PHÂN TÍCH GIẢN ĐỒ LƯU LƯỢNG-THỂ TÍCH TRONG PHÁT HIỆN TẮC NGHẼN KHU TRÚ ĐƯỜNG THỞ: NGHIÊN CỨU THỰC TẾ LÂM SÀNG CÓ ĐỐI CHIẾU HÌNH ẢNH HỌC

Abstract

Objective: To determine the prevalence and characteristics of localized airway obstruction on flow-volume loops among patients undergoing spirometry in routine clinical practice, and to correlate these findings with imaging or endoscopic results when available. Methods: This retrospective, descriptive cross-sectional study included 850 quality-acceptable spirometry tests performed at the University Medical Center Ho Chi Minh City from January 2021 to December 2023. Flow-volume loops were systematically analyzed and classified into variable extrathoracic obstruction, variable intrathoracic obstruction, fixed central airway obstruction, main bronchial obstruction, and atypical patterns. Results: Signs of localized airway obstruction were identified in 98 of 850 cases, accounting for 11.5%. Among these cases, 68.4% were still interpreted as having no obstructive or restrictive ventilatory defect on routine spirometric interpretation. Common patterns included variable extrathoracic obstruction in 22 cases, fixed central airway obstruction in 17 cases, main bronchial obstruction in 24 cases, and other patterns in 32 cases. Fixed obstruction showed the highest suggestive value for structural causes, with 16 of 17 cases confirmed by CT scan or endoscopy. The FEF50/FIF50 ratio provided supportive information but was not specific. Conclusion: Localized airway obstruction on flow-volume loops is not uncommon and may be missed if interpretation relies solely on quantitative spirometric indices. Systematic analysis of flow-volume loop morphology should be performed and integrated with clinical assessment, imaging, or endoscopy when appropriate.