Inspiratory Muscle Training in Hospitalized Heart Failure Patients

inspiratory muscle strenght

Inspiratory muscle strength refers to the force generated by the muscles involved in inhalation, primarily the diaphragm and accessory respiratory muscles. It reflects the ability of these muscles to overcome resistance and expand the lungs during breathing. Before the tests to assess static and dynamic inspiratory muscle strength, volunteers underwent a familiarization session with the devices and maneuvers to be performed. After measuring resting hemodynamic parameters, the evaluation of maximal static respiratory pressures was conducted. Maximal inspiratory pressure (MIP) was measured using an analog manovacuometer (MURENAS brand, Anvisa Registration: 80244900005), following the protocol of the American Thoracic Society and the European Respiratory Society. MIP was determined after a maximal inspiratory effort starting from residual volume against airway occlusion.

Assessment of Functional Status

For the assessment of functional status, the 1-minute sit-to-stand test (1MSTS) will be performed. Participants will be instructed to stand up and sit down as quickly as possible without using their arms for 1 minute and will be advised to stop whenever they wish, if necessary. Heart rate (HR), respiratory rate (RR), blood pressure (BP), peripheral oxygen saturation (SpO2), and assessments of dyspnea and leg fatigue using the Modified Borg Scale will be recorded before and after the test. One repetition is defined as standing up fully straight and returning to a seated position.

Peripheral Muscle Strength

Peripheral muscle strength (PMS) will be measured using a digital dynamometer (Digital Dynamometer MG4800). Volunteers will perform the maneuver seated at a 90-degree angle, with the elbow flexed at 90 degrees and the wrist in a neutral position. They will be instructed and encouraged to perform a maximal handgrip contraction for 3 seconds on both sides. Three maximal isometric contractions will be performed, and the highest value from the dominant hand will be used for analysis . Predicted normal values will be based on the reference equation for dominant upper limb grip strength in middle-aged and elderly Brazilians. Values below 70% of the predicted will be considered reduced peripheral muscle strength .

Adverse events

The safety of the IMT protocol will be evaluated by monitoring the occurrence of any adverse events during the intervention. Adverse events will be classified as mild, moderate, or severe (Table 1). The control group will also have adverse events recorded. The heterogeneity in the definition of safety criteria and adverse events is a limitation in the literature, due to the lack of standardization in the definitions and naming of adverse events in clinical practice . Mild events are considered transient and do not require clinical intervention. Moderate events cause temporary symptoms that require clinical intervention. Severe events are those that result in permanent sequelae, serious complications, or even life-threatening conditions, such as cardiac arrest, loss of consciousness, and death .During the intervention period, hemodynamic effects of IMT will be assessed by monitoring vital signs before and after protocol.