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Analysis of inspiratory muscle oxygenation responses to performing the maximal inspiratory pressure maneuver in patients with chronic obstructive pulmonary disease

Grant number: 21/03432-5
Support Opportunities:Scholarships in Brazil - Scientific Initiation
Effective date (Start): May 01, 2021
Effective date (End): December 31, 2021
Field of knowledge:Health Sciences - Physiotherapy and Occupational Therapy
Principal Investigator:Aparecida Maria Catai
Grantee:Ana Carolina Aparecida Marcondes Scalli
Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
Associated research grant:16/22215-7 - Impact of inspiratory muscle training and aging on metabolic mapping, autonomic modulation, and cardiovascular, respiratory and metabolic responses, and prediction of cardiorespiratory health through wearables, AP.TEM


Chronic obstructive pulmonary disease (COPD) is characterized by chronic airflow obstruction associated with a systemic inflammatory response. This generates limitations such as loss of respiratory muscle strength, leading to increased dyspnea and decreased tolerance to exercise. In addition, respiratory signs and symptoms such as chronic cough, wheezing and sputum are frequently present. The measurement of the maximum inspiratory pressure (MIP) is a common practice in daily clinical practice, as a way of measuring the strength of the inspiratory muscles. These muscles need adequate oxygenation to meet the metabolic demands in times of greatest demand or overload, such as during the PIMÁX maneuver and physical exercise. However, despite the wide use in the clinical practice of this maneuver, little is known about the oxygenation responses of the inspiratory muscles in response to its performance, in individuals with COPD. Objective: To evaluate the oxygenation responses of the external intercostal inspiratory (IE) and sternocleidomastoid (ECM) muscles, before, during and after performing the MIP test, in patients with COPD.Materials and Methods: 45 male and female participants, aged between 40 and 60 years, will be evaluated, 15 apparently healthy participants and 30 participants with clinical diagnosis of mild and moderate COPD according to the Global Initiative for Chronic Obstructive Lung Disease classification ( GOLD, 2020). This group will be divided into 15 participants, with GOLD 1 (mild) (forced expiratory volume in the first minute - FEV1 e 80% of predicted) and 15 being GOLD 2 (moderate) (50% d FEV1 <80% of predicted). All participants will be submitted to two days of evaluations of the PIMÁX maneuver, with a minimum interval of 48 hours and a maximum of 1 week, between evaluations. The oxygenation variables of the inspiratory muscles (IE and ECM) will be collected by means of near-infrared spectroscopy (NIRS) (Oxymon Mk III, Artinis Medical Systems, Netherlands), before, during and after performing the PIMÁX maneuvers. The behavior pattern of the variables will be determined: oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb) and total hemoglobin (tHb), through qualitative analysis. The comparison between the groups studied will be carried out by visual analysis and by parametric and non-parametric statistical tests, according to the data distribution. P <0.05 will be considered. Expected results: It is believed that there is a greater demand for oxygen to perform the contraction of the respiratory muscles in patients with COPD, when compared to the control group during the PIMÁX maneuver, assessed through the NIRS; and that this difference will be greater depending on the classification regarding the severity of COPD. Thus, considering that: i) COPD generates a high cost for the health system, limits the individual's physical activity, generating respiratory muscle weakness, air trapping and that the MIP may be reduced in this population; ii) the PIMÁX maneuver is not invasive, has a low cost for its performance and assesses the inspiratory muscle strength; iii) NIRS assesses the dynamic changes in muscle oxygenation, through the metabolic variables (O2Hb, HHb and tHb), of the muscles in question. The assessment of muscle oxygenation before, during and after the PIMÁX maneuver in individuals with COPD, at different levels of severity, compared to healthy individuals, could assist as a complementary functional assessment technique of the respiratory musculature and therefore enable rehabilitation intervention strategies and / or preventive in this population.

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