Thorax: first published as 10.1136/thx.35.1.31 on 1 January 1980. Downloaded from Thorax, 1980, 35, 31-36 Respiratory function changes after asbestos pleurisy P H WRIGHT, A HANSON, L KREEL, AND L H CAPEL From the Cardiothoracic Institute, London Chest Hospital, East Ham Chest Clinic, London, and the Division of Radiology, Clinical Research Centre, Northwick Park Hospital, Harrow ABSTRACT Six patients with radiographic evidence of diffuse pleural thickening after industrial asbestos exposure are described. Five had computed tomography of the thorax. All the scans showed marked circumferential pleural thickening often with calcification, and four showed no significant evidence of intrapulmonary fibrosis (asbestosis). Lung function testing showed reduc- tion of the inspiratory capacity and the single-breath carbon monoxide transfer factor (TLco). The transfer coefficient, calculated as the TLCO divided by the alveolar volume determined by helium dilution during the measurement of TLco, was increased. Pseudo-static compliance curves showed markedly more negative intrapleural pressures at all lung volumes than found in normal people. These results suggest that the circumferential pleural thickening was preventing normal lung expansion despite abnormally great distending pressures. The pattern of lung function tests is sufficiently distinctive for it to be recognised in clinical practice, and suggests that the lungs are held rigidly within an abnormal pleura. The pleural thickening in our patients may have been related to the condition described as "benign asbestos pleurisy" rather than the copyright. interstitial fibrosis of asbestosis. Malignant pleural effusion associated with meso- necessary in many of these early cases, and opera- thelioma or bronchial carcinoma is a recognised tion notes recorded the presence of marked http://thorax.bmj.com/ complication of asbestos exposure. Pleural visceral pleural thickening. effusions without obvious tumour among both Radiographic surveys have shown a greater asbestos workers and ex-workers were first re- prevalence of pleural thickening (even excluding ported by Eisenstadt.' Originally called "asbestos hyaline and calcified pleural plaques) among pleurisy" the condition was later called "benign asbestos workers than among the general popula- asbestos pleurisy,"2 although one of the first four tion.910 This thickening has been shown to be reported patients developed a pleural mesothelioma associated with a reduction of the vital capacity, 10 years after his effusion first appeared, and total lung capacity, and the single-breath carbon another after 12 years. Further cases were subse- monoxide transfer factor."1513 on September 26, 2021 by guest. Protected quently reported538 and the clinical features were The case reports of asbestos pleurisy give recognised (table 1). Diagnostic thoracotomy was insufficient data to assess the degree of any residual functional impairment. The surveys based on radiographic appearances show statistically Table 1 Summary of clinical features of benign significant but small defects of lung function asbestos pleurisy among grouped subjects with pleural thickening. attempt to Subacute or chronic course with pleurisy This paper represents a systematic 2 Tends to recur assess and analyse lung function in a selected 3 Exacerbations are usually unilateral but may affect either side group of asbestos workers with marked diffuse 4 Pleural fluid shows no diagnostic features 5 Few asbestos fibres can be found in pleural biopsies pleural thickening. 6 The subpleural lung usually shows alveolitis 7 Many asbestos fibres can be found in the subpleural lung 8 The subjects are probably more likely to develop asbestosis and Methods mesothelioma than unaffected workers Reviewing cases of asbestos-related disease seen at East Ham Chest Clinic one of us (AH) noted that Address for reprint requests: Dr PH Wright, Department of Medicine, StThomas's Hospital Medical School, London SE1 7EH. four of some 70 patients showed radiographic 31 c Thorax: first published as 10.1136/thx.35.1.31 on 1 January 1980. Downloaded from 32 P H Wright, A Hanson, L Kreel, and L H Capel evidence of marked pleural thickening. A review Case histories of the records of the lung function laboratory of the London Chest Hospital revealed two more PATIENT 1 similar cases referred from other consultants. This man worked as a lagger for 20 years from The clinic notes and radiographs of the six the age of 16 years, and was heavily exposed to patients were reviewed and details obtained of asbestos. At the age of 25 years he attended East their industrial exposure, and the course of their Ham Chest Clinic because of transient right-sided lung disease. All the patients then attended for pleurisy with radiographic evidence of a small lung function testing. All had determinations of pleural reaction. He returned with left-sided forced expiratory volume in the first second pleuritic pain 11 years later. By this time his chest (FEV1), forced expiratory vital capacity (FVC), radiograph showed bilateral pleural thickening. He and vital capacity (VC). The forced expiratory had abnormal lung function tests (table 2). No volume in the first second as a percentage of the pleural fluid could be obtained when aspiration forced expiratory vital capacity (FEV%) was cal- was attempted. At review eight years later the culated. The single-breath carbon monoxide trans- radiographic changes and lung function tests had fer factor was measured with a Resparameter worsened (fig 1, table 2). Computed axial tomog- (PK Morgan, Chatham); from this measurement raphy scanning showed circumferential pleural the transfer factor (TLCO) was obtained, also the thickening most marked over the middle and alveolar volume measured by helium dilution dur- lower lobes (fig 2). Pleural thickening was visible ing the measurement of transfer factor (Va) and along the mediastinum and over the right heart so the transfer coefficient (Kco) obtained as border. There were no significant pulmonary TLco/Va. Further lung function tests were per- changes and there was a normal gravity dependent formed in some patients. Lung volumes were gradient of perfusion. This gradient is lost in the measured in a constant-volume body plethysmo- graph. Pseudostatic lung compliance curves were Table 2 Lung function of patient I copyright. also obtained. After passage of a 4 ml oesophageal predicted balloon the patients were instructed to expire % slowly from full inspiration, so that the expiratory Test Age 37yr Age 45 yr flow rate did not exceed 0-5 1 s-1. The pressure FEV, 68 59 FEV,% 105 97 difference between the oesophageal balloon and vc 71 65 http://thorax.bmj.com/ the mouth was displayed on one channel of an TLCO -71 X-Y oscilloscope, while the expired volume Kco 125 measured from an Ohio 850 spirometer was dis- played on the other. A series of breaths was ob- served and the traces photographed with a Polaroid camera. When similar traces were re- peatedly obtained a characteristic one was selected for analysis. The static compliance (Cstat) was obtained by measuring the slope of the line joining on September 26, 2021 by guest. Protected points on the compliance curve at FRC and 0-5 1 above FRC. The specific compliance (sC) was ob- tained by dividing Cstat by the measured lung volume. The lung function test results were ex- pressed related to predicted reference values. For the spirometric results, gas transfer values, plethys- mograph volumes, Cstat, and sC the values quoted by Cotes14 were used. For the compliance curves mean values and standard deviations were cal- culated from the extreme ranges of the values reported by Turner et al.15 Computed axial tomography (CAT) was per- formed using a general purpose scanner (EMI 5005). The resulting scans were interpreted Fig 1 Chest radiograph of patient I at age 44 years, by one of us (LK) using criteria derived from 19 years after first pleurisy, showing bilateral pleural scans of patients known to have asbestosis.'6 thickening. Thorax: first published as 10.1136/thx.35.1.31 on 1 January 1980. Downloaded from Respiratory function changes after asbestos pleurisy 33 presence of the interstitial fibrosis of asbestosis.'0 PATIENT 2 The patient continues to smoke 40 cigarettes a This man worked as a wood machinist in a firm day. He has never had finger clubbing or lung making car batteries from the age of 14 to 65 crackles. He is now dyspnoeic on hurrying up years. Although he never handled asbestos himself stairs or hills. the whole factory was filled with asbestos dust from an adjoining shop where Dagenite was made from asbestos for the battery cases. He first at- tended East Ham Chest Clinic when aged 60 years, with complaints of exertional dyspnoea and angina. His chest radiograph showed cardiac en- largement and bilateral pleural thickening which was sufficiently dense to obscure the lung fields. Over the next nine years the pleural shadowing increased and lung function deteriorated (table 3). He has no finger clubbing but a few late inspira- tory crackles were heard at the right base in 1969; these have increased a little since and crackles have appeared at the left base. Computed axial tomography scanning showed bilateral circum- ferential pleural thickening with almost complete encasement of the left lung, and to a lesser extent the right. There were no significant pul- monary changes, and there was a gravity- dependent perfusion gradient. He continues to (a) smoke 2 oz tobacco a week as rolled cigarettes. He cannot walk a quarter of a mile without stopping, copyright. but this is because of angina rather than dyspnoea. Table 3 Lung function of patient 2 http://thorax.bmj.com/ (Y. predicted) Test Age 60 yr Age 65 yr Age 69 yr FEV1 72 69 53 FEV% 104 91 104 VC 73 67 54 TLCO 77 63 56 Kco 131 123 128 PATIENT 3 on September 26, 2021 by guest. Protected This man worked between the ages of 14 and 18 years as a boiler scaler and assistant stoker.