Normal FVC Research Articles

FRI0377 High rate of false negatives in the early detection of interstitial lung disease associated with systemic sclerosis by pulmonary function tests

BackgroundPulmonary function tests (PFT) are recommended and frequently used as a single test for routine screening and early detection of interstitial lung disease (ILD) in systemic sclerosis (SSc). However, more...

Bronchodilator Response in Patients With Normal Baseline Spirometry

Spirometry before and after bronchodilator is performed to assess air flow-limitation reversibility. In patients with normal baseline spirometry the frequency of a positive bronchodilator response, as defined by American Thoracic Society/European Respiratory Society criteria, has not been described. We retrospectively analyzed adult patients tested in 2 academic pulmonary function testing laboratories over a 7-year period, with specific attention to patients who underwent bronchodilator testing after a normal baseline spirometry (FEV(1), FVC, and FEV(1)/FVC within normal limits). The frequency of a positive response to bronchodilator, defined as a 12% and 200 mL increase in either FEV(1) or FVC, was calculated and associated with demographic factors. Of the 1,394 patients with normal spirometry who were administered bronchodilator, 43 (3.1%) had a positive response. The percent of patients responding to bronchodilator were grouped according to pre-bronchodilator FEV(1): > lower limit of normal to 90% of predicted = 6.9%, 90-100% of predicted = 1.9%, and > 100% of predicted = 0%. An FEV(1)/FVC in the lowest 2 quartiles was associated with a higher frequency of bronchodilator response. Older patients were more likely to respond to bronchodilator, but no other demographic factors were associated with a positive bronchodilator response. In our study population the frequency of a positive bronchodilator response in patients with normal baseline spirometry is 3.1%. None of the patients with a pre-bronchodilator FEV(1) > 100% of predicted and only 1.9% of patients with an FEV(1) between 90% and 100% of predicted responded. Bronchodilator testing can be omitted in patients with normal spirometry and an FEV(1) above 90% of predicted, as they have a low probability of a positive response.

Clinical features of subjects with an isolated FEV1 reduction

The clinical significance of an isolated reduction in forced expiratory volume in 1 second (FEV(1); i.e., low FEV(1), but normal forced vital capacity [FVC] and FEV(1)/FVC) has not been established. To examine the clinical features of subjects with an isolated FEV(1) reduction. Clinical, spirometry and radiological data were retrospectively collected from 15,192 subjects attending a medical check-up at the Health Promotion Center of the Asan Medical Center, Korea. Predicted spirometry values were calculated from the Korean reference equations, and the lower limit of normal was set at the 5th percentile. Subjects were divided into four groups: isolated FEV(1) reduction, normal (normal FVC, FEV(1) and FEV(1)/FVC), obstructive (low FEV(1)/FVC) and restrictive (low FVC and normal FEV(1)/FVC). The groups were compared in terms of clinical characteristics. Of the 15,192 subjects, 323 (2.1%) had an isolated FEV(1) reduction, 10,591 (69.7%) were normal, 951 obstructive (6.3%) and 3327 (22.0%) restrictive. The isolated FEV(1) reduction group had a higher proportion of subjects with smoking history (63.2% vs. 45.7%), radiology abnormalities (15.5% vs. 4.3%) and history of respiratory disease (8.4% vs. 3.0%) than the normal group (all P < 0.001). An isolated FEV(1) reduction suggests abnormal spirometry, and further study is needed to evaluate whether these cases belong to the obstructive or restrictive group.

Use of respiratory function tests to predict survival in amyotrophic lateral sclerosis

Respiratory function tests (RFTs) are commonly used as a measure of progression in ALS. This study assessed the ability of various RFTs to predict survival in ALS patients. Subjects with ALS had one or more measurements of seated and supine FVC, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Kaplan-Meier (KM) analysis was used to determine whether patients with abnormal RFTs had shorter survival than those with normal RFTs. The sensitivity and specificity of RFTs as predictors of two-year survival were calculated from receiver operating characteristic (ROC) curves. With KM analysis, subjects with abnormal values of seated FVC, supine FVC, MIP and MEP had significantly reduced survival compared to subjects with normal values. With ROC curves, a normal supine FVC was highly predictive for two-year survival and had superior sensitivity over seated FVC. Slower rates of decline in seated or supine FVC were strong predictors of two-year survival. Our study demonstrates that respiratory function measurements are useful to predict survival in ALS patients. We show that measurements of FVC in the supine position are worth including in the assessment of respiratory function in ALS.

Pulmonary Function Abnormalities in Never-Smoking Flight Attendants Exposed to Secondhand Tobacco Smoke in the Aircraft Cabin

To determine whether the flight attendants who were exposed to secondhand tobacco smoke in the aircraft cabin have abnormal pulmonary function. We administered questionnaires and performed pulmonary function testing in 61 never-smoking female flight attendants who worked in active air crews before the smoking ban on commercial aircraft (preban). Although the preban flight attendants had normal FVC, FEV1, and FEV1/FVC ratio, they had significantly decreased flow at mid- and low-lung volumes, curvilinear flow-volume curves, and evidence of air trapping. Furthermore, the flight attendants had significantly decreased diffusing capacity (77.5% +/- 11.2% predicted normal) with 51% having a diffusing capacity below their 95% normal prediction limit. This cohort of healthy never-smoking flight attendants who were exposed to secondhand tobacco smoke in the aircraft cabin showed pulmonary function abnormalities suggestive of airway obstruction and impaired diffusion.

The Utility of Spirometry in Diagnosing Pulmonary Restriction

The aim of this retrospective study was to determine the utility of the spirometric measurements FVC, FEV1, and FEV1/FVC in diagnosing pulmonary restriction. Spirometry and lung volume measurements performed on the same patient visit were analyzed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of (1) FVC<lower limit of normal (LLN) (NHANES III reference values) and (2) FVC<LLN and FEV1/FVC>or=LLN were compared to diagnose restriction based on lung volume measurements. In all, 18,282 pulmonary function tests from 8,315 patients were analyzed. Twenty-six percent of the patients (n=2,213) had restriction based on lung volume measurements. The sensitivity, specificity, PPV, and NPV of FVC<LLN to diagnose restriction based on lung volume measurement criteria were 88.6%, 56.8%, 39.9%, and 93.9%, respectively. The sensitivity, specificity, PPV, and NPV of FVC<LLN and FEV1/FVC>or=normal to diagnose restriction based on lung volume criteria were 72.4%, 87.1%, 64.4%, and 90.7%, respectively. Analysis of ROC curves showed that spirometric criteria based on FVC alone performed better (area under the curve=0.817) than those based on the combined criteria of FVC and FEV1/FVC (area under the curve=0.584). Consistent with earlier findings, the negative predictive value for a normal FVC (>or=LLN) to exclude pulmonary restriction was high in this series (up to 95.7%). Also, a spirometric diagnosis of "restriction" (FVC<LLN and FEV1/FVC>or=LLN) had a positive predictive value of 26.3-73.9%. On this basis, normal FVC can be regarded as excluding restriction with high reliability.

Prevalence and Reversibility of Pulmonary Dysfunction in Refractory Systemic Lupus: Improvement Correlates With Disease Remission Following Hematopoietic Stem Cell Transplantation

To report the prevalence and reversibility of pulmonary function test (PFT) abnormalities among systemic lupus erythematosus (SLE) patients, refractory to therapy, undergoing hematopoietic stem cell transplantation (HSCT).Thirty-four SLE patients received 200 mg/kg cyclophosphamide and 90 mg/kg equine antithymocyte globulin followed by HSCT. PFTs were performed prior to, at 6 months, and yearly following HSCT.The prevalence of significant PFT abnormalities was high (97%). Low FEV(1) and FVC occurred in 26 of 34 patients (76%). A significant abnormality in diffusion capacity of the lung for carbon monoxide (Dlco) occurred in 26 of 32 individuals able to complete Dlco testing (81%). Dlco <or= 50% of predicted occurred in 18 of 32 patients (56%). Of these 18 patients, 4 had no thoracic diagnosis and 7 had no pulmonary diagnosis. For 3 of 11 patients with a Dlco <or= 50% of predicted and a prior pulmonary diagnosis, the only diagnosis had been pleurisy. Ten of the 34 patients (29%) identified the lung as a target organ of the lupus and carried a pulmonary diagnosis, as indicated in Table 1 . Three patients had acute alveolar hemorrhage, four patients had acute lupus pneumonitis, two patients had shrinking lung syndrome (SLS), and one patient had SLE-related pulmonary hypertension. Of these 10 patients, 4 had received prior mechanical ventilation, and 7 had required home supplemental inspired oxygen. Patients have been monitored <or= 77 months, and 28 patients have been monitored > 18 months after HSCT. Five of 28 patients had a normal entry FVC; for each, the FVC remains normal. Of the 23 patients with an abnormal baseline FVC, 18 have improved, 15 completely and 3 partially. Eight of these 18 patients also have improved Dlco. The two patients with a diagnosis of SLS and one patient with SLE-related pulmonary hypertension improved in both parameters. Only 5 of 23 patients with an abnormal FVC did not improve. Each of these five patients retained active lupus in spite of HSCT.The prevalence of lung impairment among SLE patients requiring long-term immune suppression is high. Following HSCT, pulmonary impairments can improve, which is sustained if disease control is sustained.

Editorial: Small Airways Disease and Asthma

Editorial: Small Airways Disease and Asthma

Cough and Phlegm Are Important Predictors of Health Status in Smokers Without COPD

The health-related quality of life of smokers without COPD and that of ex-smokers has not been defined. If abnormal, the role of small airways disease and that of cough and phlegm have never been evaluated. Therefore, the aim of the study was to explore whether the differences in quality of life between smokers and ex-smokers could be explained by cough and phlegm, differences in pulmonary function tests, or exercise capacity. Observational, prospective. Pulmonary and Critical Care Division, COPD Center at St. Elizabeth's Medical Center. In 36 smokers, 21 ex-smokers (stopped smoking for > 20 years), 19 never-smokers with normal FVC and FEV(1) values, and 41 patients with COPD (FEV(1) 38 +/- 11% predicted [mean +/- SD]), the St. George's Respiratory Questionnaire (SGRQ), pulmonary function tests, and a 6-min walk distance (6MWD) were performed. The total SGRQ scores were worse in current smokers (15 +/- 15) than in ex-smokers (6 +/- 4) or never-smokers (4 +/- 3) [p < 0.05]. As expected, the worst score was seen in COPD (50 +/- 15). After correcting for cough and phlegm, the difference in SGRQ scores between smokers and ex-smokers disappeared. In current and ex-smokers, the SGRQ score was associated with the exposure to pack-years smoking history (r = 0.45, p < 0.01, and r = 0.83, p < 0.0001, respectively) but independent of lung function or exercise parameters (6MWD). In smokers without COPD, the abnormal SGRQ score is due to the noxious effect of cigarette smoke, resulting in cough and phlegm, independent of its physiologic effects.

Pediatric Reference Values for Respiratory Resistance Measured by Forced Oscillation

To determine, in North American children, reference values for respiratory resistance measurements by the forced oscillation (Rfo) technique and to examine whether sitting height, as index of truncal length, is a better determinant of resistance, less influenced by race and gender, than standing height. A prospective cross-sectional study of healthy nonobese children, carefully selected for absence of atopy, exposure to tobacco smoke, and recent upper respiratory tract infection. Three measurements of respiratory resistance by forced oscillation were obtained at the fixed frequencies of 8 Hz (Rfo8), 12 Hz (Rfo12), and at 16 Hz (Rfo16) using the Custo Vit R (Custo Med GMBH; Munich, Germany). In cooperative children, routine spirometry (FEV1, FVC, and peak expiratory flow rate [PEFR]) was also performed. We recruited 217 healthy children aged 3 to 17 years. Reproducible measurements of Rfo8 were obtained for 206 children, Rfo12 for 197 children, and Rfo16 for 209 children. Normal FEV1, FVC, and PEFR values were documented in all 69 subjects who were able to reproducibly cooperate with spirometry. Multiple linear regression identified measurements of either sitting or standing height as the best, and equally strong, determinants of respiratory resistance at all three frequencies. Gender and race were not important factors once either sitting or standing height measurement was considered. Our regression equations at 8 Hz are comparable to published reference values obtained at fixed frequencies of 6, 8, and 10 Hz using other instruments. However, in comparison to our results, prior values tended to underestimate resistance in the shortest children or to overestimate it in the tallest ones. Our regression equation for Rfo12 is similar to the only previously published one, while no reference values at 16 Hz were available for comparison. Height is the best predictor for total respiratory resistance at 8, 12, and 16 Hz in children aged > or = 3 years. Use of sitting height does not appear to be a stronger determinant of resistance than standing height.

Pulmonary toxicity of continuous infusion 5-fluoro-2’-deoxyuridine

This report describes a patient who developed pulmonary toxicity, manifest by dyspnea on exertion, a low pO2, a normal FEV1 and FVC, and a low DLCO while receiving 5-fluoro-2'-deoxyuridine (FUDR) by intermittent continuous i.v. infusion. No other cause of his low DLCO could be identified. The dyspnea on exertion and DLCO improved gradually after the FUDR was discontinued. This case was felt to represent a previously undescribed toxicity of the continuous i.v. infusion of FUDR.

Graded Comprehensive Cardiopulmonary Exercise Testing in the Evaluation of Dyspnea Unexplained by Routine Evaluation

The evaluation of dyspnea is problematic when a cause is inapparent after initial diagnostic studies. We examined the results and role of cardiopulmonary exercise testing (CPET) in 50 patients with a mean 23 months of dyspnea and normal FEV1 and FVC. The CPET studies were interpreted by a panel and a consensus reached. Subsequent tests ordered by the primary physician were reviewed, and a final diagnosis was agreed on by the panel. Seven of 50 patients had cardiac limitation, 17 of 50 had pulmonary limitation, 14 of 50 had obesity and/or deconditioning, 1 of 50 had gastroesophageal reflux, and 16 of 50 had either psychogenic dyspnea or no identifiable disease. Five patients had more than one clinical diagnosis accounting for 55 diagnoses in the 50 patients. Those with a normal CPET had a higher VO2max and O2 pulse than those with cardiac disease, deconditioning, or hyperactive airways disease (HAD) (p < 0.05). Electrocardiographic changes identified cardiac disease while studies demonstrating ventilatory limitation identified a pulmonary process. In 24, deconditioning could not be distinguished from cardiac limitation. Of these, 14 responded to exercise training and/or weight loss, whereas 3 had cardiac disease, 7 had HAD, and 4 had psychogenic dyspnea (4 had more than one clinical diagnosis). In the 13 patients with normal CPET results, one had gastroesophageal reflux, two had HAD, four had psychogenic dyspnea, and six had no identifiable disease. We conclude that a diagnosis can be made in most patients with chronic dyspnea; however, further studies including bronchoprovocation are often required. Cardiopulmonary exercise testing is useful in identifying a cardiac or pulmonary process, but it is insensitive in distinguishing cardiac disease from deconditioning.

Isolated diffusing capacity reduction in systemic sclerosis.

To determine the long-term outcome of patients with systemic sclerosis (SSc) and an isolated reduction in the diffusing capacity for carbon monoxide (DLCO) at the time of initial evaluation. Patients with an isolated reduction in DLCO (i.e., normal forced vital capacity [FVC] and normal ratio of the forced expiratory volume in one second [FEV1] to the FVC) on initial evaluation were identified from among 815 patients with SSc who were carefully followed up throughout their illness. We requested that patients have repeat pulmonary function testing (PFT), and the outcomes of these tests, as well as cardiopulmonary and survival outcomes, were determined. An isolated reduction in DLCO, with a normal FVC was detected in 152 (19%) of the 815 patients. A subset of those with an isolated reduction in DLCO (11%) developed isolated pulmonary hypertension and had severely reduced survival rates. Pulmonary hypertension was strongly associated with an initial DLCO of less than 55% of predicted normal and a FVC (% predicted)/DLCO (% predicted) ratio of greater than 1.4. Among all patients in whom this ratio was greater than 1.4, 22% developed isolated pulmonary hypertension, compared with only 2% of those whose ratio was less than 1.4 (P less than 0.01). Of the 152 patients with isolated DLCO reduction, 73 (48%) underwent PFTs a mean of 5.4 years (range 2.0-13.2) after the initial PFT. Only 6 (8%) of these 73 patients ever had serious pulmonary disease: 5 had isolated pulmonary hypertension, and 1 had severe pulmonary fibrosis. Half of the patients with a low initial DLCO demonstrated a significant improvement (greater than 20%) at followup testing that could not be explained by the demographic, clinical, or laboratory findings at the first visit. Isolated reduction in DLCO is a frequent abnormality in SSc. Overall, it is associated with a good prognosis for survival and for pulmonary morbidity. A small subset of patients (11%) who have a very low DLCO (less than 55% of predicted) have developed isolated pulmonary hypertension, all of whom had limited scleroderma.

Small airways function of silica-exposed workers.

Small airways obstruction may be present for many years before chronic airway obstruction becomes evident. Several spirometric indices, especially flow rates at low lung volumes, may reflect the status of small airways. Time domain indices, by using moments analysis of the volume time spirogram, have also been shown to be sensitive indicators of small airways obstruction. In this study, we have applied the various spirometric indices as well as time domain indices to a group of granite quarry workers without radiographic evidence of silicosis or physiological evidence of obstruction to the larger airways. The aim was to evaluate small airways function in relation to dust exposure in subjects with normal ratio of the forced expiratory volume in one second to the forced vital capacity (FEV1/FVC) and normal FVC. The volume-time spirograms of 140 quarry workers were digitized using an electronic digitizer connected to a microcomputer where flow and time domain indices were computed. The workers were divided into three exposure groups based on their occupational history. With adjustment for age, height, and smoking status, all the time domain indices showed significant small airways obstruction with increasing dust exposure. Smokers had greater degree of airways obstruction than the non-smokers, with a similar trend of increase in small airways obstruction in relation to higher exposure. Our present study suggests that small airways obstruction is present among silica exposed workers in the absence of radiological evidence of silicosis and large airways obstruction. There was also evidence of increasing small airways obstruction in higher dust exposure group. Our study also suggests that time domain indices are more sensitive to small airways obstruction.

Prediction of maximal oxygen uptake and power during cycle ergometry in subjects older than 55 years of age.

One hundred twenty-eight healthy volunteers (81 women, 47 men) older than 55 yr of age were studied with an incremental progressive cycle ergometer test to a symptom-limited, maximal tolerable work load. Mean (+/- SD) age was 66 +/- 6 yr in women and 66 +/- 5 years in men. Subjects with a history of ischemic heart disease, diabetes, pulmonary disease, or neuromuscular disease were excluded. Smokers were included, but all subjects had normal FEV1 and FVC. The objective of the study was to compare measured values of VO2max and Wmax in this older population with previously published predicted values based on subjects of all ages. We found that Wmax observed exceeded Wmax predicted by 9.5 +/- 22% (mean +/- SD) and that VO2max observed exceeded VO2max predicted by 17.5 +/- 22%. Because of this systematic underestimate of VO2max and Wmax by the previous prediction equations, we constructed new prediction equations for use in subjects older than 55 yr of age using height, weight, age, and sex as variables. We conclude that these new prediction equations more accurately predict Wmax and VO2max in subjects older than 55 yr of age because they are based solely on subjects in this age group.

Case of Suprapubic Lithotomy in a Child

<h3>BACKGROUND:</h3> Obesity reduces FVC, the most commonly used measurement of vital capacity (VC) and slow VC (SVC). It is unknown whether the difference between SVC and FVC is constant in different body mass indices (BMIs). We hypothesized that the difference between SVC and FVC increases as a function of BMI. <h3>METHODS:</h3> We retrospectively reviewed pulmonary function tests (PFTs) that included spirometry and plethysmography and were performed in adults from January 2013 to August 2013. A total of 1,805 PFTs were enrolled. The non-parametric Wilcoxon signed-rank test was used to compare FVC with SVC, and to compare FEV₁/FVC with FEV₁/SVC ratio. Spearman correlation analysis was used to determine whether BMI has an effect on the discordance between FVC and SVC. Finally, we used the McNemar test for paired binary data to compare the prevalence rate of obstruction when using different measurements of VC. <h3>RESULTS:</h3> In individuals with BMI &lt; 25 kg/m² and no evidence of obstruction in the PFTs, FVC was larger than SVC (<i>P</i> = .03), whereas in overweight and obese individuals, SVC was significantly larger than FVC. The difference between SVC and FVC was positively correlated with BMI (<i>P</i> &lt; .001). One hundred thirty-one patients had a normal FEV₁/FVC but low FEV₁/SVC ratio. Fifty of these 131 individuals also had a normal FVC; the majority of them (46 of 50) had the PFTs for investigation of respiratory symptoms and had BMI &gt; 25 kg/m² (42 of 50). <h3>CONCLUSIONS:</h3> Our results indicate that FVC is larger than SVC in patients with low and normal BMI and no evidence of obstruction in the PFTs, whereas FVC is smaller than SVC in overweight and obese individual. Our findings add to the existing literature that use of FEV₁/FVC may lead to underdiagnosis of obstructive airway disease in overweight and obese individuals.