Cricothyrotomy

Anatomy and Physiology

Cricothyrotomy is performed by inserting a tube through an incision in the cricothyroid membrane (see Image. Anatomy and Airway Framework of the Neck). To perform a cricothyrotomy under emergent circumstances, physicians must have some knowledge of the relevant anatomy. The cricothyroid membrane (CTM) is bordered superiorly by the thyroid cartilage, inferiorly by the cricoid cartilage, and laterally by the bilateral cricothyroideus muscles. Begin by palpating the laryngeal prominence, colloquially known as the “Adam’s Apple,” on the thyroid cartilage. Within the thyroid cartilage are the vocal cords. Inferiorly, palpate the round “signet ring” of the cricoid cartilage. The CTM is approximately 2 cm inferior to the laryngeal prominence and superior to the cricoid cartilage, which is identified by palpating a slight depression between the two cartilaginous structures.

Indications

The emergency cricothyrotomy is the final step in the emergency airway management algorithm, becoming necessary when you find yourself in a CICO scenario. (Cannot Intubate, Cannot Oxygenate is sometimes referred to as "Cannot Intubate, Cannot Ventilate").[6] Failure to recognize and intervene in a CICO scenario can rapidly lead to brain hypoxia and patient death. A percutaneous airway must be established immediately in a CICO scenario.[9] 

The emergency cricothyrotomy is indicated in any CICO scenario.[10] Some situations in which a physician may encounter CICO include:

• Oral or maxillofacial trauma
• Cervical spine trauma
• Profuse oral hemorrhage
• Copious emesis
• Anatomic abnormalities that prevent endotracheal intubation

Contraindications

In the CICO situation, there are no absolute contraindications to emergent cricothyrotomy.

Relative contraindications include possible or known tracheal surgery, fractured larynx, laryngotracheal disruption, and children. Patients with an acute laryngeal disease may have a higher rate of subglottic stenosis, making elective cricothyrotomy relatively contraindicated.[11] Cricothyrotomy is a relative contraindication in children less than 5 to 12 years because of the funnel shape of the pediatric airway and a theoretically increased risk of subglottic stenosis.[12]

Equipment

The equipment needed for a cricothyrotomy includes (see Image. Cricothyroidotomy, Equipment):

• Yankauer suction
• Scalpel (preferably #20 blade)
• Gum elastic bougie
• Cuffed tracheostomy tube 6.0
• Ten cc syringe
• Securement device
• Ventilator and tubing

Personnel

• Physician
• Nurse
• Respiratory therapist 

Preparation

Patient counseling and informed consent are integral parts of any procedure. However, the emergency conditions under which this procedure is usually performed generally preclude the discussion of risks, benefits, and complications with the patient or family. Ideally, these discussions should be held with patients with predicted difficult airways before airway management is required.

Often the most significant barriers to a surgical airway are cognitive. The emergent cricothyrotomy is no more complicated than placing a chest tube or other routine emergency procedures. However, the terms "failed airway" and "cannot intubate, cannot oxygenate" may be correlated with personal failure in the physician's mind, leading to an unacceptable delay in the decision to cut the neck. Regular practice on simulators or cadavers is necessary to become familiar with the technique will help to reduce the anxiety associated with the procedure when it becomes clinically required. Before any intubation, especially a potential "difficult airway," a physician should go through a difficult airway algorithm, reducing both the anxiety and difficulty of the final step in that pathway, the emergent cricothyrotomy. The airway plan should be verbalized out loud to healthcare team members, from intubation medications to the stops following a failed intubation attempt. The physician should identify critical neck anatomy and landmarks in case a cricothyrotomy becomes necessary. Finally, all equipment should be readily available at the bedside.[13]

Technique or Treatment

Ideally, before managing a difficult airway, it is recommended to identify the CTM (cricothyroid membrane) in all patients, especially before the induction of anesthesia and in the critical care setup. It plays a crucial role in emergency front-of-neck access (eFONA) to prevent complications such as device misplacement, injury to local structures, and airway trauma. The methods to identify CTM include several methods. Visualization of the anterior neck crease is only effective in 50 percent of patients and should not be relied upon solely. [14]The clinical palpation method to identify CTM depends on sex, position, and body habitus. It is more commonly misidentified in females than males.[15]

The Difficult Airway Society (DAS) recommends a three-step technique called the "laryngeal handshake" technique. In case of insufficient clinical examination, ultrasound identification should be taken into account to confirm the position of CTM, which is superior to the palpation technique in morbidly obese patients.[16][17]

The literature describes several techniques, including tools, dilators, or specialized cannulas, to obtain tracheal access. It is the author's belief, and the idea of many within the Emergency Medicine/Critical Care community, that the bougie-aided cricothyroidotomy, also known as the "Three-Step Method," combines the most critical steps in both the Seldinger technique and the "rapid four-step" surgical approach, providing a simple process to maximize success in this rarely performed, high-stress situation.[18]

1. Using your non-dominant hand, identify the cricothyroid membrane with your index finger while stabilizing the larynx between the thumb and middle finger.
2. Make a 4 cm vertical incision through the skin overlying the cricothyroid membrane.
3. Bluntly dissect with fingers through the subcutaneous tissue until the cricothyroid membrane is identifiable. **Ignore bleeding
4. Using the scalpel, puncture the cricothyroid membrane, slicing horizontally.
5. Insert your finger through the incision.
6. Slide a gum elastic bougie through the incision, using your finger to guide it inferiorly into the trachea. 
7. Pass a 6.0 cuffed endotracheal tube over the bougie until the balloon is no longer visible, and inflate the cuff.
8. Using a BVM, confirm placement with end-tidal capnography.
9. Secure the ET tube in place with a securement device.[19]

Standard Technique 

1. Immobilize the larynx and identify the cricothyroid membrane by palpation with the index finger of your non-dominant hand. This is achieved by placing the inferior border of the thyroid cartilage and the superior border of the cricoid cartilage in the midline of the neck. 
2. While keeping the larynx stable, create a vertical incision in the skin overlying the CTM in the midline of the neck, extending the incision approximately 3-5 cm in length. 
3. After creating your vertical skin incision, palpate the CTM and make a horizontal incision through the membrane. Be sure to direct your scalpel caudally to avoid the vocal cords and carefully create the incision, preventing the trachea's posterior wall.  
4. Keep the tip of your index finger in the incision through the CTM while you insert a tracheal hook into the hole under the thyroid cartilage. Put traction upwards on the thyroid cartilage.
5. Insert a trousseau dilator to extend the horizontal incision vertically. 
6. Insert the tracheostomy tube through the trousseau dilator and advance it caudally into the trachea.
7. Remove the trousseau dilator and tracheal hook. 
8. Remove the obturator of the tracheostomy tube. 
9. Insert the inner cannula of the tracheostomy tube. 
10. Inflate the balloon.
11. Attach the tube to a BVM or ventilator.[20]

Needle Cricothyroidotomy 

1. Stabilize the larynx and create tension overlying the cricothyroid membrane (CTM) by using your non-dominant hand's thumb and middle finger to stretch the skin in a vertical direction, palpating the CTM with the index finger. 
2. With your dominant hand, use a 3-10 mL syringe filled with 50% saline attached to an angiocatheter, and puncture the skin overlying the CTM at the inferior margin of the CTM. Direct your needle caudally at a 30-45 degree angle. While advancing, apply continuous negative pressure on the syringe. When air bubbles are visualized within the syringe, you have confirmed placement within the trachea. Stop running the needle. 
3. Advance the catheter until the hub abuts the skin. Remove the needle. 
4. Attach the saline syringe to the catheter and confirm intratracheal placement by aspirating air. 
5. Hold the catheter in place at all times. Do not rely on a suture to maintain correct positioning. 
6. Connect the catheter to high-pressure tubing or a BVM with 100% oxygen. Ventilation should be at a rate of 10-12 breaths per minute, using an I: E ratio of approximately 1:4.[21]

Complications

The emergency cricothyrotomy is the last step in the CICO algorithm and is a step taken to save a patient's life. Therefore, it is a procedure in which the benefit drastically outweighs the risk. However, the procedure is not without complications. Complication rates differ from study to study based on the clinical scenario, level of training, or procedure location, ranging from 0% to as high as 54%. The most common complication is bleeding. Bleeding is expected and should be ignored during the procedure. Pressure or packing at the site should provide control if severe bleeding occurs. Other immediate complications include lacerations of tracheal cartilage, including the thyroid, cricoid, or tracheal rings, perforation of the trachea, creation of a false tract (passage of the ET tube into a potential space other than the trachea), and infection.[22][23] Long-term complications include subglottic stenosis and voice changes.[24]

Clinical Significance

The cricothyrotomy is the final step in the difficult airway algorithm when a provider encounters a CICO scenario. 

Preparing to perform a manually simple but cognitively challenging procedure can be the difference between life and death for a patient requiring an emergent airway. 

Enhancing Healthcare Team Outcomes

The emergent cricothyroidotomy is not a complicated procedure from a technical standpoint. However, from a cognitive perspective, it may be prohibitive to the unprepared team. To perform this procedure successfully, it must involve an interprofessional team that includes physicians, nurses, and respiratory therapists. Before attempting intubation in a presumed difficult airway, the physician should announce to everyone involved in patient care that there is a potential need for emergent cricothyroidotomy. Often, this may include marking landmarks on the patient's neck. Announcing the potential for cricothyroidotomy eliminates the cognitive barriers before the procedure becomes required. All interprofessional team members must utilize open communication with the rest of the team as the patient's status changes. Interprofessional coordination will enhance patient outcomes. [Level 5]

The American College of Surgeons recommends the emergent cricothyroidotomy as the airway of choice in the can't intubate, can't ventilate situation. As per the Advanced Trauma Life Support guidelines, the "...surgical cricothyroidotomy is preferable to a tracheostomy for most patients who require the establishment of an emergency surgical airway, because it is easier to perform, associated with less bleeding, and requires less time to perform than an emergency tracheostomy."