Closed-loop parameter optimization for patient-specific phrenic nerve stimulation.

BACKGROUND: Ventilator-induced diaphragm dysfunction occurs rapidly following the onset of mechanical ventilation and has significant clinical consequences. Phrenic nerve stimulation has shown promise in maintaining diaphragm function by inducing diaphragm contractions. Non-invasive stimulation is an attractive option as it minimizes the procedural risks associated with invasive approaches. However, this method is limited by sensitivity to electrode position and inter-individual variability in stimulation thresholds. This makes clinical application challenging due to potentially time-consuming calibration processes to achieve reliable stimulation. METHODS: We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. A closed-loop system recorded the respiratory flow produced by stimulation and automatically adjusted the electrode position and stimulation amplitude based on the respiratory response. By iterating over electrodes, the optimal electrode was selected. A binary search method over stimulation amplitudes was then employed to determine an individualized stimulation threshold. Pulse trains above this threshold were delivered to produce diaphragm contraction. RESULTS: Nine healthy volunteers were recruited. Mean threshold stimulation amplitude was 36.17 ± 14.34 mA (range 19.38-59.06 mA). The threshold amplitude for reliable nerve capture was moderately correlated with BMI (Pearson's r = 0.66, p = 0.049). Repeating threshold measurements within subjects demonstrated low intra-subject variability of 2.15 ± 1.61 mA between maximum and minimum thresholds on repeated trials. Bilateral stimulation with individually optimized parameters generated reliable diaphragm contraction, resulting in significant inhaled volumes following stimulation. CONCLUSION: We demonstrate the feasibility of a system for automatic optimization of electrode position and stimulation parameters using a closed-loop system. This opens the possibility of easily deployable individualized stimulation in the intensive care setting to reduce ventilator-induced diaphragm dysfunction.

Non-invasive phrenic nerve stimulation to avoid ventilator-induced diaphragm dysfunction in critical care.

BACKGROUND: Diaphragm muscle atrophy during mechanical ventilation begins within 24 h and progresses rapidly with significant clinical consequences. Electrical stimulation of the phrenic nerves using invasive electrodes has shown promise in maintaining diaphragm condition by inducing intermittent diaphragm muscle contraction. However, the widespread application of these methods may be limited by their risks as well as the technical and environmental requirements of placement and care. Non-invasive stimulation would offer a valuable alternative method to maintain diaphragm health while overcoming these limitations. METHODS: We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. Respiratory pressure and flow, diaphragm electromyography and mechanomyography, and ultrasound visualization were used to assess the diaphragmatic response to stimulation. The electrode positions and stimulation parameters were systematically varied in order to investigate the influence of these parameters on the ability to induce diaphragm contraction with non-invasive stimulation. RESULTS: We demonstrate that non-invasive capture of the phrenic nerve is feasible using surface electrodes without the application of pressure, and characterize the stimulation parameters required to achieve therapeutic diaphragm contractions in healthy volunteers. We show that an optimal electrode position for phrenic nerve capture can be identified and that this position does not vary as head orientation is changed. The stimulation parameters required to produce a diaphragm response at this site are characterized and we show that burst stimulation above the activation threshold reliably produces diaphragm contractions sufficient to drive an inspired volume of over 600 ml, indicating the ability to produce significant diaphragmatic work using non-invasive stimulation. CONCLUSION: This opens the possibility of non-invasive systems, requiring minimal specialist skills to set up, for maintaining diaphragm function in the intensive care setting.

Morphea After Liposuction Ultrasonography.

Liposuction is a common aesthetic procedure; however, to date, liposuction has not been linked to morphea. The aim was to review cases with a history of liposuction that presented active morphea lesions in the same surgery regions and were confirmed by ultrasound and histology. A retrospective descriptive analysis of the clinical, ultrasonographic, and pathology database took place (2014-2020). Eleven patients met the criteria. Ultrasound supported the diagnosis, and the ultrasonographic signs of activity in these cases matched the features described in the literature in 100% of cases. In summary, morphea may appear after liposuction and ultrasound can support its early detection.

Distribution of Dental Fluorosis in the Southern Zone of Ecuador: An Epidemiological Study.

In recent decades, the increase in fluoride exposure has raised the numbers of dental fluorosis in fluoridated and non-fluoridated communities In Ecuador, but the last national epidemiological study on DF was conducted more than a decade ago. The objective of this cross-sectional descriptive study was to determine the prevalence, distribution and severity of dental fluorosis (DF) using the Dean index in 1606 schoolchildren aged 6 to 12 years from urban and rural environments in provinces that make up the Southern Region of Ecuador. Participants met the inclusion criteria which were age, locality, informed consent document and no legal impediment. The results are presented using percentage frequency measures and chi-square associations. The prevalence of dental fluorosis was 50.1% in the areas of Azuay, Cañar and Morona Santiago, with no significant differences (x2 = 5.83, p = 0.054). The types of DF found most frequently were very mild and mild in all provinces; a moderate degree was more prevalent in Cañar (17%). There was no significant association (p > 0.05) between sex and the presence of dental fluorosis and, with respect to severity, the most frequent degree was moderate at the age of 12 years. The prevalence of dental fluorosis in the area evaluated is high, especially in the light and very light degrees, with a tendency toward moderate levels. It is necessary to carry out studies on the factors that are predisposing to the development of this pathology in the population studied. This research is an update regarding this pathology in Ecuador, so it is concluded that it is necessary to continue developing studies based on the findings obtained, thus contributing to the public health of the country.

Gait Subphases Classification Based on Hidden Markov Models using in-shoes Capacitive Pressure Sensors: Preliminary Results.

Gait cycle analysis is widely practiced to determine alterations of normal walking. The challenge is to choose the ideal systems that suit the studies. One possibility is to measure the interaction of the sole and the support surface and detect gait events related to the positioning of the foot. This work proposes a gait subphase classification based on Hidden Markov Model that identifies gait stance subphases from a foot pressure measurement. A sensorized insole was used to record the pressure under the foot with eight custom-made capacitive sensors. Tests were performed on six volunteers with a 10-meter trial test. Mean cadence and stance/swing ratio were calculated. These parameters match the normal range for the age of the volunteers found in the literature. The results show that the proposed model can classify the gait in 5 subphases using the Center of Pressure (CoP) anteroposterior position and velocity as input. Changes in the slope of the CoP marks the step between subphases. Clinical Relevance- Most gait studies are performed in highly equipped gait laboratories. Due to technical requirements and the high cost of implementing a gait laboratory, access to these services is difficult for a large population. For this reason, it is necessary to develop equipment, devices, and algorithm to further study pathological and healthy gait.

Ergonomic Factors That Impact Job Satisfaction and Occupational Health during the SARS-CoV-2 Pandemic Based on a Structural Equation Model: A Cross-Sectional Exploratory Analysis of University Workers.

This paper presents a structural equation model to determine the job satisfaction and occupational health impacts concerning organizational and physical ergonomics, using (as a study) objective unionized workers from the University of Sonora, South Campus, as an educational enterprise, during the SARS-CoV-2 pandemic. The above is a key element of an organizational sustainability framework. In fact, there exists a knowledge gap about the relationship between diverse ergonomic factors, job satisfaction, and occupational health, in the educational institution's context. The method used was a stratified sample of workers to which a job satisfaction-occupational health questionnaire was applied, consisting of 31 items with three-dimensional variables. As a result, the overall Cronbach's Alpha coefficient was determined, 0.9028, which is considered adequate to guarantee reliability (i.e., very high magnitude). Therefore, after the structural equation model, only 12 items presented a strong correlation, with a good model fit of 0.036 based on the root mean square error of approximation, 1.09 degrees of freedom for the chi-square, 0.9 for the goodness of fit index, and a confidence level of 95%. Organizational and physical factors have positive impacts on job satisfaction with factor loads of 0.37 and 0.53, respectively, and p-values of 0.016 and 0.000, respectively. The constructs related to occupational health that are considered less important by the workers were also determined, which would imply a mitigation strategy. The results contribute to the body of knowledge concerning the ergonomic dimensions mentioned and support organizational sustainability improvements in educational institutions and other sectors.

Diagnóstico prenatal de anomalías nefrourológicas en el Centro de Referencia Perinatal Oriente, Santiago, Chile / Prenatal diagnosis of nefrourological anomalies at the Eastern Perinatal Referral Center, Santiago, Chile

INTRODUCCIÓN: Las anomalías congénitas de los riñones y las vías urinarias (CAKUT, Congenital Anomalies of the Kidney and Urinary Tract) representan un 20-30% de las anomalías detectadas en el periodo prenatal. Si bien la mayoría son de buen pronóstico, un 25% se asocian a enfermedad renal crónica en la infancia y en los casos graves a mortalidad perinatal. OBJETIVO: Describir los casos ingresados al Centro de Referencia Perinatal Oriente (CERPO) y determinar los resultados perinatales y la sobrevida al año. MÉTODO: Estudio descriptivo y retrospectivo. Se incluyeron pacientes ingresadas en la base de datos CERPO, entre los años 2003 y 2019, con diagnóstico de anomalía nefrourológica. Se incluyeron antecedentes prenatales, perinatales y de seguimiento posnatal al año. RESULTADOS: Se evaluaron 273 pacientes. La edad gestacional promedio de derivación fue de 29 semanas + 2 días. El diagnóstico más frecuente fueron las anomalías del tracto de salida (69%). Un 40% de los casos se asociaron a otras anomalías congénitas, siendo las cardiopatías las más frecuentes (19%). Aceptaron la realización de estudio genético invasivo 38 pacientes, de las cuales un 34% presentaron aneuploidías, siendo las trisomías 18 y 13 las más frecuentes (17% y 6%, respectivamente). Se instalaron cinco shunts derivativos vesicoamnióticos en fetos diagnosticados con megavejiga. La sobrevida global para la patología nefrourológica fue del 63% al año, y la mortalidad fetal y neonatal fue del 7% y el 16%, respectivamente. La sobrevida al año según el grupo de clasificación CAKUT fue del 22% para las anomalías de número de riñones, del 46% para las anomalías de tamaño y de morfología renal, del 60% para las anomalías de la posición renal y del 72% para las anomalías del tracto de salida. En este último grupo, la sobrevida alcanza el 81% al excluir los pacientes con diagnóstico prenatal de megavejiga, que presentaron una sobrevida al año del 28%. Los casos de patología nefrourológica asociada a oligohidramnios (índice de líquido amniótico < 5 cm) sin evidencias de uropatía obstructiva asociada presentaron una sobrevida al año del 3%. CONCLUSIONES: Las anomalías del sistema nefrourológico son un diagnóstico prenatal frecuente. La sobrevida al año fue del 63%, pero es necesario prolongar el seguimiento a largo plazo para determinar la evolución de la función renal en cada diagnóstico. La asociación de patología nefrourológica y oligohidramnios conlleva una sobrevida menor.

INTRODUCTION: Congenital anomalies of the kidneys and urinary tract (CAKUT) represent 20 to 30% of the anomalies detected prenatally. Although most are of good prognosis, 25% are associated with chronic kidney disease in childhood and severe cases with perinatal mortality. OBJECTIVE: To describe the cases studied in the Eastern Perinatal Referral Center (CERPO) and to determine the perinatal outcome and survival at one year. METHOD: Descriptive and retrospective study. Patients registered on the CERPO database, between 2003 to 2019, with diagnosis of nephrourological anomaly were included. Antenatal, perinatal and postnatal follow-up information was collected. RESULTS: 273 patients were evaluated. The average gestational age at referral was 29 + 2 weeks. The main diagnosis was urinary tract outlet disorders (69%). Thirty nine percent of the cases were associated with other congenital anomalies, with heart disease being the most frequent (19%). Thirty-eight patients accepted an invasive procedure for genetic study, 34% presented aneuploidy, trisomy 18 and 13 were the most frequent (17% and 6% respectively). Five vesico-amniotic derivative shunts were installed in fetuses diagnosed with megabladder. Overall survival at one year was 63% and fetal and neonatal mortality were 7% and 16% respectively. One-year survival per group according to CAKUT classification was 22% in kidney number abnormalities, 46% in kidney size and morphology abnormalities, 60% in renal position abnormalities and 72% in outflow tract abnormalities. In the latter, survival reaches 81% excluding the patients with prenatal diagnosis of megabladder who had a one-year survival of 28%. The cases of nephrourological pathology associated with oligohydramnios (amniotic fluid index < 5 cm) without evidence of associated obstructive uropathy presented a survival of 3% at one year. CONCLUSIONS: The anomalies of the nephrourological system correspond to a frequent prenatal diagnosis. Overall, the one-year survival was 63%; however, follow-up must continue to determine the evolution of renal function in relation to each diagnosis.