Slow Chest Compression on Dynamic Hyperinflation, Dyspnea and Peripheral Muscle Deoxygenation in Patients With COPD

Effects of Slow Chest Compression on Dynamic Hyperinflation, Dyspnea and Peripheral Muscle Deoxygenation Induced by Exercise in Patients With COPD

Background: Commonly, patients with chronic obstructive pulmonary disease (COPD) present dyspnea, dynamic hyperinflation (DH) and important peripheral muscle deoxygenation when performing their activities of daily living (ADLs). The slow chest compression (SCC) technique is a physiotherapy strategy that could maybe reduce DH, dyspnea and peripheral muscle deoxygenation in patients with COPD. The aim of the study is to analyse the effects of SCC in DH, dyspnea and peripheral muscle deoxygenation induced by exercise tests. The secondary objective was to identify responders and non-responders to the technique.

Design: Randomized cross-over study. Setting: The study will be conducted in an outpatient pulmonary rehabilitation program in Florianopolis, Brazil

Subjects: Patients with COPD (GOLD 2-4).

Interventions: Patients will randomly receive or not the SCC after six-minute step test (6MST-SCC and 6MST-NonSCC).

Main measures: At baseline and 1 minute after the tests, the inspiratory capacity (IC) will be assessed by the slow vital capacity (SVC) maneuver. At baseline, immediately after, and 1 minute after the tests, the dyspnea score will be assessed. The physiological responses and the peripheral muscle deoxygenation will be assessed during the tests and 1 minute after them.

The period from August 2015 to April 2016 was designated to clinical trial design and to its submission/approval by the Human Research Ethics Committee. The recruitment of subjects and the study evaluations following described will be only initiated after registration and publication on the ClinicalTrials.gov platform.

Pulmonary function tests:

• Lung function will be tested using a total body plethysmography (Eric Jaeger, Germany), and the calibration will be checked before each evaluation. Spirometry will be performed in accordance with American Thoracic Society and European Respiratory Society (ATS/ERS) standards (Miller et al., 2005; Wanger et al., 2005). The predicted values will be calculated with the equations derived from Brazilian population (Pereira et al., 2007; Neder et al., 1999).
• SVC maneuver: IC will be measured with the patient in the sitting position, using a portable spirometer (NDD Medical Technologies®, Switzerland), before and 1 minute after the tests, by the SVC 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 reliable, two curves could not vary more than 5% or 150 ml. The higher value of two reproducible curves will be used for analysis (O'Donnell et al., 2001). This outcome will be collected by a third evaluator blinded for the SCC or non-SCC application.

Six-minute step test (6MST): The patients will be instructed to walk up and down the step in order to perform the largest number of steps during six minutes. The walking speed will be selected by the patient (da Costa et al., 2014;. Pessoa et al., 2014). Two 6MSTs will be conducted by two evaluators: the main evaluator will be responsible for conducting the tests and the other will count the number of steps performed by the patient.

Dyspnea: Before and after the completion of each 6MST and each 6MWT, patients will be asked about their perception of dyspnea, using the modified Borg scale. Immediately after completion the SCC (or not), patients will be asked again about the dyspnea score. This outcome will be collected by a third evaluator blinded for the SCC or non-SCC application.

Peripheral muscle oxygenation: During the tests, before and after the completion of each 6MST, it will be measured the peripheral muscle oxygenation by near-infrared spectroscopy (NIRS) (Artinis Medical Systems®, Netherlands). The device will be positioned over the vastus lateralis muscle of dominant leg.

Slow chest compression: The patient will receive in a randomized order the application or not of SCC for one minute immediately after 6MST. During the SCC, the patient will remain in the sitting position; a bimanual slow compression on his/her upper chest will be performed always by the same evaluator, who will stand behind the patient. This compression will be done only in the expiratory phase, during one minute, in all respiratory cycles, respecting the chest mobility of each patient. For all patients, during SCC, it will be given a standardized verbal command: "Exhale all the air". After the test in which the patient will not receive the SCC, he/she must remain seated, at rest, for one minute without any interventions, although it will be given the same standardized verbal command.

Inclusion Criteria:

• Clinical diagnosis of COPD confirmed by spirometry (COPD GOLD stages B, C and D)
• Absence of change in respiratory symptoms in the past four weeks
• No hospital admission in the past 12 weeks
• Age between 40 and 80 years-old

Exclusion Criteria:

• Any other disease or health condition that could compromise the test´s execution
• Participation in pulmonary rehabilitation program completed in the last six months
• Current smoking or its cessation in less than six months
• Any change in symptoms during the study protocol