Intermittent Positive Pressure Breathing (IPPB) in the Outpatient Management of Chronic Obstructive Pulmonary Disease: Description of the NIH Clinical Trial

Abstract

Chronic obstructive pulmonary disease (COPD) is a major health problem of increasing incidence and importance as a cause of morbidity, disability, suffering, mortality, and economic loss. Supportive and rehabilitative therapy can be expensive, and whether treatment alters the course of disease is controversial. Perhaps most controversial in the treatment of COPD is the use of intermittent positive pressure breathing (IPPB), which has not been shown to be hazard-free or to be more beneficial than simple nebulizer devices. Furthermore, IPPB may be very costly. Past studies of IPPB do not permit valid evaluation because of study faults or because patients were often too ill to benefit significantly from any therapy. For these reasons, the 1975 Sugarloaf Conference recommended that the role of IPPB in treatment of stable COPD be studied. Furthermore, the effect of IPPB on the quality of COPD patients' lives has not been studied. In consequence, the Lung Division of the National Heart, Lung and Blood Institute has funded a multicenter study to evaluate the efficacy of IPPB therapy compared to compressor-nebulizer therapy in outpatients with COPD. Five clinical centers, one pathology center, and one data center are participating in the study. Two primary objectives of the study are (1) to determine the relative effects of long-term IPPB and compressor-powered nebulizer treatments used as adjuncts of the comprehensive care of ambulatory patients with COPD, and (2) to determine the relative safety of the two therapy modes when so used. A secondary objective is to determine the effects and safety of these therapy modes on various subgroups among the patients, such as those with differing degrees of airflow obstruction and those from different age ranges. Patients admitted to the study had to satisfy various entering and exclusion criteria. Between January 1978 and November 1980, 985 patients entered the study. After a stabilization period, and after baseline histories, physical examinations, laboratory studies, pulmonary function tests, exercise testing, and quality of life measurements, patients were randomized into either the IPPB or the compressor-nebulizer treatment group. Patients were instructed about their diseases and standard therapy, and trained in use of the therapy devices. IPPB patients use the Bennett AP-5 respirator, and the other group uses the Bennett compressor. Metaproterenol is the standard bronchodilator. Tidal volume and breathing pattern are controlled as closely as possible. Therapy is carried out in the patients' homes, study personnel make follow-up home visits, baseline data are re-evaluated, and postmortem examinations of lungs and hearts are sought when study patients die. The last patients will complete the study in 1983 and reports of the findings will appear in the literature thereafter.