Association among cardiopulmonary and metabolic rehabilitation, arrhythmias, and myocardial ischemia responses of patients with HFpEF or HFmrEF.

There's limited evidence of the potential benefits of cardiopulmonary and metabolic rehabilitation (CPMR) in patients with heart failure with preserved ejection fraction (HFpEF) or mildly reduced ejection fraction (HFmrEF) and coronary artery disease (CAD). The aim of this study was to investigate the impact of CPMR on the myocardial ischemia response (MIR), exercise-induced arrhythmias (EIA), New York Heart Association (NYHA) functional class, heart rate recovery (HRR), Borg CR10 perceived symptoms, and the SF-36 physical and mental health summary scores. A prospective cohort study was conducted with 106 patients undergoing 12 weeks of CPMR who completed two exercise tests pre- and post-CPMR: 1) maximum incremental test (CPX) and 2) submaximal constant load test (SUB). After CPMR, the effects on MIR, EIA, NYHA functional class, and HRR during both tests were analyzed. There was a significant change in NYHA functional classes after CPMR, with 96% of the patients in class I (vs 62% pre-CPMR, P<0.0001), 4% in class II (vs 32%), and none in class III (vs 6%). There was a significant reduction in the frequency of EIA (P<0.05) and MIR (P<0.001) and a significantly improved performance on both CPX and SUB tests (P<0.0001). Lastly, there was significant progress in the recovery metrics like HRR (P<0.0001), the Borg CR10 (P<0.0001), and the SF-36 summary scores (P<0.0001). The CPMR resulted in a significant decrease in EIA, delayed ischemia threshold in CPX and SUB tests, increased functional capacity, and improved quality of life.

Texture-based classification of lung disease patterns in chronic hypersensitivity pneumonitis and comparison to clinical outcomes.

Computer-aided detection algorithms applied to CT lung imaging have the potential to objectively quantify pulmonary pathology. We aim to develop an automatic classification method based on textural features able to classify healthy and pathological patterns on CT lung images and to quantify the extent of each disease pattern in a group of patients with chronic hypersensitivity pneumonitis (cHP), in comparison to pulmonary function tests (PFTs).27 cHP patients were scanned via high resolution CT (HRCT) at full-inspiration. Regions of interest (ROIs) were extracted and labeled as normal (NOR), ground glass opacity (GGO), reticulation (RET), consolidation (C), honeycombing (HB) and air trapping (AT). For each ROI, statistical, morphological and fractal parameters were computed. For automatic classification, we compared two classification methods (Bayesian and Support Vector Machine) and three ROI sizes. The classifier was therefore applied to the overall CT images and the extent of each class was calculated and compared to PFTs. Better classification accuracy was found for the Bayesian classifier and the 16x16 ROI size: 92.1±2.7%. The extent of GGO, HB and NOR significantly correlated with forced vital capacity (FVC) and the extent of NOR with carbon monoxide diffusing capacity (DLCO).Clinical Relevance- Texture analysis can differentiate and objectively quantify pathological classes in the lung parenchyma and may represent a quantitative diagnostic tool in cHP.

Short-term effects of stored homologous red blood cell transfusion on cardiorespiratory function and inflammation: an experimental study in a hypovolemia model

The pathophysiological mechanisms associated with the effects of red blood cell (RBC) transfusion on cardiopulmonary function and inflammation are unclear. We developed an experimental model of homologous 14-days stored RBC transfusion in hypovolemic swine to evaluate the short-term effects of transfusion on cardiopulmonary system and inflammation. Sixteen healthy male anesthetized swine (68±3.3 kg) were submitted to controlled hemorrhage (25% of blood volume). Two units of non-filtered RBC from each animal were stored under blood bank conditions for 14 days. After 30 min of hypovolemia, the control group (n=8) received an infusion of lactated Ringer's solution (three times the removed volume). The transfusion group (n=8) received two units of homologous 14-days stored RBC and lactated Ringer's solution in a volume that was three times the difference between blood removed and blood transfusion infused. Both groups were followed up for 6 h after resuscitation with collection of hemodynamic and respiratory data. Cytokines and RNA expression were measured in plasma and lung tissue. Stored RBC transfusion significantly increased mixed oxygen venous saturation and arterial oxygen content. Transfusion was not associated with alterations on pulmonary function. Pulmonary concentrations of cytokines were not different between groups. Gene expression for lung cytokines demonstrated a 2-fold increase in mRNA level for inducible nitric oxide synthase and a 0.5-fold decrease in mRNA content for IL-21 in the transfused group. Thus, stored homologous RBC transfusion in a hypovolemia model improved cardiovascular parameters but did not induce significant effects on microcirculation, pulmonary inflammation and respiratory function up to 6 h after transfusion.

Short-term effects of stored homologous red blood cell transfusion on cardiorespiratory function and inflammation: an experimental study in a hypovolemia model.

The pathophysiological mechanisms associated with the effects of red blood cell (RBC) transfusion on cardiopulmonary function and inflammation are unclear. We developed an experimental model of homologous 14-days stored RBC transfusion in hypovolemic swine to evaluate the short-term effects of transfusion on cardiopulmonary system and inflammation. Sixteen healthy male anesthetized swine (68±3.3 kg) were submitted to controlled hemorrhage (25% of blood volume). Two units of non-filtered RBC from each animal were stored under blood bank conditions for 14 days. After 30 min of hypovolemia, the control group (n=8) received an infusion of lactated Ringer's solution (three times the removed volume). The transfusion group (n=8) received two units of homologous 14-days stored RBC and lactated Ringer's solution in a volume that was three times the difference between blood removed and blood transfusion infused. Both groups were followed up for 6 h after resuscitation with collection of hemodynamic and respiratory data. Cytokines and RNA expression were measured in plasma and lung tissue. Stored RBC transfusion significantly increased mixed oxygen venous saturation and arterial oxygen content. Transfusion was not associated with alterations on pulmonary function. Pulmonary concentrations of cytokines were not different between groups. Gene expression for lung cytokines demonstrated a 2-fold increase in mRNA level for inducible nitric oxide synthase and a 0.5-fold decrease in mRNA content for IL-21 in the transfused group. Thus, stored homologous RBC transfusion in a hypovolemia model improved cardiovascular parameters but did not induce significant effects on microcirculation, pulmonary inflammation and respiratory function up to 6 h after transfusion.

There is no cephalocaudal gradient of computed tomography densities or lung behavior in supine patients with acute respiratory distress syndrome.

BACKGROUND: There is debate whether pressure transmission within the lungs and alveolar collapse follow a hydrostatic pattern or the compression exerted by the weight of the heart and the diaphragm causes collapse localized in the areas adjacent to these structures. The second hypothesis proposes the existence of a cephalocaudal gradient in alveolar collapse. We aimed to define whether or not lung density and collapse follow a 'liquid-like' pattern with homogeneous isogravitational layers along the cephalocaudal axis in acute respiratory distress syndrome lungs. METHODS: Acute respiratory distress syndrome patients were submitted to full lung computed tomography scans at positive end-expiratory pressure (PEEP) zero (before) and 25 cmH2 O after a maximum-recruitment maneuver. PEEP was then decreased by 2 cmH2 O every 4 min, and a semi-complete scan performed at the end of each PEEP step. RESULTS: Lung densities were homogeneous within each lung layer. Lung density increased along the ventrodorsal axis toward the dorsal region (ß = 0.49, P < 0.001), while there was no increase, but rather a slight decrease, toward the diaphragm along the cephalocaudal axis and toward the heart. Higher PEEP attenuated density gradients. At PEEP 18 cmH2 O, dependent lung regions started to collapse massively, while best compliance was only reached at a lower PEEP. CONCLUSIONS: We could not detect cephalocaudal gradients in lung densities or in alveolar collapse. Likely, external pressures applied on the lung by the chest wall, organs, and effusions are transmitted throughout the lung in a hydrostatic pattern with homogeneous consequences at each isogravitational layer. A single cross-sectional image of the lung could fully represent the heterogeneous mechanical properties of dependent and non-dependent lung regions.

Lymphatic fluctuation in the parenchymal remodeling stage of acute interstitial pneumonia, organizing pneumonia, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis

Because the superficial lymphatics in the lungs are distributed in the subpleural, interlobular and peribroncovascular interstitium, lymphatic impairment may occur in the lungs of patients with idiopathic interstitial pneumonias (IIPs) and increase their severity. We investigated the distribution of lymphatics in different remodeling stages of IIPs by immunohistochemistry using the D2-40 antibody. Pulmonary tissue was obtained from 69 patients with acute interstitial pneumonia/diffuse alveolar damage (AIP/DAD, N = 24), cryptogenic organizing pneumonia/organizing pneumonia (COP/OP, N = 6), nonspecific interstitial pneumonia (NSIP/NSIP, N = 20), and idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP, N = 19). D2-40+ lymphatic in the lesions was quantitatively determined and associated with remodeling stage score. We observed an increase in the D2-40+ percent from DAD (6.66 ± 1.11) to UIP (23.45 ± 5.24, P = 0.008) with the advanced process of remodeling stage of the lesions. Kaplan-Meier survival curves showed a better survival for patients with higher lymphatic D2-40+ expression than 9.3%. Lymphatic impairment occurs in the lungs of IIPs and its severity increases according to remodeling stage. The results suggest that disruption of the superficial lymphatics may impair alveolar clearance, delay organ repair and cause severe disease progress mainly in patients with AIP/DAD. Therefore, lymphatic distribution may serve as a surrogate marker for the identification of patients at greatest risk for death due to IIPs.

Lymphatic fluctuation in the parenchymal remodeling stage of acute interstitial pneumonia, organizing pneumonia, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis.

Because the superficial lymphatics in the lungs are distributed in the subpleural, interlobular and peribroncovascular interstitium, lymphatic impairment may occur in the lungs of patients with idiopathic interstitial pneumonias (IIPs) and increase their severity. We investigated the distribution of lymphatics in different remodeling stages of IIPs by immunohistochemistry using the D2-40 antibody. Pulmonary tissue was obtained from 69 patients with acute interstitial pneumonia/diffuse alveolar damage (AIP/DAD, N = 24), cryptogenic organizing pneumonia/organizing pneumonia (COP/OP, N = 6), nonspecific interstitial pneumonia (NSIP/NSIP, N = 20), and idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP, N = 19). D2-40+ lymphatic in the lesions was quantitatively determined and associated with remodeling stage score. We observed an increase in the D2-40+ percent from DAD (6.66 ± 1.11) to UIP (23.45 ± 5.24, P = 0.008) with the advanced process of remodeling stage of the lesions. Kaplan-Meier survival curves showed a better survival for patients with higher lymphatic D2-40+ expression than 9.3%. Lymphatic impairment occurs in the lungs of IIPs and its severity increases according to remodeling stage. The results suggest that disruption of the superficial lymphatics may impair alveolar clearance, delay organ repair and cause severe disease progress mainly in patients with AIP/DAD. Therefore, lymphatic distribution may serve as a surrogate marker for the identification of patients at greatest risk for death due to IIPs.

Tunnel excavation triggering pulmonary sarcoidosis.

CONTEXT: A definite cause of sarcoidosis has not been identified, however past research suggests that environmental factors may be triggers of the granulomatous response in genetically susceptible individuals. CASE PRESENTATION: A 22-year-old male non-smoker, presented with progressive exertional dyspnea and cough of 3 months duration. One year before, when he started working in tunnel excavation, he had a normal chest radiograph. Chest imaging revealed bilateral nodules and masses of peribronchovascular distribution plus mediastinal lymphadenomegaly. Histologic lymph node analysis revealed non-caseating confluent granulomas. Sarcoidosis was diagnosed. The patient was treated with corticosteroids and advised to change jobs. Complete remission of the disease was achieved and persisted for at least one year without steroid treatment. DISCUSSION: Sarcoidosis is believed to have environmental triggers. The timing of the onset of sarcoidosis in this patient following intensive exposure to tunnel dust suggests an environmental contribution. The recognition that sarcoidosis may have occupational triggers have medical, employment, and legal implications.

Atelectasis observed by computerized tomography after Caesarean section.

BACKGROUND: Atelectasis after either vaginal or Caesarean delivery has not been adequately quantified. This study addresses the hypothesis that atelectasis may be worse in women who undergo Caesarean section when compared with vaginal delivery under regional anaesthesia. METHODS: Twenty healthy non-smoking women submitted to a chest computed tomography (CT) 2 h after delivery in a University Hospital, who had experienced vaginal delivery (n=10) under combined spinal-epidural analgesia or a Caesarean section (n=10) under spinal anaesthesia, were evaluated. The percentage cross-sectional area of atelectasis in dependent lung regions were measured from the CT images obtained at cross-section of the xiphoid process and the top of the diaphragm. RESULTS: The percentage cross-sectional area of atelectasis was 3.95% in the vaginal delivery group and 14.1% in the Caesarean group (P<0.001, Mann-Whitney rank sum test). CONCLUSIONS: These results suggested that pulmonary atelectasis is greater after Caesarean section delivery under spinal anaesthesia than after vaginal delivery with combined spinal-epidural analgesia.

Lung hyperinflation stimulates the release of inflammatory mediators in spontaneously breathing subjects

Lung hyperinflation up to vital capacity is used to re-expand collapsed lung areas and to improve gas exchange during general anesthesia. However, it may induce inflammation in normal lungs. The objective of this study was to evaluate the effects of a lung hyperinflation maneuver (LHM) on plasma cytokine release in 10 healthy subjects (age: 26.1 ± 1.2 years, BMI: 23.8 ± 3.6 kg/m²). LHM was performed applying continuous positive airway pressure (CPAP) with a face mask, increased by 3-cmH2O steps up to 20 cmH2O every 5 breaths. At CPAP 20 cmH2O, an inspiratory pressure of 20 cmH2O above CPAP was applied, reaching an airway pressure of 40 cmH2O for 10 breaths. CPAP was then decreased stepwise. Blood samples were collected before and 2 and 12 h after LHM. TNF-á, IL-1â, IL-6, IL-8, IL-10, and IL-12 were measured by flow cytometry. Lung hyperinflation significantly increased (P < 0.05) all measured cytokines (TNF-á: 1.2 ± 3.8 vs 6.4 ± 8.6 pg/mL; IL-1â: 4.9 ± 15.6 vs 22.4 ± 28.4 pg/mL; IL-6: 1.4 ± 3.3 vs 6.5 ± 5.6 pg/mL; IL-8: 13.2 ± 8.8 vs 33.4 ± 26.4 pg/mL; IL-10: 3.3 ± 3.3 vs 7.7 ± 6.5 pg/mL, and IL-12: 3.1 ± 7.9 vs 9 ± 11.4 pg/mL), which returned to basal levels 12 h later. A significant correlation was found between changes in pro- (IL-6) and anti-inflammatory (IL-10) cytokines (r = 0.89, P = 0.004). LHM-induced lung stretching was associated with an early inflammatory response in healthy spontaneously breathing subjects.

Effects of proportional assisted ventilation on exercise performance in idiopathic pulmonary fibrosis patients.

BACKGROUND: Patients with idiopathic pulmonary fibrosis (IPF) present an important ventilatory limitation reducing their exercise capacity. Non-invasive ventilatory support has been shown to improve exercise capacity in patients with obstructive diseases; however, its effect on IPF patients remains unknown. OBJECTIVE: The present study assessed the effect of ventilatory support using proportional assist ventilation (PAV) on exercise capacity in patients with IPF. METHODS: Ten patients (61.2+/-9.2 year-old) were submitted to a cardiopulmonary exercise testing, plethysmography and three submaximal exercise tests (60% of maximum load): without ventilatory support, with continuous positive airway pressure (CPAP) and PAV. Submaximal tests were performed randomly and exercise capacity, cardiovascular and ventilatory response as well as breathlessness subjective perception were evaluated. Lactate plasmatic levels were obtained before and after submaximal exercise. RESULTS: Our data show that patients presented a limited exercise capacity (9.7+/-3.8 mL O(2)/kg/min). Submaximal test was increased in patients with PAV compared with CPAP and without ventilatory support (respectively, 11.1+/-8.8 min, 5.6+/-4.7 and 4.5+/-3.8 min; p<0.05). An improved arterial oxygenation and lower subjective perception to effort was also observed in patients with IPF when exercise was performed with PAV (p<0.05). IPF patients performing submaximal exercise with PAV also presented a lower heart rate during exercise, although systolic and diastolic pressures were not different among submaximal tests. Our results suggest that PAV can increase exercise tolerance and decrease dyspnoea and cardiac effort in patients with idiopathic pulmonary fibrosis.

Lung hyperinflation stimulates the release of inflammatory mediators in spontaneously breathing subjects.

Lung hyperinflation up to vital capacity is used to re-expand collapsed lung areas and to improve gas exchange during general anesthesia. However, it may induce inflammation in normal lungs. The objective of this study was to evaluate the effects of a lung hyperinflation maneuver (LHM) on plasma cytokine release in 10 healthy subjects (age: 26.1 +/- 1.2 years, BMI: 23.8 +/- 3.6 kg/m(2)). LHM was performed applying continuous positive airway pressure (CPAP) with a face mask, increased by 3-cmH(2)O steps up to 20 cmH(2)O every 5 breaths. At CPAP 20 cmH(2)O, an inspiratory pressure of 20 cmH(2)O above CPAP was applied, reaching an airway pressure of 40 cmH(2)O for 10 breaths. CPAP was then decreased stepwise. Blood samples were collected before and 2 and 12 h after LHM. TNF-alpha, IL-1beta, IL-6, IL-8, IL-10, and IL-12 were measured by flow cytometry. Lung hyperinflation significantly increased (P < 0.05) all measured cytokines (TNF-alpha: 1.2 +/- 3.8 vs 6.4 +/- 8.6 pg/mL; IL-1beta: 4.9 +/- 15.6 vs 22.4 +/- 28.4 pg/mL; IL-6: 1.4 +/- 3.3 vs 6.5 +/- 5.6 pg/mL; IL-8: 13.2 +/- 8.8 vs 33.4 +/- 26.4 pg/mL; IL-10: 3.3 +/- 3.3 vs 7.7 +/- 6.5 pg/mL, and IL-12: 3.1 +/- 7.9 vs 9 +/- 11.4 pg/mL), which returned to basal levels 12 h later. A significant correlation was found between changes in pro- (IL-6) and anti-inflammatory (IL-10) cytokines (r = 0.89, P = 0.004). LHM-induced lung stretching was associated with an early inflammatory response in healthy spontaneously breathing subjects.

Esophageal involvement and interstitial lung disease in mixed connective tissue disease.

RATIONALE: Mixed connective tissue disease is a systemic inflammatory disorder that results in both pulmonary and esophageal manifestations. OBJECTIVES: We sought to evaluate the relationship between esophageal dysfunction and interstitial lung disease in patients with mixed connective tissue disease. METHODS: We correlated the pulmonary function data and the high-resolution computed tomography findings of interstitial lung disease with the results of esophageal evaluation in manometry, 24-hour intraesophageal pH measurements, and the presence of esophageal dilatation on computed tomography scan. MEASUREMENTS AND MAIN RESULTS: Fifty consecutive patients with mixed connective tissue disease, according to Kasukawa's classification criteria, were included in this prospective study. High-resolution computed tomography parenchymal abnormalities were present in 39 of 50 patients. Esophageal dilatation, gastroesophageal reflux, and esophageal motor impairment were also very prevalent (28 of 50, 18 of 36, and 30 of 36, respectively). The presence of interstitial lung disease on computed tomography was significantly higher among patients with esophageal dilatation (92% vs. 45%; p<0.01) and among patients with severe motor dysfunction (90% vs. 35%; p<0.001). CONCLUSIONS: Although we were not able to prove a causal relationship between esophageal and pulmonary involvement, our series revealed a strong association between esophageal motor dysfunction and interstitial lung disease in patients with mixed connective tissue disease.

Comparison of two questionnaires which measure the health-related quality of life of idiopathic pulmonary fibrosis patients.

The objective of the present study was to determine if there is a health-related quality of life (HRQL) instrument, generic or specific, that better represents functional capacity dysfunction in idiopathic pulmonary fibrosis (IPF) patients. HRQL was evaluated in 20 IPF patients using generic and specific questionnaires (Medical Outcomes Short Form 36 (SF-36) and Saint George's Respiratory Questionnaire (SGRQ), respectively). Functional status was evaluated by pulmonary function tests, 6-min walking distance test (6MWDT) and dyspnea indexes (baseline dyspnea index) at rest and after exercise (modified Borg scale). There was a restrictive pattern with impairment of diffusion capacity (total lung capacity, TLC = 71.5 +/- 15.6%, forced vital capacity = 70.4 +/- 19.4%, and carbon monoxide diffusing capacity = 41.5 +/- 16.2% of predicted value), a reduction in exercise capacity (6MWDT = 435.6 +/- 95.5 m) and an increase of perceived dyspnea score at rest and during exercise (6 +/- 2.5 and 7.1 +/- 1.3, respectively). Both questionnaires presented correlation with some functional parameters (TLC, forced expiratory volume in 1 s and carbon monoxide diffusing capacity) and the best correlation was with TLC. Almost all of the SGRQ domains presented a strong correlation with functional status, while in SF-36 only physical function and vitality presented a good correlation with functional status. Dyspnea index at rest and 6MWDT also presented a good correlation with HRQL. Our results suggest that a specific instead of a generic questionnaire is a more appropriate instrument for HRQL evaluation in IPF patients and that TLC is the functional parameter showing best correlation with HRQL.

Comparison of two questionnaires which measure the health-related quality of life of idiopathic pulmonary fibrosis patients

The objective of the present study was to determine if there is a health-related quality of life (HRQL) instrument, generic or specific, that better represents functional capacity dysfunction in idiopathic pulmonary fibrosis (IPF) patients. HRQL was evaluated in 20 IPF patients using generic and specific questionnaires (Medical Outcomes Short Form 36 (SF-36) and Saint George's Respiratory Questionnaire (SGRQ), respectively). Functional status was evaluated by pulmonary function tests, 6-min walking distance test (6MWDT) and dyspnea indexes (baseline dyspnea index) at rest and after exercise (modified Borg scale). There was a restrictive pattern with impairment of diffusion capacity (total lung capacity, TLC = 71.5 ± 15.6 percent, forced vital capacity = 70.4 ± 19.4 percent, and carbon monoxide diffusing capacity = 41.5 ± 16.2 percent of predicted value), a reduction in exercise capacity (6MWDT = 435.6 ± 95.5 m) and an increase of perceived dyspnea score at rest and during exercise (6 ± 2.5 and 7.1 ± 1.3, respectively). Both questionnaires presented correlation with some functional parameters (TLC, forced expiratory volume in 1 s and carbon monoxide diffusing capacity) and the best correlation was with TLC. Almost all of the SGRQ domains presented a strong correlation with functional status, while in SF-36 only physical function and vitality presented a good correlation with functional status. Dyspnea index at rest and 6MWDT also presented a good correlation with HRQL. Our results suggest that a specific instead of a generic questionnaire is a more appropriate instrument for HRQL evaluation in IPF patients and that TLC is the functional parameter showing best correlation with HRQL.

Pulmonary artery distensibility in pulmonary arterial hypertension: an MRI pilot study.

Pulmonary arterial hypertension (PAH) is a disease of the small vessels in which there is a substantial increase in pulmonary vascular resistance leading to right ventricle failure and death. Invasive haemodynamic evaluation is mandatory not only for diagnosis confirmation but also to address prognosis and eligibility for the use of calcium-channel blockers through an acute vasodilator challenge. Noninvasive surrogate response markers to the acute vasodilator test have been sought. In the present study, the relationship between pulmonary artery distensibility, assessed using magnetic resonance imaging (MRI), and response to acute vasodilator tests was investigated. In total, 19 patients diagnosed with idiopathic PAH without any specific treatment were evaluated. Within a 48-h window after pulmonary artery catheterisation, patients underwent cardiac MRI. Cardiac index, calculated after the determination (invasively and noninvasively) of cardiac output, showed excellent correlation, as did right atrial pressure and right ventricle ejection fraction. Pulmonary artery distensibility was significantly higher in responders. A receiver operating characteristic curve analysis has shown that 10% distensibility was able to differentiate responders from nonresponders with 100% sensitivity and 56% specificity. The present findings suggest that magnetic resonance imaging and pulmonary artery distensibility may be useful noninvasive tools for the evaluation of patients with pulmonary hypertension.

Collagen and elastic system in the remodelling process of major types of idiopathic interstitial pneumonias (IIP).

AIMS: Structural remodelling in acute and chronic idiopathic interstitial pneumonia (IIP) has been extensively investigated, but little attention has been directed to the elastic tissue in these situations. The aim of this study was to determine whether elastic deposition accompanies collagen deposition in the four major histological patterns of IIP: diffuse alveolar damage (DAD), organizing pneumonia (OP), non-specific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP). METHODS AND RESULTS: We measured, by image analysis, the content of fibres of the collagenous and elastic systems of the alveolar septum in histological slides of open lung biopsies, using the picrosirius-polarization method and Weigert's resorcin-fuchsin stain, respectively. Five groups were studied: 10 cases of DAD; nine cases of OP; nine cases of NSIP; and 10 cases of UIP. Four normal lungs were used for comparison. The content of collagen fibres was significantly higher in UIP when compared to DAD, NSIP, OP and normal lung. The content of elastic fibres was increased in comparison with normal lungs but this was not significantly different among the histological patterns. CONCLUSION: Acute and chronic IIP cause a similar increase in the collagen and elastic contents of the lungs, representing a process of 'fibroelastosis' rather than an exclusive process of fibrosis. A profibrogenic mechanism is responsible for the unparallelled collagen augmentation observed in UIP subjects, the nature of which is yet to be determined.