Why is the tracheostomy tube inserted between the second and third tracheal rings?

Why Tracheostomy Tubes Are Inserted at Tracheal Rings 2-3

The tracheostomy tube is inserted between the second and third tracheal rings to avoid critical anatomical structures while maintaining safe distance from both the larynx above and the innominate artery below, thereby minimizing life-threatening complications such as tracheo-innominate fistula, subglottic stenosis, and injury to the cricoid cartilage.

Anatomical Safety Considerations

The placement at rings 2-3 represents a critical balance between multiple anatomical hazards:

Avoiding Superior Structures

• Placement above the second ring (at ring 1 or through the cricothyroid membrane) risks subglottic stenosis and cricoid cartilage injury, which is particularly devastating in pediatric patients where the small airway caliber makes any stenotic segment catastrophic 1.
• The cricoid cartilage is the only complete cartilaginous ring in the airway and must be preserved to maintain structural integrity 1.
• In patients who have undergone cricothyroid approximation procedures, the cricothyroid membrane may be completely obliterated, making emergency front-of-neck access impossible and necessitating percutaneous access between the second and third tracheal rings as the only viable option 1.

Avoiding Inferior Structures

• Placement too low (below ring 3-4) increases the risk of tracheo-innominate artery fistula, a catastrophic complication with high mortality 1.
• The innominate artery crosses anterior to the trachea typically at the level of the 9th tracheal ring in adults, but the risk zone extends higher, making rings 2-3 the safest location 2, 3.

Optimal Tube Positioning Requirements

The guidelines specify precise positioning parameters that are achievable with ring 2-3 placement:

• The tracheostomy tube should extend at least 2 cm beyond the stoma and remain 1-2 cm above the carina 1.
• The distal portion of the tube must be concentric and colinear with the trachea to prevent complications including esophageal obstruction, partial tube occlusion by the tracheal wall, tracheal wall erosion, tracheoesophageal fistula, and stomal breakdown 1.
• Placement at rings 2-3 allows adequate tube length for secure positioning while maintaining this critical distance from the carina 4.

Technical Advantages in Emergency Situations

The ring 2-3 location provides practical benefits during complications:

• In emergency tube replacement scenarios, this location allows for easier identification and access, particularly when using stay sutures to widen the stoma and bring the trachea anteriorly 1.
• Percutaneous tracheostomy techniques specifically target the space between the second and third tracheal rings, with bronchoscopic transillumination facilitating identification of this appropriate site 4.
• This location provides sufficient distance from the larynx to allow for proper tube curvature assessment via neck/chest radiographs or flexible bronchoscopy 1.

Special Pediatric Considerations

In children, the ring 2-3 placement becomes even more critical:

• A vertical tracheotomy (not a cartilage window) must be used in children to avoid creating a stenotic segment, as the small tracheal diameter cannot tolerate cartilage removal 1.
• The pediatric trachea is small, pliable, and difficult to palpate, with the short neck and proximity of head/neck vessels making the ring 2-3 location the only safe option that avoids both the cricoid cartilage superiorly and the pleura extending into the neck inferiorly 1.
• Maturation sutures and stay sutures are placed at this level to accelerate stoma formation and aid emergency tube replacement before the planned first tube change 1.

Common Pitfalls to Avoid

• Never place the tracheostomy through the first tracheal ring or cricothyroid membrane as this guarantees subglottic complications and cricoid injury 1.
• Avoid placement below the third ring as this increases the risk of innominate artery erosion and makes tube positioning relative to the carina problematic 2, 3.
• Do not use cartilage window techniques in pediatric patients at any level, as this creates stenosis in the small-caliber airway 1.
• Ensure the tube curvature matches the patient's anatomy so the distal tip remains colinear with the trachea, as malposition at any level causes the complications mentioned above 1.