Changes in ventilation–perfusion during and after an COPD exacerbation: an assessment using fluid dynamic modeling

Abstract

Bita Hajian,1 Jan De Backer,2 Wim Vos,2 Wouter H van Geffen,3 Paul De Winter,1 Omar Usmani,4 Tony Cahn,5 Huib AM Kerstjens,3 Massimo Pistolesi,6 Wilfried De Backer1 1Department of Respiratory Medicine, University Hospital Antwerp, Edegem, Belgium; 2FLUIDDA nv, Kontich, Belgium; 3Department of Respiratory Medicine, University Medical Center Groningen, Groningen, the Netherlands; 4Department of Pulmonology, Brompton Hospital, London, UK; 5GSK, London, UK; 6Department of Pulmonary Diseases, University of Firenze, Florence, Italy Introduction: Severe exacerbations associated with chronic obstructive pulmonary disease (COPD) that require hospitalization significantly contribute to morbidity and mortality. Definitions for exacerbations are very broad, and it is unclear whether there is one predominant underlying mechanism that leads to them. Functional respiratory imaging (FRI) with modeling provides detailed information about airway resistance, hyperinflation, and ventilation–perfusion (V/Q) mismatch during and following an acute exacerbation. Materials and methods: Forty-two patients with COPD participating in a multicenter study were assessed by FRI, pulmonary function tests, and self-reported outcome measures during an acute exacerbation and following resolution. Arterial blood gasses and lung function parameters were measured. Results: A significant correlation was found between alveolar–arterial gradient and image-based V/Q (iV/Q), suggesting that iV/Q represents V/Q mismatch during an exacerbation (p<0.05). Conclusion: Recovery of an exacerbation is due to decreased (mainly distal) airway resistance (p<0.05). Improvement in patient-reported outcomes were also associated with decreased distal airway resistance (p<0.05), but not with forced expiratory volume. FRI is, therefore, a sensitive tool to describe changes in airway caliber, ventilation, and perfusion during and after exacerbation. On the basis of the fact that FRI increased distal airway resistance seems to be the main cause of an exacerbation, therapy should mainly focus on decreasing it during and after the acute event. Keywords: acute exacerbation, high-resolution computed tomography, functional respiratory imaging, ventilation–perfusion, airway resistance

Keywords

• Acute exacerbation
• high-resolution computed tomography
• functional respiratory imaging
• ventilation-perfusion
• airway resistance