IMAGE-BASED IN VIVO QUANTITATIVE ASSESSMENT OF HUMAN AIRWAY OPENING AND CONTRACTILITY BY FIBER OPTICAL NASOPHARYNGOSCOPY IN HEALTHY AND ASTHMATIC SUBJECTS

Assessment of human airway lumen opening is important in diagnosing and understanding the mechanisms of airway dysfunctions such as the excessive airway narrowing in asthma and chronic obstructive pulmonary disease (COPD). Although there are indirect methods to evaluate the airway calibre, direct in vivo measurement of the airway calibre has not been commonly available. With recent advent of the flexible fiber optical nasopharyngoscope with video recording it has become possible to directly visualize the passages of upper and lower airways. However, quantitative analysis of the recorded video images has been technically challenging. Here, we describe an automatic image processing and analysis method that allows for batch analysis of the images recorded during the endoscopic procedure, thus facilitates image-based quantification of the airway opening. Video images of the airway lumen of volunteer subject were acquired using a fiber optical nasopharyngoscope, and subsequently processed using Gaussian smoothing filter, threshold segmentation, differentiation, and Canny image edge detection, respectively. Thus the area of the open airway lumen was identified and computed using a predetermined converter of the image scale to true dimension of the imaged object. With this method we measured the opening/narrowing of the glottis during tidal breathing with or without making "Hee" sound or cough. We also used this method to measure the opening/narrowing of the primary bronchus of either healthy or asthmatic subjects in response to histamine and/or albuterol treatment, which also provided an indicator of the airway contractility. Our results demonstrate that the image-based method accurately quantified the area change waveform of either the glottis or the bronchus as observed by using the optical nasopharygoscope. Importantly, the opening/narrowing of the airway lumen generally correlated with the airflow and resistance of the airways, and could differentiate the level of airway contractility between the healthy and asthmatic subjects. Thus, this quantitative assessment of airway opening may provide a useful tool to assist clinical diagnosis of airway dysfunctions and understanding the mechanisms of associated pathophysiologies.

Endoscopic treatment of glottic stenosis: a report on the safety and efficacy of CO2 laser

Background:Treatment of glottic stenosis is a considerable challenge to the otolaryngologist. Glottic airway patency can be compromised by bilateral vocal fold palsy, anterior webbing or a posterior segment scar, which may be significant enough to impair arytenoid movement.Method:A retrospective analysis of a prospective database of patients (n = 34) treated by a specialist airway surgeon. All patients underwent endoscopic treatment with a CO2 laser in an attempt to improve airway calibre and, in 12 patients, to decannulate tracheostomy tubes.Results:Twenty-one patients had bilateral vocal fold palsy and 13 had predominantly posterior glottic stenosis. A variety of pathology-directed treatment approaches were used to achieve good functional results. Four patients required a second endoscopic procedure. The overall revision rate was 5 per cent for bilateral fold palsy and 23 per cent for posterior glottic stenosis (p < 0.05). All patients had an adequate functional airway calibre, and all 12 tracheotomised patients were decannulated.Discussion:Pathology-directed endoscopic laser surgery is safe and effective treatment for glottic stenosis. Rather prescriptive use of unilateral or bilateral cordotomy or combined cordo-arytenoidectomy, clinicians must perform the procedure that will treat the lesion most adequately. Our success rate compared favourably with the best reported results.