| Research Background:Pulmonary function test is an important examination of respiratory medicine, which plays an important role in diagnosis, severity judgment, treatment and prognosis assessment. We usually use FEV1/FVC, TLC to judge the type of ventilation dysfunction, but we often encounter a type of pulmonary function, which FEV1/FVC is normal, TLC is normal, but FEV1or FVC decreases, or both of them decrease. According to current diagnosis standard, this kind of pulmonary function does not belong to the obstructive ventilation disorder, nor does it belong to the restrictive ventilation dysfunction. In2009, Robert named this type of pulmonary function non-specific pulmonary function (NSPF).According to2005ATS/ERS interpretation of pulmonary function test, this type represents inadequate aspiration or expiration. In the process of diagnosis, it will be classified as obstructive ventilation dysfunction, which is considered as a rare phenomenon. However, a series of studies suggest that, NSPF is not a rare phenomenon and has existed for a long time, so some scholars suggest that NSPF is an independent and stable type of pulmonary function, and we should no longer regard NSPF as a short course of obstructive ventilation dysfunction. In this study, we use a retrospective case-control study to explore distribution, clinical characteristics and evolution of NSPF in order to further understand NSPF. It will guide clinical treatment of patients with this type of lung function in future.Research Objectives:1. Retrospective analysis of the proportion of NSPF in results of pulmonary function test.2. Investigation of clinical, imaging and pulmonary function characteristics of patients who have NSPF. Preliminarily discussion of forming mechanism of NSPF.3. Investigation of evolution and influencing factors of NSPF.Research Method:This research reviewed the pulmonary function test results which were obtained in one machine of Beijing Hospital for10consecutive years, and a case-control study was carried out based on said data.1. Distribution of NSPFWe analyzed the proportion of NSPF in pulmonary function test results, which were obtained from the same machine in south department of Beijing Hospital, from January1,2003to December31,2012.2. Clinical Characteristics of NSPFWe selected clinical features, imaging manifestations and pulmonary function data of patients from January1,2012to June30,2012. All of them had complete data. Then we analyzed differences between NSPF and normal ventilation function group (hereinafter referred to as normal group), obstructive ventilation dysfunction group (hereinafter referred to as obstructive group), restrictive ventilation dysfunction group (hereinafter referred to as restrictive group), and mixed ventilation dysfunction group (hereinafter referred to as mixed group) as control groups.The clinical, imaging features and pulmonary function data of NSPF in North Department in our hospital, from January1,2004to December31,2012, were collected. According to the definition of NSPF, they were divided into three groups, only FEV1reduced group (NSPF1), only FVC reduced group (NSPF2), both FEV1and FVC reduced group (NSPF3). Differences between the three types of NSPF were analyzed.3. Evolution of NSPFBased on pulmonary function test results in North Department in our hospital, patients who were diagnosed NSPF from January1,2004to December31,2012and who have gone through pulmonary function test at least once, are selected. Their data were analyzed to explore the factors affecting NSPF in transforming to typical obstructive ventilation dysfunction.Results:1. Distribution of NSPFThe Percentage of NSPF was18.68%(2759/14771) in complete pulmonary function test results, from January1,2003to December31,2012, in Beijing Hospital with the same machine. In2759cases of NSPF, NSPF3was the most common, a total of1901cases,12.87%of the total cases and68.9%of NSPF.2. Clinical Characteristics of NSPFFrom January2012to June2012,341patients participated in pulmonary function test, with a sex ratio of1.37:1, and an average age of66.23±11.87years old, among them183were normal cases (53.67%);83, obstructive group (24.34%);28, restrictive group (7.62%);9, mixed group (2.64%); and40, NSPF group (11.73%). Female was common in NSPF, higher than in normal group and in obstructive group (P=0.014,0.001). In NSPF group, the proportion of patients who were diagnosed airway disease previously is higher than that of normal group (p=0.035), but lower than that of obstructive group (p=0.017). Proportion of patients with respiratory symptoms (40%) was similar to that of obstructive group (43.4%, p=0.846), higher than that of normal group (21.3%, p=0.024). NSPF group and other groups did not have significant differences in age, BMI, current smoking status, history of chest surgery and so on.Compared with the normal group, NSPF group had significantly high rate of small airway abnormalities, abnormally elevated RV/TLC (P<0.05); low FEV1%pre, FVC%pre, TLC%pre, MVV%pre, FEF25%-75%%pre, FEF25%%pre, FEF50%%pre, FEF75%%pre, DLCO%pre (P<0.05), high RV%pre, RV/TLC, DLCO/VA group were higher than normal (P<0.05). Compared with the obstructive group, NSPF group had significantly low rate of small airway abnormalities(P<0.05); high FVC%pre, FEF25%-75%%pre, FEF25%%pre, FEF50%%pre, FEF75%%pre, DLCO/VA were higher than the obstructive group (P<0.05), low TLC%pre, but no statistical difference in MVV%pre, RV%pre, RV/TLC, DLCO%pre.Multiple logistic regression analysis showed statistical difference in gender (P<0.001, OR15.283,95%CI,3.526-66.248), TLC%pre (P=0.02, OR0.961,95%CI0.928-0.994), FEF50%%pre (P<0.001, OR1.189,95%CI1.103-1.281) between NSPF group and obstructive group, and statistical difference in gender (p=0.068, OR3.976,95%CI0.904-17.477), TLC%pre (p<0.001, OR0.668,95%CI0.563-0.791), FEF25%-75%%pre (p=0.004, OR0.963,95%CI0.939-0.988), RV%pre(p<0.001, OR1.144,95%CI1.075-1.217), RV/TLC (p<0.001,OR1.31,95%CI1.15-1.492) between NSPF group and normal group.In NSPF group,15patients (37.5%) had respiratory system diseases and38patients with other system diseases. Lung disease or other diseases were widely-ranged and with varying degrees of severity. In40cases,19cases had routine chest X-ray examination, and21cases had chest CT, but with no specific difference in results. Imaging results can be normal or with severe lung structural changes.From January1,2004to December31,2012,138pulmonary function cases with NSPF were recorded in a machine from north department of our hospital, with a male to female ratio6.67:1, and mean age69.2±12.4years old; among them57(41.30%) cases were NSPF1,16(11.59%), NSPF2; and65(47.10%), NSPF3. The average age of NSPF1was65.4years old, which was younger than those of the other two groups (p=0.012,0.008). Lung function difference between the three types of NSPF mainly lies in the small airway function. Medians of FEF25%-75%%pre were51,90and55respectively, which showed more mild small airway damage in NSPF2group. Among41cases of reversible test,7were positive (17.1%). After inhalation of bronchodilator,12cases (29.27%) became normal;7cases (17.07%) were obstructive, and22cases (53.66%) remained NSPF. The three types of NSPF have no significant differences in BMI, current smoking status, purposes of test, history of airway disease and chest surgery, respiratory symptoms, chest auscultation and the incidence of emphysema.3. Evolution of NSPFWe followed up66patients with NSPF. The median follow-up time was of35months (1-110months). According to time interval from the first confirmation of NSPF to the last pulmonary function test, patients were divided into five groups,≤12months,12～24,24～48,48～72and>72months. NSPF patients account for30%,33%,33%,25%, and33%in each group respectively. In the last follow-up result, NSPF remained32%(21/66).In an analysis of60cases of patients with complete data, univariate analysis showed that the change of BMI (p=0.031) and respiratory symptoms in first time (p=0.095) were related to change of NSPF into typical obstructive ventilation dysfunction. Age, baseline BMI, FVC%pre, FEV1%pre, RV/TLC, DLCO%pre, FEF25%-75%%pre, SVC-FVC, current smoking statue, lung disease, emphysema, and pulmonary rales were unrelated. In a multiple factors analysis, change in BMI [risk factor (95%CI)=0.398(0.167-0.946), p=0.037] was an independent factor related to change of NSPF into obstructive ventilation dysfunction.Conclusion:1. NSPF is a common pulmonary function, with a detection rate of18.68%.2. NSPF is an independent type of pulmonary function, with no specific changes in patient’s clinical and imaging manifestations.3. Among NSPF patients,1/3remain stable, and1/3change into obstructive ventilation dysfunction. If a NSPF patient suffers from weight loss in the course, we must pay attention to obstructive ventilation dysfunction. |
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