INTRODUCTION: Stridor is a medical emergency that can be related to tracheal stenosis, vocal cord edema, foreign body presence or laryngeal dyskinesia. We present an unusual case of post-intubation stridor caused by obstructive fibrinous tracheal pseudomembrane (OFTP).
CASE PRESENTATION: A 38-year-old woman was admitted with peripartum cardiomyopathy and respiratory failure 18 days after Cesarean section. Her pregnancy had been complicated by pre-eclampsia, HELLP syndrome (hemolysis, elevated liver enzymes and low platelets) and placental abruption. She returned to hospital a week after discharge with worsening dyspnea and orthopnea requiring endotracheal intubation and mechanical ventilation for 3 days while her cardiac function was optimized. A week after extubation she developed acute onset of stridor. Laryngoscopy revealed no evidence of angioedema or vocal cord dysfunction. She had intermittent stridor for the next 12 hours despite racemic epinephrine and steroids. Pulmonary function testing (PFT) revealed a very severe obstructive ventilatory defect with a FEV1 of 0.65 L (19% of predicted). Flow volume loop revealed consistent plateaus in both the inspiratory and expiratory limbs indicative of a fixed airway obstruction . A bedside bronchoscopy revealed 90% subglottic narrowing. She was taken to the operating room for direct laryngoscopy and anticipation of emergent tracheostomy. Rigid bronchoscopy revealed an annular membrane of necrotic debris (~3 cm long x 0.3 cm thick) separated from the trachea by a longitudinal plane. This membrane obstructed the trachea in a ball-valve manner and was easily separated from the posterior wall of the trachea with cryotherapy and flexible bronchoscopy leaving a widely patent tracheal orifice. Histopathology revealed “membranous fragments of fibrino-inflammatory debris with focal areas of reactive squamous epithelium”. Her stridor resolved immediately. PFTs one week later revealed only moderate obstruction (FEV1 2.2 L ; 66% of predicted) and a normal flow volume loop.
DISCUSSIONS: OFTP is a rare potential complication of endotracheal intubation. Only a few case reports and one case series of 10 patients have described the condition, which presented as intermittent positional dyspnea or stridor starting between 3 hours to 9 days after short duration endotracheal intubation (<24 hours to 6 days). A thick whitish tubular pseudomembrane molded the tracheal wall and caused an intermittent ball-valve tracheal obstruction. In reported cases, mechanical removal was curative with avoidance of the development of secondary tracheal stenosis. It is postulated that OFTP may be the initial stage in a process triggered by ischemic damage from high pressure endotracheal cuffs leading to inflammation, infarction and ultimately necrosis of the tracheal mucosa that may eventually result in tracheal stenosis. Diagnosis of OFTP can be a challenge because the clinical picture is often misleading when symptoms of dyspnea and stridor are positional and intermittent secondary to the ball-valve obstruction from the pseudomembrane. Symptoms can be misdiagnosed as bronchial asthma, vocal cord dysfunction or glottic edema. Flow volume loops are a valuable non-invasive test used to diagnosis upper airway obstruction during symptoms. Bronchoscopy is key to the diagnosis and management but should be carried out in an operating room with surgeons trained in emergency airway access on stand by. Removal of the pseudomembrane completely resolves the problem.
CONCLUSION: This patient developed upper airway obstruction secondary to an OFTP after short-term endotracheal intubation. The development of intermittent and positional post-extubation stridor and a fixed obstruction on flow-volume loop should alert clinicians to include OFTP in the differential diagnosis of upper airway obstruction. Removal of the pseudomembrane by interventional bronchoscopic procedures is key to the management and resolution of symptoms.
DISCLOSURE: Brenda Rice, No Financial Disclosure Information; No Product/Research Disclosure Information