For those of you not familiar with an iLMA, the device is designed to allow ‘blind’ intubation of the airway, using the laryngeal mask airway (LMA) as a conduit.
The progenitor, with which most rural doctors and anaesthetists will be aware of, is the FastTrach LMA. It’s reported to allow up to 73% ‘first pass’ successful intubation rates, increasing to 90% overall success with repeated attempts and the ‘Chandy manoeuvre’. It’s not a bad piece of kit and we’ve got one on our airway trolley.
However, the FastTrach requires some practice to get used to. I made a point of using it at least once a month during my anaesthetic year, just to get used to the kit. Using equipment in training is quite different to using ‘in anger’, especially when there’s an evolving airway crisis. Problems that I found were
- not always easy to pass the endotracheal tube into trachea
- removing the LMA whilst leaving the ETT in situ is fiddly and risks losing both
- overall success rate is 90% – so 1:10 will fail.
The C-Trach is an advancement on the FastTrach, improving rates for first pass and overall sucess to 96% and 98% respectively – basically this device is just a FastTrach with a video screen attached. Clearly then, addition of video allows visualisation of the cords and improves success rates.
However, neither FastTrach or CTrach allow you to place a nasogastric tube..unless you obturate the ETT and remove the LMA over the top, which is potentially fraght with difficulty.
Cue the AirQ iLMA.
This ‘new improved’ iLMA gets around the problems of FastTrach and CTrach – it’s similar in appearance to the FastTrach iLMA, albeit with a less acute angle. It also has a nifty side-port to allow passage of a nasogastric tube without having to remove the iLMA
Moreover, the device comes with dedicated nasogastric ‘blockers’ – an NG tube with an oesophageal balloon which can be inflated in the oesophagus to minimise aspiration risk and yet allow decompression of the stomach.
I tried it the other day in theatre and found it easy to use. As an LMA it functioned perfectly well, although I have heard some anecdotal evidence of increased supraglottic trauma with this device.
How then to improve success rates for passage of an ETT? Minh le Cong has described this elsewhere – use of a malleable intubating stylet such as the Levitan FPS allows visually-aided intubation through the iLMA conduit.
So we now have a staged procedure for the nightmare difficult airway where intubation has failed or priority is to oxygenate
- drop in an AirQ II and ventilate
- pass the oesophageal blocker to decompress the tummy
- use a fibreoptic device to intubate through the iLMA, improving intubation rate
This strategy (fibreoptic intubation through an iLMA) is Plan B of the UK’s Difficult Airway Society algorithm. Yet how many of us are really prepared to do this and have practiced on kit? Most rural docs have access to a FastTrach…so ventilation and blind intubation are possible – yet the addition of an NG tube port and allowance of fibreoptic intubation seems to offer a higher standard of care. Of course, for many small hospitals fibreoptic devices have traditionally been out of range – high cost and difficulty acquiring and maintaining skills.
But for under $3K you can pick up a Levitan scope (malleable fibreoptic intubating stylet) or the Ambu Ascope II (five disposable flexible fibreoptic scopes). They may not be as good as the fibreoptic towers that people use for an awake fibreoptic intubation…but they are bloody good gadgets to use with the above technique.
So, what would be my preferred kit for a ‘difficult airway’? Well, I’d use the Difficult Airway Society (UK) and ANZCA T04 guidelines as a starting point…and in addition to the AirQ and some sort of fibreoptic device, I’d add in a videolaryngoscope. Sounds expensive? Well my suggestions for purchase are in square brackets below – for under $4K should be affordable for small rural hospitals…
Plan A – Initial Intubation Strategy
Standard laryngoscopy – if fail, change position, blade, operator. Consider use of a videolaryngoscope in case of difficult airway. If fail, move to…
[KingVision Videolaryngoscope ~ A$1000 inc. blades]
Plan B – Alternative Intubation Strategy
iLMA to maintain oxygenation and ventilation, then secure airway using fibreoptic intubation through iLMA. If fail, move to…
[AirQ II iLMAs A$30 each]
[either Levitan FPS or AmbuAscope II fibreoptic devices to intubate through iLMA]
Plan C – Maintain Oxygenation & Ventilation, Abandon Procedure and Wake Up
Bag-mask ventilation and reverse non-depolarising neuromuscular blocker (suggamadex for rocuronium) or wait for suxamethonium to wear off. If fail, move to…
[Rocuronium for RSI – prolong time to desat]
[Suggamadex to reverse rocuronium]
Plan D – Rescue Techniques for Failed Oxygenation & Ventilation
Bag 1 – Paediatric or Easy Anatomy
Needle Cricothyroidotomy technique
Bag 2 – Adult or Easy Anatomy
Bag 3 – Impossible Anatomy
I wouldn’t bother with the pre-packaged kits like QuickTrach or Seldinger kits as first line for CICV – in the heat of the moment, faffing around with wires etc can be a disaster. Better to have three equipment bags set up as above using standard equipment – oxygenate first – then move on to seldinger or formal tracheostomy. Some have commented that doing the above is sufficient to ‘save the day’ then either wake up the patient or proceed to successful laryngoscopy.