BACKGROUND:
Intermittent positive pressure breathing may be a useful adjunct therapy for patients with chronic obstructive pulmonary disease. It is, however, quite expensive; moreover, in 1976 its treatment efficacy had not been determined. Although the effectiveness of IPPB had been previously studied, the influence of long-term treatment was not known for the following reasons: The individuals studied had been too few and were not randomly assigned to treatment groups, the patient groups were not homogeneous and their clinical and functional status were not well-documented, and precise descriptions of the manner in which IPPB was administered were not recorded.
Based on these facts, a conference on the Scientific Basis of Respiratory Therapy, co-sponsored by the American Thoracic Society and the Division of Lung Diseases, issued a recommendation to develop a controlled clinical study of IPPB. Contracts were awarded to five clinical centers and a data center in November 1976. Planning of the trial ended in November 1977. Recruitment began in April 1978 for the 985 individuals who took part in this trial and ended in October 1980. Patients enrolled after March 31, 1980, were followed for 30 months instead of 36 months. Follow-up was completed in May 1983.
DESIGN NARRATIVE:
Randomized, fixed sample of 985 patients. Eligible patients were assigned to a treatment group using intermittent positive pressure breathing or to a control group using a powered nebulizer for treatment 3-4 times a day. Treatments continued for 3 years. Endpoints related to quality of life and respiratory function and capability.
