Pursed-lips Breathing and Dynamic Hyperinflation
Condition: Chronic Obstructive Pulmonary Disease
MeSH terms: Lung Diseases, Obstructive; Pulmonary Disease, Chronic Obstructive
Study type: Interventional

Summary: 
      Background: Dynamic hyperinflation (DH) is an important factor leading to dyspnea and
      consequent limitations in functional capacity of chronic obstructive pulmonary disease (COPD)
      patients. It has not been completely elucidated whether pursed-lips breathing (PLB) is able
      to minimize DH and its effects on exercise tolerance in these patients. The aim of this study
      was to evaluate the acute effect of PLB on DH and functional capacity in patients with COPD.

      Design: Randomized cross-over study. Setting: The study will be conducted in an outpatient
      pulmonary rehabilitation program in Florianópolis, Brazil.

      Subjects: Twenty-five patients with COPD (16 men, mean age 64 (7) years, FEV1=41.7 (14.7)%
      predicted, BMI=27.6 (5.13)kg/m2).

      Interventions: Patients will randomly perform two six-minute walk tests with and without PLB
      (6MWTPLB and 6MWTNon-PLB) and two Glittre-ADL tests with and without PLB (TGlittrePLB and
      TGlittreNon-PLB).

      Main measures: At baseline and immediately after the tests, the inspiratory capacity (IC)
      will be assessed by the slow vital capacity (SVC) maneuver.
    

Detailed description: 
      Pulmonary function testing Lung function will be tested using an Easy One spirometer (NDD
      Medical Technologies Inc., Zurich, Switzerland), and calibration checked before each
      evaluation. Spirometry will be performed in accordance with ATS/ERS standards (Miller et al,
      2005). The predicted values will be calculated from the equations proposed by Pereira et al.
      (2007).

      Inspiratory capacity (IC) measurement IC will be measured with the patient in the sitting
      position, using an Easy One portable spirometer (NDD Medical Technologies Inc., Zurich,
      Switzerland), before and immediately after the tests, by the slow vital capacity maneuver
      starting from a stable end-expiratory volume, in accordance with ATS/ERS standards (Miller et
      al,2005). A minimum of three maneuvers (maximum of eight) will be performed and, in order to
      be considered reproducible, two curves could not vary by more than 5% or 150mL. The higher
      value of two reproducible curves will be used for analysis. DH is considered when the IC
      decreased 10% and/or 150mL or more compared to the basal value (O'Donnell et al, 2001).

      Six-minute walk test The 6MWT will be performed according to the guidelines of the American
      Thoracic Society (2002). Pulse oxygen saturation (SpO2; Oxi-Go, Oximeter Plus, Roslyn
      Heights, New York, USA) and dyspnea (Borg CR10 scale) will be measured at the beginning and
      at the end of the test. Predicted values for walking distance will be calculated according to
      Iwama et al. (2009).

      Glittre-ADL test The TGlittre consists of completing a circuit as follows: from a sitting
      position, the subject stands up and walks along a flat 10-m long course, in the middle of
      which there is a two-step ladder (each step 17 cm high x 27 cm deep) to be climbed; after
      completing the 10 m, the subject faces a shelf containing three 1-kg objects positioned on
      the top shelf (shoulder height) and moves them one by one to the bottom shelf (waist height)
      and then to the floor; the objects are then returned to the bottom shelf and finally to the
      top shelf again; the subject walks back, climbing up and down the steps, until reaching the
      starting point (chair), sits down and immediately begins the next lap. The subjects carry a
      weighted backpack (2.5 kg for women, 5.0 kg for men) and are instructed to complete five laps
      on this circuit as quickly as possible. SpO2 and dyspnea index (Borg CR10 scale) will be
      measured at the beginning of the test, at the end of each lap, and at the end of the test
      (Skumlien et al, 2006).
    

Intervention name(s): Pursed-lips breathing; No pursed-lips breathing
Intervention type(s): Other; Other
Intervention description(s): Expiration with pursed-lips during functional capacity tests.; To avoid pursed-lips breathing, subjects use a a mouthpiece (2cm diameter X 2cm length) such as the one used in pulmonary functional tests.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Keywords: Inspiratory capacity; Positive-pressure respiration; Exercise; Activities of daily living; COPD.