Objective: Heimlich valve has been described as a substitute for water-sealed drainage systems. The objective of this study by the Thoracic Surgery Service of the "Hospital das Clínicas", University of São Paulo Medical Center, is to assess its effectiveness in the treatment of pneumothorax and its ease of operation, safety, and patient toleration. Methods: From June/97 to August/00, 107 patients with pneumotoraxes of different etiologies were analyzed. The majority (76%) were classified radiologically as suffering from moderate or large pneumothorax, three hypertensive pneumothorax, and one was bilateral. The pleural cavity was drained with teflon or polyurethane plastic pig-tail catheters (10.2F, 14F, straight 11F connected to the Heimlich valve or the valve was connected directly to the thoracic drain in post-thoracotomy patients). Results: The valve remained in place for one to 120 days (mean 4 days). Tolerance to the system was good in 89% of cases. There were no serious complication linked to the system. Associated pleural effusion in 20 patients (18.5%) did not prevent the system from functioning well. Only two patients (1.8%) developed subcutaneous emphysema, and therefore, a 36F Tubular drain under water seal was chosen. Thoracotomy for decortication was indicated in one patient (0.9%). Twenty patients (18.5%) were treated on an outpatient basis. Conclusions: The Heimlich valve confirmed its effectiveness in resolving pneumothorax of different etiologies and in postoperative air leaks. Its operation was simpler than that of conventional systems. The good toleration and safety mentioned by the patients was a determining factor in early hospital discharge and a motive for outpatient treatment.

Keywords: Pneumothorax. Pleura. Postural drainage.