Bubbling therapy for dysfunctional breathing in difficult-to-treat asthma – a pilot study
New therapies (English)Introduction
Vocal cord dysfunction or paradoxical vocal fold motion is a disorder characterized by abnormal adduction of the vocal cords during respiration causing intermittent airway obstruction. Dysfunctional breathing is common in uncontrolled asthma. Bubbling therapy (blowing through a glass straw in water) by a specialized speech therapist, may influence breathing pattern according to clinical experience. In this pilot study we investigate whether bubbling therapy is effective to improve asthma control in patients with a difficult-to-treat asthma and signs of vocal cord dysfunction.
Twenty-four patients with uncontrolled asthma under optimal treatment (inhaled corticosteroid and long acting beta-agonist), with an asthma control questionnaire (ACQ) score of > 1.5 and pCO2 < 35 mmHg or clinical signs of vocal cord dysfunction with Pittsburgh vocal cord dysfunction index (PVCDI) > 4 were included. Eleven patients were randomized to usual care and 13 patients were referred for bubbling therapy. The effect of bubbling therapy on asthma control, quality of life, chronic hyperventilation and pCO2 was measured at week 6 and week 18.
Twenty-four patients with uncontrolled asthma were included in this study: 22 female and 2 male patients. There was no difference in baseline characteristics between the two groups. The median ACQ at baseline was 2.17 for the usual care group and 1.83 for the bubbling therapy group, at 6 weeks ACQ usual care 1.83 and ACQ bubbling group 1.50 and at 18 weeks ACQ usual care 2.0 and ACQ bubbling group 1.83. An ACQ reduction of >0.5 was considered clinically relevant and was achieved by 3 out of 7 patients in the usual care group vs 4 out of 7 in the bubbling therapy group at week 6 (p=0.99). A significant increase in pCO2 in the capillary blood gas was found after four weeks of bubbling therapy (baseline mean(SD) pCO2=31.56(5.96) mmHg; week 6 pCO2=35.42(3.77) mmHg, p=0.01; week 18 pCO2= 33.87(4.21) mmHg, p=0.16). No difference was found in pCO2 levels in the usual care group (baseline mean(SD) pCO2=33.23(1.44) mmHg; week 6 pCO2=34.01(2.95) mmHg, p=0.35; week 18 pCO2= 34.12(2.47) mmHg, p=0.09). There was no difference in quality of life measured by mini-asthma quality of life questionnaire (mini-AQLQ), and Nijmeegse hyperventilation score (NHV) at week 6 and week 18.
In this pilot study, no difference in ACQ, mini-AQLQ and NHV score was found after bubbling therapy in patients with a difficult-to-treat asthma compared to the usual care group. However, after four weeks of bubbling therapy, pCO2 levels were higher. This may be an indication of a better controlled breathing. This is a pilot study with a small sample size, further research studying a greater population is needed to ascertain benefits of bubble therapy in patients with a difficult-to-treat asthma.