryngoscope with a Macintosh type blade. It provides the option of video laryngoscopy, wherever and whenever the clinician may need to intubate. This makes VL a viable option in places where the higher initial costs of purchasing a reusable device may previously have been prohibitive. With the new focus in airway management of ensuring the first attempt at intubation is the best attempt, i-view may have a contribution to make to supporting this objective. Whilst it may not be suitable in all situations, such as when a hyper-angulated blade is required, it may be ideal in situations where use is infrequent, standard blade geometry is preferable and the nature of use makes it a more viable option economically.

Deciding on the most appropriate video laryngoscope to purchase and use is not straightforward, and in addition to the clinical requirements and preferences, consideration may need to be given to a number of other factors, including financial, environmental and infection control related issues. It is important to recognise this assessment may change according to where, when and how often the device is to be used.

References:

  1. Cook TM & Kelly FE. Seeing is believing: getting the best out of videolaryngoscopy. British Journal of Anaesthesia 117 (S1): i9–i13 (2016)
  2. Infection Control in Anaesthesia 2. Association of Anaesthetists of Great Britain & Ireland. 2008
  3. UK Difficult Airway Society Newsletter. Summer 2017. Page 20.
  4. Cook TE & Kelly FE. A national survey of videolaryngoscopy in the United Kingdom. British Journal of Anaesthesia, 118 (4): 593–600 (2017)

 

 

 

Advertisements

The Macintosh laryngoscope – is there a pretender to the crown?

Over 70 years after Sir R R Macintosh first described it in his landmark study published in The Lancet in 1943, the Macintosh laryngoscope remains universally popular.

Intersurgical plastic single use Macintosh laryngoscope blade, InterForm stylet and InTube ET tube

The dominant position of the Macintosh cannot be attributed to a lack of alternatives. Dorsch and Dorsch, in their huge 1,000+ page book, Understanding anesthesia equipment, list over 45 types of laryngoscope blade. Although some of these are described as modifications of the Macintosh, including the Oxiport Macintosh, Polio, Fink, Tull Macintosh, Bizarri-Giuffrida, Upsher Low Profile, Upsher ULX Macintosh, Improved vision Macintosh and the Left handed Macintosh, the list of alternatives also includes a significant number of other designs, including the Wisconsin, Schapira, Soper, Guedel, Bennett, Seward, Phillips, Alberts, Robertshaw and the Bainton. This list is not exhaustive. If you don’t have easy access to a copy of Dorsch & Dorsch, an extract is included in Annex D of the international standard, ISO 7376:2009: Anaesthetic and respiratory equipment – Laryngoscopes for tracheal intubation.

 In current practice, the two major types of Macintosh blade are generally considered to be the American, also called the ‘standard’, and the English, sometimes known as the ‘classic’ or ‘e-type’. The latter description is a particular favourite, conjuring up the image of the classic E-Type Jaguar, once described by Enzo Ferrari as, ‘The most beautiful car ever made’. Such a comparison may seem a little tenuous, but surely they can both be considered design classics?

The primary differences between the English or German and the American Macintosh are the shape, height and length of the proximal flange and the distance from the light to blade tip. The performance of both types was compared in a 2003 study by Asai et al, published in the British Journal of Anaesthesia, entitled ‘Comparison of two Macintosh laryngoscope blades in 300 patients.’ There was a difference in the view of the glottis in 80 patients. Among these patients, the view was better for the English blade for 63 patients and the standard blade was better for 17 patients. The authors concluded, ‘In patients in whom laryngoscopy was unexpectedly difficult, the English blade provided a better glottic view significantly more frequently than the standard blade.’

Probably the closest rival to the Macintosh in terms of popularity is the Miller blade. Described two years earlier than the Macintosh, the 1941 paper by Miller in Anesthesiology and simply entitled, ‘A new laryngoscope’, described a straight blade which when compared to an ‘old style medium sized blade’, was ’rounded on the bottom, smaller at the tip, and has an extra curve beginning about two inches from the end. The internal diameter of the base is shallow, but adequate to permit the passage of a 38 catheter.’ This landmark study is free to access on the Anesthesiology web-site. Miller also described a modification of his adult laryngoscope for children in 1946, ‘A new laryngoscope for intubation of infants’, Anesthesiology. 7(2):205, March 1946. This paper is also free to access.

The Miller blade remains popular for children, with straight blades in general having been described as ‘superior in elevating the tongue, removing it from the field of view to facilitate a better visualization of the infant larynx than the curved blade laryngoscope’. Doherty JS et al, 2009. Pediatric Anesthesia, 19: 30–37.

 In 2009, The UK NHS Purchasing & Supply Agency’s Centre for Evidence-based Purchasing (CEP) produced a  Buyer’s Guide for Laryngoscopes (CEP08048). The scope of this guide only extended to Macintosh blades sizes 3 and 4. No Miller or other alternative blades were included, perhaps reflecting the fact that ‘The Macintosh is the most popular [blade] for use with adults in the United Kingdom…’

 In the UK 4th National Audit Project (NAP4) – Major complications of airway management in the UK, it is confirmed in relation to tracheal intubation that, ‘Direct laryngoscopy with a Macintosh blade remains the technique of first choice if not actively contraindicated when difficulty is not anticipated.’

 Intersurgical single use plastic Macintosh laryngoscope blade

Given the huge variety of options available, why is the popularity of the Macintosh so enduring?

 Scott and Baker provide some answers in their 2009 review article, How did the Macintosh laryngoscope become so popular? In a very informative and entertaining article, the authors, New Zealanders like Macintosh, suggest that poor straight blade laryngoscopy technique prior to the widespread use of muscle relaxants, commercial availability, Macintosh’s connections in the industrial sector and unprecedented influence on the development of anaesthesia, as key factors in the success of the Macintosh blade that can be traced back to ‘prevailing circumstances’ in the 1940s. They conclude that, ‘Despite being able to achieve superior laryngoscopy with paraglossal straight blade technique and the multiple alternatives available, the Macintosh laryngoscope remains ubiquitous and is regarded as the gold standard of direct laryngoscopy’.

 In 1984, over 40 years after publication of the original description of the Macintosh laryngoscope and 25 years before the review article published by Scott and Baker, Jephcott published  A historical note on its clinical and commercial development. It was estimated by Jephcott that well over 1 million Macintosh blades had been made and sold in the previous 40 years. With regard to the origin of the design, Jephcott confirmed Macintosh’s own account from a letter he received from him:

 “I had a bit of luck and the nous to take advantage of it. On opening a patient’s mouth with a Boyle-Davis gag I found the cords perfectly displayed. Richard Salt (a really excellent chap) was in the theatre with me: before the morning had finished he had gone out and soldered a Davis blade on to a laryngoscope handle and this functioned quite adequately as a laryngoscope. The important point being that the tip finishes up proximal to the epiglottis.” Interestingly, he continued by noting that, ‘The curve, although convenient when intubating with naturally curved tubes, is not of primary importance as I emphasised subsequently.’

 Jephcott confirms the Macintosh laryngoscope was originally produced by Medical and Industrial Equipment Ltd (MIE), quickly followed by The Longworth Scientific Instrument Company Ltd. In the USA, Foregger of New York started to make the device in 1943. Jephcott concluded his article by noting that, ‘Today the Macintosh laryngoscope is known throughout the world and is made by many firms in many countries. The technique discovered by Macintosh and the instrument he designed for its achievement has survived translation into plastic and the adoption of the fibre-light. No doubt they will endure other developments in years to come.’

 Jephcott’s prediction was correct. Since his article in 1984, the Macintosh blade has also survived translation in to single use metal blades and is incorporated in to the design of a number of video laryngoscopes. The Macintosh blade remains the dominant blade for direct laryngoscopy in the 21st century, with no obvious pretender to the crown.

The bougie – is it immortal?

Despite the technique of using an introducer to facilitate intubation being described over 65 years ago, the bougie, or tracheal tube introducer, remains a popular airway adjunct. With the development of more hi-tech aids to manage the airway, such as video laryngoscopes, is the demise of the bougie imminent or is it destined for immortality?

As Dr J J Henderson confirmed in correspondence entitled, ‘Development of the gum-elastic bougie’ – published in Anaesthesia in 2003, although Robert Reynolds Macintosh, who designed the Macintosh Laryngoscope – described by Sir Anthony Jephcott  as, ‘the most numerously and widely made durable item in the history of anaesthesia’ – is usually given credit for the first use of introducers to facilitate tracheal intubation, the technique was described a year earlier by Minnitt & Gillies in their ‘Textbook of Anaesthetics’, published by E & S Livingstone Ltd in 1948.

Dr Henderson confirms that in relation to passage of a tracheal tube with the Macintosh laryngoscope, the Minnitt & Gillies publication suggested, ‘This is an easy matter when a semi-rigid gum elastic catheter is passed’. 

 Sir Robert Macintosh (1897 – 1989), knighted in 1955, described the technique in his landmark illustrated 1949 article entitled, ‘An aid to oral intubation’ as follows:

 ‘One of the difficulties in passing tubes beyond a certain size is that the body of the tube obscures the view of the cords through which the tip must be directed. In order to overcome this I thread the tube over a long gum-elastic catheter, the tip of which is then passed through the cords under direct vision. Using the catheter as a guide, the tube is gently pushed down into position and the guide is then withdrawn.’

A few years later in 1952, responding to correspondence from a Dr Rook, Barnard (Anaesthesia 1952;7:119) described a technique he found of practical value when for any reason intubation proved difficult:

‘A small gum-elastic bougie is pushed through the Magill’s tube until about two inches extend beyond the distal end. The bougie is then bent forwards at an angle of 45 degrees or less. A Macintosh’s laryngoscope is passed and the bougie is passed through the larynx. The Magill’s tube is then passed well into the trachea and the bougie is removed’.

Use was not widespread until after the introduction of the Endotracheal Tube Introducer by Eschmann Bros & Walsh Ltd in the 1970s. This device incorporated a coudé tip, one of a number of differences to the device originally described by Macintosh in 1949. Dr Venn, who designed the device whilst working as an anaesthetic advisor to Eschmann, has described the development of the bougie in correspondence published in Anaesthesia in 1993 and the story was expanded further by Dr Henderson, from additional information provided by Dr Venn, in an article entitled, ‘Development of the gum-elastic bougie’ published in the same journal ten years later.

One irony is, as El-Orbany et al noted in Anesthesiology in 2004, the Eschmann Tracheal Tube Introducer is not gum, elastic or a bougie. The gum elastic bougie was originally a urinary catheter designed for dilation of urethral strictures. The material of the Eschmann device was different in that it had two layers: a core of tube woven from polyester threads and an outer resin layer. Other differences were the length, longer at 60cm, to allow the railroading of an endotracheal tube and the ‘presence of a 35 degree curved tip, permitting it to be steered around obstacles’.

Since its introduction, the bougie, or tracheal tube introducer, has grown in popularity, and whilst an equipment list for management of the difficult airway might include a number of different types of devices and airway adjuncts, such as alternative styles of rigid laryngoscope blades, supraglottic airways, video laryngoscopes and flexible fibreoptic intubation equipment, it is also likely to include some form of tracheal tube introducer or guide – single use or reusable.

The Difficult Airway Society (DAS) 2005 list of recommended equipment for routine airway management includes a ‘Tracheal tube introducer (gum-elastic-bougie)’ and an ‘Introducer (bougie)’ is included as part of ‘Plan A: Initial tracheal intubation plan’ in the DAS algorithm for ‘Unanticipated difficult tracheal intubation – during routine induction of anaesthesia in an adult patient’. Intubating bougies are also mentioned in the section on Recommendations for Extubation in the ‘Practice Guidelines for Management of the Difficult Airway’ , an updated report by the American Society of Anesthesiologists (ASA) Task Force on Management of the Difficult Airway, published in 2013.

Single use alternatives from a variety of manufacturers have been available for a number of years, and the Association of Anaesthetists of Great Britain and Ireland (AAGBI) Safety Guideline document, Infection Control in Anaesthesia, published in 2008, states:

Bougies: ‘Re-use of these items has been associated with cross-infection. Manufacturers recommend that a gum elastic bougie may be disinfected up to five times between patients and stored in a sealed packet. It is preferable that alternative single-use intubation aids are employed where possible.’

Even a cursory search of the published literature relating to tracheal tube introducers produces literally hundreds of studies, case reports and correspondence, comparing different types of introducers and a variety of potential extended applications, as well as the effects of sterilisation on multi-use devices, (Anaesthesia, 2011, 66, pages 1134 – 1139), and the forces required to remove bougies from tracheal tubes (Anaesthesia, 2009, 64, pages 320 – 322). There is even a report, published in Anaesthesia in 2007, regarding a home-made bougie. A quite alarming story in this modern age of device regulation, the author describes fashioning a bougie in Indonesia from a wire coat hanger and an ordinary giving set whilst waiting for a bougie to arrive from England! The author used the device on more than 40 occasions, commenting that, ‘In four patients I do not think I would have been able to intubate the trachea without it.’

It seems the bougie continues to be perceived as a useful airway adjunct for the persistent epiglottis-only view, but as Dr Richard Levitan has described in his overview of the Bougie (Tube Introducer), ‘The bougie is not a heat seeking missile, i.e., it does not ‘find’ the trachea automatically; laryngeal landmarks, i.e. the epiglottis at a minimum, or preferably the posterior cartilages must be sighted to place the bougie in the trachea.’

Given that many airway conferences now often include a debate comparing direct laryngoscopy to video laryngoscopy and provocatively ask whether the days of the standard laryngoscope are numbered, it is interesting that even those who feel the value of a bougie may sometimes be overstated, do not seem to suggest the bougie is in imminent danger of being consigned to the history books as a relic of anaesthesia practice from days gone by. Perhaps the bougie is immortal?