Evaluation and application of CO2 laser fiber delivery for single port transoral robotic surgery.

BACKGROUND: Transoral robotic surgery (TORS) using the Single-Port system (SPS) relies on electrocautery, limiting its applications in the upper aerodigestive tract. We evaluated the feasibility of a CO2 delivery system for the SPS. METHODS: Otolaryngology residents performed a cutting exercise using a handheld CO2 laser and participated in a cadaveric oropharyngeal dissection using the SPS with monopolar cautery (SP + EC) and CO2 laser (SP + CO2 ). Residents completed the System Usability Scale (SUS) questionnaire to evaluate these techniques. RESULTS: The same laser fiber was used for all combined dissections. The handheld CO2 laser, SP + EC, and SP + CO2 demonstrated similar SUS scores. On individual domain scores, SP + CO2 received less favorable ratings compared to the handheld CO2 laser for complexity, integration, and cumbersome experience (p < 0.05). On subgroup stratification, less TORS experience was associated with worse SUS scores. CONCLUSION: SP-guided CO2 laser delivery is a viable alternative to electrocautery in robotic surgery, and should be considered when performing TORS.

Tinnitus and auditory cortex; Using adapted functional near-infrared-spectroscopy to expand brain imaging in humans.

OBJECTIVES: Phantom sound perception (tinnitus) may arise from altered brain activity within auditory cortex. Auditory cortex neurons in tinnitus animal models show increased spontaneous firing rates. This may be a core characteristic of tinnitus. Functional near-infrared spectroscopy (fNIRS) has shown similar findings in human auditory cortex. Current fNIRS approaches with cap recordings are limited to ∼3 cm depth of signal penetration due to the skull thickness. To address this limitation, we present an innovative fNIRS approach via probes adapted to the external auditory canal. The adapted probes were placed deeper and closer to temporal lobe of the brain to bypass confining skull bone and improve neural recordings. METHODS: Twenty adults with tinnitus and 20 nontinnitus controls listened to periods of silence and broadband noise (BBN) during standard cap and adapted ear canal fNIRS neuroimaging. The evaluators were not blinded, but the protocol and postprocessing for the two groups were identical. RESULTS: Standard fNIRS measurements in participants with tinnitus revealed increased auditory cortex activity during silence that was suppressed during auditory stimulation with BBN. Conversely, controls displayed increased activation with noise but not during silence. Importantly, adapted ear canal fNIRs probes showed similar hemodynamic responses seen with cap probes in both tinnitus and controls. CONCLUSIONS: In this proof of concept study, we have successfully fabricated, adapted, and utilized a novel fNIRS technology that replicates established findings from traditional cap fNIRS probes. This exciting new innovation, validated by replicating previous and current cap findings in auditory cortex, may have applications to future studies to investigate brain changes not only in tinnitus but in other pathologic states that may involve the temporal lobe and surrounding brain regions. LEVEL OF EVIDENCE: NA.

Tinnitus and auditory cortex: using adapted functional near-infrared spectroscopy to measure resting-state functional connectivity.

OBJECTIVE: Tinnitus, phantom sound perception, arises from aberrant brain activity within auditory cortex. In tinnitus animal models, auditory cortex neurons show increased spontaneous firing and neural synchrony. In humans, similar hyperactivation in auditory cortex has been displayed with functional near-infrared spectroscopy (fNIRS). Resting-state functional connectivity (RSFC) or increased connectivity between brain regions has also been shown in tinnitus using fNIRS. However, current fNIRS technology utilizes infrared (IR)-sources and IR-detectors placed on the scalp that restricts (~3 cm depth IR penetration) signal capture to outer cerebral cortex due to skin and skull bone. To overcome this limitation, in this proof of concept study, we adapted fNIRS probes to fit in the external auditory canal (EAC) to physically place IR-probes deeper within the skull thereby extracting neural signals from deeper auditory cortex. METHODS: Twenty adults with tinnitus and 20 nontinnitus controls listened to periods of silence and broadband noise before and after 5 min of silence to calculate RSFC. Concurrent scalp probes over auditory cortex and an adapted probe placed in the right EAC were utilized. RESULTS: For standard probes, left and right auditory cortex in tinnitus showed increased RSFC to each other and to other nonauditory cortices. Interestingly, adapted fNIRS probes showed trends toward increased RSFC. CONCLUSION: While many areas for the adapted probes did not reach significance, these data using a highly innovative and newly created probe adapting fNIRS technology to the EAC substantiates our previously published data in human tinnitus and concurrently validates this technology as a useful and expanded brain imaging modality.

Effect of the diet type and temperature on the C. elegans transcriptome.

The transcriptomes of model organisms have been defined under specific laboratory growth conditions. The standard protocol for Caenorhabditis elegans growth and maintenance is 20°C on an Escherichia coli diet. Temperatures ranging from 15°C to 25°C or feeding with other species of bacteria are considered physiological conditions, but the effect of these conditions on the worm transcriptome has not been well characterized. Here, we compare the global gene expression profile for the reference Caenorhabditis elegans strain (N2) grown at 15°C, 20°C, and 25°C on two different diets, Escherichia coli and Bacillus subtilis. When C. elegans were fed E. coli and the growth temperature was increased, we observed an enhancement of defense response pathways and down-regulation of genes associated with metabolic functions. However, when C. elegans were fed B. subtilis and the growth temperature was increased, the nematodes exhibited a decrease in defense response pathways and an enhancement of expression of genes associated with metabolic functions. Our results show that C. elegans undergo significant metabolic and defense response changes when the maintenance temperature fluctuates within the physiological range and that the degree of pathogenicity of the bacterial diet can further alter the worm transcriptome.

Variation in Spending around Surgical Episodes of Urinary Stone Disease: Findings from Michigan.

PURPOSE: To help rein in surgical spending there is growing interest in the application of payment bundles to common outpatient procedures like ureteroscopy and shock wave lithotripsy. However, before urologists can move to such a payment system they need to know where episode costs are concentrated. MATERIALS AND METHODS: Using claims data from Michigan Value Collaborative we identified patients who underwent ureteroscopy or shock wave lithotripsy at hospitals in Michigan from 2012 to 2015. We then totaled expenditures for all relevant services during the 30-day surgical episodes of these patients and categorized component payments (ie those for the index procedure, subsequent hospitalizations, professional services and postacute care). Finally we quantified the variation in total episode expenditures for ureteroscopy and shock wave lithotripsy across hospitals, examining drivers of this variation. RESULTS: A total of 9,449 ureteroscopy and 6,446 shock wave lithotripsy procedures were performed at 62 hospitals. Among these hospitals there was threefold variation in ureteroscopy and shock wave lithotripsy spending. The index procedure accounted for the largest payment difference between high vs low cost hospitals (ureteroscopy $7,936 vs $4,995 and shock wave lithotripsy $4,832 vs $3,207, each p <0.01), followed by payments for postacute care (ureteroscopy $2,207 vs $1,711 and shock wave lithotripsy $2,138 vs $1,104, each p <0.01). Across hospitals the index procedure explained 68% and 44% of the variation in episode spending for ureteroscopy and shock wave lithotripsy, and postacute care payments explained 15% and 28%, respectively. CONCLUSIONS: There exists substantial variation in ambulatory surgical spending across Michigan hospitals for urinary stone episodes. Most of this variation can be explained by payment differences for the index procedure and for postacute care services.

Tinnitus alters resting state functional connectivity (RSFC) in human auditory and non-auditory brain regions as measured by functional near-infrared spectroscopy (fNIRS).

Tinnitus, or phantom sound perception, leads to increased spontaneous neural firing rates and enhanced synchrony in central auditory circuits in animal models. These putative physiologic correlates of tinnitus to date have not been well translated in the brain of the human tinnitus sufferer. Using functional near-infrared spectroscopy (fNIRS) we recently showed that tinnitus in humans leads to maintained hemodynamic activity in auditory and adjacent, non-auditory cortices. Here we used fNIRS technology to investigate changes in resting state functional connectivity between human auditory and non-auditory brain regions in normal-hearing, bilateral subjective tinnitus and controls before and after auditory stimulation. Hemodynamic activity was monitored over the region of interest (primary auditory cortex) and non-region of interest (adjacent non-auditory cortices) and functional brain connectivity was measured during a 60-second baseline/period of silence before and after a passive auditory challenge consisting of alternating pure tones (750 and 8000Hz), broadband noise and silence. Functional connectivity was measured between all channel-pairs. Prior to stimulation, connectivity of the region of interest to the temporal and fronto-temporal region was decreased in tinnitus participants compared to controls. Overall, connectivity in tinnitus was differentially altered as compared to controls following sound stimulation. Enhanced connectivity was seen in both auditory and non-auditory regions in the tinnitus brain, while controls showed a decrease in connectivity following sound stimulation. In tinnitus, the strength of connectivity was increased between auditory cortex and fronto-temporal, fronto-parietal, temporal, occipito-temporal and occipital cortices. Together these data suggest that central auditory and non-auditory brain regions are modified in tinnitus and that resting functional connectivity measured by fNIRS technology may contribute to conscious phantom sound perception and potentially serve as an objective measure of central neural pathology.

Neural Network Evidence for the Coupling of Presaccadic Visual Remapping to Predictive Eye Position Updating.

As we look around a scene, we perceive it as continuous and stable even though each saccadic eye movement changes the visual input to the retinas. How the brain achieves this perceptual stabilization is unknown, but a major hypothesis is that it relies on presaccadic remapping, a process in which neurons shift their visual sensitivity to a new location in the scene just before each saccade. This hypothesis is difficult to test in vivo because complete, selective inactivation of remapping is currently intractable. We tested it in silico with a hierarchical, sheet-based neural network model of the visual and oculomotor system. The model generated saccadic commands to move a video camera abruptly. Visual input from the camera and internal copies of the saccadic movement commands, or corollary discharge, converged at a map-level simulation of the frontal eye field (FEF), a primate brain area known to receive such inputs. FEF output was combined with eye position signals to yield a suitable coordinate frame for guiding arm movements of a robot. Our operational definition of perceptual stability was "useful stability," quantified as continuously accurate pointing to a visual object despite camera saccades. During training, the emergence of useful stability was correlated tightly with the emergence of presaccadic remapping in the FEF. Remapping depended on corollary discharge but its timing was synchronized to the updating of eye position. When coupled to predictive eye position signals, remapping served to stabilize the target representation for continuously accurate pointing. Graded inactivations of pathways in the model replicated, and helped to interpret, previous in vivo experiments. The results support the hypothesis that visual stability requires presaccadic remapping, provide explanations for the function and timing of remapping, and offer testable hypotheses for in vivo studies. We conclude that remapping allows for seamless coordinate frame transformations and quick actions despite visual afferent lags. With visual remapping in place for behavior, it may be exploited for perceptual continuity.

Secular motion around synchronously orbiting planetary satellites.

We investigate the secular motion of a spacecraft around the natural satellite of a planet. The satellite rotates synchronously with its mean motion around the planet. Our model takes into account the gravitational potential of the satellite up to the second order, and the third-body perturbation in Hill's approximation. Close to the satellite, the ratio of rotation rate of the satellite to mean motion of the orbiter is small. When considering this ratio as a small parameter, the Coriolis effect is a first-order perturbation, while the third-body tidal attraction, the ellipticity effect, and the oblateness perturbation remain at higher orders. Then, we apply perturbation theory and find that a third-order approach is enough to show the influence of the satellite's ellipticity in the pericenter dynamics. Finally, we discuss the averaged system in the three-dimensional parametric space, and provide a global description of the flow.

Insuficiencia respiratoria aguda I / Acute respiratory failure I

La información que a continuación se presenta pretende reunir algunos conceptos básicos en relación a la insuficiencia respiratoria aguda en el niño, que sirvan de orientación general al enfoque clínico. Como objetivos específicos persigue entregar conceptos necesarios para reconocer la insuficiencia respiratoria aguda (IRA), fisiología básica, tratamiento y manejo inicial, laboratorio auxiliar mínimo y criterios de intubación y ventilación mecánica

Oxigenoterapia domiciliaria / Domicilliary oxygentherapy

Se describen los resultados de una experiencia con oxigenoterapia domiciliaria en niños con afecciones respiratorias crónicas dependientes de aportes suplementarios de oígeno, con el propósito de mostrar su factibilidad y ventajas sobre el manejo intrahospitalario. Los pacientes seleccionados provenían de un total de 25 niños que ingresaron a la unidad de enfermedades respiratorias de un hospital docente de Santiago por insuficiencia respiratoria crónica, con saturaciones de oxígeno de 93 por ciento o menores de la hemoglobina arterial, respirando en aire ambiental, secundaria a daño pulmonar por infecciones virales severas (n:10), displasia broncopulmonar (n:3), fibrosis quística (n:5) y otras afecciones (n:7) del aparato respiratorio. Todos requerían tratamiento con oxígeno suplementario por largo tiempo. La edad de comienzo de la dependencia a oxígeno , en 60 por ciento de los casos, fue previa a los 3 años. Predominaban los varones (2:1). Se escogieron 16 niños para tratamiento en sus domicilios, previo entrenamiento de las personas a cargo, con indicaciones precisas de manejo, que se cumplieron sin mayores inconvenientes. Los nueve restantes fueron enviados a la ciudad de su porcedencia en provincias (n:7) o a instituciones, por incapacidad de la familia para cumplir el tratamiento en el hogar. El tiempo promedio de permanencia en el programa de los pacientes en que finalmente fue posible suspender la oxigenoterapia (50 por ciento) fue 11,9 meses. El tratamiento domiciliario produce beneficios emocionales a los pacientes, disminución del riesgo de infecciones intrahospitalarias y ahorro en los gastos de atención de salud. El costo del tratamiento en la casa es de $ 21770 (U$ 54) mensuales, con una inversión inicial de $ 218548 (U$ 546) que se compara favorablemente con el costo de mantención de un niño en el hospital, que es de $ 1155000 (U$ 2887) mensual

Aplasia pulmonar / Pulmonary aplasia

Es una malformación congénita infrecuente de etiología desconocida, producida por defecto del desarrollo del sistema respiratorio. El diagnóstico puede sospecharse en un niño con falla respiratoria en quien la radiografía de toráx muestra una capacidad total de un pulmón con desviación del mediastino. En el diagnóstico diferencial se han utilizado la broncoscopía y la angiografía; nuestros pacientes se diagnosticaron con tomografía axial computarizada (TAC), que demostró la ausencia de perfusión y ventilación del lado afectado. Se presentan dos lactantes de sexo femenino con aplasia pulmonar. El diagnóstico fue realizado por clínica y TAC. La paciente con malformación derecha falleció poco después de hecho el diagnóstico por insuficiencia respiratoria secundaria a infección. La paciente con aplasia pulmonar izquierda sobrevive, con buen desarrollo y presenta una enfermedad pulmonar obstructiva moderada