- Management & Treatment
- Etiology
- Pathology
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- Clinical Case Studies
- Study Questions
Some individuals may be a candidate for a cricotracheal resection (a larger procedure performed through an incision in the neck in which the narrow segment is removed and the ends of the airway sewn back together).
Finally for some individuals a tracheotomy (a breathing tube is placed in the neck/trachea below the level of the narrowing) is required.
The approach tis influenced by the location, length and duration of the narrowing. In addition, any associated medication problems that you may have can influence the choice of procedure. Because the stenosis is usually made of scar tissue, with any of these interventions there is a tendency for scar tissue to reform. Patients often need multiple procedures to manage this disease.
What About Infants With Subglottic Stenosis?
Subglottic stenosis in infants is most commonly associated with intubation in the neonatal ICU. These infants often require tracheostomy (a breathing tube placed in the neck) placement in the neonatal period. They may also have lung disease related to prematurity. Endoscopic dilations can be performed on these infants when they are toddlers and older children. Open surgical repair usually requires a laryngotracheal reconstruction in which a segment of rib cartilage is used to widen the area. This can be done in a single surgery in which the tracheostomy (breathing tube in the neck) is removed at the time of surgery or in two stages in which the tracheostomy is removed at a later date.
Subglottic stenosis can be related to previous intubation. While this is most common with prolonged intubation (several days), it can occur after short durations of intubation as well.
Subglottic stenosis can also occur after trauma to the area.
It can also be associated with some autoimmune disorders (specifically Wegener's) or it can be idiopathic (of unknown origin). It is thought that gastrointestinal reflux may play a role in the development of subglottic stenosis because it causes irritation and inflammation of the airway.
Partial or complete narrowing of the subglottic area may be congenital or acquired. The problem is rare and challenging, affecting soft tissue and cartilage support.
Iatrogenic injuries cause most of the problems seen. Often, subglottic stenosis has an insidious onset, and early manifestations are usually mistaken for other disorders (eg, asthma, bronchitis).
An image depicting subglottic stenosis can be seen below.
Subglottic stenosis is a narrowing of the subglottis (the area of the windpipe just below the vocal folds. This narrowing is most often made of scar tissue.
Illustration of thyroid cartilage, vocal fold, cricoid cartilage, trachea and thyroid gland. The subglottis is the area just beneath the vocal folds. (credit: Alexander Sevy, M.D.)
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A 65-year-old man is evaluated for progressive dyspnea on exertion that has occurred over the course of the past 3 months. His medical history is significant for an episode of necrotizing pancreatitis that resulted in multiorgan failure and acute respiratory distress syndrome. He required mechanical ventilation for 6 weeks prior to his recovery. He also has a history of 30 pack-years of tobacco, quitting 15 years previously. He is not known to have chronic obstructive pulmonary disease. On physical examination, a low-pitched inspiratory and expiratory wheeze is heard, loudest over the mid-chest area. On pulmonary function testing, the forced expiratory volume in 1 second (FEV1) is 2.5 L (78% predicted), forced vital capacity (FVC) is 4.00 L (94% predicted), and FEV1/FVC ratio is 62.5%. The flow-volume curve is shown in Figure VI-4A. What is the most likely cause of the patient’s symptoms?
FIGURE VI-4A RV, residual volume; TLC, total lung capacity.
The correct answer is D. You answered A.
The answer is D. This patient is presenting with subacute dyspnea, stridor, and airflow obstruction, which are consistent with a diagnosis of subglottic stenosis related to his prior prolonged mechanical ventilation. This is confirmed by the finding of fixed airflow obstruction on the flow-volume loop. Flow-volume loops are derived from spirometry. Following a maximum inspiratory effort from residual volume, an individual forces the maximum volume of air from their lungs, and the resultant flows are plotted against the volume. By convention, inspiration is shown on the lower portion of the curve and expiration is on the top. There are characteristic patterns of airflow obstruction that can be evaluated by examining this curve. A fixed central airflow obstruction results in flattening of the flow-volume loop in both inspiration and expiration, yielding the characteristic box-like effect, as shown in Figure VI-4B. Examples of fixed airflow obstruction include tracheal stenosis and an obstructing central airway tumor. Other patterns of large airway obstruction are a variable intrathoracic obstruction and variable extrathoracic obstruction. In these situations, flattening of the flow-volume curve occurs on only one limb of the flow-volume loop, and the pattern of flattening can be explained by the dynamic changes in pressure that affect the trachea. A variable intrathoracic obstruction causes flattening of the flow-volume curve only on expiration. During inspiration, the pleural pressure is more negative than the tracheal pressure, and the trachea remains unimpeded to flow. However, when pleural pressure rises on expiration relative to tracheal pressure, there is collapse of the trachea and flattening of flow-volume curve. An example of a variable intrathoracic obstruction is tracheomalacia. In contrast, the variable extrathoracic defect leads to flattening of the flow-volume loop on inspiration but not expiration. The relevant pressure acting on airflow in the trachea in an extrathoracic obstruction is atmospheric pressure. During inspiration, the tracheal pressure drops below atmospheric pressure, leading to compromised airflow and the characteristic flattening of the flow-volume loop. However, tracheal pressure rises above atmospheric pressure during expiration, leading to a normal expiratory curve.
FIGURE VI-4B Flow-volume loops. A. Normal. B. Airflow obstruction. C. Fixed central airway obstruction. RV, residual volume; TLC, total lung capacity.