Clinical evaluation of a respiratory resistance biofeedback training.

This study evaluated the effectiveness of a respiratory resistance biofeedback training. Fifteen adult asthmatic subjects participated in a feedback training program including twelve feedback sessions (three sessions weekly). Respiratory resistance (Ros) was measured using the forced oscillation method; to prevent subjects from lung hyperinflation, feedback was interrupted when functional residual capacity increased. One-second forced expiratory volume (FEV1), usage of self-administered medication, degree of asthmatic dyspnoea, and general activity were daily recorded in symptom diaries for at least three months, starting four weeks before the first feedback session. Seven subjects showed significant average Ros decreases within the sessions, while mean Ros in two subjects was increased. However, these direct feedback effects were not related to transfer effects outside the laboratory: e.g., not one of the seven successful subjects showed FEV1 improvements, and only in one of them were within-session Ros reductions accompanied by a decreased frequency of self-administered medication during the training period. These results lead to the conclusion that Ros feedback may not be an effective technique for the treatment of bronchial asthma in adults.