Cricothyroidotomy

Synonym: Cricothyrotomy

This procedure provides a temporary emergency airway in situations where there is obstruction at or above the level of the larynx, such that oral/nasal endotracheal intubation is impossible. Compared to an emergency tracheostomy, it is quicker and easier to perform and associated with fewer complications.¹ It is a relatively quick procedure, taking up to about 2 minutes to complete.² In an emergency without access to medical equipment, cricothyroidotomy has even been improvised using a drinking straw and pen-knife.³

There are three techniques:

• Needle
• Intubation (with purpose-built kits)
• Surgical

All require a good working knowledge of regional anatomy to be able to carry the procedure out safely and effectively. It should be used as a last resort, reserved for life-and-death situations and is best carried out by experienced hands, or under their instruction where possible. The techniques can be taught on animal or mannequin models⁴ but conditions in the 'field' are frequently much more challenging.

Need for an emergency airway where:

• Intubation is not possible via the oral or nasal route
• Need to avoid neck manipulation (e.g. basal skull/cervical spine injury or fracture)
• Severe maxillofacial trauma
• Oedema of throat tissues preventing visualisation of the cords (e.g. angioneurotic oedema, anaphylaxis, burns, smoke inhalation)
• Severe oropharyngeal/tracheobronchial haemorrhage
• Foreign body in upper airway
• Lack of equipment for endotracheal intubation
• Technical failure of intubation
• Severe trismus/clenched teeth
• Masseter spasm after succinylcholine

• Availability of a less invasive means of securing the airway
• Patients <5 years old (needle technique may be used but formal tracheostomy is preferred)
• Laryngeal fracture
• Pre-existing or acute laryngeal pathology
• Tracheal transection with retraction of trachea into mediastinum
• Anatomical landmarks obscured by gross haemorrhage/surgical emphysema etc.

Needle cricothyroidotomy

A needle or cannula (usually a large bore IV cannula) is inserted through the cricothyroid membrane:

• Place the patient supine and, assuming no cervical spine injury, extend the neck using a pillow under the shoulders
• Run a finger down the front of the neck in mid-line and find the notch in the upper border of the thyroid cartilage. Below this is a depression between the thyroid and cricoid cartilages – the cricothyroid membrane.
  
  
• Stabilise the cricothyroid membrane with one hand between finger and thumb.
• Pierce it with a large-bore cannula (14G) attached to a syringe aiming at 45° to the skin, caudally in the sagittal plain.
• Aspirate as the needle is introduced and confirm position by withdrawal of air; slide cannula over needle into airway.
• Connect to O₂ supply via Y-connector - give 15 l/min for an adult or, in a child, set the gas flow to the age of the child in years.
• Ventilate by covering the patent port of Y-connector with a thumb to allow O₂ to flow for 1 second (transtracheal insufflation). Remove thumb to allow expiration for 4 seconds via the upper airway. If no Y-connector available, use 2 ml syringe or IV giving set with hole in the side that can be occluded by the thumb.
  
  

Note, expiration is not possible through the cannula so with complete upper airway obstruction of the upper airway, reduce oxygen flow.
A needle cricothyroidotomy can usually only be used for 30–45 mins before CO₂ retention becomes significant.

Cricothyroid intubation with purpose-built kits

Cricothyroidotomy may be achieved with a narrow tube using a pre-prepared kit such as the Mini Trach® II which contains a guarded blade, plastic introducer, 4mm uncuffed tube to slide over introducer, ISO connection, tracheal suction tube and neck fastenings. The patient can breathe spontaneously or be bagged using this form of airway, but they are usually only used as a temporary measure until a more permanent airway is secured. Retrograde intubation can be practised with a Mini Trach® II set by passing the introducer upwards into the mouth and feeding an endotracheal tube into place over it.⁶

Surgical cricothyroidotomy

This is usually not performed in children under 12.

• Delineate anatomy as above, clean skin and instil local anaesthetic (if patient conscious).
• Make a small vertical skin incision in midline, spread the wound edges laterally and identify cricothyroid membrane.
• Take care not to cut or remove the thyroid or cricoid cartilages.
• Make a horizontal incision through the membrane's inferior half and then extend gently through it.
• Dilate the opening with curved forceps or rotation of inverted scalpel handle. Insert small, cuffed endotracheal tube or tracheotomy tube (max. 8mm).
• Aim downwards as tube is inserted to avoid damage to vocal cords.
• Inflate the tube cuff and confirm its position with visualisation of chest movements and auscultation over lungs and stomach.
• Finally, secure the tube.

Although complications do occur they are minor when compared to the catastrophic outcome normally associated with a failure to secure an airway. Complications can affect up to 40% in the emergency situation, but in experienced hands the complication rate is usually much lower. Elective complication rate is ~ 6–8%.²

As cricothyroidotomy is usually performed as an emergency airway of last resort, patients receiving them tend to be critically ill. Unsurprisingly, one US study showed that only 27% of trauma patients receiving pre-hospital cricothyroidotomy survived to hospital discharge but 62% survived to Emergency Department admission, indicating reasonable utility as a holding emergency airway.⁷ Amongst longer term survivors, good functional status is unusual with frequent neurological disability.⁸