Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 8 de 8
Filter
Add more filters











Database
Language
Publication year range
1.
PLoS One ; 17(12): e0277131, 2022.
Article in English | MEDLINE | ID: mdl-36477075

ABSTRACT

INTRODUCTION: Fatigue is defined as loss of capacity to develop muscle force and/or velocity that is reversible at rest. We assessed non-invasively the fatigue and recovery of inspiratory rib cage muscles during two respiratory endurance tests in healthy individuals. METHODS: The sniff nasal inspiratory pressure (SNIP) was assessed before and after two respiratory endurance tests: normocapnic hyperpnea (NH) and inspiratory pressure threshold loading (IPTL). Contractile (maximum rate of pressure development and time to peak pressure) and relaxation parameters (maximum relaxation rate [MRR], time constant of pressure decay [τ], and half relaxation time) obtained from sniff curves and shortening velocity and mechanical power estimated using optoelectronic plethysmography were analyzed during SNIP maneuvers. Respiratory muscle activity (electromyography) and tissue oxygenation (near-infrared spectroscopy-NIRS) were obtained during endurance tests and SNIP maneuvers. Fatigue development of inspiratory rib cage muscles was assessed according to the slope of decay of median frequency. RESULTS: Peak pressure during SNIP decreased after both protocols (p <0.05). MRR, shortening velocity, and mechanical power decreased (p <0.05), whereas τ increased after IPTL (p <0.05). The median frequency of inspiratory rib cage muscles (i.e., sum of sternocleidomastoid, scalene, and parasternal) decreased linearly during IPTL and exponentially during NH, mainly due to the sternocleidomastoid. CONCLUSION: Fatigue development behaved differently between protocols and relaxation properties (MRR and τ), shortening velocity, and mechanical power changed only in the IPTL.


Subject(s)
Health Status , Relaxation , Humans , Muscles
2.
PLoS One ; 17(4): e0266365, 2022.
Article in English | MEDLINE | ID: mdl-35363800

ABSTRACT

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.


Subject(s)
Asthma , Pulmonary Disease, Chronic Obstructive , Respiration Disorders , Case-Control Studies , Exercise Test , Humans , Respiratory Muscles , Walking/physiology
3.
PLoS One ; 16(7): e0253132, 2021.
Article in English | MEDLINE | ID: mdl-34292943

ABSTRACT

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.


Subject(s)
Diaphragm/physiology , Inhalation/physiology , Maximal Respiratory Pressures , Adolescent , Adult , Electromyography , Female , Humans , Male , Nose , Young Adult
4.
Sci Rep ; 11(1): 12475, 2021 06 14.
Article in English | MEDLINE | ID: mdl-34127754

ABSTRACT

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.


Subject(s)
Intercostal Muscles/physiology , Muscle Fatigue/physiology , Adult , Electromyography , Female , Humans , Male , Muscle Contraction/physiology , Muscle Relaxation/physiology , Muscle Strength/physiology , Plethysmography , Young Adult
5.
Pediatr Pulmonol ; 56(7): 2136-2145, 2021 07.
Article in English | MEDLINE | ID: mdl-33866686

ABSTRACT

OBJECTIVE: To assess thoracoabdominal asynchrony (TAA) and inspiratory paradoxical motion at different positionings in subjects with Duchenne muscular dystrophy (DMD) versus healthy subjects during quiet spontaneous breathing (QB) and cough. METHODS: This is a case control study with a matched-pair design. We assessed 14 DMD subjects and 12 controls using optoelectronic plethysmography (OEP) during QB and spontaneous cough in 3 positions: supine, supine with headrest raised at 45°, and sitting with back support at 80°. The TAA was assessed using phase angle (θ) between upper (RCp) and lower rib cage (RCa) and abdomen (AB), as well as the percentage of inspiratory time the RCp (IPRCp ), RCa (IPRCa ), and AB (IPAB ) moved in opposite directions. RESULTS: During cough, DMD group showed higher RCp and RCa θ (p < .05), RCp and AB θ (p < .05) in supine and 45° positions, and higher RCp and Rca θ (p = .006) only in supine position compared with controls. Regarding the intragroup analysis, during cough, DMD group presented higher RCp and AB θ (p = .02) and RCa and AB θ (p = .002) in supine and higher RCa and AB θ (p = .002) in 45° position when compared to 80°. Receiver operating characteristic curve analyzes were able to discriminate TAA between controls and DMD in RCa supine position (area under the curve: 0.81, sensibility: 78.6% and specificity: 91.7%, p = .001). CONCLUSION: Subjects with DMD yields TAA with insufficient deflation of chest wall compartments and rib cage distortion during cough, by noninvasive assessment.


Subject(s)
Cough , Muscular Dystrophy, Duchenne , Case-Control Studies , Cough/etiology , Healthy Volunteers , Humans , Muscular Dystrophy, Duchenne/complications , Plethysmography
6.
ERJ Open Res ; 4(3)2018 Jul.
Article in English | MEDLINE | ID: mdl-30151370

ABSTRACT

Small airway and interstitial pulmonary involvements are prominent in chronic hypersensitivity pneumonitis (cHP). However, their roles on exercise limitation and the relationship with functional lung tests have not been studied in detail. Our aim was to evaluate exercise performance and its determinants in cHP. We evaluated maximal cardiopulmonary exercise testing performance in 28 cHP patients (forced vital capacity 57±17% pred) and 18 healthy controls during cycling. Patients had reduced exercise performance with lower peak oxygen production (16.6 (12.3-19.98) mL·kg-1·min-1versus 25.1 (16.9-32.0), p=0.003), diminished breathing reserve (% maximal voluntary ventilation) (12 (6.4-34.8)% versus 41 (32.7-50.8)%, p<0.001) and hyperventilation (minute ventilation/carbon dioxide production slope 37±5 versus 31±4, p<0.001). All patients presented oxygen desaturation and augmented Borg dyspnoea scores (8 (5-10) versus 4 (1-7), p=0.004). The prevalence of dynamic hyperinflation was found in only 18% of patients. When comparing cHP patients with normal and low peak oxygen production (<84% pred, lower limit of normal), the latter exhibited a higher minute ventilation/carbon dioxide production slope (39±5.0 versus 34±3.6, p=0.004), lower tidal volume (0.84 (0.78-0.90) L versus 1.15 (0.97-1.67) L, p=0.002), and poorer physical functioning score on the Short form-36 health survey. Receiver operating characteristic curve analysis showed that reduced lung volumes (forced vital capacity %, total lung capacity % and diffusing capacity of the lung for carbon dioxide %) were high predictors of poor exercise capacity. Reduced exercise capacity was prevalent in patients because of ventilatory limitation and not due to dynamic hyperinflation. Reduced lung volumes were reliable predictors of lower performance during exercise.

7.
Front Neurol ; 9: 306, 2018.
Article in English | MEDLINE | ID: mdl-29770120

ABSTRACT

The relaxation rates and contractile properties of inspiratory muscles are altered with inspiratory muscle weakness and fatigue. This fact plays an important role in neuromuscular disorders patients and had never been extensively studied in amyotrophic lateral sclerosis (ALS). In this cross-sectional study, these parameters were investigated non-invasively through nasal inspiratory sniff pressure test (SNIP) in 39 middle stage spinal onset ALS subjects and compared with 39 healthy controls. ALS patients were also divided into three subgroups according to a decline in their percentage of predicted forced vital capacity (FVC%pred) as well as a decline in the ALS functional rating scale score and its respiratory subscore (R-subscore) in order to determine the best parameter linked to early respiratory muscle weakness. When compared with healthy subjects, middle stage ALS subjects exhibited a significantly lower (p < 0.0001) maximum relaxation rate and maximum rate of pressure development (MRPD), as well as a significantly higher (p < 0.0001) tau (τ), contraction time, and half-relaxation time. The results from receiver operating characteristic curves showed that MRPD (AUC 0.735, p < 0.001) and FVC%pred (AUC 0.749, p = 0.009) were the best discriminator parameters between ALS patients with ≤30 and >30 points in the ALS functional rating scale. In addition, 1/2RT (AUC 0.720, p = 0.01), FVC%pred (AUC 0.700, p = 0.03), τ (AUC 0.824, p < 0.0001), and MRPD (AUC 0.721, p = 0.01) were the parameters more sensitive in detecting a fall of three points in the R-subscore. On the other hand, MRPD (AUC 0.781, p < 0.001), τ (AUC 0.794, p = 0.0001), and percentage of predicted of SNIP (AUC 0.769, p = 0.002) were the parameters able to detect a fall in 30% of the FVC%pred in middle stage ALS patients. The contractile properties and relaxation rates of the diaphragm are altered in middle stage spinal onset ALS when compared with healthy subjects. These parameters are able to discriminate between those middle stage ALS subjects with early decline in inspiratory muscle function and those who not.

8.
Expert Rev Respir Med ; 12(1): 5-13, 2018 01.
Article in English | MEDLINE | ID: mdl-29048936

ABSTRACT

INTRODUCTION: Hypersensitivity pneumonitis (HP) is a disease with variable clinical presentation in which inflammation in the lung parenchyma is caused by the inhalation of specific organic antigens or low molecular weight substances in genetically susceptible individuals. Alterations of the acute, subacute and chronic forms may eventually overlap, and the diagnosis based on temporality and presence of fibrosis (acute/inflammatory HP vs. chronic HP) seems to be more feasible and useful in clinical practice. Differential diagnosis of chronic HP with other interstitial fibrotic diseases is challenging due to the overlap of the clinical history, and the functional and imaging findings of these pathologies in the terminal stages. Areas covered: This article reviews the essential features of HP with emphasis on imaging features. Moreover, the main methodological limitations of high-resolution computed tomography (HRCT) interpretation are discussed, as well as new perspectives with volumetric quantitative CT analysis as a useful tool for retrieving detailed and accurate information from the lung parenchyma. Expert commentary: Mosaic attenuation is a prominent feature of this disease, but air trapping in chronic HP seems overestimated. Quantitative analysis has the potential to estimate the involvement of the pulmonary parenchyma more accurately and could correlate better with pulmonary function results.


Subject(s)
Alveolitis, Extrinsic Allergic/diagnostic imaging , Tomography, Spiral Computed/methods , Diagnosis, Differential , Humans , Lung/diagnostic imaging
SELECTION OF CITATIONS
SEARCH DETAIL