Tracheal abnormalities requiring reconstruction are rare but can affect patients of all ages. Tracheal stenosis makes up 1% of all laryngotracheal stenoses, but mortality can range from 20 to 30% and reach as high as 70% when present within the first month of life. Tracheal anomalies are typically divided into two categories: congenital and acquired. Congenital lesions are present at birth and frequently present in conjunction with other abnormalities. Concomitant cardiopulmonary abnormalities are present in up to 50% of patients. Acquired tracheal stenosis can result from a variety of insults and is often multifactorial; however, it is most frequently a result of prolonged intubation, leading to pressure-induced necrosis injury of the tracheal mucosa. Poiseuille's law states that airflow is directly proportional to the radius to the fourth power, highlighting the potential detriment of even a small decrease in tracheal lumen diameter. The pediatric population is at increased risk of clinically significant tracheal airway compromise due to the small caliber of the trachea in the early years. The diameter of the trachea from 0 to 2 years of age ranges from 4 to 7 mm and does not reach 1 cm in diameter until around 8 years of age. As a result, children are less able to tolerate stenotic lesions of the airway and more frequently require surgical management.
Congenital tracheal stenosis can arise from embryologic malformations resulting in a wide variety of abnormalities. These are often associated with underlying genetic mutations or syndromes. Some of these include:
Complete tracheal rings
Tracheal cartilaginous sleeve
External vascular compression (rings and slings)
Acquired lesions can occur in pediatric and adult populations. These are often iatrogenic, but the differential must remain broad and may include:
Intubation trauma and high cuff pressure (pressure-induced ischemic necrosis)
Complications of tracheostomy tubes (granulation tissue, suprastomal granuloma, A-frame deformity)
Inflammatory or infectious conditions and their sequelae
Blunt or penetrating trauma
Neoplasms, both benign and malignant
After diagnosing tracheal stenosis, it is important to grade it appropriately. Typically, tracheal stenosis is divided into the long segment (LSTS) or short segment (SSTS) lesions. SSTS typically spans fewer than 5 tracheal rings, and LSTS is typically defined as a lesion that spans over 50 to 75% of the airway, but these definitions can vary based on patient age and size. Also, it is important to know if the stenotic segment is intrathoracic or extrathoracic (above sternal notch), as this will greatly alter surgical approaches and anesthetic considerations. Intrathoracic stenoses often require a sternotomy and extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass (CPB). Aside from length, the caliber of the luminal stenosis must be quantified. The original Cotton-Meyer grading scale initially introduced for grading subglottic stenosis is used to grade tracheal stenosis, and is based on the percentage of airway lumen narrowing.
Grade I: 0 to 50%
Grade II: 51 to 70%
Grade III: 71 to 99%
Grade IV: no detectable lumen
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