Thirty six patients previously treated for pulmonary tuberculosis by thoracoplasty were studied to determine the prevalence and effect of airflow obstruction. The mean (SD) FEV, was 1-3 (0 65) 1 and the mean forced expiratory ratio (FER) 64% (12%). FEV, was less than predicted in every patient whereas FER was less than predicted in 30, being below the lower 98th percentile in 15 (42%). In the 18 patients who complained of breathlessness the means of the standardised residuals (SR) for FEVy, peak expiratory flow (PEF), and FER were significantly lower and that for residual volume/total lung capacity (RV/TLC) significantly higher than those for the 18 patients who were not breathless (all p < 0-0001). There was no difference in the smoking history of the two groups. Only three of the 23 patients in whom reversibility of airflow obstruction was assessed showed a greater than 25% increase in PEF. None showed an increase in FEV, of greater than 15%. The 18 who were breathless had significantly lower values of arterial oxygen tension (Pao2) and higher values of arterial carbon dioxide tension (PaCo2) (p < 0-0001). Thirteen of these patients were in chronic respiratory failure (Pao2 < 8-0 kPa or PaCO2 > 5-9 kPa, or both) compared with only one of the 18 who were not breathless. The indices correlating best with Pao2 and Paco2 were SR FEV, and SR PEF respectively. SR FEV, accounted for 34% of the variance in Pao2 and SR PEF for 29% of the variance in PaCO2. Airflow obstruction has been found to be common in patients with a thoracoplasty and to be associated with hypoxia and hypercapnia.Many patients who were treated for pulmonary tuberculosis by thoracoplasty in the prechemotherapy era are now breathless.' Some of them develop respiratory failure2 or cor pulmonale.3 These complications may even occur in patients with a thoracoplasty who were not previously breathless and who were leading apparently normal lives.4 The reasons why some patients are affected while others remain well have not been elucidated. A restrictive ventilatory defect is inevitable after thoracoplasty5 6 and there is some evidence that hypercapnia is related to decreased inspiratory muscle strength.7 Because several studies from the prechemotherapy era suggested that airflow obstruction was common in patients with pulmonary tuberculosis,8'-1 we studied a group of patients treated for tuberculosis by thoracoplasty to determine the prevalence of airflow obstruction, its possible mechanisms, and its clinical importance in determining breathlessness and respiratory failure in these patients.Address for reprint requests: Dr MS Phillips, Papworth Hospital, Papworth Everard, Cambridge, CB3 8RE. Accepted 6 January 1987 Subjects and methodsWe studied 36 patients who had previously been treated for pulmonary tuberculosis by thoracoplasty. They were divided into two groups. The first group of 18 (10 men, 8 women) had sought medical attention in recent years because of breathlessness. Seven were known to have suffered episodes of hypercapnic respiratory...

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