Cyclomedica Australia Pty Ltd.

Little is currently known about the immediate and long-term effect of COVID-19 on lung ventilation (delivery of air to the lungs) and lung perfusion (delivery of blood to the lungs). Some people who survive COVID-19 may have lung ventilation and/or perfusion injury that persists following COVID-19 recovery. This lung injury may be related to inflammation in the lung, breathlessness, exercise limitation and reduced quality of life. Therefore, towards the goal of understanding the effects of COVID-19 on lung health, the purpose of this study is to characterize and understand the clinical relevance of COVID-19 related lung ventilation and perfusion injury and associated inflammatory status, ≤4 weeks and 6-months following COVID-19 recovery in an asthmatic and healthy population. To do this, an asthmatic and healthy population who have, and have not, been previously diagnosed with COVID-19 will be studied.

This is a single centre prospective six-week observational study to understand the prevalence and clinical relevance of abnormal ventilation of the lung (assessed by Technegas ventilation single photon emission computed tomography (V SPECT) and hyperpolarized 129Xe magnetic resonance imaging (MRI)), in the presence or absence of airway inflammation (assessed by sputum cell counts), in lung cancer patients prior to lung resection surgery.

Ventilation heterogeneity is a hallmark feature of most obstructive pulmonary diseases. In particular, chronic obstructive pulmonary disease (COPD) is pathologically and physiologically characterized by small airway destruction and marked airway cellular inflammation, which result in prominent expiratory airflow limitation, air trapping, hyperinflation and abnormal gas exchange. COPD is strongly linked with the exposition to inhaled irritants, most notably tobacco smoke, and is as such a potentially preventable disease. COPD-related morbidity, mortality and social costs are high: in Canada, COPD is the main cause of hospital admission among all chronic diseases and is the fourth leading cause of death.
Diagnosis of COPD requires the objective demonstration of expiratory airflow limitation using spirometry. In the right clinical context, a post-bronchodilator forced vital capacity (FVC) / forced expiratory volume in 1 second (FEV1) ratio <0.70 is considered indicative of the presence of COPD, and therefore pulmonary function testing is required to make the diagnosis. However, the natural history of COPD represents a slowly-progressive continuum: active smokers that do not meet the criteria for COPD are still at risk of developing the disease. In fact, when compared to healthy non-smokers, active smokers without overt COPD can already show some pathological and clinical features of the disease. Notably, they report increased levels of resting dyspnea, chronic cough, lower exercise capacity, exercise-induced dynamic hyperinflation and marked airway inflammatory cellular infiltration, while conserving normal pulmonary function test values.
These findings highlight the negative, clinically-measurable effects of tobacco smoking on pulmonary function, but also the limitations of standard pulmonary function testing in identifying the presence of early, mild airway disease and quantifying physiological limitations in these subjects. As such, there is a need for a novel, simple and reliable method of quantifying airway disease in this population.
Quantitative lung ventilation single-photon emission computed tomography (SPECT) allows an objective quantification of the regional heterogeneity of ventilation in humans. The coefficient of variation (CV) of the distribution of a radioactive tracer, inhaled during the test, allows the generation of heterogeneity maps and density curves of small elements of the lung. These variables are sensitive to the presence of COPD, asthma, air trapping and are correlated to even slight anomalies in pulmonary function testing in otherwise healthy subjects. As such, SPECT could prove useful as an early marker of airway disease in active smokers at risk of developing COPD, but its use in this context has never been formally tested.
This pilot study addresses the question of whether lung SPECT could provide clinically relevant information on airway disease in active smokers without overt lung disease on pulmonary lung function testing.