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PubMed2002

[The mechanisms and effects of panax notoginside and methylprednisolone in a rat model of pulmonary fibrosis].

OBJECTIVE: To study the effects of panax notoginside (PNS) and methylprednisolone (solu-medrol) on the development of pulmonary fibrosis and the possible underlining mechanisms. METHODS: Rats were divided into 3 groups: pulmonary fibrosis group, PNS treated group and solu-medrol treated group. On days 1, 3, 7, 14, and 28 after bleomycin treatment, 5 rats in each group were killed and the lungs and plasma were harvested for histopathological studies, immunohistochemical determination of collagen I and III and ELISA detection of MIP-1alpha and MCP-1. RESULTS: The degrees of fibrosis, the levels of collagen I and III, and the levels of MIP-1alpha and MCP-1 decreased significantly in the PNS and solu-medrol treated groups as compared with the fibrosis group (P < 0.05). CONCLUSION: Both PNS and solu-medrol are effective in modulating the process of pulmonary fibrosis induced by bleomycin in rats.

Animals↗

PubMed1994

Trichloroethylene induces pulmonary fibrosis in mice.

Trichloroethylene elicits acute pulmonary cytotoxicity in mice, which involves Clara cells of bronchioles. In this study, we have examined the effects of an acute dose of trichloroethylene in lungs of mice over 3 months. Pulmonary fibrosis was first detected at 15 days and was progressive with time elapsed after trichloroethylene exposure. Diffuse interstitial fibrosis was observed in the alveolar zone, resulting in thickening of alveolar septa and distortion of lung structure. The fibrosis was most pronounced at 90 days after treatment, resulting in deposition of connective tissue in the alveolar septa. Levels of total lung hydroxyproline were not significantly different in control and treated mice at 30 and 60 days after trichloroethylene treatment, but were significantly increased at 90 days. Proline content remained unchanged during the course of this study. The increase in collagen deposition at 90 days coincided with a significant increase in lung elastic recoil. Our results show that a single acute dose of trichloroethylene causes structural and functional abnormalities that are progressive for at least 3 months.

Animals↗

PubMed2005

Health-related quality of life in patients with idiopathic pulmonary fibrosis: a systematic review.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) profoundly affects the quality of patients' lives. A systematic review was performed to evaluate critically the published literature and to examine what is known about health-related quality of life (HRQL) in patients with IPF. METHODS: The MEDLINE, EMBASE, Health and Psychosocial Instruments, and Cochrane Library databases were searched to 1 April 2004. Abstracts and bibliographies of published articles were scanned and contact was made with investigators. Included studies analysed HRQL (or quality of life) in at least 10 patients with IPF. Two reviewers independently selected studies, evaluated their quality according to predetermined criteria, and abstracted data on study design, patients' demographic and clinical characteristics, and quality of life outcome measures. RESULTS: Seven studies met the inclusion criteria. The studies enrolled 512 patients with IPF and used three different instruments to measure HRQL. All studies had important limitations in methodological quality; none measured longitudinal changes in HRQL over time. Patients reported substantially impaired HRQL, especially in domains that measured physical health and level of independence. Patients with IPF appear to have similar impairments in HRQL to those with chronic obstructive pulmonary disease. Measures of dyspnoea were moderately correlated with scores from domains that measured physical health (R2 = 0.03-0.66) and energy/fatigue/pep (R2 = 0.19-0.55), but measures of pulmonary function and gas exchange did not correlate as strongly with these and other domains. CONCLUSION: Studies of HRQL in patients with IPF suggest that, in addition to the obvious effect on physical health, general health, energy level, respiratory symptoms, and level of independence are also impaired. Variability in HRQL among patients is not fully explained by measures of dyspnoea or pulmonary function, suggesting that HRQL measures provide unique information. More research is needed to identify or design appropriate measurement instruments for patients with IPF and to examine changes in HRQL over time or in response to specific treatments.

Aged↗

PubMed2003

[Prevention and treatment of pulmonary-fibrosis by traditional Chinese medicine].

Pulmonary-fibrosis (PF) is the result of interstitial lung disease which has different causes and it is one of the most intractable diseases in respiratory system. The PF is characterized by progressive difficulty of breath and dying of respiratory failure, seriously threatening the health of people. Immunosuppressive drugs and glucocorticoids have been widely adopted as the main methods in treatment, but the results are not satisfactory and the side effects are obvious. Many specialists have tried traditional Chinese medicine in recent years with satisfactory effect, indicating that the prospect of using traditional Chinese medicine in the treatment of PF is optimistic. This article outlines the researches about using traditional Chinese medicine in the treatment of PF.

China↗

PubMed2004

Idiopathic pulmonary fibrosis: emerging concepts on pharmacotherapy.

Idiopathic pulmonary fibrosis (IPF) is a progressive, fibrosing disease of the distal air spaces of the lung of unknown aetiology. IPF is usually fatal with a median survival of < 3 years. There are currently no effective pharmacotherapeutic agents for the treatment of IPF. In this review, unifying concepts on the pathogenesis of IPF based on understanding of host responses to tissue injury are presented. These host responses involve tightly regulated and contextually orchestrated inflammatory and repair processes. Dysregulation of either of these processes can lead to pathological outcomes. Fibrosis results from an exaggerated or dysregulated repair process that proceeds 'uncontrolled' even after inflammatory responses have subsided. Disease heterogeneity may arise when inflammation and repair are in different (dys)regulatory phases, thus accounting for regional disparity. Usual interstitial pneumonia (UIP), the histopathological correlate of clinical IPF, represents a more fibrotic tissue reaction pattern and for which anti-inflammatory agents are ineffective. Emerging 'antifibrotic' drugs and strategies for UIP/IPF are discussed. The importance of accurately phenotyping a highly heterogeneous disease process that may require individualised and 'combined' therapies is emphasised.

Acetylcysteine↗

PubMedDate not supplied

[Pulmonary fibrosis in children: diagnosis and therapy].

Pulmonary fibrosis is a chronic disorder characterized by inflammation, injury and fibrosis of the alveolar structures and consequent loss of functional alveolar-capillary units. It involves a number of unresolved terminologic, pathogenetic, diagnostic and therapeutic controversies. The key to understanding the disease is the recognition that inflammation is the first event. The staging of the patients, important for correct therapy decision, is made using methods that specifically evaluate the inflammation such as open lung biopsy, bronchoalveolar lavage, and Gallium 67 scanning. The most rational therapeutic approach is to suppress the inflammation and to prevent further injury and scarring. The drugs of choice for treatment are corticosteroids (prednisone particularly). It is suggested to use large doses during the initial portion of the therapeutic trial followed by a tapering of the dose. If the patient does not respond to corticosteroids other immunosuppressive agents can be considered, particularly cyclophosphamide. The frequency and duration of response to these regimens remains to be defined.

Adrenal Cortex Hormones↗

PubMed2006

Current perspectives on the treatment of idiopathic pulmonary fibrosis.

The clinical course of idiopathic pulmonary fibrosis (IPF) is variable; however, the long-term survival in IPF is poor. Prednisone has been the mainstay of therapy since its release for clinical use in 1948. Recently, prednisone combined with azathioprine or cyclophosphamide has been used. A number of other drug combinations have been tried with prednisone (e.g., methotrexate, colchicine, penicillamine, or cyclosporine) but have failed or are not well tolerated by the patient. Few high quality, prospective, controlled clinical trials have been performed. Thus, there is no good evidence to support the routine use of any specific therapy in the management of IPF. Additional large clinical trials are needed to confirm the potential usefulness of the newer agents (e.g., IFN-gamma1b, pirfenidone, N-acetylcysteine, coumadin, bosentan, or etanercept). This article examines the body of evidence supporting the current therapies and reviews the newer agents being tested in patients with IPF.

Acetylcysteine↗

PubMed2002

[Treatment of pulmonary fibrosis].

A RECENTLY MODIFIED CONCEPT: Idiopathic pulmonary fibrosis (IPF) is characterized by dyspnea on exertion, diffuse radiological infiltrates and alterations in respiratory function. The approach to IPF has recently changed with a more precise definition of the histological diagnostic criteria (hence excluding other disorders such as non-specific interstitial pneumonia), and with the hypothesis that fibro-proliferation and abnormalities in epithelial repair may have a greater physiopathological role than inflammation. DEBATABLE RESULTS FOR CORTICOSTEROIDS: To date, no treatment has demonstrated its efficacy in this disorder and few randomised studies are available. Although early observations showed some benefit of corticosteroids, it is now well established that these studies in fact included a proportion of other corticosteroid-sensitive diseases, such as non-specific interstitial pneumonia. In more recent studies, in which the diagnosis of IPF was made more rigorously, no convincing demonstration of the efficacy of corticosteroids or of immunosuppressive treatments (cyclophosphamide, azathioprine) was made. A trial of corticosteroid therapy for a period of 3 to 6 months (possibly combined with immunosuppressors) is still recommended in the absence of contraindications, but with rigorous and objective assessment of the efficacy, and careful monitoring of the side effects. TREATMENTS UNDER STUDY: Treatments aimed at limiting fibrogenesis have also been proposed. However, clinical studies have not confirmed the initial results obtained with colchicine. Nevertheless, encouraging results have been obtained with other "anti-fibrosing" agents (such as pirfenidone) or immunomodulators (interferon-gamma-1b); such treatment should be further evaluated by larger, randomised, controlled trials in order to know whether these results are applicable to a less selected population. BETWEEN SYMPTOMATIC CARE AND TRANSPLANTATION: In the absence of effective treatment, the management of IPF, the diagnosis of which has been confirmed by rigorous criteria (ideally lung biopsy) is primarily symptomatic. Young patients should be assessed with a view of pulmonary transplantation.

Adjuvants, Immunologic↗

PubMed2005

Treatment of idiopathic pulmonary fibrosis: is there anything new?

Idiopathic pulmonary fibrosis (IPF) is a specific form of chronic fibrosing interstitial pneumonia of unknown aetiology and is associated with the histological picture of usual interstitial pneumonia. Treatment in most cases is unsatisfactory and the prognosis remains poor. There is insufficient evidence to suggest that any treatment, apart from lung transplantation, improves survival or halts disease progression for IPF patients. Data on treatment response are limited by the paucity of clinical trails, the lack of homogenous clinical features, the small number of patients, and the absence of histological and radiological documentation in many cases. Anti-inflammatory medications such as corticosteroids, azathioprine and cyclophosphamide remain the commonly used medications. More recently, it has been proposed that IPF is a primary fibrotic disease rather than an inflammatory condition. Antifibrotic agents such as colchicine, pirfenidone and interferon-gamma (IFN-gamma) have been tried. However, a recent placebo-controlled trial has failed to demonstrate a significant effect of IFN-gamma on disease progression, lung function or quality of life in IPF patients, though a clinically significant survival benefit of the drug could not be ruled out.

Anti-Inflammatory Agents↗

PubMed2001

Infection of TT virus in patients with idiopathic pulmonary fibrosis.

The precipitating factors of idiopathic pulmonary fibrosis (IPF) have not been elucidated. Recently, a novel DNA virus named TTvirus (TTV) was discovered in a patient with post-transfusion hepatitis of unknown aetiology TTV is a circular, single-stranded DNA virus of 3.8 kB. To evaluate the relationship between TTV and IPF, the sera of 33 patients with IPF were tested for the presence of TTV DNA by semi-nested polymerase chain reaction. TTV DNA was detected in 12 (36.4%) IPF patients. The serum lactate dehydrogenase (LDH) level was significantly higher in the IPF patients withTTV than in those without TTV (802 +/- 121 vs. 530 +/- 49 IU l(-1), p < 0.05). Six (50%) of 12 patients in theTTV DNA-positive group died during the observation period, while only six (28.6%) of 21 patients in theTTV DNA-negative group died. The 3-year-survival rate was significantly lower in the TTV DNA-positive group than in theTTV DNA-negative group (58-3% vs. 95.2%, P <0-02). Replicative intermediate forms of TTV DNA were detected in the lung specimen from a TTV-infected IPF patient. TTV infection influences the disease activityand prognosis of IPF in some cases. Further studies are required to elucidate the clinical significance of TTV in IPF.

Acute Disease↗

PubMed2006

[Clinical analysis of the acute exacerbation in patients with idiopathic pulmonary fibrosis].

The clinical course of idiopathic pulmonary fibrosis (IPF) is chronic, but some patients with IPF have phases of accelerated deterioration superimposed on the chronic course of their illness, which is referred to as acute exacerbation (Aex) of IPF. To evaluate the clinical feature of Aex of IPF, we analyzed clinical findings of the 112 patients with IPF admitted to our hospital from 1994 to 2004. Of the 112 patients 56 with IPF died during the observation period due to Aex (42.9%), lung cancer (21.4%), chronic respiratory failure (14.3%), and lower respiratory infections (8.9%). Aex of IPF was seen 28 of 112 patients with IPF (25.0%) and 24 patients (85.7%) died with Aex. The median survival time (MST) after the onset of Aex was 0.9 months. The 5-yr survival rate of all patients with IPF was 38.3% and the MST was 3.1 yrs after diagnosis. On the other hand, the 5-yr survival rate and MST was 10.7% and 0.6 yrs in patients with Aex of IPF. We treated the patients with Aex with methylprednisolone pulse therapy in combination with cyclophosphamide or cyclosporine A, which did not significantly improve the outcome of Aex. In conclusion, there is little evidence that currently accepted treatments are effective in Aex of IPF, and further studies are needed to clarify the pathogenesis and contribute to the prevention of Aex.

Aged↗

PubMed1983

Effect of the beige mutation on bleomycin-induced pulmonary fibrosis in mice.

A single endotracheal administration of bleomycin causes pulmonary fibrosis in several animal species. In view of the functional deficits in neutrophil function as a result of the beige mouse (bg/bg) mutation, its effect on bleomycin-induced pulmonary fibrosis was examined to evaluate the role of the neutrophil in such a response. Neutrophils from beige mice showed a selective defect in the ability to degranulate in response to cytochalasin B and formyl-methionyl-leucyl-phenylalanine, without impairing their ability to produce superoxide anion and H2O2 in response to the same stimuli as well as phorbol myristate acetate. Despite this functional deficit, beige mice responded more intensely to bleomycin than did their heterozygote controls at both 2 wk and 1 month after drug instillation, as assessed by both lung collagen and deposition. This suggests that the inability to mobilize hydrolytic enzymes has no effect on the ability to mount a fibrogenic response, and it would even be detrimental by enhancing such a response caused by decreased connective tissue catabolism as a consequence of the inability to release the granule enzymes to the extracellular space.

Animals↗

PubMed1992

Use of intermittent, intravenous cyclophosphamide for idiopathic pulmonary fibrosis.

STUDY OBJECTIVE: To determine the safety and efficacy of intravenous cyclophosphamide for patients with idiopathic pulmonary fibrosis. DESIGN: Nonrandomized, open-labeled study of efficacy in symptomatic patients. SETTING: Patients were treated as outpatients in a referral clinic. PATIENTS: All patients had idiopathic pulmonary fibrosis with symptoms of dyspnea on exertion. Patients had either worsening disease or contraindication to corticosteroids. INTERVENTION: Thirty-three patients were treated with intravenous cyclophosphamide every two weeks. Initial dosage was 500 mg, and the dose was escalated provided the total white blood cell count remained > 3,000 cells per cubic millimeter. The maximum dose administered was 1,000 to 1,800 mg of cyclophosphamide. Corticosteroid therapy was tapered as tolerated by the patient. MEASUREMENTS AND RESULTS: Patients were treated for at least six months or until death. For the 33 patients, 18-month probability of survival was > 50 percent. For those patients surviving six months, there was a significant rise in the vital capacity (from 1.6 +/- .61 L [mean +/- SD] to 1.8 +/- .52 L, p < 0.01) which persisted for at least 18 months of treatment. This was associated with a significant fall in the average prednisone dosage from 32 +/- 13.0 mg/day to 4 +/- 10.4 mg/day (p < 0.01) by 12 months. Only one patient required hospitalization for possible drug-related toxic reaction. CONCLUSIONS: Intermittent, intravenous cyclophosphamide therapy was associated with improved pulmonary function and reduced corticosteroid dosage in patients with idiopathic pulmonary fibrosis who survived at least six months after institution of therapy.

Cyclophosphamide↗

PubMed2003

Suboptimal erythropoietic response to hypoxemia in idiopathic pulmonary fibrosis.

BACKGROUND AND STUDY OBJECTIVES: Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory process characterized by severe derangement of gas exchange in the advanced stages of disease. However, erythrocytosis is infrequent in IPF. The aim of this study was to investigate the potential relation between the blunted erythropoietic response and the chronic inflammation. SUBJECTS: Nine patients (6 men and 3 women) with IPF and profound hypoxemia (PO(2) < 65 mm Hg) and 34 sex- and age-matched healthy volunteers participated in the study. METHODS: We evaluated the hematologic parameters, serum erythropoietin, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 levels. We also studied the development of burst-forming unit-erythroid (BFU-E)-derived colonies in semisolid methylcellulose cultures in blood samples from all patients. RESULTS: Hemoglobin and serum erythropoietin levels were almost comparable between the two studied groups. On the contrary, serum TNF-alpha, IL-6, and IL-8 values were significantly higher in patients with IPF (p < 0.05, p < 0.01, and p < 0.001, respectively). IPF sera induced a significant growth inhibition of erythroid bursts arising from mononuclear cells of either patients or control subjects compared with heat-inactivated AB serum (p < 0.05 and p < 0.01, respectively). Moreover, there was an apparent increment in the number of BFU-E colonies when patients' mononuclear cells were cultured in comparison with those of healthy subjects (p < 0.05). CONCLUSIONS: Our findings suggest that in IPF there is an increased number of primitive erythroid progenitors, which fail to proliferate and differentiate in vivo, suggesting a kind of ineffective erythropoiesis. As a consequence, hemoglobin levels do not rise in proportion to the severity of hypoxemia. Cytokines released from alveolar macrophages seem to have not only local but also systemic effects, since the serum of these patients directly suppressed erythropoiesis; however, the suboptimal erythropoietic response to hypoxia cannot be entirely attributed to this suppression. It is possible that several other factors interfere, synergistically or additively.

Aged↗

PubMedDate not supplied

Systemic immune cell activation in a subgroup of patients with idiopathic pulmonary fibrosis.

BACKGROUND: The prognosis of idiopathic pulmonary fibrosis (IPF/UIP) is poor and its immunopathogenesis is insufficiently understood. OBJECTIVES: The aim of our study was to elucidate the compartmentalization of cell activation and the influence of corticosteroid therapy upon this activation in IPF/UIP. We determined the concentrations of proinflammatory cytokines released by bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMNC) in treated and untreated patients with IPF/UIP. We chose tumor necrosis factor-alpha (TNFalpha) since it is a cytokine predominantly secreted by cells of the monocyte/macrophage lineage and interleukin-2 (IL-2) exclusively by T lymphocytes. METHODS: The release of TNFalpha and IL-2 by BAL cells and PBMNC was measured in cell culture supernatants of 72 treated and untreated IPF/UIP patients. Additionally, in the blood compartment serological parameters reflecting the monocyte/macrophage and lymphocyte activation, such as neopterin and soluble IL-2 receptor (sIL-2R), were determined. RESULTS: The TNFalpha release by BAL cells was significantly elevated in both groups compared to controls but did not differ between treated and untreated patients with IPF/UIP. In 7 of 19 untreated patients with IPF, PBMNC were activated and released increased amounts of TNFalpha. In only 1 of 17 treated patients with IPF, TNFalpha release by PBMNC could be found. The serum level of neopterin, a marker of cell activation of the monocyte/macrophage lineage did not differ between treated and untreated patients. The BAL lymphocyte and PBMNC IL-2 release was significantly elevated in IPF/UIP patients without therapy compared to controls (p < 0.05). In contrast, no IL-2 release of BAL cells or PBMNC was observed in treated IPF/UIP patients. Lymphocyte activation was furthermore identified in untreated IPF patients by elevated soluble IL-2 receptor serum concentrations (p < 0.0001). CONCLUSIONS: Cells of the monocyte/macrophage lineage and T lymphocytes are activated in BAL cells and PBMNC of patients with IPF/UIP. During treatment, the systemic and local activation of T cells is suppressed. BAL macrophages, however, maintain their activated status, which might be the cause for the frequent chronic progression of the disease.

Bronchoalveolar Lavage Fluid↗

PubMed2006

Constitutive ALK5-independent c-Jun N-terminal kinase activation contributes to endothelin-1 overexpression in pulmonary fibrosis: evidence of an autocrine endothelin loop operating through the endothelin A and B receptors.

The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor beta (TGF-beta) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-beta induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-beta are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis.

Actins↗

PubMed1994

[Effects of tanshionone to bleomycin induced pulmonary fibrosis of rats on histological changes and production of lipid peroxides and hydroxyproline].

Study was designed to explore the effect of sodium tanshionone IIA sulfonate on bleomycin-induced pulmonary fibrosis in rat. The amount of lipid peroxides (LPO), hydroxyproline in rat lung tissue homogenate was determined at 3, 7, 14, 28 day after administration respectively. The results suggest that the amount of LPO, hydroxyproline of rat lung homogenate were significantly decreased in sodium tanshionone IIA sulfonate group. In addition, histological changes and width of alveolar septa and percentage area of pulmonary fibrosis scars was measured. The results show that sodium tanshionone IIA sulfonate could ameliorate bleomycin induced pulmonary fibrosis in rat. The mechanism that sodium tanshionone IIA sulfonate could prevent and treat bleomycin-induced pulmonary fibrosis in rat was discussed.

Animals↗

PubMed1993

Cause of regional ventilation-perfusion mismatching in patients with idiopathic pulmonary fibrosis: a combined CT and scintigraphic study.

OBJECTIVE: Regional ventilation and perfusion were studied in patients with idiopathic pulmonary fibrosis (cryptogenic fibrosing alveolitis) to seek an explanation for the mismatched ventilation/perfusion (V/Q) seen on scintigrams, which may suggest pulmonary embolic disease. SUBJECTS AND METHODS: Eight patients with idiopathic pulmonary fibrosis were examined with inspiratory and expiratory CT scans. Planar and tomographic (single-photon emission computed tomography, SPECT) scintigraphy, using inhalation of krypton-81m gas (ventilation) and IV injection of 99mTc-albumin macroaggregates (perfusion), also was performed. The lungs were divided into quadrants (cranial, caudal, right, left) for analysis. RESULTS: Cystic air spaces with a "honeycomb" appearance occupied more than 33% of the cross-sectional area in 75% of all lung quadrants (n = 16), more than 66% of the area in 44% of quadrants, and less than 33% of the area in the remaining 25% of quadrants. On expiratory CT scans, the cross-sectional area of the cystic spaces diminished significantly (unlike emphysematous spaces). Sixty-seven percent of lung quadrants, corresponding to those with marked or moderate involvement with cystic spaces, showed a mismatched V/Q pattern on scintigrams (absent perfusion, normal ventilation); 27% of quadrants had matched V/Q defects, and 6% did not show defects. Two patients had, in addition, large cystic spaces typical of emphysema, but the coexistent fibrosis prevented the gross air trapping seen in bullous emphysema. CONCLUSION: The cystic air spaces that are often seen on CT scans of patients with idiopathic pulmonary fibrosis are unperfused (probably due to vascular obliteration) but are usually normally ventilated. This V/Q mismatch on scintigrams explains the large physiologic dead space seen at rest and on exercise and could suggest pulmonary embolism unless a CT scan is obtained. Conversely, the larger cystic spaces might be mistaken for emphysema unless V/Q scintigraphy is done.

Adult↗