Obstructive Fibrinous Tracheal Pseudomembrane: A Rare Condition in Postextubation Stridor

Discussion

Several etiologies of postextubation stridor have been described. OFTP is a rare cause of this condition. We presented a case of a worsening dyspnea and inspiratory stridor in the postextubation period, with OFTP diagnosed by observation of a thick, reddish/whitish, tubular pseudomembrane molding within the tip of the ETT, leading to complete luminal obstruction.

Postintubation tracheal complication is a result of airway damage, with the most common entities being tracheal stenosis and tracheomalacia,² whereas OFTP is rare and little known. Etiologically, high endotracheal cuff pressure leads to local ischemia, subsequent infarction, and ultimately necrosis of the tracheal mucosa.² It is postulated that OFTP may be the initial process that can lead to tracheal stenosis afterwards.³ This process results in superficial tracheal damage, leading to a macroscopic visible tissue plug at the site of the endotracheal tube cuff. Pathological findings include superficial abrasions of the mucosa and desquamated necrotic tracheal epithelium.² Several factors have been proposed that predispose patients to tracheal injury after intubation⁴; however, the risk factors for OFTP remain difficult to ascertain due to the rarity of the condition. We postulate that diabetes may have been a contributing factor to the development of OFTP in this subject, as microcirculatory changes in diabetes that are well described may directly affect tissue healing.

Diagnosis of OFTP can be challenging because clinicians are often misled to diagnose patients with other causes of postextubation stridor. We believe that positional and intermittent stridor due to ball-valve obstruction from the pseudomembrane may be an important clinical clue. Onset of respiratory distress in OFTP varies, ranging from within the first hour to 14 d after extubation.^3,5–9 The type of ETT may directly affect development of OFTP; however, we have no explanation as to why OFTP still occurred in our subject despite the fact that a low-pressure high-volume cuff was used in conjunction with intensive monitoring of cuff pressure.

Early detection of OFTP is important to avoid further deterioration of a patient. However, diagnosis of this condition remains difficult. A recent report suggested that flexible or rigid bronchoscopy appears to be of value diagnostically and may also allow removal of the lesion.⁵ Macroscopically, bronchoscopy usually reveals a thick, circular, rubber-like membrane adhering to the tracheal wall at the site of the cuff. However, our subject was surprisingly diagnosed with a visible pseudomembrane blocking the ETT lumen. We suppose that re-intubation may have detached the tissue from the tracheal wall. Unfortunately, repeat bronchoscopy was not performed to evaluate the residual tissue and tracheal mucosa due to the subject's refusal. However, in most cases, OFTPs are easily removed by bronchoscopy, and patients almost always recover without residual lesions.^7–9 In addition to bronchoscopy, chest imaging, particularly chest computed tomography, is also helpful in diagnosing OFTP.^8,9 Occasionally, this condition may be diagnosed by spontaneous expectoration of the OFTP tissue. However, prompt recognition of this condition is vital, as management of the patient will be completely altered.