Behavioral interventions in asthma biofeedback techniques

Objectives: Biofeedback techniques have long been recommended as an adjunctive treatment for bronchial asthma. Techniques that target lung function directly, or indirectly by altering facial muscle tension, heart rate, heart rate variability (HRV) or inspiratory volume together with accessory muscle tension, have been proposed. We review evidence for the effectiveness of these biofeedback interventions and discuss the psychophysiological rationale behind individual techniques. Method: Controlled studies of biofeedback in asthma were retrieved using relevant search engines and reference lists of published articles. Effect sizes comparing intervention with control groups were calculated where appropriate. Results: Most of the studies suffer from methodological inadequacies or poor reporting of methods and results. Interventions targeting respiratory resistance directly have yielded only small and inconsistent changes in lung function and are difficult to implement without producing dynamic hyperinflation. Biofeedback-assisted facial muscle relaxation as an indirect intervention has yielded mixed results across studies, with only half of the studies showing significant albeit very small and clinically irrelevant improvements in lung function. The underlying physiological assumptions of the technique are questionable in the light of current knowledge of respiratory physiology. For other indirect techniques, only preliminary evidence of small effects is available. Conclusion: Currently, there is little good evidence that biofeedback techniques can contribute substantially to the treatment of asthma. (C) 2004 Elsevier Inc. All rights reserved.