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.

Endoplasmic reticulum stress and muscle dysfunction in congenital lipodystrophies.

Lipodystrophy syndromes are a group of rare diseases related to the pathological impairment of adipose tissue and metabolic comorbidities, including dyslipidemia, diabetes, insulin resistance, hypoleptinemia, and hypoadiponectinemia. They can be categorized as partial or generalized according to the degree of fat loss, and inherited or acquired disorders, if they are associated with genetic mutations or are related to autoimmunity, respectively. Some types of lipodystrophies have been associated with changes in both redox and endoplasmic reticulum (ER) homeostasis as well as muscle dysfunction (MD). Although ER stress (ERS) has been related to muscle dysfunction (MD) in many diseases, there is no data concerning its role in lipodystrophies' muscle physiopathology. Here we focused on congenital lipodystrophies associated with ERS and MD. We also described recent advances in our understanding of the relationships among ERS, MD, and genetic lipodystrophies, highlighting the adiponectin-protective roles.

Effects of Inspiratory Load on Chest Wall Kinematics, Breathing Pattern, and Respiratory Muscle Activity of Mouth-Breathing Children.

BACKGROUND: We sought to evaluate the acute effects of different inspiratory loads using nasal and oral interfaces on the volumes of the chest wall and its compartments, breathing pattern, and respiratory muscle activation in children with mouth-breathing syndrome. METHODS: Children with mouth-breathing syndrome were randomized into 2 groups, one with an inspiratory load intensity 20% of maximum inspiratory pressure (n = 14), and the other with an inspiratory load intensity 40% of maximum inspiratory pressure (n = 15). The chest wall volumes and electromyography of sternocleidomastoid, rectus abdominis, scalene, and internal intercostal muscles were used to analyze respiration against the 2 load intensities and using 2 interfaces (ie, nasal and oral). RESULTS: A total of 72 children with mouth-breathing syndrome were recruited, and 29 were evaluated in this study. The use of inspiratory load promoted improvement in the components of the breathing pattern: breathing frequency (P = .039), inspiratory time (P = .03), and total respiratory time (P = .043); and increases in tidal volume (P < .001), end-inspiratory volume (P < .001), and electrical activity of scalene muscles and sternocleidomastoid muscles (P < .001) when compared to quiet breathing. The load imposed via a nasal interface versus an oral interface provided an increase in tidal volume (P = .030), end-inspiratory volume (P = .02), and electrical activity of scalene muscles (P < .001) and sternocleidomastoid muscles (P = .02). CONCLUSIONS: The use of acute inspiratory loads improved the breathing pattern and increased lung volume and electrical activity of inspiratory muscles. This work brings new perspective to the investigation of using nasal interfaces during the application of inspiratory loads. The nasal interface was more effective compared to the oral interface commonly used in clinical practice.

Effects of Positioning on Cough Peak Flow and Muscular Electromyographic Activation in Duchenne Muscular Dystrophy.

BACKGROUND: Advanced stages of Duchenne muscular dystrophy (DMD) result in muscle weakness and the inability to generate an effective cough. Several factors influence the effectiveness of cough in patients with DMD. The aim of this study was to assess whether differences in positioning affect cough peak flow (CPF) and muscular electromyographic activation in subjects with DMD compared with paired healthy subjects. METHODS: Optoelectronic plethysmography and surface electromyography were used to assess chest wall volumes, chest wall inspiratory capacity, CPF, breathing pattern, and electromyographic activity of sternocleidomastoid, scalene, rectus abdominis, and external oblique muscles during inspiratory and expiratory cough phases in the supine position, supine position with headrest raised at 45°, and sitting with back support at 80° in 12 subjects with DMD and 12 healthy subjects. RESULTS: Subjects with DMD had lower CPF (P < .01) in comparison to control subjects in all positions; the DMD group also exhibited lower CPF (P = .045) in the supine position versus 80°. Moreover, the relative volume contributions of the rib cage and abdominal compartments to tidal volume modified significantly with posture. The electromyographic activity during inspiratory and expiratory cough phases was lower in subjects with DMD compared to healthy subjects for all evaluated muscles (P < .05), but no significant differences were observed with posture change. CONCLUSIONS: In subjects with DMD, posture influenced CPF and the relative contribution of the rib cage and abdominal compartments to tidal volume. However, muscular electromyographic activation was not influenced by posture in subjects with DMD and healthy subjects.

Air Stacking: A Detailed Look Into Physiological Acute Effects on Cough Peak Flow and Chest Wall Volumes of Healthy Subjects.

BACKGROUND: Air stacking (AS) is a lung insufflation method that requires the use of a manual insufflator to provide air volumes higher than inspiratory capacity. Neuromuscular patients benefit the most from the maneuver; however, the acute effects of AS in healthy subjects are still unclear. METHODS: Twenty healthy subjects (8 males) were studied by optoelectronic plethysmography to investigate the immediate effects of AS on cough peak flow, operational volume variations, distribution of these volumes in the chest wall compartments (pulmonary rib cage, abdominal rib cage, and abdominal), breathing pattern, and shortening velocity of the respiratory muscles during a protocol that included vital capacity maneuvers and spontaneous coughs before and after AS. RESULTS: Statistically significant increases in cough peak flow (P < .03) and inspiratory capacity (P < .001) were found immediately after AS. During its application, the pulmonary rib cage compartment was the largest contributor (P = .002) to chest wall volume displacement. A significant increase in chest wall tidal volume (P < .001), mainly in the pulmonary rib cage (P < .001), was observed. Significant increases (P < .001) in end-inspiratory chest wall volume were observed with main distribution in pulmonary (P < .001) and abdominal rib cage (P = .01). Significant increases in shortening velocity index of inspiratory muscles (P < .001), expiratory muscles (P < .001), and diaphragm (P < .001) were also observed. In addition, significant decreases in expiratory time (P < .001) and increases in duty cycle (P = .02), breathing frequency (P = .02), minute ventilation (P < .001), maximum inspiratory (P < .001), and expiratory flow (P < .001) were observed. CONCLUSIONS: In healthy subjects, cough peak flow and chest wall volumes can be increased immediately after the application of the AS maneuver.

[Domiciliary respiratory muscle training in myotonic dystrophy]. / Entrenamiento muscular respiratorio domiciliario en la distrofia muscular miotónica.

A 42-year-old man diagnosed with myotonic dystrophy experienced loss of respiratory muscle strength over a period of 6 months. We report the application of a domiciliary training program targeting both inspiratory and expiratory muscles. Maximal inspiratory and expiratory pressures, forced vital capacity, and forced midexpiratory flow rate were measured 6 months before start of training, just before commencement of the program, and immediately after 12 weeks of training. Adherence to the program was satisfactory. Inspiratory muscle training was efficacious in increasing respiratory muscle strength. Expiratory muscle training, which made use of the Threshold PEP bronchial hygiene device incorporating an adapted flutter valve, was not efficacious in increasing maximal expiratory pressure or halting its loss. However, decreased obstruction of medium-caliber airways was observed with use of the device.