Resting ventilation in patients with asthma compared to healthy controls

Abstract

Dysfunctional breathing and hyperventilation has been related to asthma, but no detailed baseline measurements of breathing have been available (Bruton, A et al. Curr Opin Allergy Clin Immunol 2011,11:53-57). The aim of the study was to compare ventilation at rest in asthmatics and healthy controls. Methods: 36 asthmatics (43.1±14.6 years) using short-acting β2 antagonist at least once a week in the last four weeks and 17 healthy controls were evaluated. Participants attended to the laboratory before breakfast and without medication usage. Ventilation (V´E), O2 consumption (V´O2),partial end-tidal pressure of CO2 (PETCO2) and O2 (PETO2) measures were sampled at rest for 10 minutes with facemask while listening to relaxing recording. The average of the last 4 minutes was used for statistics. Resting pulmonary ventilation per V´O2 (V´E/V´O2) and alveolar ventilation per V´O2 (V´A/V´O2) was calculated. The average of three breath holding times (BHT), the post expiratory period with no respiratory sensation, was measured before spirometry, where FEV1 and FVC were measured. Results: Groups were comparable regarding age, gender and body mass index. FEV1/ FVC approached to be less for asthmatics (75.7±10.7 vs. 81.1±7.1, p=0.06). V´E/V´O2 was higher (41.0±9.5 vs. 35.3±7.1, p<0.05) and BHT was shorter (14.2±7.9 vs. 18.9±6.9 sec, p<0.05) for asthmatics. V'A/V'O2, PETCO2 and PETO2 were equal in both groups. Conclusion: Higher V'E/V'O2 but equal V'A/V'O2 and PETCO2 in asthmatics compared to controls could comply with dysfunctional breathing but not hyperventilation. The shorter BHT for asthmatics could indicate higher respiratory center sensitivity, partially explaining the dysfunctional breathing.