A chest wall restrictor to study effects on pulmonary function and exercise. 1. Development and validation

Chest wall-restrictive loading reduces a person's ability to expand the chest wall during inhalation and results in decrements in lung capacities, resting pulmonary function, and ultimately, exercise performance. Chest wall restriction is observed in some forms of skeletal and pulmonary diseases (e.g., scoliosis) as well as in occupational situations (e.g., bulletproof vests). We have designed a constant-pressure chest wall-restrictive device that provides a quantifiable and reproducible load on the chest. This paper describes the device and the initial pulmonary function tests conducted. Ten subjects participated in this study. Subjects wore the restrictive device while performing pulmonary function tests at four externally added restrictive loads on three separate occasions. A two-way repeated-measures multivariate analysis of variance revealed significant decreases in forced expiratory vital capacity (FVC) and forced expiratory volume in 1 s (FEV1.0) at each load while the ratio of FEV1.0 to FVC (FEV1.0%) was maintained. No significant differences in any variable were found across time or between the seated and standing position. These results indicate that this chest wall-restrictive device provides a quantifiable added inspiratory load in the breathing cycle that results in reproducible decrements in pulmonary function representative of those seen in some restrictive pulmonary disease and occupational situations.