To Örebro University

Subglottic stenosis (SGS) is a rare condition of upper airway obstruction transforming tracheal mucosa below the vocal folds into scar tissue. It is primarily caused by laryngotracheal trauma and infrequent autoimmune conditions ofsystemic inflammation. Cases without an evident cause despite a comprehensive investigation are classified as idiopathic. SGS’s unspecific clinical presentation and the underrated findings from conventional spirometry, conceal the diagnosis. Hence, the role of spirometry in the preoperative evaluation and the postoperative monitoring of patients with SGS is unclear. The goal of treatment is to maintain a patent airway while recurrence is part of the natural course of the condition.

This thesis focuses on the diagnosis, preoperative functional and self-reported assessment, choice of endoscopic treatment and the postoperative follow-up of patients with SGS.

Dyspnea Index (DI), a 10-item, 5-point Likert questionnaire with scores ranging from 0 to 40, specifically developed for patients with upper airway obstruction, is now translated and validated in Swedish. The expiratory disproportion index (EDI), which is the ratio of forced expiratory volume in 1 second divided by the peak expiratory flow (PEF), is the spirometry measurement of choice to diagnose patients with SGS from those with obstructive lung disease, when found above 0.39. The percent deterioration of the EDI or PEF ( ) from each patient’s best achieved values correlates with a percent deterioration of the DI and thus, it could be used to monitor treatment effects indicating a disease recurrence. Furthermore, a DI score over 14 refines the diagnostic value of crude spirometry measurements and could be helpful to detect recurrence in patients treated for SGS. Finally, balloon dilatation was found more favorable regarding short-term disease recurrence compared to CO2 laser treatment and patients with a younger age of SGS onset, overweight or obesity showed an increased risk for restenosis