Reply to Anile et al.

Abstract

We appreciate the interest showed by Anile et al. [1] in our article. We thank the authors for sharing their experience with four cases of obstructive fibrinous tracheal pseudomembrane (OFTP) removed by rigid bronchoscopy (RB) [2] and for the opportunity to clarify some of the key points regarding such issues. First, OFTP is a diagnostic challenge. In most cases, it is misdiagnosed as benign post-intubation tracheal stenosis, and the patient is referred to the thoracic surgery unit for endoscopic and/or surgical treatment. Chest CT scans show a tracheal stenosis without radiological signs for which pseudomembrane may be suspected, while its observation during flexible bronchoscopic (FB) is difficult for the reasons reported by the same authors [2]. However, last week we performed an FB in a patient who had tracheostomy. The patient presented with acute respiratory failure. We found an annular lesion with a septum that was partially torn and downwardly detached with obstruction of tracheal lumen. Remembering our previous experience, a diagnosis of OFTP was made. Thus, we believe that pseudomembrane is considered as a rare event because it is poorly known, but it might be much more common than thought. Stridor and respiratory failure are common findings after extubation due to a variety of causes. Thus, pseudomembranes may be detached and removed by tracheal suctioning and/or reintubation, and thus might remain unrecognized [3]. Secondly, the pathogenesis of OFTP remains unclear. Deslee et al. [4] postulated that ischaemic injury due to pressure at the site of the endotracheal cuff is the first step of developing pseudomembrane. However, formation of pseudomembrane has been associated with various other conditions including pulmonary infection, traumatic intubation, aspiration of gastric contents, diabetic microcirculation changes as reported by Talwar et al. [5]. Two of the four cases reported by the authors [2] had Candidal infection. However, it would be interesting to know whether the other two patients presented other predisposing factors for development of pseudomembrane. In our patient, in theory, the traumatic intubation may cause superficial damage to tracheal mucosa that, in addition to injury due to endotracheal cuff, develops pseudomembrane. Conversely, real tracheal ischaemic injury at the site of intubation, resulting from more profound tissue injury may lead to stenosis afterward [3]. Whether the use of marijuana is a risk factor of OFTP remains to be validated. Thirdly, we agree with the authors that the removal of pseudomembrane should be performed via RB. It allows the extraction of it in one piece while maintaining sufficient ventilation during the procedure. Lins et al. [3] in a recent review reported that, in only 4 of 22 cases, the ablation of membrane was made during FB. No case was reported by the authors [3] in which pseudomembrane was spontaneously coughed up to confirm that our case is unique in literature. In closure, OFTP should always be considered in the differential diagnosis of OFTP that requires immediate treatment. However, if you have experienced previous episodes of pseudomembrane, it will help you in diagnosing new cases in the future!