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A Doppler ultrasound (DUS) is essential for detecting blood flow abnormalities in the umbilical cord (UC). Any morphological abnormalities of the UC may lead to morbidity and stillbirth. Some abnormalities such as torsion, strictures and true-knot, however, may only be discovered at birth. This study proposes a novel approach of using machine learning analysis of flow velocity waveforms to improve the diagnosis of UC abnormalities.A dynamic in-vitro simulator for DUS and three UC models, each representing a different morphology: true-knot, straight and coiled, were designed. DUS flow field images were captured from four cases of flow through the models: straight, coiled, at mid- and exit of the UC true-knot. The images were transformed into vector profiles of average flow signals that were segmented into 250 flow waves, each comprising 120 samples, for each of the four cases. Three sets of features were extracted from each flow wave and different machine learning algorithms were used for dimensional reduction and binary and multiclass classification.Significant differences were obtained between flow signals measured at the mid-knot compared to all other cases, which were also reflected in the average high accuracy rates of 97.5%-99.2%. Good accuracy rates of ∼80% and up were also generated, allowing the differentiation between the straight, coiled and exit true-knot.Our dynamic simulator can produce an unlimited database, and combined with the proposed machine learning analysis, may be used as decision support system and increase the ability to diagnose unseen pathologies of the UC.

Different rehabilitation programs are used to relieve dyspnea for hyper-inflated lung patients. In this study, a new approach, based on integrated changes in respiratory rate and pattern, for inspiratory muscles rehabilitation and training was examined utilizing noninvasive measurements of the two inspiratory muscles (rib cage inspiratory and neck inspiratory muscles) activity during controlled breathing in healthy subjects. Muscles activity was measured using electromyography, while subjects, breathed at different combinations of respiratory rate (6, 10, 16 breath per minutes) and inspiratory duty cycles (TI/Ttot). The results clearly show that both muscles were most active at the lowest evaluated respiratory rate, and that alteration of the duty cycle at the lowest rate significantly (p< 0.05) changes their electrical activity. Breathing at low respiratory rate RR is recommended for hyper-inflated lung patients in order to improve their gas exchange, therefore, it is recommended for these patients to find their most effective combination of RR and TI/Ttot and to use control breathing to practice their breath at optimum combination.

A flexible piezoelectric thin film sensor has been proposed recently in several studies for detection of muscle movements. The objective of this study was to investigate the ability of this sensor to assess skeletal muscle performance and fatigue under isokinetic contractions. Simultaneous noninvasive measurements of muscles activity were done using surface electromyography (EMG) electrodes and two thin film piezoelectric sensors. Measurements were taken from the biceps during slow and fast elbow flexion with and without strong grip, during different weight lifting and from the gastrocnemius during treadmill marching at speeds of 4 and of 10 kph. The results shows correlation between the onset of EMG and the piezoelectric sensors (Piezo) signals during muscle contraction. Increasing contraction intensity increase significantly both EMG and Piezo signals. Higher contractions velocity increased Piezo signal. Opposite linear relation was found between the average maximal EMG envelope amplitudes and the average maximal Piezo peaks with increasing loads. The significant decrease in the maximal Piezo peaks with time of all 3 subjects during elbow flexion while holding weight suggests the ability of piezoelectric thin film sensor to track muscle fatigue during isokinetic contractions.

BACKGROUND: Breastfeeding is a dynamic process in which the infant recruits several muscle groups in his face, head and throat. OBJECTIVE: The objective of this study was to explore the relative role of the submental muscle group, the orbicularis oris and the sternocleidomastoid muscles to breastfeeding process and to the relatively high intra-oral vacuum measured during this process.METHODS: Electromyography (EMG) measurements were conducted on 11 infants (mean age 1.91 ± 1.0 days, mean weight 3364 ± 328 g) using surface electrodes. The EMG data were filtered with a low pass filter to yield the linear envelopes (IEMG). The maximal and mean value and the area under each linear envelope curve were examined.RESULTS: During active suckling significantly higher activity (P< 0.05) of the submental muscle group were measured compared with the orbicularis oris and sternocleidomastoid muscles (mean ± SE values of the maximal linear envelope were 24.4 ± 1 μV, 9.6 ± 0.6 μV and 14 ± 0.7 μV, respectively). CONCLUSION: These results confirmed that jaw movements have the primary role during breastfeeding, but also revealed that the inspiratory muscles have a substantial contribution to this process and probably have an important role in the generation of intra oral vacuum measured during breastfeeding.

Airway stents improve pulmonary function and quality of life in patients suffering from airway obstruction. The aim of this study was to compare main types of stents (silicone, balloon-dilated metal, self-expanding metal, and covered self-expanding metal) in terms of their mechanical properties and the radial forces they exert on the trachea. Mechanical measurements were carried out using a force gauge and specially designed adaptors fabricated in our lab. Numerical simulations were performed for eight different stent geometries, inserted into trachea models. The results show a clear correlation between stent diameter (oversizing) and the levels of stress it exerts on the trachea. Compared with uncovered metal stents, metal stents that are covered with less stiff material exert significantly less stress on the trachea while still maintaining strong contact with it. The use of such stents may reduce formation of mucosa necrosis and fistulas while still preventing stent migration. Silicone stents produce the lowest levels of stress, which may be due to weak contact between the stent and the trachea and can explain their propensity for migration. Unexpectedly, stents made of the same materials exerted different stresses due to differences in their structure. Stenosis significantly increases stress levels in all stents.

A system for noninvasive assessment of an all-inclusive function of respiratory muscles at different lung volumes is presented. The apparatus was based on the interrupter technique and facilitated simultaneous measurements of mouth pressure and airflow rate during dynamic or quasi-static manoeuvres. In this study, mouth pressure values were continuously acquired during and after interruption of a forced inspiratory or expiratory manoeuvre for as long as the subject could sustain an elevated mouth pressure against the obstructed opening. These measurements provided information on both muscle strength and power. A total of 420 forced maximal inspiratory and expiratory manoeuvres performed by six healthy subjects were monitored at different lung volumes. The pattern of maximal pressure-time curves was consistent for the same subject regardless of lung volume. Similar values of maximal mouth pressure can be generated by healthy subjects by using either a flange-style mouthpiece or facial mask. For both methods mouth pressure shows a significant ( p < 0.05) second order dependency on lung volume for both inspiration and expiration. The standard deviation of measurements from a single subject about a second order curve is of the order of 5-15%. The findings of interchangeability between methods of measurement may be useful in allegedly non-compliant patients. Keywords: mouth pressure, respiratory muscle strength, respiratory muscle endurance, interrupter technique

Activity-based anorexia (ABA) occurs when there is limited access to food and an opportunity to engage in high levels of physical activity. While the ABA effect is well established, the distinct functions of exercise and food restriction in maintaining ABA have not been determined. The current study examined the effect of pre-exposure to a restricted feeding schedule and pre-exposure to a running wheel on the incidence of ABA in 36 rats. Access to food and the running wheel was also varied in the recovery phase of the study in order to establish the effect of these variables on recovery from ABA. Three adaptation conditions (pre-exposed to food restriction, pre-exposed to wheel access and non-exposed) and two recovery conditions (wheel access and food restriction recovery) defined the six groups in the current study. Pre-exposure to food restriction was found to ameliorate the ABA effect during the anorexia phase while pre-exposure to wheel access exacerbated ABA. It was also found that subjects in the wheel access recovery condition gained more weight than the subjects in the food restriction recovery. In food restriction recovery, there was an interaction between the adaptation and recovery condition, with subjects that were pre-exposed to food restriction gaining the most weight. The results of the current study aid in understanding the distinct functions of food restriction and exercise in maintaining and recovering from ABA and have possible implications for the treatment of people diagnosed with some types of anorexia nervosa.

Obesity is a risk factor for asthma. The purpose of this study was to determine whether metformin, an agent used in the treatment of an obesity-related condition (type II diabetes), might have therapeutic potential for modifying the effects of obesity on airway smooth muscle (ASM) function. Metformin acts via activation of AMP-activated protein kinase (AMPK), a cellular sensor of energy status. In cultured murine ASM cells, metformin (0.2-2 mM) caused a dose-dependent inhibition of cell proliferation induced by PDGF (10(-8) M) and serotonin (10(-4) M). Another AMPK activator, 5-aminoimidazole-4-carboxamide-1-beta-Driboruranoside (AICAR), also inhibited PDGF-induced proliferation. Furthermore, cells treated with metformin or AICAR, also exhibited an attenuation in the rate of cytoskeletal remodeling, as quantified by spontaneous nanoscale motions of microbeads tightly anchored to the cytoskeleton (CSK) of the ASM cell. ASM cells treated with metformin or AICAR, however, exhibited no appreciable differences in stiffness as measured by optical magnetic twisting cytometry (OMTC) or their abilities to stiffen in response to contractile agonist serotonin. Taken together, these findings suggest that metformin, probably through activation of AMPK, reduces the rate of ongoing reorganization of the CSK and inhibits ASM cell proliferation.

Obesity is a risk factor for asthma. The purpose of this study was to determine whether metformin, an agent used in the treatment of another obesity-related condition, type II diabetes, might have therapeutic potential for airway smooth muscle (ASM) function in obesity.

Background: Emphysema and pulmonary fibrosis force the patients to breathe at an abnormal lung volume, which alters the lengths of the respiratory muscles and thereby their work capability is reduced. After single-lung transplantation, muscle function is restored on the side of the transplant but it may be asymmetric to that on the side of the native diseased lung. Objective: Investigating the hypothesis that single-lung transplantation induces mechanical asymmetry of the respiratory muscles on the two sides. Methods: Simultaneously noninvasive measurements of inspiratory and expiratory mouth pressure, airflow rate and electromyography signals from the sternomastoid, external intercostal, rectus abdominis and external oblique muscles were acquired during different breathing maneuvers. The study group included 10 single-lung transplant recipients (5 with pulmonary fibrosis and 5 with emphysema) and 10 healthy controls. Results: Analysis of the finding shows a significant lower global strength of the respiratory muscles of single-lung transplant recipients compared to that of healthy subjects. No significant difference in the EMG signals of respiratory muscles was found either between the different groups or between the sides of the transplant and the native lung in the patient groups. Both single-lung transplant recipients and healthy subjects demonstrated high EMG activity of the inspiratory muscles during inspiration at different breathing efforts. Conclusion: Patients after single-lung transplantation have lower respiratory muscle strength than healthy subjects, but apparently normal electrical activity. The lower global respiratory muscle strength emphasizes the importance of their rehabilitation before and after single-lung transplantation.

Single-lung transplantation may induce asynchronous performance between the respiratory muscles of the chest. The objective of this study was to investigate the influence of a single transplanted lung on respiratory muscle mechanics. The force and power of the sternomastoid, external intercostal and external oblique muscles were evaluated throughout a range of respiratory maneuvers in emphysematic patients with a single transplanted lung and compared with that of healthy subjects. A significant differences was observed between the force, work and power of the muscles on the two sides of the chest in emphysematic patients (P < 0.05). The control group demonstrated higher averaged maximal force, work and power. The total work done during either inspiration or expiration by the external intercostal and external oblique muscles on the side of the transplanted lung were higher compared with that of the native lung side and compared with the control group. The asynchrony between the lungs after single-lung transplant leads to asynchronous muscle force and work and lesser muscle strength compared to healthy subjects.

The respiratory muscles constitute the respiratory pump, which determines the efficacy of ventilation. Any functional disorder in their performance may cause insufficient ventilation. This study was designed to quantitatively explore the relative contribution of major groups of respiratory muscles to global lung ventilation throughout a range of maneuvers in healthy subjects. A computerized experimental system was developed for simultaneous noninvasive measurement of inspired/expired airflow, mouth pressure and up to 8 channels of EMG surface signals from major respiratory muscles which are located near the skin (e.g., sternomastoid, external intercostal, rectus abdominis and external oblique) during various respiratory maneuvers. Lung volumes values were calculated by integration of airflow data. Hill's muscle model was utilized to calculate the forces generated by the muscles from the acquired EMG data. Analysis of EMG measurements and respiratory muscles forces revealed the following characteristics: (a) muscle activity increased with increased breathing effort, (b) inspiratory muscles contributed to inspiration even at relatively low flow rates, while expiratory muscles are recruited at higher flow rates, (c) the forces generated by the muscle depended on the muscle properties as well as on their EMG performance and (d) the pattern of the muscle's force curves varied between subjects, but were generally consistent for the same subject regardless of breathing effort.

Normal breathing is made possible by the adequate performance of the respiratory pump which is driven by the respiratory muscles. A system for the noninvasive measurement of mouth pressure, airflow and EMG signals from respiratory muscles during different respiratory maneuvers was developed to assess the performance of individual groups of respiratory muscles. A Hill-based muscle model was utilized to estimate the forces generated by each of the respiratory muscles during the various maneuvers. The results show the potential of this method in both the diagnosis of weak muscle groups and development of rehabilitation programs.

Simultaneous measurements of the electrical activity of the major respiratory muscles may provide new information of the symmetric performance of the chest wall. The authors developed an experimental system for the noninvasive measurement of mouth pressure, airflow and EMG signals from major respiratory muscles by surface electrodes during different respiratory maneuvers. In order to analyze the asymmetry of muscle activity the authors simultaneously measured the activity from each side of the chest wall. Preliminary results show the relative contribution of individual groups of the respiratory muscles in healthy subjects and thus may help in the clinical diagnosis and medical follow up of respiratory muscles pathology.

The respiratory muscles may fatigue during prolonged exercises and thereby become a factor that limits extreme physical activity. The aim of the current study was to determine whether respiratory muscle fatigue imposes a limitation on extreme physical activity of well-trained young men. Electromyography (EMG) signals of respiratory (external intercostal and sternomastoid) and calf muscles (gastrocnemius) were measured (N = 8) during 1 hr of treadmill marching at a speed of 8 km/hr with and without a 15 kg backpack. The root mean square (RMS) and the mean power frequency of the EMG signals were evaluated for calculating fatigue indices. The EMG RMS revealed that the respiratory and calf muscles did not fatigue during the marching without a backpack load. The study did show, however, a significant rise in the EMG values when a backpack was carried with respect to the no-load condition (p < .05), which suggests that respiratory muscles should be trained in military recruits who are required to carry loaded backpacks while marching.