Reliability and validity of the Brief Pain Inventory in individuals with chronic obstructive pulmonary disease

BACKGROUND

Pain is prevalent in chronic obstructive pulmonary disease (COPD) and the Brief Pain Inventory (BPI) appears to be a feasible questionnaire to assess this symptom. However, the reliability and validity of the BPI have not been determined in individuals with COPD. This study aimed to determine the internal consistency, test-retest reliability and validity (construct, convergent, divergent and discriminant) of the BPI in individuals with COPD.

METHODS

In order to examine the test-retest reliability, individuals with COPD were recruited from pulmonary rehabilitation programmes to complete the BPI twice 1 week apart. In order to investigate validity, de-identified data was retrieved from two previous studies, including forced expiratory volume in 1-s, age, sex and data from four questionnaires: the BPI, short-form McGill Pain Questionnaire (SF-MPQ), 36-Item Short Form Survey (SF-36) and Community Health Activities Model Program for Seniors (CHAMPS) questionnaire.

RESULTS

In total, 123 participants were included in the analyses (eligible data were retrieved from 86 participants and additional 37 participants were recruited). The BPI demonstrated excellent internal consistency and test-retest reliability. It also showed convergent validity with the SF-MPQ and divergent validity with the SF-36. The factor analysis yielded two factors of the BPI, which demonstrated that the two domains of the BPI measure the intended constructs. The BPI can also discriminate pain levels among COPD patients with varied levels of quality of life (SF-36) and physical activity (CHAMPS).

CONCLUSION

The BPI is a reliable and valid pain questionnaire that can be used to evaluate pain in COPD.

SIGNIFICANCE

This study formally established the reliability and validity of the BPI in individuals with COPD, which have not been determined in this patient group. The results of this study provide strong evidence that assessment results from this pain questionnaire are reliable and valid.

Polymorphisms in the superoxide dismutase-3 gene are associated with emphysema in COPD

Superoxide dismutase-3 (SOD3) is a major extracellular antioxidant enzyme, and previous studies have indicated a possible role of this gene in chronic obstructive pulmonary disease (COPD). We hypothesized that polymorphisms in the SOD3 gene would be associated with COPD and COPD-related phenotypes. We genotyped three SOD3 polymorphisms (rs8192287 (E1), rs8192288 (I1), and rs1799895 (R213G)) in a case-control cohort, with severe COPD cases from the National Emphysema Treatment Trial (NETT, n = 389) and smoking controls from the Normative Aging Study (NAS, n = 472). We examined whether the single nucleotide polymorphisms (SNPs) were associated with COPD status, lung function variables, and quantitative computed tomography (CT) measurements of emphysema and airway wall thickness. Furthermore, we tried to replicate our initial findings in two family-based studies, the International COPD Genetics Network (ICGN, n = 3061) and the Boston Early-Onset COPD Study (EOCOPD, n = 949). In NETT COPD cases, the minor alleles of SNPs E1 and I1 were associated with a higher percentage of emphysema (%LAA950) on chest CT scan (p = .029 and p = .0058). The association with E1 was replicated in the ICGN family study, where the minor allele was associated with more emphysema (p = .048). Airway wall thickness was positively associated with the E1 SNP in ICGN; however, this finding was not confirmed in NETT. Quantitative CT data were not available in EOCOPD. The SNPs were not associated with lung function variables or COPD status in any of the populations. In conclusion, polymorphisms in the SOD3 gene were associated with CT emphysema but not COPD susceptibility, highlighting the importance of phenotype definition in COPD genetics studies.

Prediction of the rate of decline in FEV(1) in smokers using quantitative Computed Tomography

BACKGROUND

A study was undertaken to determine if quantitative CT estimates of lung parenchymal overinflation and airway dimensions in smokers with a normal forced expiratory volume in 1 s (FEV(1)) can predict the rapid decline in FEV(1) that leads to chronic obstructive pulmonary disease (COPD).

METHODS

Study participants (n = 143; age 45-72 years; 54% male) were part of a lung cancer screening trial, had a smoking history of >30 pack years and a normal FEV(1) and FEV(1)/forced vital capacity (FVC) at baseline (mean (SD) FEV(1) 99.4 (12.8)%, range 80.2-140.7%; mean (SD) FEV(1)/FVC 77.9 (4.4), range 70.0-88.0%). An inspiratory multislice CT scan was acquired for each subject at baseline. Custom software was used to measure airway lumen and wall dimensions; the percentage of the lung inflated beyond a predicted maximal lung inflation, the low attenuation lung area with an x ray attenuation lower than -950 HU and the size distribution of the overinflated lung areas and the low attenuation area were described using a cluster analysis. Multiple regression analysis was used to test the hypothesis that these CT measurements combined with other baseline characteristics might identify those who would develop an excessive annual decline in FEV(1).

RESULTS

The mean (SD) annual change in FEV(1) was -2.3 (4.7)% predicted (range -23.0% to +8.3%). Multiple regression analysis revealed that the annual change in FEV(1)%predicted was significantly associated with baseline percentage overinflated lung area measured on quantitative CT, FEV(1)% predicted, FEV(1)/FVC and gender.

CONCLUSION

Quantitative CT scan evidence of overinflation of the lung predicts a rapid annual decline in FEV(1) in smokers with normal FEV(1).

Airway wall geometry in asthma and nonasthmatic eosinophilic bronchitis

BACKGROUND

Variable airflow obstruction and airway hyperresponsiveness (AHR) are features of asthma, which are absent in nonasthmatic eosinophilic bronchitis (EB). Airway remodelling is characteristic of both conditions suggesting that remodelling and airway dysfunction are disassociated, but whether the airway geometry differs between asthma and nonasthmatic EB is uncertain.

METHODS

We assessed airway geometry by computed tomography (CT) imaging in asthma vs EB. A total of 12 subjects with mild-moderate asthma, 14 subjects with refractory asthma, 10 subjects with EB and 11 healthy volunteers were recruited. Subjects had a narrow collimation (0.75 mm) CT scan from the aortic arch to the carina to capture the right upper lobe apical segmental bronchus (RB1). In subjects with asthma and EB, CT scans were performed before and after a 2-week course of oral prednisolone (0.5 mg/kg).

RESULTS

Mild-moderate and refractory asthma were associated with RB1 wall thickening in contrast to subjects with nonasthmatic EB who had maintained RB1 patency without wall thickening [mean (SD) % wall area and luminal area mild-t0-moderate asthma 67.7 (7.3)% and 6.6 (2.8) mm(2)/m(2), refractory asthma 67.3 (5.6)% and 6.7 (3.4) mm(2)/m(2), healthy control group 59.7 (6.3)% and 8.7 (3.8) mm(2)/m(2), EB 61.4 (7.8)% and 11.1 (4.6) mm(2)/m(2) respectively; P < 0.05]. Airway wall thickening of non-RB1 airways generation three to six was a feature of asthma only. There was no change in airway geometry of RB1 after prednisolone. Proximal airway wall thickening was associated with AHR in asthma (r = -0.56; P = 0.02).

CONCLUSIONS

Maintained airway patency in EB may protect against the development of AHR, whereas airway wall thickening may promote AHR in asthma.

Quantitative computed tomography: emphysema and airway wall thickness by sex, age and smoking

We investigated how quantitative high-resolution computed tomography (HRCT) measures of emphysema and airway wall thickness (AWT) vary with sex, age and smoking history. We included 463 chronic obstructive pulmonary disease (COPD) cases and 431 controls. All included subjects were current or ex-smokers aged > or = 40 yrs, and all underwent spirometry and HRCT examination. The HRCT images were quantitatively assessed, providing indices on lung density and airway dimensions. The median (25-75th percentile) %LAA950 (% low-attenuation area < -950 HU) was 8.9 (3-19) and 4.7 (1-16) in male and female COPD cases, respectively, and 0.71 (0.3-1.6) and 0.32 (0.1-0.8) in male and female controls, respectively. %LAA950 was higher in ex-smokers and increased with increasing age and with increasing number of pack-years. The mean+/-SD standardised AWT was 0.504+/-0.030 and 0.474+/-0.031 in male and female COPD cases, respectively, and 0.488+/-0.028 and 0.463+/-0.025 in male and female controls, respectively. AWT decreased with increasing age in cases, and increased with the degree of current smoking in all subjects. We found significant differences in quantitative HRCT measures of emphysema and AWT between varying sex, age and smoking groups of both control and COPD subjects.

Evaluation of serum CC-16 as a biomarker for COPD in the ECLIPSE cohort

BACKGROUND

Circulating levels of Clara cell secretory protein-16 (CC-16) have been linked to Clara cell toxicity. It has therefore been suggested that this protein may be a useful marker of chronic obstructive pulmonary disease (COPD).

METHODS

Serum CC-16 levels were measured in 2083 individuals aged 40-75 years with COPD and a smoking history of >or=10 pack-years, 332 controls with a smoking history of >or=10 pack-years and normal lung function and 237 non-smoking controls.

RESULTS

Serum CC-16 had a coefficient of repeatability of 2.90 over 3 months in a pilot study of 267 individuals. The median serum CC-16 level was significantly reduced in a replication group of 1888 current and former smokers with COPD compared with 296 current and former smokers without airflow obstruction (4.9 and 5.6 ng/ml, respectively; p<0.001) and 201 non-smokers (6.4 ng/ml; p<0.001). Serum levels of CC-16 were lower in current than in former smokers with GOLD stage II and III COPD but were not different in individuals with stage IV disease. Former, but not current smokers, with COPD had lower serum CC-16 levels with increasing severity of COPD (GOLD II vs GOLD IV COPD: 5.5 and 5.0 ng/ml, p = 0.006; r = 0.11 with forced expiratory volume in 1 s, p<0.001) and had significantly higher levels if they also had reversible airflow obstruction (p = 0.034). Serum CC-16 was affected by gender and age (r = 0.35; p<0.001) in subjects with COPD but not by body mass index or the presence of either chronic bronchitis or emphysema.

CONCLUSIONS

Serum CC-16 levels are reduced in individuals with COPD and there is a weak correlation with disease severity in former smokers.

Lung structure and function of infants with recurrent wheeze when asymptomatic

Infants with recurrent wheeze have repeated episodes of airways obstruction; however, relatively little is known about the structure and function of their lungs when not symptomatic. The current authors evaluated whether infants with recurrent wheeze have smaller airway lumens or thickened airway walls, as well as decreased airway function. High-resolution computed tomography images 1 mm thick were obtained at three anatomic locations at an elevated lung volume and at functional residual capacity. Forced expiratory flows were also measured in subjects with recurrent wheeze. Airway lumen, wall areas and lung tissue density were not significantly different for recurrent wheeze (n = 17) and control (n = 14) subjects; however, subjects with recurrent wheeze had lower forced expiratory flows than predicted. Similar findings were obtained when subjects were grouped by exposure to tobacco smoke. These findings indicate that infants with recurrent wheeze, as well as exposure to tobacco smoke, have lower airway function when not symptomatic. The lower forced expiratory flows may result from a degree of airway narrowing that could not be resolved with the methodology employed or from other mechanisms, such as more collapsible airways or decreased pulmonary elastic recoil.

Computed tomography assessment of lung volume changes after bronchial valve treatment

The aim of the present study was to correlate clinical outcome measures following treatment with bronchial valves with regional lung volume. Computed tomography (CT) scan data from 57 subjects with severe emphysema were obtained from nine North American clinical trial sites. IBV(R) Valves (Spiration, Inc., Redmond, WA, USA) were placed to occlude segmental and subsegmental bronchi in right and left upper lobes using a flexible bronchoscope. Subjects completed a St George's Respiratory Questionnaire (SGRQ), pulmonary function test (PFT) and exercise capacity test. CT scans were analysed at baseline and at 1, 3 or 6 months after treatment to measure total and lobar lung density, volume and mass. Total lung volumes measured using CT were strongly correlated with PFT and did not change with treatment. However, the treated upper lobes significantly decreased in volume in 88% of the observations, by mean+/-sd 335+/-444 mL, or a decrease of 10.2% in the 6 month data. The untreated lobes had an 11.6% increase in volume. Changes in regional lung volume were associated with clinically meaningful improvements in SGRQ (-8.95+/-16.22), but not clinically meaningful PFT changes. The significant health status improvements reported by subjects following bilateral bronchial valve treatment are associated with regional lung volume changes and interlobar shift measured using computed tomography.

Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE)

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease and not well understood. The forced expiratory volume in one second is used for the diagnosis and staging of COPD, but there is wide acceptance that it is a crude measure and insensitive to change over shorter periods of time. Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE) is a 3-yr longitudinal study with four specific aims: 1) definition of clinically relevant COPD subtypes; 2) identification of parameters that predict disease progression in these subtypes; 3) examination of biomarkers that correlate with COPD subtypes and may predict disease progression; and 4) identification of novel genetic factors and/or biomarkers that both correlate with clinically relevant COPD subtypes and predict disease progression. ECLIPSE plans to recruit 2,180 COPD subjects in Global Initiative for Chronic Obstructive Lung Disease categories II-IV and 343 smoking and 223 nonsmoking control subjects. Study procedures are to be performed at baseline, 3 months, 6 months and every 6 months thereafter. Assessments include pulmonary function measurements (spirometry, impulse oscillometry and plethysmography), chest computed tomography, biomarker measurement (in blood, sputum, urine and exhaled breath condensate), health outcomes, body impedance, resting oxygen saturation and 6-min walking distance. Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points is the largest study attempting to better describe the subtypes of chronic obstructive pulmonary disease, as well as defining predictive markers of its progression.

Computed tomographic estimation of lung dimensions throughout the growth period

The aim of the current study was to use computed tomography (CT) to estimate airway wall and lumen, and arterial and parenchyma dimensions in children throughout the growth period, and to provide normative data to study alterations caused by pulmonary disease. Clinical CT scans reported as normal that were performed in children for nonpulmonary and noncardiac reasons were analysed for lung weight, gas volume, lung expansion, lung surface/volume ratio, airway wall area, airway lumen area, airway lumen perimeter, arterial area and airway surface length/area ratio. The age range of the 50 subjects was 0-17.2 yrs. The data showed only little increase in lung expansion throughout childhood (n = 32). There was substantial variability in lung expansion between subjects. Airway wall and lumen and arterial area were exponentially associated with subjects' height (n = 50). Airway surface length/area ratio was linearly associated to alveolar surface/volume ratio. The data from the current study provide normative computed tomography estimates of airway wall and lumen, and arterial and parenchyma dimensions throughout the growth period that may be useful for the study of alterations in disease.

Bronchiolitis obliterans following lung transplantation: early detection using computed tomographic scanning

BACKGROUND

Computed tomographic (CT) scanning may enable earlier diagnosis of chronic lung allograft dysfunction than forced expiratory volume in 1 second (FEV1). A study was undertaken to determine intra-observer and inter-observer agreement of composite and air trapping CT scores, to examine the association of FEV1 with the composite and air trapping CT score, and to relate the baseline composite CT score to changes in FEV1 and changes in the composite CT score over 1 year.

METHODS

Lung function and baseline CT scans following transplantation and at subsequent annual follow ups were analysed in 38 lung transplant recipients. Scans were randomly scored by two observers for bronchiectasis, mucus plugging, airway wall thickening, consolidation, mosaic pattern, and air trapping, and re-scored after 1 month. CT scores were expressed on a scale of 0-100 and correlated with FEV1 as a percentage of the post-transplant baseline value.

RESULTS

The mean (SD) interval between baseline and follow up CT scans was 11.2 (4.7) months. Inter-observer and intra-observer agreement was good for both the composite and air trapping CT scores. There was a significant association between FEV1 and the composite CT score, with each unit of worsening in the baseline composite CT score predicting a 1.55% and 1.37% worsening in FEV1 over the following year (p<0.0001) and a 1.25 and 1.12 unit worsening in the composite CT score (p<0.0001) for observers 1 and 2, respectively.

CONCLUSION

These findings indicate a potential role for a composite CT scoring system in the early detection of bronchiolitis obliterans.

Computed tomographic imaging of the airways: relationship to structure and function

Alterations in the structure of the airways, collectively termed airway remodelling, contribute to airflow obstruction in a variety of chronic lung diseases. While histology has provided valuable insights into the structure of airway wall remodelling, this technique is invasive and does not allow the longitudinal analysis of airway wall dimensions. Technical advances in computed tomography allow the assessment of airway wall dimensions, and are ideally suited for the noninvasive investigation of the pathogenesis of airway wall remodelling and the evaluation of new therapeutic interventions. The aim of this article is to review the use of computed tomography in the investigation of airway structure and function in health and disease.

Estimation of lung growth using computed tomography

Anatomical studies suggest that normal lungs grow by rapid alveolar addition until about 2 yrs of age followed by a gradual increase in alveolar dimensions. The aim of this study was to examine the hypothesis that normal lung growth can be monitored by computed tomography (CT). Therefore, the gas volume per gram of lung tissue was estimated from measurements of lung density obtained from CT scans performed on children throughout the growth period. CT scans were performed on 17 males and 18 females, ranging in age from 15 days-17.6 yrs. CT-measured lung weight was correlated with predicted post mortem values and CT measured gas volume with predicted values of functional residual capacity. The median value for lung expansion was 1.86 mL x g(-1) at 15 days, decreased to 0.79 mL x g(-1) by 2 yrs and then increased steadily to 5.07 mL x g(-1) at 17 yrs. Computed tomography scans can be used to estimate lung weight, gas volume and expansion of normal lungs during the growth period. The increase in the lung expansion after the age of 2 yrs suggests progressive alveolar expansion with increasing lung volume.

Selection of patients for lung volume reduction surgery using a power law analysis of the computed tomographic scan

BACKGROUND

A study was undertaken to test the hypothesis that patients respond better to lung volume reduction surgery (LVRS) if their emphysema is confluent and predominantly located in the upper lobes.

METHODS

A density mask analysis was used to identify voxels inflated beyond 10.2 ml gas/g tissue (-910 HU) on preoperative and postoperative CT scans from patients receiving LVRS. These hyperinflated regions were considered to represent emphysematous lesions. A power law analysis was used to determine the relationship between the number (K) and size (A) of the emphysematous lesions in the whole lung and two anatomical regions using the power law equation Y=KA(-D).

RESULTS

The analysis showed a positive correlation between the change in the power law exponent (D) and the change in exercise (Watts) after surgery (r=0.47, p=0.03). There was also a negative correlation between the power law exponent D in the upper region of the lung preoperatively and the change in exercise following surgery (r=-0.60, p<0.05).

CONCLUSIONS

These results confirm that patients with large upper lobe lesions respond better to LVRS than patients with small uniformly distributed disease. Power law analysis of lung CT scans provides a quantitative method for determining the extent and location of emphysema within the lungs of patients with COPD.

Core to rind distribution of severe emphysema predicts outcome of lung volume reduction surgery

Computed tomography (CT) has shown that emphysema is more extensive in the inner (core) region than in the outer (rind) region of the lung. It has been suggested that the concentration of emphysematous lesions in the outer rind leads to a better outcome following lung volume reduction surgery (LVRS) because these regions tend to be more surgically accessible. The present study used a recently described, computer-based CT scan analysis to quantify severe emphysema (lung inflation > 10.2 ml gas/g tissue), mild/moderate emphysema (lung inflation = 10.2 to 6.0 ml gas/g tissue), and normal lung tissue (lung inflation < 6.0 ml gas/g tissue) present in the core and rind of the lung in 21 LVRS patients. The results show that the quantification of severe emphysema independently predicts change in maximal exercise response and FEV(1). We conclude that a greater extent of severe emphysema in the rind of the upper lung predicts greater benefit from LVRS because it identifies the lesions most accessible to removal by LVRS.

Bullae, bronchiectasis and nutritional emphysema in severe anorexia nervosa

STUDY OBJECTIVES

Pulmonary complications of anorexia nervosa are rarely documented. The case of a patient with anorexia nervosa and pulmonary disease is presented, a new quantitative computed tomography (CT) method for the detection of emphysema is employed, the literature is reviewed and the concept of 'nutritional' emphysema is discussed.

RESULTS

The case of a 34-year-old, nonsmoking woman with long-standing severe anorexia nervosa who was evaluated for cough and progressive shortness of breath is reported. Pulmonary function testing showed a predominant restrictive pattern with a marked reduction in carbon monoxide transfer and respiratory muscle strength, and an elevated residual volume. Imaging revealed bullae and bronchiectasis, and quantitative analysis of the CT scan was consistent with mild, generalized emphysema. Bronchial washings grew Pseudomonas aeruginosa. Known causes for bronchiectasis were excluded. A literature review disclosed few reported noninfectious pulmonary complications of anorexia nervosa.

CONCLUSIONS

To the authors' knowledge, this is the first report of bullae and bronchiectasis in a patient with anorexia nervosa, and the CT analysis was consistent with mild emphysema. Malnutrition has been associated with emphysematous changes in animals and may be the primary insult in the development of emphysema, bullae and bronchiectasis in the present patient.

Amplification of inflammation in emphysema and its association with latent adenoviral infection

This study examines the hypothesis that the cigarette smoke-induced inflammatory process is amplified in severe emphysema and explores the association of this response with latent adenoviral infection. Lung tissue from patients with similar smoking histories and either no (n = 7), mild (n = 7), or severe emphysema (n = 7) was obtained by lung resection. Numbers of polymorphonuclear cells (PMN), macrophages, B cells, CD4, CD8 lymphocytes, and eosinophils present in tissue and airspaces and of epithelial cells expressing adenoviral E1A protein were determined using quantitative techniques. Severe emphysema was associated with an absolute increase in the total number of inflammatory cells in the lung tissue and airspaces. The computed tomography (CT) determined extent of lung destruction was related to the number of cells/m(2) surface area by R(2) values that ranged from 0.858 (CD8 cells) to 0.483 (B cells) in the tissue and 0.630 (CD4 cells) to 0.198 (B cells) in the airspaces. These changes were associated with a 5- to 40-fold increase in the number of alveolar epithelial cells expressing adenoviral E1A protein in mild and severe disease, respectively. We conclude that cigarette smoke-induced lung inflammation is amplified in severe emphysema and that latent expression of the adenoviral E1A protein expressed by alveolar epithelial cells influenced this amplification process.

Pulmonary embolism: comparison of gadolinium-enhanced MR angiography with contrast-enhanced spiral CT in a porcine model

RATIONALE AND OBJECTIVES

The purpose of this study was to compare gadolinium-enhanced magnetic resonance (MR) angiography with contrast material-enhanced computed tomography (CT) for the detection of small (4-5-mm) pulmonary emboli (PE), with a methacrylate cast of the porcine pulmonary vasculature used as the diagnostic standard.

MATERIALS AND METHODS

In 15 anesthetized juvenile pigs, colored methacrylate beads (5.2 and 3.8 mm diameter-the size of segmental and subsegmental emboli in humans) were injected via the left external jugular vein. After embolization, MR angiographic and CT images were obtained. The pigs were killed, and the pulmonary arterial tree was cast in clear methacrylate, allowing direct visualization of emboli. Three readers reviewed CT and MR angiographic images independently and in random order.

RESULTS

Forty-nine separate embolic sites were included in the statistical analysis. The mean sensitivity (and 95% confidence intervals) for CT and MR angiography, respectively, were 76% (68%-82%) and 82% (75%-88%) (P > .05); the mean positive predictive values, 92% (85%-96%) and 94% (88%-97%) (P > .05). In this porcine model, PE were usually seen as parenchymal perfusion defects (98%) with MR angiography and as occlusive emboli (100%) with CT.

CONCLUSION

MR angiography is as sensitive as CT for the detection of small PE in a porcine model.

Preoperative severity of emphysema predictive of improvement after lung volume reduction surgery: use of CT morphometry

STUDY OBJECTIVE

To determine how the volume and severity of emphysema measured by CT morphometry (CTM) before and after lung volume reduction surgery (LVRS) relates to the functional status of patients after LVRS.

DESIGN

A histologically validated CT algorithm was used to quantify the volume and severity of emphysema in 35 patients before and after LVRS: total lung volume (TLV), normal lung volume (< 6.0 mL gas per gram of tissue), volume of mild/moderate emphysema (ME; 6.0 to 10.2 mL gas per gram of tissue), volume of severe emphysema (> 10.2 mL gas per gram of tissue), surface area/volume (SA/V; meters squared per milliliter), and surface area (SA; meters squared). Outcome parameters included maximal cardiopulmonary exercise (CPX) performance in 21 patients and routine pulmonary function in all patients. We hypothesized that baseline CTM parameters predict response to LVRS and that the change in these parameters may offer insight into mechanisms of improvement.

PATIENTS AND INTERVENTION

Thirty-five patients with severe emphysema who had successful LVRS.

RESULTS

The significant decrease in TLV following LVRS was entirely accounted for by a decrease in severe emphysema. The SA/V and the SA both increased significantly following LVRS. The change in maximal CPX in watts following surgery correlated significantly with baseline values of severe emphysema (r = 0.60), which was collinear with TLV, and SA/V. The change in diffusing capacity of the lung for carbon monoxide revealed a significant positive linear relationship with preoperative severe emphysema (r = 0.37) and a negative relationship with ME (r = -0.37). Change in watts revealed a strong relationship with changes in severe emphysema (r = -0.75) and weaker but significant relationships with change in TLV, ME, SA/V, and SA. Other measures of pulmonary function revealed significant albeit less dominant relationships with baseline CTM and change in these indexes.

CONCLUSION

Using CTM, we have identified a close relationship between baseline severe emphysema, or change in severe emphysema, and the improvement in CPX after LVRS. These observations support a potential role of CTM in future clinical trials for predicting responders to LVRS and identifying mechanisms of improvement.

A quantification of the lung surface area in emphysema using computed tomography

Quantitative analysis of computed tomography (CT) has been combined with a stereologically based histologic analysis of lung structure to assess regional lung inflation and the structural features of the lung parenchyma. In this study, CT measurements of lung inflation were compared with histologic estimates of surface area in order to develop prediction equations that allow lung surface to volume ratio and surface area to be predicted from an analysis of the CT scan. The results show that mild emphysema is associated with an increase in lung volume and a reduction in surface to volume ratio, whereas surface area and tissue weight were only decreased in severe disease. The CT predicted surface to volume ratio correlated with histology, and both predicted and measured surface areas correlated with the diffusing capacity. We conclude that this CT analysis can be used to monitor the progression of emphysematous lung destruction in individual patients, and to assess the impact of both surgical and medical treatments for emphysema.

Quantification of idiopathic pulmonary fibrosis using computed tomography and histology

We used computed tomography (CT) and histologic analysis to quantify lung structure in idiopathic pulmonary fibrosis (IPF). CT scans were obtained from IPF and control patients and lung volumes were estimated from measurements of voxel size, and X-ray attenuation values of each voxel. Quantitative estimates of lung structure were obtained from biopsies obtained from diseased and normal CT regions using stereologic methods. CT density was used to calculate the proportion of tissue and air, and this value was used to correct the biopsy specimens to the level of inflation during the CT scan. The data show that IPF is associated with a reduction in airspace volume with no change in tissue volume or weight compared with control lungs. Lung surface area decreased two-thirds (p < 0.001) and mean parenchymal thickness increased tenfold (p < 0.001). An exudate of fluid and cells was present in the airspace of the diseased lung regions and the number of inflammatory cells, collagen, and proteoglycans was increased per 100 g of tissue in IPF. We conclude that IPF reorganized lung tissue content causing a loss of airspace and surface area without increasing the total lung tissue.

Physiological and morphological determinants of maximal expiratory flow in chronic obstructive lung disease

Maximal expiratory flow in chronic obstructive pulmonary disease (COPD) could be reduced by three different mechanisms; loss of lung elastic recoil, decreased airway conductance upstream of flow-limiting segments; and increased collapsibility of airways. We hypothesized that decreased upstream conductance would be related to inflammation and thickening of the airway walls, increased collapsibility would be related to decreased airway cartilage volume, and decreased collapsibility to inflammation and thickening of the airway walls. Lung tissue was obtained from 72 patients with different degrees of COPD, who were operated upon for a solitary peripheral lung lesion. Maximal flow-static recoil (MFSR) plots to estimate upstream resistance and airway collapsibility were derived in 59 patients from preoperatively measured maximal expiratory flow-volume and pressure-volume curves. In 341 transversely cut airway sections, airway size, airway wall dimensions and inflammatory changes were measured. Airflow obstruction correlated with lung elastic recoil and the MFSR estimate of airway conductance but not to airway collapsibility or to the amount of airway cartilage. The upstream conductance decreased as the inner wall became thicker. Airway collapsibility did not correlate with the amount of airway cartilage, inflammation, or airway wall thickness. We conclude that the maximal flow-static recoil model does not adequately reflect the collapsibility of the flow-limiting segment.

Measurement of lung expansion with computed tomography and comparison with quantitative histology

The total and regional lung volumes were estimated from computed tomography (CT), and the pleural pressure gradient was determined by using the milliliters of gas per gram of tissue estimated from the X-ray attenuation values and the pressure-volume curve of the lung. The data show that CT accurately estimated the volume of the resected lobe but overestimated its weight by 24 +/- 19%. The volume of gas per gram of tissue was less in the gravity-dependent regions due to a pleural pressure gradient of 0.24 +/- 0.08 cmH2O/cm of descent in the thorax. The proportion of tissue to air obtained with CT was similar to that obtained by quantitative histology. We conclude that the CT scan can be used to estimate total and regional lung volumes and that measurements of the proportions of tissue and air within the thorax by CT can be used in conjunction with quantitative histology to evaluate lung structure.

Quantitation of neutrophil migration in acute bacterial pneumonia in rabbits

The circulating neutrophils must slow down, adhere to the vessel walls, and migrate out of the microvasculature into the tissue and air spaces to defend the lung against microorganisms. The present study was designed to provide quantitative information about each of these steps. Streptococcus pneumoniae was instilled into the left lower lobe of New Zealand White rabbits to induce a pneumonia, and this lobe was compared with the same region of the opposite lung. The distribution of blood flow was determined by using radiolabeled macroaggregated albumin, and the patterns of perfusion within the capillary bed were quantitated using Monastral blue. The number of neutrophils delivered to the pneumonic site was determined by multiplying the circulating neutrophil count and blood flow. The results show that retention of 51Cr-labeled neutrophils was increased in the pneumonic region 2, 4, and 8 h after instillation of the organisms. The number of intracapillary neutrophils was increased in the pneumonic regions at all time points and in the control regions at 1 and 4 h. Neutrophil migration occurred in the pneumonic site, but only 1-2% of the total neutrophils delivered to the region migrated out of the pulmonary vessels into the air space. We conclude that the circulating neutrophils undergo a generalized response that increases their margination throughout the lung, that increased margination in the pneumonic site changes the distribution of capillary flow, and that the majority of neutrophils delivered to a pneumonic site are returned to the circulation without migrating into the air space.

Erythrocyte and polymorphonuclear cell transit time and concentration in human pulmonary capillaries

Pulmonary capillary transit times were examined in patients who required lung resection by use of 99mTc-labeled macroaggregates (99Tc-MAA) and chromium-labeled erythrocytes (51Cr-RBC) to measure regional blood flow and volume in the resected lung. Cell flow (cells.ml-1.s-1) to each resected lung sample was determined by multiplying the number of polymorphonuclear leukocytes (PMN) per milliliter of circulating blood by the blood flow to that sample. Capillary blood volume was obtained by multiplying the morphometrically determined fraction of pulmonary blood in capillaries by the total 51Cr-RBC volume in each sample. Cell concentrations (cells/ml) in capillary blood were calculated morphometrically, and capillary transit times were obtained by dividing cell concentration by cell flow. The results show that PMN transit times were 60-100 times longer than the RBC transit times, with a 22% overlap between their distributions. We conclude that PMN are concentrated with respect to RBC in pulmonary capillary blood because of differences in their transit times and that these long transit times provide an opportunity for PMN-endothelial interactions.

Lung structure and function in cigarette smokers

BACKGROUND

Cigarette smoking produces an inflammatory response in the airways of everyone but only 15-20% of smokers develop airways obstruction. The present study concerns the relative importance of peripheral airways inflammation and the emphysematous destruction of the parenchymal support of the airways in the pathogenesis of this obstruction.

METHODS

A total of 407 patients with a diagnosis of lung tumour performed pulmonary function tests a day or two before a lung or lobar resection. The specimens were fixed in inflation and analysed at the gross and microscopic level to determine the extent and severity of the emphysematous process, the number of alveoli supporting the outer walls of the airways, and the average distance between alveolar walls. The severity of the inflammatory process in the respiratory and nonrespiratory bronchioles was also assessed using a previously established grading system.

RESULTS

The lung function test showed that a decline in FEV1 was associated with an increase in residual volume and a decrease in the diffusing capacity for carbon monoxide and a reduction in the lung maximum elastic recoil pressure. The prevalence of grossly visible emphysema increased as FEV1 declined, but the extent and severity of these lesions and the number of alveoli supporting the outer walls of the peripheral airways was similar at all levels of FEV1. The system used to grade inflammatory response in the peripheral airways failed to identify a specific defect responsible for the physiological abnormalities.

CONCLUSION

The reduction in FEV1 associated with chronic cigarette smoking can be partially explained by loss of lung elastic recoil pressure which reduces the force driving air out of the lung. This loss of elastic recoil pressure is attributed to microscopic enlargement of the air spaces rather than to grossly visible emphysema. The exact nature of the lesions responsible for the peripheral airways obstruction remains to be identified.

Comparison of neutrophil and capillary diameters and their relation to neutrophil sequestration in the lung

Neutrophils [polymorphonuclear leukocytes (PMNs)] are sequestrated in the lung capillary bed because PMNs are delayed with respect to red blood cells (RBCs) as they pass through these microvessels. The present study examines circulating PMN size in relation to the distribution of capillary segment diameters in human, dog, and rabbit lungs and compares the shape of PMNs in suspension to that found within the pulmonary capillaries. The data show that 61, 67, and 38% of the capillary segments are narrower than the mean diameter of spherical PMNs in the rabbit, dog, and human, respectively. They also show that PMNs deform from a spherical to an ellipsoid shape in the pulmonary capillaries of all three species. These findings are consistent with previous studies showing that the pulmonary circulation restricts the passage of PMNs through the lungs and suggest that PMNs are delayed because they must deform to pass through restrictions encountered in the pulmonary capillary bed. We conclude that the discrepancy between PMN and pulmonary capillary size and the decreased deformability of PMNs with respect to RBCs are major determinants of the delay that PMNs experience with respect to RBCs in the pulmonary circulation.

Neutrophil-associated lung injury after the infusion of activated plasma

Previous studies from our laboratory have shown that the infusion of zymosan-activated plasma (ZAP) caused large numbers of neutrophils (PMN) to accumulate in the lung. Although PMN are known to be activated by ZAP, it is unclear whether PMN delayed in the lung by ZAP infusion actually cause lung injury. The present study was designed to examine this question by measuring airway epithelial and endothelial injury. Airway epithelial injury was determined by depositing a known dose of fluorescein isothiocyanate-labeled dextran in the lung and measuring its appearance in the blood, and endothelial injury was measured by injecting colloidal carbon and measuring its accumulation in the microvasculature of the lung. The data show that ZAP infusion caused a mild epithelial and endothelial injury that did not increase either extravascular water or protein. This injury could be prevented either by depleting the animals of PMN or by pretreating them with indomethacin. In addition, the effect of ZAP infusion could be partially restored by transfusing donor PMN into the PMN-depleted animals. We conclude that ZAP infusion produces a mild lung injury that is dependent on PMN and the products of the cyclooxygenase pathway of arachidonic acid metabolism.

CD18-dependent and -independent mechanisms of neutrophil emigration in the pulmonary and systemic microcirculation of rabbits

Neutrophil (PMN) migration in the systemic and pulmonary circulation of rabbits was compared by using different inflammatory stimuli to determine the role of the leukocyte adhesion complex, CD11/CD18, in each of these vascular beds. The adhesion complex was blocked by administering the anti-CD18 mAb 60.3. The data show that mAb 60.3 blocks PMN emigration into inflammatory foci in the abdominal wall produced by implanting sponges containing either hydrochloric acid, Streptococcus pneumoniae, Escherichia coli endotoxin, or PMA. mAb 60.3 also inhibited PMN emigration in response to peritoneal instillation of S. pneumoniae. The effect of mAb 60.3 on PMN emigration in the lungs varied depending upon the stimulus. PMN failed to migrate into the PMA-induced pneumonia; however, mAb 60.3 pretreatment only partially inhibited endotoxin-induced pneumonia and did not inhibit S. pneumoniae or hydrochloric acid-induced pneumonias. PMN lavaged from the alveolar spaces in the Streptococcal pneumonia had similar quantities of mAb 60.3 bound to their surfaces as the circulating PMN. We conclude that the CD11/CD18 complex mediates PMN adherence in the systemic circulation. However, PMN adherence in the pulmonary circulation may occur by either CD18-dependent or -independent mechanisms that are specific to the inciting stimulus.

CD18-dependent and -independent mechanisms of neutrophil emigration in the pulmonary and systemic microcirculation of rabbits

Neutrophil (PMN) migration in the systemic and pulmonary circulation of rabbits was compared by using different inflammatory stimuli to determine the role of the leukocyte adhesion complex, CD11/CD18, in each of these vascular beds. The adhesion complex was blocked by administering the anti-CD18 mAb 60.3. The data show that mAb 60.3 blocks PMN emigration into inflammatory foci in the abdominal wall produced by implanting sponges containing either hydrochloric acid, Streptococcus pneumoniae, Escherichia coli endotoxin, or PMA. mAb 60.3 also inhibited PMN emigration in response to peritoneal instillation of S. pneumoniae. The effect of mAb 60.3 on PMN emigration in the lungs varied depending upon the stimulus. PMN failed to migrate into the PMA-induced pneumonia; however, mAb 60.3 pretreatment only partially inhibited endotoxin-induced pneumonia and did not inhibit S. pneumoniae or hydrochloric acid-induced pneumonias. PMN lavaged from the alveolar spaces in the Streptococcal pneumonia had similar quantities of mAb 60.3 bound to their surfaces as the circulating PMN. We conclude that the CD11/CD18 complex mediates PMN adherence in the systemic circulation. However, PMN adherence in the pulmonary circulation may occur by either CD18-dependent or -independent mechanisms that are specific to the inciting stimulus.