Interstitial lung disease in polymyositis and dermatomyositis: longitudinal evaluation by pulmonary function and radiology.

OBJECTIVE: To estimate predictors and long-term outcome of interstitial lung disease (ILD) in patients with polymyositis (PM) and dermatomyositis (DM). METHODS: We conducted a prospective study in which newly diagnosed PM/DM patients, regardless of clinical symptoms of pulmonary disease, were investigated with repeated chest radiography, high-resolution computed tomography (HRCT) of the lungs, and pulmonary function test (PFT). Clinical, radiologic, and lung function outcome was based on the last followup results. RESULTS: Twenty-three patients with a mean followup period of 35 months were included. Findings on radiographic examination and/or PFT compatible with ILD were recorded in 18 patients (78%). Patients with ILD had lower lung function, higher radiologic scores, and higher creatine kinase values than those without ILD. All patients were treated with high-dose glucocorticoids and other immunosuppressive agents. Two patients died due to ILD, both with active myositis. During the followup, total lung capacity (TLC) improved in 33%, remained stable in 39%, and deteriorated in 28%. Changes in TLC correlated only partially with HRCT findings, which persisted even after normalizing for lung function. CONCLUSION: ILD associated with PM/DM is in most cases mild, chronic, and has a nonprogressive course during immunosuppressive treatment. PFT can be normalized during treatment with immunosuppressive therapy, even if radiologic signs of ILD persist. The course of ILD could not be predicted on the first examination. Therefore, myositis patients with ILD need careful evaluation of clinical features as well as PFT and radiologic features during followup.

Uneven distribution of ventilation in acute respiratory distress syndrome.

INTRODUCTION: The aim of this study was to assess the volume of gas being poorly ventilated or non-ventilated within the lungs of patients treated with mechanical ventilation and suffering from acute respiratory distress syndrome (ARDS). METHODS: A prospective, descriptive study was performed of 25 sedated and paralysed ARDS patients, mechanically ventilated with a positive end-expiratory pressure (PEEP) of 5 cmH2O in a multidisciplinary intensive care unit of a tertiary university hospital. The volume of poorly ventilated or non-ventilated gas was assumed to correspond to a difference between the ventilated gas volume, determined as the end-expiratory lung volume by rebreathing of sulphur hexafluoride (EELVSF6), and the total gas volume, calculated from computed tomography images in the end-expiratory position (EELVCT). The methods used were validated by similar measurements in 20 healthy subjects in whom no poorly ventilated or non-ventilated gas is expected to be found. RESULTS: EELVSF6 was 66% of EELVCT, corresponding to a mean difference of 0.71 litre. EELVSF6 and EELVCT were significantly correlated (r2 = 0.72; P < 0.001). In the healthy subjects, the two methods yielded almost identical results. CONCLUSION: About one-third of the total pulmonary gas volume seems poorly ventilated or non-ventilated in sedated and paralysed ARDS patients when mechanically ventilated with a PEEP of 5 cmH2O. Uneven distribution of ventilation due to airway closure and/or obstruction is likely to be involved.

Regional ventilation and distribution of emphysema - a quantitative comparison.

The distribution of ventilation and emphysema throughout the lung was compared in 20 emphysematous patients who were candidates for lung volume reduction surgery. Ventilation distribution among 1.6-cm-high stripe regions was obtained in supine position by planar gamma camera scintigraphy after inhalation of technegas. Results from nine healthy subjects provided normal stripe count rates. Patient count rates were expressed as the difference from predicted normal stripe count rate (DeltaSVI). Thus, DeltaSVI is a relative index of abnormal ventilation. Emphysema was assessed quantitatively by a density mask method on corresponding slices of high resolution computed tomography (HRCT). The results show that in the majority of patients, there is a highly significant relationship between the degree of stripe hypoventilation and the amount of distribution of emphysema, but in some patients no such relationship is found. We speculate that the distribution of airway obstruction not necessarily follows the distribution of emphysema, which could explain the lack of concordance between ventilation and emphysema distribution in some patients. We conclude that ventilation scintigraphy contains complementary information to lung HRCT.

Classification of emphysema in candidates for lung volume reduction surgery: a new objective and surgically oriented model for describing CT severity and heterogeneity.

OBJECTIVE: To elaborate a surgically oriented and objective model for classification of emphysema heterogeneity. PATIENTS AND INTERVENTIONS: CT examinations of 66 candidates for lung volume reduction surgery. DESIGN: Emphysema severity was calculated by computer as the emphysema index (EI), a commonly used computer-based quantification that accurately assesses the extent of emphysema of a CT image. The distribution of the EI in different parts of each lung was illustrated in a diagram with the position in the lung (from cranial to caudal) on the x-axis and the EI on the y-axis. The slope of the fitted line was calculated. As a measure of the variation of the EI within each lung, the EI difference was calculated. RESULTS: A diagram was constructed with the absolute value of slope, k, on the x-axis and EI difference on the y-axis. This resulted in a diagram differentiating markedly heterogeneous, intermediately heterogeneous, and homogeneous emphysema. Nineteen patients fulfilled the criteria of bilateral markedly heterogeneous emphysema, 3 patients filled the criteria of bilateral intermediately heterogeneous emphysema, and 18 patients filled the criteria of bilateral homogeneous emphysema. Twenty-six patients had different types of emphysema in the right and left lung. CONCLUSION: We present a method for classification of emphysema heterogeneity that is (1) objective, (2) surgically oriented, and (3) classifies both lungs separately.