Given that this is a very ICU-oriented procedure, the topic of percutaneous tracheostomy has come up several times in the exam. Question 1 from the first paper of 2008 asked about the anatomy of the trachea as related to percutaneous tracheostomy, and Question 9 from the second paper of 2000 asked the candidates to list advantages and disadvantages of three commonly used techniques which may be used to perform this procedure. With the usual attitude of overdoing things, six tracheostomy techniques are offered here.
Epstein's "Anatomy and physiology of tracheostomy" (2005) is the best free resource for this purpose. I have used their images without any permission; a picture says a thousand words. The rest of the following text is also liberally borrowed from Epstein. Trauma.org also has an excellent tutorial on this technique. Lastly, ANZICS also has a position statement for percutaneous tracheostomy, which probably represents the "state of the art" as far as the exam candidate is concerned. That 2014 statement can be recommended to the time-poor candidate as the sole revision resource for the topic of tracheostomy as a whole.
The following is a brief non-pictorial explanation of what the lower airway looks like. Let us use the imagination to move through the airway, through the vocal cords and down towards the lung.
Immediately under the vocal cords is the subglottic space, which is bounded by the cricoid cartilage. The way to gain access to that space is by the cricothyroid membrane. This membrane is fairly narrow, and the space there si bounded by two rigid structures which resist dilation: this is why the cricothyroidotomy is not much of a long-term option (the tubes fitted through there will be by necessity very narrow and unsuited to chronic use).
The trachea is next. It is made up of 18-22 cartilaginous rings, which are incomplete rings (they open posteriorly). The trachea is about 10-13 cm long. Usually, it has an internal diameter of around 2.3cm. The non-cartilaginous posterior trachea is called the "membranous portion" and this is where the trachealis muscle tends to be seen. During bronchoscopy, one orients themselves so that the trachealis muscle is the "floor" of the trachea.
Superficial anatomy of relevance to the tracheostomy is largely a tour of soft tissues and minor vessels. The picture here is from Wikipedia.
Anterior to the second and third rings of the trachea, is merely skin, subcutaneous tissue, sternothyroid and sternohyoid muscles, and pretracheal fascia. Sometimes, there is an anterior communicating jugular vein which also travels through this space.
Laterally, on both sides there are the vagus nerves, carotid arteries and the jugular veins, covered by the carotid sheath. Posterolaterally, on either side of the oesophagus lie the recurrent laryngeal nerves. These structures are mentioned in the chapter on the complications of tracheostomy as something one might damage during a blind percutaneous attempt, but seriously - you'd have to be fairly mad to be so lateral and so deep.
The spaces reserved for percutaneous tracheostomy are the second and third tracheal spaces (i.e. the spaces between cartilaginous rings). Superiorly to these spaces lie the cricoid cartilage and the cricothyroid membrane. Inferiorly lies the isthmus of thyroid and the inferior thyroid veins. The main reason for this choice of spaces is to avoid hitting the thyroid, though it seems to be a fairly benign complication: Duanne et al reported on a "successful percutaneous tracheostomy via puncture through the thyroid isthmus" which did not bleed as torrentially as one might expect. As far the precise location of the tracheostomy goes, the Epstein article from 2005 (and therefore my stolen trachea artwork) disagrees somewhat with the the ANZICS statement (who recommend "cannulation of trachea between 1st & 2nd or 2nd & 3rd tracheal ring with a guide wire"). As the ANZICS committee is probably composed of college examiners, we will regard their opinion as unquestioned gospel.
Surgical tracheostomy may involve the removal of a cartilaginous ring, but the dilational percutaneous technique relies on gently dilating them apart so that the pressure of adjacent cartilages on the tube forms a sort of natural haemostasis. The disadvantage of such a tight fit is the potential for subcutaneous emphysema, as air cannot escape through the edges of the wound.
Posteriorly to the membranous portion of the trachea lies the oesophagus. That membranous portion is a frequently lacerated bystander to the act of tracheostomy, and the oesophagus is perforated surprisingly frequently even when the procedure is guided by bronchoscopy.
Say, you behold a given neck. What makes you think it's going to be an easy tracheostomy?
The article by Muhammad et al (2000) is usually quoted as the classic of literature where it comes to assessing a neck. The ANZICS statement quotes this exact article in their "risk assessment" section. Unfortunately, it is not available as free full text.
The ANZICS position statement does not recommend one technique over another, as "there is no data supporting one or the other approach". This lack of commitment is unfortunate. Thankfully, Alvaro Sanabria has published an article to rescue the situation ("Which percutaneous tracheostomy method is better? A systematic review.") In summary, the Blue Rhino single dilator technique is probably "the best", because fewer steps are involved and "physicians ...have more experience with this technique". This article is probably the best one to answer Question 9 from the second paper of 2000, which asks for a comparison of techniques. In order to simplify revision, the tabulated discussion section from Question 9 is reproduced below.
|Ciaglia Blue Rhino||
Griggs forceps technique
|Cianchi balloon dilation technique||
|Frova and Quintel (PercuTwist) technique||
Even though Sheldon et al developed this procedure in 1955, it is named after Pasquale Ciaglia, a thoracic surgeon. Sheldon et al had no dilators, and basically just cut their way in to the trachea percutaneously. In contrast, Ciaglia introduced the percutaneous tracheostomy to the world as an anterograde Seldinger technique, using minimal dissection, multiple sequential dilators and a J-wire.
Cook Medical had made a disposable kit for the classical Ciaglia technique, which can be seen in this stolen photograph from Vigliaroli et al (1999). One can see a series of dilators, which were used to progressively widen the stoma. The dilators were advanced via the smooth white Teflon guide, a 5Fr pece of flexible tubing which- together with the guidewire- ensures you stay in the trachea while dilating.
The gist of the technique is as follows: the ETT is withdrawn until it is supraglottic (so its cuff doesn't get stabbed by the needles) and a guide wire is advanced through the first puncture (16G cannula) into the trachea, ideally under direct bronchoscopic guidance. Over the guidewire and Teflon guide, multiple dilators are then used to gradually enlarge the stoma until finally the whole tracheostomy tube is inserted, and the cuff inflated.
The advantages of this method are that it is old, and therefore well known, well studied and well practiced. The complication rate is notoriously low. Of the studies which comprise the meta-analsysis favouring percutaneous tracheostomy over surgical, many were using this technique. Multiple sequential dilators ensure that little force and little pressure is required for each dilation, which means that there is less deformation to the airway and there is better control of the dilator tip, resulting in less posterior tracheal trauma and reduced risk of injury to surrounding structures. If one does not need to push very hard, one is unlikely to ever hear the sickening "crack" of the tracheal cartilages.
The disadvantages must also be mentioned. With multiple sequential dilators, the procedure is fiddly and multi-staged. This has implications for the junior operator: if you are unused to Seldinger tracheostomy, you will be overwhelmed by the long sequence of practical steps. Moreover, the dilators (as you can see in the kit) are fairly straight, which means that one may easily lacerate the posterior tracheal wall unless one intentionally aims down towards the patient's feet. As you fiddle with the dilators, multiple exchanges result in constant handling of the J-wire, which can easily be dislodged out of the trachea (which can be a complete disaster).
Then during the dilations, there are several stages where the airway is left open to the atmosphere. This causes a loss of airway pressure, and increases the amount of derecruitment which must necessarily occur during a tracheostomy like this. With the airway open and the ventilator blowing gas on pressure control mode, the tracheal stoma becomes a fountain of bloody froth, which has implications not only for the operator (you'd better be wearing eye protection!) but also for the rest of the team, as clouds of aerosolised Hepatitis C and HIV are sent into the room.
In answer to some of the disadvantages mentioned above, the kit was altered somewhat and in its modern form includes only one main dilator, which is the Rhino (though it is not always blue). The use of this single dilator allowed the technique to become smoother, and the steps were fewer. The speed of the procedure increased, and the time spent with a depressurised airway was minimised. Because the dilator was curved, damage to the posterior tracheal wall was also supposedly reduced (it is unclear by how much, because that complication is still seen with this technique).
The disadvantage of the Blue Rhino is its size. Without sequential dilation of the stoma, brutal force is required to part the tracheal rings. Though it has never been demonstrated in any sort of clinical trial, the risk of tracheal or cricoid cartilage damage is anecdotally greater.
Grigg et al published their modifications to the percutaneous technique in 1990. The original article is not available to me, but fortunately in 2007 Park and Goldberg described it in glorious detail. A collage of images is available to describe the technique, of which I will only reproduce one - the one where the forceps are in use.
The main difference in this technique is all about those forceps. These Griggs Forceps are actually adapted Kelly Clamps (a type of arterial forceps used to clamp larger arterial vessels, a larger relative of the mosquito forceps). Their major characteristic feature is the smooth channel which runs between the teen in the curved mouth: this is where the guide wire goes. The technique differs from Ciaglia by the use of these forceps instead of the later series of dilators (or the Blue Rhino). The forceps are shoved into the trachea, and the tracheal stoma is dilated by the use of the forceps - closed initially, and then opened so as to widen the stoma. The whole lot of equipment is available as a kit from Portex.
The advantage of this technique is it's speed. In 1991 Griggs Myburgh and Worthley reported on a mad scramble for the airway during which they were able to perform it in 30 seconds. The matter that the trachea is being dilated in one step is similar to the Blue Rhino technique, but the Griggs method was available about 8 years prior to the Rhino. By using curved forceps and a controlled sideways force for dilation one also minimises the risks of trauma to the posterior wall. Because one does not rely on a specific kit (fitting a dilator to a certain sort of tube), the Griggs technique could theoretically be used to introduce any tube (or any object whatsoever) into the trachea. One could conceivably use it to put a standard endotracheal tube down there, or a hollow bamboo reed for that matter. There is also less blood spray: one may keep one hand on the wound with a handy swab, keeping the froth at bay while dilating with the other hand.
The disadvantages lie in the tendency to dilate too hard: it is possible to damage tracheal rings in this way. The use of the sterile forceps may result in more infectious complications, as the forceps may pick up bits of skin and subcutaneous fat and drug it into the lower airway. The potential for guidewire loss is probably greater.
In 2002, Frova and Quintel published their description of a novel tracheostomy technique which they described as "controlled rotating dilation" using - for lack of a better word - a screw.
The dilator is depicted here, stolen from the two free-to-read pages of the otherwise paywalled seminal paper. This thing looks hideous, but was in fact sold as an atraumatic method of dilating the tracheal cartilages, with less force required to gradually enlarge the stoma. In essence, each twist corresponds to a larger Ciaglia dilator in the sequence. The goal was again to reduce the chances of tracheal cartilage fracture and posterior wall injry while maintaining the speed advantages of the single-dilator techniques such as the Blue Rhino. Surpisingly, it looks fairly safe (viewed from a bronchoscope, emerging gradually into the tracheal lumen). If you want, you can buy these from various manufacturers, which (according to a quick Google search) seem to mainly be in Europe.
The seminal paper certainly confirmed that the procedure is quick and safe (in the hands of its developers). However, there was no major advantages observed with it, and there is nothing inherently safe about the device itself when compared to other dilators. If you are careless and push hard enough, this technique will lacerate the tracheal wall and break cartilage just like the others. If you are careful and experienced, you will be safe with any dilator device.
This is the most recent entry into the arena of tracheostomy techniques (Cianchi et al, 2010), using a "Blue Dolphin" instead of a "Blue Rhino". The Dolphin is a Rhino-like introducer which contains a balloon. Once in the tracheal the balloon is filled with saline to a pressure of 11atm. and kept inflated for 10 seconds. The tracheostomy tube is introduced via the same introducer, over the deflated balloon and into the newly formed stoma.
The chief advantage of this technique is the complete lack of dilators. There is no point at which you are shoving anything forcefully into the patient's trachea. Therefore, the risk of cartilage damage and the likelihood of posterior tracheal tears is greatly decreased.
The disadvantage is the time it takes, and the fiddly nature of the procedure, with measurement of the balloon pressure, timing of the inflation, and the limited familiarity of most operators with this technique. Cianchi et al also found it was more difficult to pass the balloon into the opening because of the fact that the balloon only dilates the stoma radially.
This method is unlike any of the others, as it theoretically requires only one operator and involves a reversal of the normal Ciaglia approach. Fantoni and Ripamonti (1997) developed it in response to criticism of the Ciaglia method as being too aggressive and too prone to damaging the tracheal structures.
The method is describe above, in a series of pictures found in this excellent 2006 article by Konopke et al. In short, the steps are as follows. First, the endotracheal tube is retracted to the supraglottic space, just as always. Through a needle in the trachea, a guide wire is threaded past the ETT balloon and out of the patient's mouth. A device is then passed over the guidewire which is described as a "flexible plastic cone with a pointed metal tip". Then, the original ETT is removed, and another special long narrow ETT is advanced past the tracheostomy stoma (this special narrow ETT is included as a part of the disposable kit). Konopke et al found this step to be pointless because they were able to do the rest of the procedure quickly enough, and required no other airway.
At this stage, the pointy metal cannula is pushed into the patient's mouth and through the larynx. It is then pushed out through the tracheal wall and through the skin like the Alien erupting out of a chest. At this stage, once the cannula had passed through the stoma up to the cuff, the end-piece with the wire was cut off. To properly position, an obturator was inserted and then rotated 180 degrees such that the cuff then faced the carina.
The advantage of this technique is supposed to be the complete lack of any contact with the posterior wall. At no stage is anything pushed into the trachea - always the pushing is out. However, one may still puncture the posterior wall with one's needle. In addition, there is every chance that the airway will be lost (at one stage one needs to completely remove both the ETT and the bronchoscope, and so the patient has no airway for a period. IOf you rely on the small narrow tube supplied with the kit, issues of airway resistance may arise. Finally, a lack of broad familiarity with this technique combined with its multiple steps has made it an unpopular choice.
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Griggs, W. M., J. A. Myburgh, and L. I. Worthley. "Urgent airway access--an indication for percutaneous tracheostomy?." Anaesthesia and intensive care 19.4 (1991): 586.
Cianchi, G., et al. "Comparison between single-step and balloon dilatational tracheostomy in intensive care unit: a single-centre, randomized controlled study." British journal of anaesthesia 104.6 (2010): 728-732.
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Konopke, Ralf, et al. "Prospective evaluation of the retrograde percutaneous translaryngeal tracheostomy (Fantoni procedure) in a surgical intensive care unit: technique and results of the Fantoni tracheostomy." Head & neck 28.4 (2006): 355-359.