LETTER TO EDITOR
Year : 2013 | Volume
: 29 | Issue : 2 | Page : 276--278
Paratracheal cyst rupture: A false alarm for tracheal rupture
Gaurav Chauhan1, Pavan Nayar1, Sahil Diwan1, Firdoos Ahmad Mir2,
1 Department of Anesthesia and Intensive Care, Safdarjang Hospital, New Delhi, India
2 Department of Cardio Thoracic Vascular Surgery, Safdarjang Hospital, New Delhi, India
Department of Anesthesia and Intensive Care, Safdarjang Hospital, New Delhi
|How to cite this article:|
Chauhan G, Nayar P, Diwan S, Mir FA. Paratracheal cyst rupture: A false alarm for tracheal rupture.J Anaesthesiol Clin Pharmacol 2013;29:276-278
|How to cite this URL:|
Chauhan G, Nayar P, Diwan S, Mir FA. Paratracheal cyst rupture: A false alarm for tracheal rupture. J Anaesthesiol Clin Pharmacol [serial online] 2013 [cited 2021 Apr 18 ];29:276-278
Available from: https://www.joacp.org/text.asp?2013/29/2/276/111739
A 55-year-old man, American Society of Anesthesiologists (ASA) class I, was scheduled for elective subacromial arthroscopic rotator cuff repair of right shoulder under general anesthesia with ultrasound guided inter-scalene block. Personal history was significant for chronic smoking with no diagnosis of pulmonary disease. Monitoring was done according to ASA guidelines and anesthesia was induced with propofol 140 mg, fentanyl 100 mcg and vecuronium 6 mg and maintained with O2/N2O/Isoflurane mixture and infusion of vecuronium at 60 mcg/min for muscle relaxation. On laryngoscopy the Cormack-Lehane classification of laryngeal view was III. Trachea was intubated with the help of a bougie, with 8.0 mm internal diameter endotracheal tube. Immediately after intubation it was noticed that there was no ETCO 2 curve on monitor but patient had SpO 2 of 99%. Second attempt at laryngoscopy, visually confirmed the endotracheal placement of tube and capnography curve too appeared on the monitor screen. Fifteen minutes after induction while performing USG guided inter-scalene block it was observed that, peak inspiratory pressure increased to 42 cm H 2 O with ETCO 2 60 mmHg and SpO 2 dropped to 88%. Immediately, surgeon was notified and patient was administered 100% O 2. Auscultation revealed audible crepitations and rhonchi diffusely all over the chest. At this time, focus was shifted towards diagnosis of pulmonary edema as underlying pathology. Patient was subsequently administered, inj. Lasix 40 mg I.V, inj. Hydrocortisone 200 mg I.V and inj. Theophylline 300 mg I.V given over 20 min. Respiratory parameters returned to normal and subsequent arterial blood gases report was also within normal limits and rest of the surgery and extubation were uneventful. Immediate post-operative chest X-ray and ABG revealed no abnormality.
In the post-anesthesia recovery room patient was intensively monitored (electrocardiogram, SpO 2 and non-invasive blood pressure) and a post-operative ABG done 2 h post-surgery and chest X-ray were within normal limits. Six hours into the post-operative period, patient developed subcutaneous cervical emphysema. This emphysema extended during the next 2 days to face and upper arms. Auscultation revealed crackling crepitus and bilaterally decreased breath sounds (right > left). Pneumomediastinum and right pneumothorax were reported on chest radiographs. A right chest tube was placed anteriorly at the level of the 3 rd intercostal space by surgeon. He was transferred to Intensive Care Unit where fiber optic bronchoscopy revealed a normal tracheobronchial tree, with no obvious orifices in the tracheal wall. Computed tomography (CT) disclosed a thin walled 10-20 mm air cyst in the posteromeidal aspect of trachea along with posterolateral tracheal wall defect 20 mm long, located 2 cm above the carina, which opened on inspiration. A 3-dimensional (3-D) reconstruction CT revealed very small communication between cyst and the trachea. Antibiotic prophylaxis was administered to the patient and he was shifted for emergency cardiothoracic surgery. A diagnosis of paratracheal cyst rupture leading to focal breach in airway continuity was made and was confirmed by cardiothoracic surgeon.
Iatrogenic tracheo-bronchial rupture (TBR) can be caused by intubation, tracheostomy, bronchoscopy and pre-existing pulmonary diseases along with wide presentations that can mimic rare conditions like paratracheal cyst rupture.  Paratracheal air cysts are usually incidental findings on radiographic or CT scan and have right-sided predominance due to the supportive effect of the esophagus on the left side.  Paratracheal air cysts are usually asymptomatic and not frequently associated with underlying lung pathology. However, they may sometimes cause compression of the trachea or get infected leading to sepsis and mediastinitis. Communicating channel between cyst and trachea is found rarely.  Primarily, one sided intubation, inappropriate cuff inflation with high cuff pressures, tube replacement without deflation of cuff, coughing against blocked tube or closed expiratory valve, are the common pathomechanics for TBR and avoiding these iatrogenic misadventures can significantly reduce the risk. Diagnosis can be made provisionally during the intra-operative period if there is air leakage or inadequate high cuff pressure followed by typical symptoms of unexplained pneumothorax, subcutaneous or mediastinal emphysema.  Differential diagnosis of paratracheal air cysts includes tracheal diverticulum, pharyngocele, laryngocele, zenker diverticulum, apical lung hernia, blebs, bulla, and pneumomediastinum.  The other differential diagnoses mentioned above can be ruled out by pharyngo-esophagogram, fiber optic bronchoscopy and chest CT scan. Although, our case was not pathologically proven, but the presence of another communicating paratracheal air cyst adjacent to trachea on 3-D reconstruction chest CT scan and negative fibre optic bronchoscopy confirmed beyond reasonable doubt our diagnosis of paratracheal cyst rupture as etiology of ongoing pathological sequence of events in the patient. Surgery is indicated for transmural tracheal leisons with protrusion of mediastinal tissue or if features of sepsis and mediastinitis appear. Principles of mechanical ventilation in these patients include positioning of tube distal to leison, if possible, pressure controlled ventilation, alveolar recruitment (Positive end expiratory pressure, spontaneous breathing, prone positioning), reduction of airway pressure, regular monitoring of cuff pressure, low threshold for tracheostomy, intensive care and surveillance with frequent suctioning. Conservative management is indicated in spontaneously breathing patients without protrusion of mediastinal structures, independent of length or location of tracheal leison. 
Paratracheal air cysts, infrequently described in literature, seem to be associated weaknesses in membranous part of right posterior lateral wall of the trachea at thoracic inlet level. Diagnosis of this lesion may be made via CT scan with 3-D reconstructions. It is vital for clinicians to be aware that paratracheal cyst rupture can be a rare and unusual addition to the long list of differential diagnosis for iatrogenic TBR.
|1||Deja M, Menk M, Heidenhain C, Spies CD, Heymann A, Weidemann H, et al. Strategies for diagnosis and treatment of iatrogenic tracheal ruptures. Minerva Anestesiol 2011;77:1155-66.|
|2||Goo JM, Im JG, Ahn JM, Moon WK, Chung JW, Park JH, et al. Right paratracheal air cysts in the thoracic inlet: Clinical and radiologic significance. AJR Am J Roentgenol 1999;173:65-70.|
|3||Tanaka H, Mori Y, Kurokawa K, Abe S. Paratracheal air cysts communicating with the trachea: CT findings. J Thorac Imaging 1997;12:38-40.|
|4||Buterbaugh JE, Erly WK. Paratracheal air cysts: A common finding on routine CT examinations of the cervical spine and neck that may mimic pneumomediastinum in patients with traumatic injuries. AJNR Am J Neuroradiol 2008;29:1218-21.|