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PubMed2001

[Measurement of the Fowler dead space in patients with pulmonary emphysema using C18O2].

In patients with lung emphysema, changes in lung volumes as well as changes in airway resistance are well known. The change in airway resistance is caused by obstruction of central airways, which is supposed to reduce the respiratory dead space. Until now, it was not possible to measure the respiratory dead space in patients with lung emphysema using the method of Fowler [2], because in this method distinction of the three phases of an inert gas expirogram is essential. While this distinction is easy in healthy subjects (fig. 1; expirogram 3), the separation of the three phases in patients with lung emphysema is not possible due to gradual transition of phase II into phase III in these patients (fig. 1; expirogram 2). The use of C18O2 as tracer gas allows to separate phase II and phase III even if the patients have severe emphysema (fig. 1; expirogram 1). CO2 labeled with the stable oxygen isotope 18O (C18O2) is completely taken up in the gas exchanging region of the lung, but not from the conducting airways. Therefore C18O2 is only expired from the dead space of the lung, but not from the alveolar region. Hence, C18O2 allows exact measurement of the respiratory dead space in patients with lung emphysema. 21 healthy nonsmoking subjects and 29 patients with clinical signs of lung emphysema participated in this study. There was a good correlation between respiratory dead space, measured by the use of Ar-gas and C18O2-gas in healthy subjects (fig. 2). This indicates, that the use of C18O2 is a valid method to measure the functional dead space. As expected, there was also a correlation between the airway resistance and respiratory dead space in patients with lung emphysema (fig. 3), but not in healty subjects. There was no significant difference of the mean values of the respiratory dead space between these two groups (223 +/- 43 ml in healthy subjects vs. 227 +/- 52 ml in patients), even though there were large differences in airway resistance (0.20 +/- 0.10 kPa/l/s vs. 0.49 +/- 0.27 kPa/l/s). This may be due to a loss of alveolar function in the area of the terminal bronchioli, which is typical for emphysematous patients. This entails a shift of functional dead space towards lung periphery and therefore causes an increase of the volume of functional dead space. But this enlargement may be compensated by the volume reduction, caused by the airway obstruction. Hence, these two oppositional mechanisms may result in only minimal change of dead space volume.

Adult↗

PubMed2002

Gain and subsequent loss of lung function after lung volume reduction surgery in cases of severe emphysema with different morphologic patterns.

OBJECTIVE: Surgical lung volume reduction improves lung function and dyspnea in advanced emphysema to a variable degree. Because long-term results with this procedure are scant, we prospectively investigated lung function over several years after lung volume reduction surgery with regard to emphysema morphology. METHODS: Bilateral video-assisted thoracoscopic lung volume reduction surgery was performed in severely symptomatic patients with marked hyperinflation caused by advanced nonbullous emphysema. Emphysema heterogeneity was visually graded on chest computed tomography. Symptoms and lung function were assessed before the operation and 3, 6, and then every 6 months after the operation. RESULTS: A total of 115 patients with a median forced expiratory volume in 1 second of 0.73 L (27% of predicted value) underwent lung volume reduction surgery. Follow-up extended over a median of 37 months. Median forced expiratory volume in 1 second significantly increased within 6 months after the operation by 37% in homogeneous (n = 27), by 38% in intermediately heterogeneous (n = 37), and by 63% in markedly heterogeneous emphysema (n = 51, P <.05 vs. other morphologies). Maximal forced expiratory volume in 1 second was reached within 6 months after lung volume reduction surgery and decreased in the first postoperative year by 0.16 L per year in homogeneous, by 0.19 L per year in intermediately heterogenous, and by 0.32 L per year in markedly heterogeneous emphysema (P <.01 vs. other morphologies). The decline in forced expiratory volume in 1 second over subsequent years decelerated according to an exponential decay and was similar for all morphologic types (median annual decrease of 0.09 L [9%]). CONCLUSIONS: Lung volume reduction surgery improves lung function in severe homogeneous and, to an even greater extent, heterogeneous emphysema. Forced expiratory volume in 1 second peaks within 6 months postoperatively. The subsequent decline is most rapid in the first year and slows down in succeeding years according to an exponential decay. Therefore, long-term functional results of lung volume reduction surgery may be more favorable than expected from linear extrapolations of short-term observations.

Adult↗

PubMed2005

Detection of mild emphysema by computed tomography density measurements.

PURPOSE: To assess the ability of a conventional density mask method to detect mild emphysema by high-resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema. MATERIAL AND METHODS: Fifty-five healthy male smokers and 34 never-smokers, 61-62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated. RESULTS: Forty-nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65-100% in the apical levels, but low in the rest of the lung. CONCLUSION: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect.

Absorptiometry, Photon↗

PubMed2006

The effect of exercise on peripheral muscle in emphysema: a preliminary investigation.

Emphysema has been associated with loss of aerobic muscle fibers and decreased blood supply. However, when these changes begin and whether exercise can prevent these changes is unknown. The purpose of this study was to examine peripheral muscle at different time points during the development of emphysema and to determine the additional effects of muscle activity. In a series of 3 experiments, emphysema was induced in hamsters. Exercise was simulated through surgical overload (OV) of the plantaris muscle of one leg. Animals were sacrificed at 1, 3, and 5 months following emphysema induction. Fiber type composition and capillary-to-fiber ratio (CFR) were determined. There were no significant changes in fiber type composition in the 1-month group. A significant increase in type IIA fiber composition (mean 72.0 vs. 54.5%) and decrease in type IIB fiber (mean 13.3 vs. 28.1%) was seen in the non-overloaded muscles following 3 months. In the 5-month group, there was a significant decrease in percentage of type I fibers (mean 14.7 vs. 28.0%). There were no significant differences in fiber type composition in the OV limb, regardless of duration. The CFR was significantly lower in the OV limb after 5-months of emphysema (mean 0.92 vs. 1.55 cap/fiber). Muscle overload prevented emphysema-associated changes in fiber type composition, but not in CFR. Peripheral muscle is affected early in the course of emphysema and chronic overload may play an important role in preserving normal muscle composition.

Animals↗

PubMed2005

Different modulation of decorin production by lung fibroblasts from patients with mild and severe emphysema.

We have previously reported diminished immunohistochemical staining of decorin in lung tissue from patients with severe emphysema. The aim of this study is to investigate whether this diminished staining is due to a quantitative abnormal production of decorin by pulmonary fibroblasts in vitro. Therefore, we measured decorin (Western blot), collagen type I (ELISA), and fibronectin (ELISA) production by fibroblasts obtained from lung tissue of patients with severe and mild emphysema at basal culture conditions and after modulation with transforming growth factor-beta1, basic fibroblast growth factor, and interferon-gamma. Decorin production at basal culture conditions was significantly higher in fibroblast cultures from patients with severe emphysema compared to fibroblasts from mild emphysema. After stimulation with transforming growth factor-beta1 and basic fibroblast growth factor, decorin production was significantly more reduced in fibroblast cultures from patients with severe emphysema whereas collagen type I and fibronectin production were not affected. We conclude that decorin production by lung fibroblasts of patients with severe emphysema is dysregulated after modulation with cytokines known to be important in smoking associated inflammation. This dysregulation of decorin production may contribute to the impaired lung tissue repair, present in patients with emphysema, since these alterations in the extracellular matrix may cause diminished cytokine binding and neutralization.

Adult↗

PubMed2006

Modulators of cigarette smoke-induced pulmonary emphysema in A/J mice.

Mice develop pulmonary emphysema after chronic exposure to cigarette smoke (CS). In this study, the influence of gender, exposure duration, and concentration of CS on emphysema, pulmonary function, inflammation, markers of toxicity, and matrix metalloproteinase (MMP) activity was examined in A/J mice. Mice were exposed to CS at either 100 or 250 mg total particulate material/m(3) (CS-100 or CS-250, respectively) for 10, 16, or 22 weeks. Evidence of emphysema was first seen in female mice after 10 weeks of exposure to CS-250, while male mice did not develop emphysema until 16 weeks. Female mice exposed to CS-100 did not have emphysema until 16 weeks, suggesting that disease development depends on the concentration and duration of exposure. Airflow obstruction and increased pulmonary compliance were observed in mice exposed to CS-250 for 22 weeks. Decreased elasticity was likely the major contributor to airflow obstruction because substantial remodeling of the conducting airways, beyond mild mucous cell hyperplasia, was lacking. Exposure to CS increased the number of macrophages, neutrophils, lymphocytes (B cells and activated CD4- and CD8-positive T cells), and activity of MMP-2 and -9 in the bronchoalveolar lavage fluid (BALF). Treatment with antioxidants N-acetylcysteine or epigallocatechin gallate (EGCG) did not decrease emphysema severity, but EGCG slightly decreased BALF inflammatory cell numbers and lactate dehydrogenase activity. Inflammation and emphysema persisted after a 17-week recovery period following exposure to CS-250 for 22 weeks. The similarities of this model to the human disease make it promising for studying disease pathogenesis and assessing new therapeutic interventions.

Animals↗

PubMed2004

Traumatic epidural emphysema.

STUDY DESIGN: This is a case report. OBJECTIVE: A rare case of epidural emphysema secondary to traumatic pneumomediastinum in the absence of pneumothorax is reported. SUMMARY OF BACKGROUND DATA: Epidural air secondary to traumatic pneumomediastinum in the absence of pneumothorax has only been reported previously by Willing. Other causes of traumatic epidural emphysema include pneumothorax, pelvic fracture, dural enteric fistula, and herniation of a spinal disc. METHODS: A young man who sustained blunt cervical and chest trauma after a basketball game accident was found to have pneumomediastinum and surgical emphysema on a chest radiograph and underwent computed tomography (CT). RESULTS: The CT scan demonstrated surgical emphysema, pneumomediastinum, and epidural emphysema with no pneumothorax. The patient was managed conservatively, and the epidural emphysema and pneumomediastinum resolved spontaneously. CONCLUSION: Epidural emphysema secondary to traumatic pneumomediastinum is benign and self-limiting. However, the life-threatening causes should be considered and ruled out.

Adult↗

PubMed2006

Characterization of 133Xe gas washout in pulmonary emphysema with dynamic 133Xe SPECT functional images.

PURPOSE: To characterize regional ventilation impairment of pulmonary emphysema using dynamic 133Xe single photon emission computed tomography (SPECT) functional images, compared with other forms of chronic obstructive pulmonary disease (COPD). METHODS: Dynamic 133Xe SPECT was performed in 34 patients with emphysema and 15 patients with other forms of COPD. Three-dimensional voxel-based functional images of the half-clearance time (T1/2) mainly reflecting the initial rapid washout of 133Xe gas from the large airways, and of the mean transit time (MTT) reflecting 133Xe gas washout from the entire lungs, including the small airways and alveoli, were created based on an area-over-height method. T1/2 and MTT values were compared with the regional extent of low attenuation areas (%LAA) on density-mask computed tomography images and the diffusing capacity of the lungs for carbon monoxide (DLCO). RESULTS: The MTT/T1/2 ratio in each lung in emphysema was significantly higher than that in other forms of COPD (1.60+/-0.74 vs. 1.21+/-0.26; P<0.01). In the selected unilateral lungs with similar T1/2 values, MTT values were also significantly higher in emphysema. MTT values in each lung showed a significantly closer correlation with the corresponding %LAA values compared with T1/2 values in emphysema (R=0.698, P<0.0001 vs. R=0.338, P<0.01; P<0.05); while only the T1/2 values showed a significant correlation in other forms of COPD (P<0.0001). In correlation with DLCO, MTT values showed a significantly closer correlation compared with T1/2 values in emphysema (R=0.909, P<0.0001 vs. R=0.555, P<0.001; P<0.05); while either value did not show a significant correlation in other forms of COPD. CONCLUSION: MTT values are more critically affected in emphysema compared with other forms of COPD without significant alveolar destruction, and MTT and T1/2 values appear to be differently correlated with the regional extent of LAA between these two disorders. Direct comparison of regional T1/2 and MTT values on functional images may contribute to the demarcation of lung pathology of these two disorders.

Administration, Inhalation↗

PubMed2005

Emphysema-induced reductions in locomotory skeletal muscle contractile function.

Patients with COPD suffer from locomotory skeletal muscle contractile dysfunction. This may be due to the disease per se or as a result of some confounding factor. Therefore, the purpose of this investigation was to determine whether emphysema: (1) reduces force production; (2) increases fatigability; and (3) impairs the speed of recovery in locomotory skeletal muscle in an accepted animal model in which many confounding variables can be controlled. To explore this issue, in situ mechanical properties of gastrocnemius were measured in Syrian Golden hamsters 8 months after intratracheal instillation of either saline (control, n = 5) or elastase (emphysema, n = 7). Emphysema increased excised lung volume (80%; P < 0.01), increased fatigability (control, 25% reduction in maximal strength after 4 min of repeated contractions; emphysema, 55% reduction; P < 0.05) and decreased the recovery rate (half-times of recovery: control, 7 +/- 7 s; emphysema, 92 +/- 92 s; P < 0.05) of gastrocnemius muscle. In contrast, emphysema had no effect on maximal force, whether related to body mass or muscle mass, or force-velocity characteristics of gastrocnemius muscle. These data demonstrate that emphysema, independent of physical activity levels, pharmacological intervention, and/or nutritional status, can increase fatigability and impair the speed of recovery of locomotory skeletal muscle contractile function which may contribute to exercise intolerance of COPD patients.

Animals↗

PubMed1994

Quantitative relation between emphysema and lung mineral content in coalworkers.

The relation between quantified emphysema and measured lung content of coal and silica was investigated in the lungs of 264 deceased underground coalworkers who had been exposed to mixed coal and silica dust. Lung specimens obtained at postmortem and inflated and fixed under standard conditions were used to quantify the extent of emphysema and then to measure the amount of coal and silica present in the lungs at the time of death. These data were combined with clinical and other pathological information from the subjects. Multiple regression analysis showed that the extent of emphysema (E score) had a strong positive quantitative relation with coal content of the lungs (p < 0.0003), age (p < 0.0001), and smoking (p < 0.0001). There was a significant negative interaction of uncertain biological importance between coal content of the lungs and smoking (p < 0.004; E score = -1.79 + 0.62 coal + 0.06 age + 0.21 smoking -0.17 coal x smoking; adjusted R2 = 0.25). In lifelong non-smokers emphysema was particularly strongly related to coal content and age (coal: p < 0.001; age: p < 0.002; E score = -1.56 + 0.78 coal + 0.06 age; adjusted R2 = 0.66). The relation was basically unchanged by adding a lung silica content term. Emphysema score was highly negatively correlated with forced expiratory volume in one second (FEV1; % predicted, obtained within five years of death) (r = -0.44, p < 0.0001). Degree of lung fibrosis was highly positively associated with lung silica content (chi 2(1) = 12.9, p < 0.0003). These results provide strong evidence that emphysema in coalworkers is actually related to lung coal content. The role silica in development of emphysema, however remains unclear.

Coal Mining↗

PubMed1978

Diaphragm and body weight in emphysema.

The weight of the diaphragm has been investigated in 103 male patients and 81 female patients, and the relationship between body weight and emphysema has been assessed in 662 male and 431 female patients. Diaphragm weight is related to body weight in both male (r = + 0.76) and female patients (r = +0.77) and is relatively larger in the former. Dissecting the diaphragm free of fat or freeze drying it does not appreciably improve the relationship between body weight and diaphragm weight. Diaphragm weight is better related to body weight than body length and is diminished in emphysema. Patients with emphysema weigh less. This is apparent with only moderate grades of emphysema, and there is no further loss of body weight as emphysema in the lung becomes more severe. The loss of diaphragm weight not only reflects the loss of body weight that occurs in emphysema, but the diaphragm is also less in weight than predicted from body weight. The diaphragm also appears abnormal on gross inspection in some patients with emphysema. Heart weight and diaphragm weight are related, probably because both are related to body weight.

Airway Obstruction↗

PubMed1980

Elastic recoil changes in early emphysema.

An attempt was made to determine if emphysema and static lung recoil were related in a group of 65 excised human lungs. We studied 23 normal lungs, 24 lungs with an emphysema score of 5 or less, and 18 lungs with an emphysema score greater than 5. A comparison of the percentage of predicted elastic recoil revealed that both emphysema groups were significantly different from normal lungs. In addition, the total lung capacities were significantly different between the three groups. In the group with an emphysema score greater than 5 we found a linear negative correlation between the extent of emphysema and percent of predicted elastic recoil at 90% total lung capacity (r = -0.696, p < 0.01). We found a negative correlation between the percentage of predicted elastic recoil and the lung volume (r = -0.612, p < 0.01). We conclude that a significant loss of elastic recoil and a significant increase in total lung capacity occurs in the early stages of emphysema.

Adolescent↗

PubMed1993

The emphysemas: radiologic-pathologic correlations.

There are several forms of emphysema that should be considered as distinct disease entities. No university accepted classification system of these forms exists, but correlations of autopsy findings in 1,823 cases over a 12-year period confirm that the radiographic and pathologic features of the emphysemas are readily understood when centrilobular, panlobular, paracicatricial, and localized types of the disease are recognized. Centrilobular emphysema associated with cigarette smoking is the most common form. Panlobular emphysema is associated with alpha 1-protease inhibitor deficiency and pathologically produces uniform enlargement of all air spaces, with a mild basilar predominance. Paracicatricial emphysema is seen adjacent to areas of parenchymal scarring. Localized emphysema represents focal enlargement or destruction of air spaces with otherwise normal lung. A clear understanding of the computed tomographic appearance of all forms of emphysema is essential for the correct diagnosis of parenchymal lung abnormalities.

Adult↗

PubMed1996

Sliding thin slab, minimum intensity projection technique in the diagnosis of emphysema: histopathologic-CT correlation.

PURPOSE: To assess the accuracy of sliding thin slab, minimum intensity projection technique in the detection of emphysema. MATERIALS AND METHODS: In 29 patients without radiographic evidence of emphysema and who were undergoing lung resection, focal spiral computed tomography (CT) was performed in the lobe to be resected. Ten contiguous 1-mm-thick CT scans and sliding thin slab, minimum intensity projection images with slab thicknesses of 3-, 5-, and 8 mm were generated. From each image, the presence and extent of emphysema were recorded before histopathologic analysis was performed. To familiarize readers with the appearance of normal lung parenchyma on sliding thin slab, minimum intensity projection images, five asymptomatic volunteers underwent scanning with a similar protocol. RESULTS: Emphysema was present on both thin-section CT scans and sliding thin slab, minimum intensity projection images in 13 patients. In all cases, sliding thin slab, minimum intensity projection images improved conspicuity of small areas of hypoattenuation. When thin-section CT scans were negative (n = 16), sliding thin slab, minimum intensity projection images enabled identification of focal zones of hypoattenuation in four cases with histologic confirmation of emphysema. Sensitivity of thin-section CT (62%) and sliding thin slab, minimum intensity projection technique (81%) were significantly different (P < .01); specificity for both was 100%. Emphysema was easier to detect on 8-mm-thick slabs because of better suppression of vascular structures. CONCLUSION: The sliding thin slab, minimum intensity projection technique enabled improved detection of mild forms of emphysema.

Adult↗

PubMed1997

Pulmonary emphysema: comparison of preoperative quantitative CT and physiologic index values with clinical outcome after lung-volume reduction surgery.

PURPOSE: To compare quantitative computed tomographic (CT) and preoperative physiologic values in emphysema with outcome after lung-volume reduction surgery. MATERIALS AND METHODS: In 46 patients, emphysema was quantified by measuring lung attenuation on preoperative CT scans. Quantitative CT and preoperative physiologic values and postoperative outcomes (1-second forced expiratory volume, PaO2, and 6-minute walk distance) were compared. RESULTS: Moderately strong correlations were found between several quantitative CT and preoperative physiologic values (magnitude of r = .29-.58, P < .05) and several quantitative CT and outcome measures (magnitude of r = .31-.47, P < .05). With stratification, postoperative outcome was better with mean lung attenuation greater than -900 HU; 75% or greater of upper lung below -900 HU (emphysema index); greater than 25% of lung below -960 HU (severe emphysema index); ratio of upper- and lower-lung emphysema indexes 1.5 or greater; volume of normally attenuated lung (-850 to -701 HU) greater than 1 L; and full width at half maximum of attenuation-frequency distribution 80 HU or less. Differences in outcome measures between groups stratified with quantitative CT values were often two- to threefold; patients with greater numbers of favorable quantitative CT values had better outcome. Correlations between preoperative physiologic measures and outcome were few. CONCLUSION: In emphysema, quantitative CT values correlate with outcome. Quantitative assessment of emphysema in candidates for lung-volume reduction surgery is potentially useful.

Adult↗

PubMed1984

Pulmonary emphysema and the crossover point.

In 13 healthy subjects and 34 patients with chronic obstructive lung disease (COLD) (23 patients without and 11 patients with emphysema) the breath number at crossover point, using He and SF6 as test gases, and some pulmonary functions (spirometry, body plethysmography and washout curves) were investigated. Although the patients with emphysema did show a more severely impaired lung function than the patients without emphysema, no clear lung function pattern for patients with emphysema was demonstrated in comparison to the patients without emphysema. The pattern of the breath number at crossover point was unpredictable. Most probably this breath number is more related to the severity of impaired gas mixing than to the degree of emphysema. So the clinical diagnosis of emphysema in patients with COLD remains difficult, in spite of the use of advanced technology for fast and accurate analysis by mass spectrometry.

Adult↗

PubMed1994

Collateral ventilation and gas exchange in emphysema.

Resistance to collateral flow of gas is high in the normal human lung but may be lower in emphysema. However, the contribution of collateral ventilation to gas exchange in emphysema remains unclear. This study evaluates the role and magnitude of collateral ventilation between bronchopulmonary segments in six patients with clinical, functional, and computed tomographic evidence of emphysema, compared with our previous findings in 12 normal subjects. To assess collateral flow, a balloon-tipped catheter with a lumen that opened distal to the balloon was inflated in segmental bronchi during fiberoptic bronchoscopy. Respiratory gas tensions were sampled by mass spectrometer from beyond the occlusion via the catheter lumen. Subjects breathed air until occlusion was established and then switched to 79% helium/21% oxygen. The rate of rise of helium concentration was measured within occluded segments and used as an index of collateral ventilation. The mean (+/- SEM) rate of rise of helium concentration was ten times greater in emphysema patients (9.5 +/- 2.7%/min) compared with normal subjects (0.8 +/- 0.3%/min) (p = 0.009). The mean PO2 within occluded segments was similar in normal subjects and emphysema patients: 45.4 +/- 1.8 mm Hg and 44.8 +/- 3.6 mm Hg, respectively. Mean PCO2 within occluded segments was lower in patients (40.1 +/- 1.9 mm Hg) than in normal subjects (46.4 +/- 1.3 mm Hg), probably due to higher regional ventilation-perfusion ratios in emphysema patients rather than collateral ventilation. In emphysema patients there was a positive correlation between rate of rise of helium concentration and final PO2 within an occluded segment (r = 0.73; p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Measurement of emphysema in autopsy lungs, with emphasis on interlobar differences.

This study clarifies interlobar differences in the severity of emphysema and examines the feasibility of assessing emphysema in a whole lung using either the upper or lower lobes. Midsagittal, paper-mounted whole-lung sections from 79 consecutive autopsies were used. The whole-lung sections were scored by comparing them with the panel of standard pictures from Grades 0 to 100, after which the upper or lower lobes were scored in the same way but with the other lobe covered. Scores made on lobes and whole lungs correlated significantly, but while projections to whole-lung scores were quite accurate from the upper lobe, the projections from the lower lobe were less precise. This was particularly true in patients with mild emphysema. Individual lobes of the same lung sections were assessed by the Ryder grid method. This analysis showed that emphysema was more severe in the upper lobe of the 79 consecutive cases. The panel grading method showed more severe emphysema in the upper lobe than in the lower lobe to a panel score of 40; after this, the severity of emphysema in the two lobes was similar. Scores made from the Ryder grid were very similar to those made from the panel. Grading emphysema from one lobe, particularly the lower lobe, is not appropriate if precise clinicopathologic correlations are required.

Autopsy↗