Predictors of physical activity performance and dynamic hyperinflation in patients with bronchiectasis

Abstract

Bronchiectasis (BQT) is characterized by abnormal and irreversible dilatation of the airways and may be caused by a wide variety of diseases. Dynamic hyperinflation (DH) is characterized by progressive air trapping, which leads to increased lung volume at end expiration associated with decreased inspiratory capacity (IC), in situations where there is increased ventilation, such as exercise. The DH is one of the responsible mechanisms for dyspnea and reduced exercise tolerance in patients with conditions that lead to expiratory flow limitation such as asthma and COPD. One option for the evaluation of HD is the serial measurement of IC during maneuvers that promote hyperventilation as an incremental cardiopulmonary exercise test. Exercise capacity is reduced in many patients with BQT. There are no studies evaluating the presence of DH in patients with BQT and there are few studies on the physiology of dyspnea in this population. DH is an important mechanism of exercise limitation in COPD and may explain the dyspnea on exertion and decreased exercise capacity in patients with BQT. Hypothesis: DH is present in patients with BQT. Objectives: Primary - To assess the prevalence of DH in patients with BQT. Secondary: To assess aerobic capacity in these patients, and factors associated with DH and decreased aerobic capacity. Methodology - Patients older than 18 years from the Pulmonology outpatient clinic, Hospital das Clinicas, Faculty of Medicine, University of São Paulo - USP that meet the following criteria will be included in the study: Diagnosis of BQT confirmed by chest CT scan and signing the informed consent for study participation. Exclusion criteria: Diagnosis of Cystic Fibrosis, Asthma, COPD, allergic bronchopulmonary aspergillosis, mycobacteriosis in activity and pregnancy, inability to perform pulmonary functional tests, recent treatment (<30 days) of exacerbation with oral corticosteroid or antibiotic, contraindication to exercise tests, exercise limitation not related to pulmonary disease (orthopedic or cardiovascular problems), prior pulmonary resection, current smoking or prior smoking history greater than 10 pack / years, prolonged home oxygen therapy. Dynamics of the study: Evaluation of the prevalence of HD - Patients will be evaluated sequentially and the prevalence of DH will be determinated. Clinical variables: demographic and anthropometric data: Age, Sex, Race and BMI (Body Mass Index). Clinical data: time from onset of symptoms to study entry, time from diagnosis to study enrollment, dyspnea (classification by the Medical Research Council - MRC). Exams: spirometry, whole body plethysmography, maximum incremental cardiopulmonary exercise test by bicycle ergometer, forced Oscillometry, CT Scan. Statistical analysis: The patients will be divided in two groups (presence or absence of dynamic hyperinflation), from the analysis of serial measurements of CI during maximal incremental cardiopulmonary exercise test. Considering an estimated prevalence in accessible population, and accessible population of 366 individuals, a sample of 113 individuals was estimated for a margin of error of 10% and 0.05 significance level. For the analysis of associated factors ten candidates variables were included in the model. The planned enrollment is 120 patients in total. For the analysis of associated factors with DH and decreased aerobic capacity, a multivariate logistic regression model will be performed. Schedule: Time of study - 4 years in total. Ethical aspects: Study participants will sign an Informed Consent Term. The project will be submitted to the Incor CAPEPesq - HCFMUSP. (AU)