A cricothyrotomy is (almost exclusively) used as a rescue technique to oxygenate your patient. It is therefore the last step in a 'cannot-intubate-cannot-ventilate' (CICV) scenario. You have to know by heart the place of a cricothyrotomy within difficult airway management guidelines!
A cricothyrotomy is indicated when other methods of oxygenation following failed attempts at bag-mask ventilation and intubation have also been unsuccessful. By definition therefore the patient in whom you attempt a cricothyrotomy should have a (failed) LMA in place. In other words, if there is no LMA placed in the patient by the time you attempt a cricothyrotomy, you have not followed the CICV algorhithm!
Note that cricothyrotomies have been used electively to allow transtracheal jet ventilation in some cases of laryngeal surgery or as a holding measure whilst the airway is secured by another method, but this is not widely practiced. We will focus only on its use in the emergent situation here.
We describe the percutaneous technique for a cricothyrotomy below, although a surgical 'open' approach is possible.
In the most basic terms the purpose of a cricothyrotomy is to enable transtracheal ventilation, either as
- conventional ventilation with an anesthetic breathing system,
- or as transtracheal jet ventilation from a high-pressure oxygen source.
As mentioned above, a cricothyrotomy is almost exlusively used as a rescue technique to get you out of a CICV situation.
Tip: Get into the habit of palpating the anatomical landmarks relevant for cricothyrotomy in a variety of anesthetized patients in the OR. Appreciate how the ease with which you can identify structures varies widely between patients. Establish where you would place your cannula if you had to!
Two 'options' exist for cricothyrotomy equipment. Both are descibed in more detail here.
1. Manufactured complete kit solutions
These devices, once placed, connect to either an anesthetic breathing system via a standard 15mm tube connector or to a high-pressure oxygen source via a Luer lock adapter.
A cricothyrotomy kit with a 15mm standard connector should be immediately available in all anesthesia locations, i.e. be kept on the anesthesia machines at all times.
2. 'McGyver' device solutions
There is really no advantage to using such assemblies over kits which have been specifically designed for cricothyrotomy, unless you are in a location where no dedicated cricothyrotomy equipment is available.
Before reading through the rest of this page try to imagine what a CICV situation actually looks like: Your patient will already be hypoxic and the oxygen saturation is dropping further (fast). Alarms are going off everywhere, your pulse is racing, a bunch of nurses and surgeons are breathing down your neck and giving you (well-meant) advice as desperation takes hold... In short, this is likely to be most high-stress situation you could ever encounter in anesthesia! You will have very little time to prevent the patient from suffering hypoxic brain injury and dying! So relax and focus...
In considering the steps of the technique bear in mind that you will do this procedure in an airway emergency scenario, with a rapidly deteriorating hypoxic patient who you cannot ventilate, i.e. a 'cannot-intubate-cannot-ventilate' (CICV) situation. Again, this is going to be a highly stressful environment with very limited time to think before acting.
1. First things first
As soon as you have established that you are in a CICV situation do
1. declare the emergency clearly to all staff in the OR,
2. ask for the difficult airway cart or equipment,
3. ask for (anesthesia) help!
2. Equipment and connections
Know the equipment available in your hospital! This cannot be stressed enough. If and when you have to do a a cricothyrotomy there will be no time to read through manufacturer's instructions and to work out which bit of kit fits where. Also know before you do the procedure what you are going to connect your cricothyrotomy to, i.e. how will you actually ventilate once the device is placed. Therefore be aware of whether the device you are inserting has a standard 15mm connector or a Luer lock connector.
[Picture comparing the two types of device]
Consider two elements of correct positioning:
- Patient's head and neck position
The patient's neck should be (hyper)extended to help with landmark indentification. In practice this means pulling out pillows from under the patients head. Consider putting a towel roll under the patient's neck or shoulders to facilitate (hyper)extension.
- Your position relative to the patient
You will be working along the patient's anatomical midline which is awkward to to from the head-end. It will be easier to stand at a 90 degree angle to the patient at his/ her shoulder. If you are right-handed you should stand at the left, if you are left-handed you should stand at the right side of the patient. This also gives another practitioner room to continue with oxygenation attempts from the head-end.
[picture wrong versus correct position]
4. Identifying landmarks
Deciding where you place your cricothyrotomy cannula is the most difficult and also most crucial step of the whole procedure. At this step you are setting yourself up for success or failure.
Palpating the cricothyroid notch can be tricky, especially in patients with short necks or large circumferences. Rather than trying to identify the thyroid and cricoid cartilages right away, it is often easier to work you way up from the sternal notch (which can almost always be identified), palpating for tracheal rings with the index and middle fingers of your non-dominant hand. As you slide up the trachea you should encounter a tracheal ring which feels bigger than the ones below it- this is the cricoid cartilage. The groove above the cricoid cartilage is where the cricothyroid membrane is located.
5. Cannulating the trachea, placing and securing the cricothyrotomy device
- Technique for the 'cuffed cricothyrotomy cannula'
Using a needle of appropriate length, puncture the cricothyroid membrane with the bevel of the needle facing anteriorly, i.e. towards you. The needle should be directed to the trachea at a downward angle to reduce the risk of piercing through the posterior tracheal wall. Continuously aspirate for air as you are advancing the needle towards the trachea. Aspiration of air confirms successful placement of the needle tip in the trachea. Now advance the needle just a little further into the tracheal lumen (1-2mm only) to ensure that the distal opening of the needle is entirely inside the tracheal lumen.
Hold the hub of the needle with your left hand whilst steadying your hand against the patient to avoid accidental movement of the needle tip inside the patient's trachea and reduce the risk for trauma. Do not let go of the needle!
Feed the soft-tipped end of the guide-wire through the needle into the trachea. This should be possible without encountering resistance.
Make a horizontal stab incision along the neddle with the blade included in the kit. Make sure you make a wide enough incision to accommodate the cuffed cannula which has an outer diameter of 7.2mm (this applies to the kit we describe here).
Now pull out the needle over the guide-wire.
Grab the cuffed cannula and dilator together tightly with your right hand and feed them onto the wire.
Advance the cuffed cannula and dilator over the wire into the trachea in a downward and 'scooping' motion. Follow the course of the wire and appreciate the curve of the cannula. Prevent any movement of the dilator within the cuffed cannula! It might be helpful to steady the trachea in the midline between the thumb and index finger of you non-dominant hand as you are advancing the cannula.
Remove the dilator and wire together, inflate the cuff.
Connect your anesthetic breathing circuit and check for successful ventilation.
- Technique for the 'needle cricothyrotomy cannula'
With the needle cricothyrotomy cannula, puncture the cricothyroid membrane with the bevel of the needle facing anteriorly, i.e. towards you. The needle should be directed to the trachea at a downward angle to reduce the risk of piercing through the posterior tracheal wall. Continuously aspirate for air as you are advancing the needle towards the trachea. Aspiration of air confirms successful placement of the needle tip in the trachea. Advance the needle just a little further into the tracheal lumen (1-2mm only) to ensure that the distal opening of the needle is entirely inside the tracheal lumen.
Now feed the cannula off the needle into the tracheal lumen while keeping the needle in the same position. Advance the cannula all the way until the hub is at skin level. Hold the hub of the cannula with your left hand and pull out the needle and syringe.
Connect the syringe and aspirate again for air to confirm the correct final position of the cannula tip inside the tracheal lumen.
Hold the hub of the cannula with you left hand and do not let got until the cricothyrotomy access to the airway is no longer needed! This means hanging on to the cannula until an alternative, more permanent and secure access to the airway has been established or the patient has been woken up from anesthesia and can maintain his/ her own airway.
We strongly advise against relying on 'taping the cannula down' to keep it in place. High-pressure and high-flow jet ventilation can easily dislodge the cannula!
8. Ventilation through the cricothyrotomy device
Options for ventilation depend on the type of cricothyroytomy device placed in the patient:
- Ventilating and oxygenating your patient through a cuffed cricothyrotomy cannula is straightfoward as this device connects to any (anesthetic) breathing system via its standard 15mm connector. Bag-mask ventilation and IPPV with standard ventilator settings are possible. In addition, inhalational anesthesia can be delivered via this device.
- Ventilating and oxygenating your patient through a needle cricothyrotomy cannula requires different equipment and a high-pressure oxygen source.
A unique difficulty of the cricothyrotomy procedure is that you can't really train for it! You might be able to practice the technique on a manikin, maybe as part of a airway management course. Other than that you will most likely have had zero practical experience of the technique until you actually have to used it to get you out of a dire emergency when no alternatives exist!
Flint, N. J., W. C. Russell, and J. P. Thompson. "Comparison of different methods of ventilation via cannula cricothyroidotomy in a trachea–lung model."British journal of anaesthesia 103.6 (2009): 891-895.