FONA (Front-of-neck airway) equipment

One example (others exist) of a complete cricothyrotomy cannula kit which requires a wire-exchange Seldinger technique for insertion is the kit described below. It contains the following items:

1. Melker cricothyrotomy cannula, which is a curved 5.0 cuffed tube with flange at the proximal end, and a pre-loaded internal dilator with a tapered tip and distal opening for a wire. The Melker cannula comes in one size only.

NOTE: The cannula (after the removal of the internal dilator) is exactly the same as the cannual supplied with the 'surgical' kit described below. Only the dilators are different!

2. Wire which is soft-tiped on one end
3. Scalpel with a #15 blade
4. Cannulas
5. Syringe
6. Fabric tie

 

The Seldinger technique used with this kit is described on the FONA (front-of-neck airway) page.

One example (others exist) of a complete cricothyrotomy cannula kit which requires a 'surgical' technique for insertion is the kit described below. It contains the following items:

1. Melker cricothyrotomy cannula, which is a curved 5.0 cuffed tube with flange at the proximal end, and a pre-loaded internal dilator with a blunt tip. The Melker cannula comes in one size only.

NOTE: The cannula (after the removal of the internal dilator) is exactly the same as the cannual supplied with the 'needle'/ Seldinger kit described above. Only the dilators are different!

2. Trousseau dilator
3. Scalpel
4. Tracheal hook
5. Syringe
6. Fabric tie

 

This kit is used with a 'surgical' technique described on the FONA (front-of-neck airway) page. 'Surgical' technique does not mean that only a surgeon can use this kit, it refers to the fact that more tissue dissection is needed to get to the cricothyroid membrane compared to the 'needle'/ Seldinger technique.

Pre-packaged kits with dedicated cricothyrotomy cannulas are commercially available, but a simpler version can be assembled from what is already available in most operating rooms. A home-made 'kit' for scalpel-bougie cricothyrotomy would include the following three (plus one) items:

1. Gum-elastic bougie
2. ET tube

Use as small an ET tube as fits easily onto the bougie to minimize the 'step-up' in size from the bougie to the ET tube. This will make insertion through tissue a lot less traumatic and easier. The smallest standard ET tube that can be easily railroaded over a standard-size bougie is a size 5.5.

TIP: ​​An armored/ re-inforced ETT might be advantageous in scalpel-bougie cricothyrotomy over a standard tube, since it is more flexible, potentially easier to railroad over the bougie, and less likely to kink and obstruct once in-situ. An, in my opinion, ideal ET tube is the 5.5 Bivona® TTS tube (see picture below).

3. Scalpel
4. (Tracheal hook)

A tracheal hook is used to pull and displace the thyroid cartilage anteriorly and cranially, opening the incision in the CTM up and elevating the tracheal axis, thereby facilitating bougie insertion into the trachea and 'railroading' of the ET tube. The hook is optional but helpful.

 

It is advisable to store these three items packaged together in a readily accessible location on or near the anesthesia machine, just so you don't have to waste time looking for each item in a CICO scenario.

The 'scalpel-bougie' technique is described on the 'Scalpel-bougie FONA' page.

Different transtracheal catheter devices are being offered from a range of manufacturers. The one we discuss here is a wire-reinforced 6 Fr trans-tracheal catheter which is 7.5 cm long and introduced over a 15 G needle. By definition therefore this is a small-bore FONA device, which needs high-pressure oxygen to achieve sufficient flow rates through it.

The wire-reinforcement helps to prevent kinking and obstruction of the catheter in-situ, conferring a major advantage over using a large-bore iv cannula, which you might see being recommended for use as a trans-tracheal catheter by some. An iv cannula is much more likely to kink and obstruct, especially when the skin-trachea passageway is longer (see below: 'home-built' equipment).

 

NOTE: With transtracheal catheters/ all small-bore FONA devices, expiration occurs through the upper airway, not the device! 

Once the catheter is placed in the trachea there are a number of options as to what conduit can be connected to it to deliver oxygen. Essentially you need to hook up an oxygen source to a Luer lock connector (of the transtracheal catheter).

 

1. Enk oxygen flow modulator

This is essentially a plastic tube with several side-holes allowing for varying degrees of thumb occlusion, a distal male Luer lock connector, which hooks up to the transtracheal catheter, and a proximal end which connects to a high-pressure oxygen flowmeter/ wall outlet. The tubing also incorporates a side port for CO2 sampling.

To generate sufficient flow through the catheter a connection to a high-pressure oxygen supply, such as a common wall outlet or an ancilliary O2 outlet on the anesthesia machine is required. Select a flow rate of at least 15 l/min O2. A hook-up to a circle anesthetic breathing system (or any beathing system with an APL valve or expandable reservoir bag) will not generate sufficient driving pressure for adequate oxygen flow to occur through the device!

 

2. (Manual) jet ventilator

The manual jet ventilator is described on a separate page.

3. Self-inflating bag/ Ambu® bag

With a self-inflating bag (also often referred to as an Ambu® bag, although this is only a brand name for one of them) you can create a fairly high driving pressure for oxygen delivery through a trans-tracheal cannula. This is not possible with using a reservoir bag from an anesthetic breathing system!

CAUTION: Avoid using an anesthetic breathing system with a reservoir bag or a ventilator to deliver oxygen through a trans-tracheal catheter. They do not create a sufficiently high driving pressure for adequate oxygen flow through the catheter.

Some 'engineering' is required to make the connection between the standard 15 mm connector of the self-inflating bag and the Luer lock connector of the trans-tracheal cannula. Two options are:

1. Make this connection is with a 3 ml syringe and an ET tube connector
2. 'Intubate' a 10 ml syringe with a standard ET tube (this connection is a bit more flexible but bulkier overall)

 

4. 'Home-built' equipment

Something similar to an Enk oxygen flow modulator can be 'mcgyvered' from simple medical airway supplies such as oxygen tubing and 3-way stopcocks. This takes time to assamble, is more likely to fall apart/ malfunction under use, and is therefore not recommended, especially since superior purpose-designed alternatives exist.

 

CAUTION: A significant number of catastrophic adverse events have resulted from the use of trans-tracheal cannulas and high-pressure oxygen injection where the cannula tip was not inside the tracheal lumen. The relatively high risk of barotrauma from trans-tracheal high-pressure oxygen insufflation/ jet ventilation has led to decreasing enthusiasm for this technique as a rescue for CICO scenarios (Duggan et al., 2016).

Trans-tracheal cannula insertion and oxygenation techniques are described on the 'Trans-tracheal catheter FONA' page.