Title: Lung isolation with VivaSight DL double-lumen tube in patients with Mounier-Khun syndrome. 
Authors: Granell M1,2, Torres O1, Almenara N1, Peris R1, Crisan C1, De Andrés JA1,2.
1. General University Hospital of Valencia (Dept. of Anaesthesiology, Critical Care and Pain Relief).  2 University of Valencia.


Background:  Mounier-Kuhn syndrome (MKS) or congenital tracheobronchomegaly is a rare and chronic airway disease that presents a dilatation of the main airways and associated loss of elastic fibers in the trachea and main bronchus. These patients usually present respiratory symptoms, different degrees of recurrent infections, hemoptysis and dyspnea1. MKS causes difficulties related to the peroperative airway management due to the large and weak tracheobronchial structure, inefficient cough mechanism, tracheal diverticula, endotracheal tube dislodgement and possible postoperative tracheal collapse. Sometimes endotracheal tube cuff-leak during endotracheal intubation might be the first sign of MKS2. 

Case report: 
We present the case of a non-smoker 59 year-old man who had a history of tracheobronchomegaly, bronchiectasis, COPD (chronic obstructive pulmonary disease), dyslipidemia, effort angina pectoris and mild cognitive impairment. The highest tracheal diameter was 41 mm and the main left bronchus was 29 mm measured by chest CT. He was scheduled for elective thoracic surgery to a pulmonary lesion resection in the right lower lobe, highly suspected of being cancerous. After induction of anesthesia, the trachea was intubated with a 37Fr VivaSight DL double-lumen tube guided by the embedded camera. Then we inflated the tracheal cuff (8 ml) and bronchial cuff (5 ml) with the usual volume of air, and after that we checked it with auscultation and capnography. When we clamped the tracheal lumen to collapse the right lung, the capnography and auscultation were inadequate. A progressive increase of the tracheal cuff volume with 10 ml and bronchial cuff with 5 ml (total cuff volume was 18 and 10 ml, respectively) were necessary, until the air leak ceased, avoiding to exceed the pressure of 25 cmH2O in order to prevent the tracheobronchial isquemia.
After surgery the patient was extubated without complications and transferred to the ICU where he remained during 24 hours.

Discussion: 
Peroperative airway management in MKS is complicated due to the large and weak airway structures. Endotracheal tube and/or endobronchial tube cuff-leakage can be an usual and important problem during surgery, especially with respect to airway management during thoracic surgery. In this report, the diagnosis was already known and the maximum transverse diameter of the trachea was measured by chest CT.

References:

1.	Krustins E, Kravale Z, Buls A. Mounier-Kuhn syndrome or congenital tracheobronchomegaly: A literature review. Respiratory Medicine. 2013; 107 (12): 1822-8.  
2.	 Kim MY, Kim EJ, Min BW, Ban JS, Lee SK, Lee JH. Anesthetic experience of a patient with tracheomegaly -A case report. Korean J Anesthesiol, 2010. 58(2): 197-201.

Learning points: 

Taking into consideration the larger diameter of the patient’s trachea and the main bronchi, we used a 37Fr despite being aware of leakage risk and the need of using a high cuff volume. We knew also that there was a risk of cuff rupture during the lateral position that it´s associated with a special difficulty to change this DLT. 
This could have been avoided through the use of a 41 Fr DLT, but there existed the risk of damage to the thin and atrophied tracheal walls.