Persistent air-leak in patients with spontaneous pneumothorax (SP) is not uncommon and may present a management dilemma in those who are unfit or unwilling for surgery. Video-assisted thoracoscopic surgery (VATS) has been advocated in the management of patients with broncho-pleural fistulae (air-leak persisting beyond 7 days): however the optimum time for surgical intervention remains unclear. We reviewed the records of 130 episodes of SP in 115 patients over a 2-year period to determine clinical course and outcome, particularly with respect to duration of air-leak. There were 90 first episodes and 40 recurrent episodes. Eighty-one episodes (62%) occurred in patients with underlying lung disease (secondary pneumothorax). Initial management consisted of chest-tube drainage in 104 episodes (80%) occurring in 90 patients, percutaneous needle aspiration in five patients (4%) and observation in 21 episodes (16%) in 20 patients. In the group treated with chest-tube drainage, there was spontaneous resolution of air leak and lung re-expansion in 90 episodes (87%). The overall incidence of broncho-pleural fistula was 34.6%. In the primary SP group. 75% of air-leaks ceased by 7 days and 100% by 15 days. In the secondary SP group, 61% of air-leaks resolved by 7 days and 79% by 14 days, after which time resolution of air-leak proceeded at a much slower rate. Five patients underwent surgery while nine patients were discharged with residual pneumothoraces. There were no major complications or mortality. Based on our findings, we advocate surgery for patients with air-leak persisting beyond 14 days, while favouring a conservative approach before this time, as the majority of air-leaks (especially in patients with primary pneumothorax) would resolve by 14 days.

A total of 235 cases of sudden unexpected death syndrome (SUDS) among apparently healthy male Thai migrant workers in Singapore were reported between 1982 and 1990. Most of the deaths occurred during sleep and 13% were not sleep-related. The median age at the time of death was 33 years and the median interval between arrival and death was 8 months. These deaths occurred singly and sporadically throughout the year. Post-mortem examination revealed few abnormal findings except for haemorrhagic congestion or oedema of the lungs. There were moderate to severe intra-alveolar haemorrhages with some evidence of myocarditis or pneumonitis. Preliminary findings of serial sections of the hearts indicate evidence of anomalies in the cardiac conduction system. Epidemiological investigations showed that a family history of similar deaths and serological evidence of current or recent infection with Pseudomonas pseudomallei were significantly associated with SUDS. Extensive biochemical and toxicological investigations were inconclusive. There was no evidence of chronic deficiency in thiamine or potassium among the healthy Thai workers living and working in the same conditions as the cases, and no significant abnormalities were detected on electrocardiographic examination. As these migrant workers experienced various psychosocial problems which could stem from maladjustment to an urban environment, separation from the family, burden of debts and long hours of work, stress could be a precipitating factor for SUDS.

Polyvinylchloride (PVC) resins are widely used in industry. Asthma due to the thermal degradation products of PVC are well documented. In this first case of occupational asthma due to unheated PVC resin dust the patient was exposed to PVC resin dust during the mixing of chemicals used for making plastic seals for bottle caps.Meatwrappers' asthma and asthma due to the thermal degradation products of polyvinylchloride (PVC) are well documented.'4 Pneumoconiosis'9 and interstitial pneumonitis'°among workers exposed to PVC dust have been reported. Respiratory symptoms and abnormalities of lung function and of the chest radiograph have been described in surveys of workers exposed to PVC dust." 12 We report the first case of asthma induced by occupational exposure to unheated PVC resin dust. Case reportA 32 year old man worked for 14 years in a factory manufacturing bottle caps. Each metal cap was lined with a plastic seal on its inner surface. Both the fabrication of the metal caps and the injection moulding process of making plastic seals were carried out in the main production hall ofthe factory. The PVC resin mixture for the injection moulding process was prepared in a fairly large air conditioned room that was separated from the main production hall. For the past eight years the patient worked in this mixing room where he was exposed to PVC resin dust and other chemicals during mixing.He started to have episodes ofcough and breathlessness about five years after working in the mixing room. Initially, the frequency of symptoms was once in three to four months. During the past year, however, his symptoms had occurred almost daily and he had to depend on a ventolin inhaler for relief. He worked a five day week from 0730 to 1630. His symptoms usually started at about 0200 or 0300. Symptoms improved on weekends and holidays. Accepted 22 December 1988 There was no associated rhinitis. He had no history ofasthma or atopy. His sister had a history ofasthma. OCCUPATIONAL EXPOSUREThe preparation of PVC resin mixture in the mixing room was observed and the exposure dust concentration monitored. Three types ofchemicals were blended together to form the mixture: (i) PVC resin, a white powder, (ii) dioctylphthalate or Di-2-ethylhexylphthalate(DOP), a plasticiser in the form of a clear oily liquid, and (iii) a paste containing azodicarbonamide (a plastics blowing or foaming agent), colouring agent, and stabilisers. The PVC resin itself was a mixture of three grades of PVC resin: types A, B, and C. Type A was an emulsion resin with no stabilisers added, type B an emulsion resin that had been stabilised against heat, and type C a suspension resin with no stabilisers added. The ratio of A:B:C was 3:1:0-7. The paste containing azodicarbonamide and the liquid DOP were first placed in a tank, then five bags (120 kg) of PVC resins were manually poured into the tank. The pouring process was visibly dusty and took about 10 minutes. No local exhaust ventilation was provided.A quartz crystal microbalance cascade impactor was u...

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