After-effects of thixotropic conditionings on operational chest wall and compartmental volumes of patients with Parkinson’s disease

Individuals with Parkinson’s disease (PD) present respiratory dysfunctions, mainly due to decreased chest wall expansion, which worsens with the course of the disease. These findings contribute to the restrictive respiratory pattern and the reduction in chest wall volume. According to literature, inspiratory muscle thixotropic conditioning maneuvers may improve lung volumes in these patients. The study aimed to determine the after-effects of respiratory muscle thixotropic maneuvers on breathing patterns and chest wall volumes of PD. A crossover study was performed with twelve patients with PD (8 males; mean age 63.9±8.8 years, FVC%pred 89.7±13.9, FEV1%pred 91.2±15, FEV1/FVC%pred 83.7±5.7). Chest wall volumes were assessed using OEP during thixotropic maneuvers. Increases in EIVCW (mean of 126mL, p = 0.01) and EEVCW (mean of 150mL, p = 0.005) were observed after DITLC (deep inspiration from total lung capacity) due to increases in pulmonary (RCp) and abdominal (RCa) ribcage compartments. Changes in ICoTLC (inspiratory contraction from TLC) led to significant EIVCW (mean of 224mL, p = 0.001) and EEVCW (mean of 229mL, p = 0.02) increases that were mainly observed in the RCp. No significant changes were found when performing DERV (deep expiration from residual volume) and ICoRV (Inspiratory contraction from RV). Positive correlations were also observed between the degree of inspiratory contraction during ICoTLC and EEVRCp (rho = 0.613, p = 0.03) and EIVRCp (rho = 0.697, p = 0.01) changes. Thixotropy conditioning of inspiratory muscles at an inflated chest wall volume increases EIVCW and EEVCW in the ten subsequent breaths in PD patients. These maneuvers are easy to perform, free of equipment, low-cost, and may help patients improve chest wall volumes during rehabilitation

Breathing pattern and muscle activity using different inspiratory resistance devices in children with mouth breathing syndrome

Aim The aim of this study was to evaluate the acute effects of different inspiratory resistance devices and intensity of loads via nasal airway on the breathing pattern and activity of respiratory muscles in children with mouth breathing syndrome (MBS). Methods Children with MBS were randomised into two groups based on inspiratory load intensity (20% and 40% of the maximal inspiratory pressure). These subjects were assessed during quiet breathing, breathing against inspiratory load via nasal airway and recovery. The measurements were repeated using two different devices (pressure threshold and flow resistance). Chest wall volumes and respiratory muscle activity were evaluated by optoelectronic plethysmography and surface electromyography, respectively. Results During the application of inspiratory load, there was a significant reduction in respiratory rate (p<0.04) and an increase in inspiratory time (p<0.02), total time of respiratory cycle (p<0.02), minute ventilation (p<0.03), tidal volume (p<0.01) and scalene and sternocleidomastoid muscles activity (root mean square values, p<0.01) when compared to quiet spontaneous breathing and recovery, regardless of load level or device applied. The application of inspiratory load using the flow resistance device showed an increase in the tidal volume (p<0.02) and end-inspiratory volume (p<0.02). Conclusion For both devices, the addition of inspiratory loads using a nasal interface had a positive effect on the breathing pattern. However, the flow resistance device was more effective in generating volume and, therefore, has advantages compared to pressure threshold

Changes in electromyographic activity, mechanical power, and relaxation rates following inspiratory ribcage muscle fatigue

Muscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity

Electrical activity and fatigue of respiratory and locomotor muscles in obstructive respiratory diseases during field walking test

Introduction In subjects with obstructive respiratory diseases the increased work of breathing during exercise can trigger greater recruitment and fatigue of respiratory muscles. Associated with these changes, lower limb muscle dysfunctions, further contribute to exercise limitations. We aimed to assess electrical activity and fatigue of two respiratory and one locomotor muscle during Incremental Shuttle Walking Test (ISWT) in individuals with obstructive respiratory diseases and compare with healthy. Methods This is a case-control study. Seventeen individuals with asthma (asthma group) and fifteen with chronic obstructive pulmonary disease (COPD group) were matched with healthy individuals (asthma and COPD control groups). Surface electromyographic (sEMG) activity of sternocleidomastoid (SCM), scalene (ESC), and rectus femoris (RF) were recorded during ISWT. sEMG activity was analyzed in time and frequency domains at baseline and during the test (33%, 66%, and 100% of ISWT total time) to obtain, respectively, signal amplitude and power spectrum density (EMG median frequency [MF], high- and low-frequency bands, and high/low [H/L] ratio). Results Asthma group walked a shorter distance than controls (p = 0.0007). sEMG amplitudes of SCM, ESC, and RF of asthma and COPD groups were higher at 33% and 66% of ISWT compared with controls groups (all p<0.05). SCM and ESC of COPD group remained higher until 100% of the test. MF of ESC and RF decreased in asthma group (p = 0.016 and p < 0.0001, respectively) versus controls, whereas MF of SCM (p < 0.0001) decreased in COPD group compared with controls. H/L ratio of RF decreased (p = 0.002) in COPD group versus controls. Conclusion Reduced performance is accompanied by increased electromyographic activity of SCM and ESC and activation of RF in individuals with obstructive respiratory diseases during ISWT. These are susceptible to be more pronounced respiratory and peripheral muscle fatigue than healthy subjects during exercise

Effects of diaphragmatic control on multiparametric analysis of the sniff nasal inspiratory pressure test and inspiratory muscle activity in healthy subjects

Background We investigated the influence of diaphragmatic activation control (diaphC) on the relaxation rate, contractile properties and electrical activity of the inspiratory muscles of healthy subjects. Assessments were performed non-invasively using the sniff inspiratory pressure test (SNIP) and surface electromyography, respectively. Methods Twenty-two subjects (10 men and 12 women) performed 10 sniff maneuvers in two different days: with and without diaphC instructions. For the SNIP test with diaphC, the subjects were instructed to perform intense activation of the diaphragm. The tests with the best SNIP values were used for analysis. Results The maneuver with diaphC when compared to the maneuver without diaphC exhibited significant lower values for: SNIP (p <0.01), maximum relaxation rate (MRR) (p <0.01), maximum rate of pressure development (MRPD) (p <0.01), contraction times (CT) (p = 0.02) and electrical activity of the sternocleidomastoid (SCM) (p <0.01), scalene (SCL) (p = 0.01) and intercostal (CI) (p = 0.03) muscles. In addition, the decay constant (tau, τ) and relaxation time (½ RT) did not present any changes. Conclusion The diaphragmatic control performed during the SNIP test influences the inspiratory pressure and the contractile properties of inspiratory muscles. This occurs due to changes in the pattern of muscle recruitment, which change force velocity characteristics of the test. Thus, instruction on diaphC should be encouraged for better performance of the SNIP test and for evaluation targeting the diaphragm muscle activity