Reviewed and revised 21 July 2021
- airway rescue procedure allowing transtracheal oxygenation
- aka needle cricothyroidotomy
- “can’t intubate, can’t oxygenate’ scenario
- occasionally performed semi-electively if difficult intubation and/or preoxygenation is anticipated
- local infection
- non-identifiable anatomy (e.g. severe obesity), distortion due to radiation, trauma, swelling or a mass lesion)
- previous failed attempts
METHOD OF INSERTION
Technique (as described by Andy Heard and colleagues, see their demonstrating cannula insertion)
- extensive consent and patient preparation is not usually possible in an emergency
- extend the patient’s neck to optimise identification of anatomy and ease of procedure
- Identify cricothyroid membrane and stabilise it with the non-dominant hand. Palpate the membrane with the index finger of the non-dominant hand and stabilise the trachea with the thumb and middle fingers.
- Hold a 5ml syringe (containing 1-2ml saline) connected to a 14G cannula in the dominant hand, with fingers between the flange and the plunger. Filling the 5ml syringe with 1-2 ml of saline allows demonstration of the endpoint of bubbles when the airway is entered.
- Insert the needle through the skin at an angle of 45 degrees in a caudal direction. In order for the cannula to reach the airway, a more perpendicular approach may be needed.
- Aspirate as you continuously advance the needle-cannula unit into the airway. Stop advancing once air is aspirated, ensuring the cannula tip is in the trachea. Do not aspirate when the needle is not advancing (may cause false positive atmospheric air aspiration)
- The end point is free aspiration of air up the entire 5 mL syringe barrel.
- Stabilise the cannula hub with the non-dominant hand and then release the plunger of the syringe held by your dominant hand. If the tip of the cannula is incorrectly placed the plunger will be sucked back into the syringe barrel by the vacuum created by aspirating outside of the airway. The plunger will stay in position if the cannula is correctly placed in the airway.
- Place the dominant hand underneath the syringe, holding the needle in a pencil grip with the hand resting against the chin or neck to immobilise the cannula.
- Advance the cannula over the needle into the trachea using your non-dominant hand and remove trochar. It should advance as easily as an IV. Do not remove the needle before you advance the cannula otherwise the cannula will kink.
- Ensure the cannula is held securely in position at all times.
- Using a syringe with 1-2 mL saline, connect to the cannula and repeat the full free aspiration of air from the cannula. Again, a lack of plunger recoil confirms airway placement. If the initial aspiration fails then slightly withdraw the cannula while aspirating — free aspiration of air suggests that the cannula tip was impacted against posterior tracheal wall.
- Attach an appropriate oxygen supply source and provide oxygenation
- Technique failure — most commonly due to:
- Poor technique (in a stressful situation)
- Kinking of cannula
- Blood or vomitus in the airway
- Difficult anatomy
- cannula obstruction
- cannula dislodgement
- injury to local structures (tracheal perforation, esophageal injury, nerve injury, vessel puncture)
- surgical emphysema (if high flow oxygen admistered through a malpositioned cannula)
Advantages of cannula cricothyroidotomy
- relatively safe and simple, quick technique
- The ability to provide oxygenation quickly
- equipment and technique is more familar to non-surgically trained practitioners
- minimal blood loss
- Enables stabilisation of the situation to facilitate further planning
- can be used to allow insertion of a Melker tube
- allows transtracheal oxygenation to be established
- stabilisation buys time to allow further planning
- transtracheal oxygenation may facilitate further attempts at laryngoscopic intubation as oxygen escaping cranially through the glottis may allow its identification
- can be rescued by other techniques (e.g. scalpel-based emergency surgical airway)
- identified in the NAP4 study as having a higher failure rate than scalpel-based surgical cricothyroidotomy)
- slower than emergency surgical airways using a scalpel (e.g. knife-finger-tube or knife-finger-bougie-tube approaches)
- does not provide a definitive airway
- does not allow for effective ventilation, leads to hypercapnia and mandates subsequent provision of a definitive airway
- there may be a time lag of up to 1 minute before SpO2 improves following commencement of effective transtracheal oxygenation
- risk of surgical emphysema from jet insufflation and other complications (see above)
Cannula comparison (see video by Andy Heard and colleagues):
- the 14G Insyte Cannula is preferred for cannula cricotyhroidotomy as it is wide bore, kink-resistant and has memory (regains shape following deformation)
- other cannulae (e.g. standard Venflon and Ravussin cannulae) lack these properties
Common mistakes in technique
- Pre-loosening or separating the cannula from the needle (can lead to false positive aspiration of atmospheric air)
- Aspirating when withdrawing the syringe from the cannula (also promotes separation of the cannula from the needle and the likelihood of false positive atmospheric air aspiration)
- Failure to appreciate that a steep angle of insertion will increase the likelihood of impaction/ perforation of the posterior tracheal wall. With a shallow angle of insertion there is more depth to traverse and the cannula is more likely to advance caudally.
- Incorrectly handled cannula (loss of control of the syringe or cannula; disconnection or sepation of the cannula from the needle leading o false positive air aspiration)
- Inserting the cannula too deep (aspiration of air will fail if the trachea is transfixed before aspiration is attempted)
- Failure to advance the cannula off the needle, rather than withdrawal of the needle from the cannula (increases risk of cannula kinking)
- Failure to use a slow ‘aspirate as you go’ technique rather than a ‘jigging back-and-forth’ technique of cannula insertion (risks needle-cannula separation, compression of the tracheal lumen and tracheal transfixation)
- A 5ml syringe is preferable as using a 10 or 20 ml syringe is more difficult to control, with the hand too far from cricothyroid membrane, and a 3ml syringe has insufficient barrel volume to facilitate effective aspiration and endpoint confirmation.
References and links
- CCC — Surgical cricothyroidotomy
- CCC — Cricothyroidotomy kits
- CCC — ENK oxygen flow delivery system
- CCC — Can’t intubate, Can’t ventilate
FOAM and web resources
- Cannula insertion by Andy Heard and colleagues (video; highly recommended)
- Cannula comparison byAndy Heard and colleagues (video; highly recommended)