Ventilatory demand and dynamic hyperinflation induced during ADL-based tests in Chronic Obstructive Pulmonary Disease patients

BACKGROUND: Airflow limitation frequently leads to the interruption of activities of daily living (ADL) in patients with Chronic Obstructive Pulmonary Disease (COPD). These patients commonly show absence of ventilatory reserve, reduced inspiratory reserve volume, and dynamic hyperinflation (DH). OBJECTIVE: To investigate ventilatory response and DH induced by three ADL-based protocols in COPD patients and compare them to healthy subjects. METHOD: Cross-sectional study. COPD group: 23 patients (65±6 years, FEV(1) 37.2±15.4%pred); control group: 14 healthy subjects (64±4 years) matched for age, sex, and body mass index. Both groups performed all three tests: Glittre-ADL test; an activity test that involved moving objects on a shelf (T(SHELF)); and a modified shelf protocol isolating activity with upper limbs (T(SHELF-M)). Ventilatory response and inspiratory capacity were evaluated. RESULTS: Baseline ventilatory variables were similar between groups (p>0.05). The ventilatory demand increased and the inspiratory capacity decreased significantly at the end of the tests in the COPD group. Ventilatory demand and DH were higher (p<0.05) in the T(SHELF) than in the T(SHELF–M) in the COPD group (p<0.05). There were no differences in DH between the three tests in the control group (p>0.05) and ventilatory demand increased at the end of the tests (p<0.05) but to a lower extent than the COPD group. CONCLUSION: The T(SHELF) induces similar ventilatory responses to the Glittre-ADL test in COPD patients with higher ventilatory demand and DH. In contrast, the ventilatory response was attenuated in the T(SHELF-M), suggesting that squatting and bending down during the Glittre-ADL test could trigger significant ventilatory overload.