Open-source navigation system for tracking dissociated parts with multi-registration.

PURPOSE: During reconstructive surgery, knee and hip replacements, and orthognathic surgery, small misalignments in the pose of prosthesis and bones can lead to severe complications. Hence, the translational and angular accuracies are critical. However, traditional image-based surgical navigation lacks orientation data between structures, and imageless systems are unsuitable for cases of deformed anatomy. We introduce an open-source navigation system using a multiple registration approach that can track instruments, implants, and bones to precisely guide the surgeon in emulating a preoperative plan. METHODS: We derived the analytical error of our method and designed a set of phantom experiments to measure its precision and accuracy. Additionally, we trained two classification models to predict the system reliability from fiducial points and surface matching registration data. Finally, to demonstrate the procedure feasibility, we conducted a complete workflow for a real clinical case of a patient with fibrous dysplasia and anatomical misalignment of the right femur using plastic bones. RESULTS: The system is able to track the dissociated fragments of the clinical case and average alignment errors in the anatomical phantoms of [Formula: see text]  mm and [Formula: see text]. While the fiducial-points registration showed satisfactory results given enough points and covered volume, we acknowledge that the surface refinement step is mandatory when attempting surface matching registrations. CONCLUSION: We believe that our device could bring significant advantages for the personalized treatment of complex surgical cases and that its multi-registration attribute is convenient for intraoperative registration loosening cases.

Multicenter validation of Early Warning Scores for detection of clinical deterioration in COVID-19 hospitalized patients.

Objective: Investigate the predictive value of NEWS2, NEWS-C, and COVID-19 Severity Index for predicting intensive care unit (ICU) transfer in the next 24 h. Design: Retrospective multicenter study. Setting: Two third-level hospitals in Argentina. Patients: All adult patients with confirmed COVID-19, admitted on general wards, excluding patients with non-intubated orders. Interventions: Patients were divided between those who were admitted to ICU and non-admitted. We calculated the three scores for each day of hospitalization. Variables: We evaluate the calibration and discrimination of the three scores for the outcome ICU admission within 24, 48 h, and at hospital admission. Results: We evaluate 13,768 days of hospitalizations on general medical wards of 1318 patients. Among these, 126 (9.5%) were transferred to ICU. The AUROC of NEWS2 was 0.73 (95%CI 0.68-0.78) 24 h before ICU admission, and 0.52 (95%CI 0.47-0.57) at hospital admission. The AUROC of NEWS-C was 0.73 (95%CI 0.68-0.78) and 0.52 (95%CI 0.47-0.57) respectively, and the AUROC of COVID-19 Severity Index was 0.80 (95%CI 0.77-0.84) and 0.61 (95%CI 0.58-0.66) respectively. COVID-19 Severity Index presented better calibration than NEWS2 and NEWS-C. Conclusion: COVID-19 Severity index has better calibration and discrimination than NEWS2 and NEWS-C to predict ICU transfer during hospitalization.

Objetivo: Investigar el valor predictivo de los scores NEWS2, NEWS-C y COVID-19 Severity Index para predecir la transferencia de urgencia a la unidad de cuidados intensivos (UCI) en las próximas 24 horas. Diseño: Estudio multicéntrico retrospectivo. Ámbito: Dos hospitales de tercer nivel en Argentina. Pacientes: Pacientes adultos con COVID-19, ingresados en salas generales, excluyendo pacientes con órdenes de no intubar. Intervenciones: Se dividió a los pacientes entre los que ingresaron en la UCI y los que no ingresaron. Calculamos las tres puntuaciones para cada día de hospitalización. Variables: Evaluamos la calibración y discriminación de las tres puntuaciones para predecir el traslado de urgencia a UCI en las 24, 48 h previas al pase a UCI y al ingreso hospitalario. Resultados: Evaluamos 13.768 días de hospitalización en internación general de 1.318 pacientes, de los cuales 126 (9,5%) fueron trasladados a UCI. El AUROC del NEWS2 fue de 0,73 (IC 95% 0,68-0,78) 24 h antes del ingreso en UCI y de 0,52 (IC 95% 0,47-0,57) al ingreso hospitalario. El AUROC de NEWS-C fue de 0,73 (IC 95% 0,68-0,78) y 0,52 (IC 95% 0,47-0,57) respectivamente, y el AUROC del COVID-19 Severity Index fue de 0,80 (IC 95% 0,77-0,84) y 0,61 (IC 95% 0,58-0,66) respectivamente. El COVID-19 Severity Index presentó una mejor calibración que NEWS2 y NEWS-C. Conclusión: El COVID-19 Severity Index presentó una mejor calibración y discriminación que NEWS2 y NEWS-C para predecir la transferencia de la UCI durante la hospitalización.

Obtaining accurate and calibrated coil models for transcranial magnetic stimulation using magnetic field measurements.

Currently, simulations of the induced currents in the brain produced by transcranial magnetic stimulation (TMS) are used to elucidate the regions reached by stimuli. However, models commonly found in the literature are too general and neglect imperfections in the windings. Aiming to predict the stimulation sites in patients requires precise modeling of the electric field (E-field), and a proper calibration to adequate to the empirical data of the particular coil employed. Furthermore, most fabricators do not provide precise information about the coil geometries, and even using X-ray images may lead to subjective interpretations. We measured the three components of the vector magnetic field induced by a TMS figure-8 coil with spatial resolutions of up to 1 mm. Starting from a computerized tomography-based coil model, we applied a multivariate optimization algorithm to automatically modify the original model and obtain one that optimally fits the measurements. Differences between models were assessed in a human brain mesh using the finite-elements method showing up to 6% variations in the E-field magnitude. Our calibrated model could increase the precision of the estimated E-field induced in the brain during TMS, enhance the accuracy of delivered stimulation during functional brain mapping, and improve dosimetry for repetitive TMS. Graphical Abstract Geometrical model of TMS coil based on TAC images is optimally deformed to match magnetic field measurements. The calibrated model's induced electric field in the brain differs from the original.

Dynamic abdominal and thoracic aortomyoplasty in heart failure: assessment of counterpulsation.

BACKGROUND: Aortic counterpulsation, either biologic or mechanical, is a useful technique to support circulation during left ventricular dysfunction. METHODS: In this study we used an induced cardiac failure model in acute open chest sheep to compare hemodynamic improvements between thoracic and abdominal aortic counterpulsation. This was achieved with left latissimus dorsi and left hemidiaphragm muscle flaps. RESULTS: Thoracic and abdominal aortic counterpulsation in heart failure resulted in a significant improvement of hemodynamic parameters. Subendocardial viability index, defined as diastolic pressure-time index to systolic tension-time index, in thoracic and abdominal aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance was performed by electrical stimulation of each muscle flap. A new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve was tested, obtaining a correlation coefficient with the subendocardial viability index of 0.758 (p<0.001). Values of subendocardial viability index and counterpulsation index showed minimal variability. CONCLUSIONS: Treatment of experimentally induced cardiac failure with dynamic abdominal aortic counterpulsation allows an effective hemodynamic improvement in open chest sheep. Furthermore, this diastolic arterial pressure augmentation could be evaluated through a new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve.

Non-invasive assessment of systemic elastic behaviour in hypertensive patients: analysis of possible determinants.

Knowledge about the viscoelastic behaviour of the arterial wall has been proved to have physiological importance and clinical usage. Our purpose was to study the changes of the systemic arterial wall's elastic properties non-invasively, in patients with established essential and with borderline hypertension, and to evaluate its possible determinants. Three groups of normotensive, borderline and established essential hypertensive patients were evaluated. Arterial pulse wave velocity (PWV) was measured and arterial compliance (Cm) was derived in all patients. Pulse wave velocity was obtained from the pressure values of digitized carotid and radial arteries. Arterial compliance (Cm = dD/dP with P pressure and D diameter) was calculated using a formula derived from the Bramwell and Hill equation: Cm = (1,334 x D)/(2 rho x PWV2), where for D humeral diameter was used as measured by high resolution echograph, and rho is the blood density (rho = 1.06). Pulse wave velocity was significantly higher in established essential hypertensive patients with respect to normotensive patients (p < 0.05). Arterial compliance was significantly diminished in established and in borderline hypertensive patients with respect to normotensive patients (p < 0.05), which implies early alterations in hypertensive cardiovascular disease. Multiple regression analysis of the cofactors showed that age and diastolic pressure are independent determinants of Cm. Impairment of the arterial wall's intrinsic elastic properties was demonstrated in established essential hypertension, independent of age and diastolic pressure.

Control barorreflejo de la frecuencia cardíaca y la variabilidad de la presión arterial: medición a través del análisis computarizado de la señal de presión arterial en sujetos normotensos y pacientes hipertensos / Heart rate baroreflex control and blood pressure variability: computarized analysis in normotensive and hypertensive subjects

La evaluación farmacológica del control barorreflejo de la frecuencia cardíaca (FC) se realiza mediante la administración de un bolo de fenilefrina (Fe) o nitroglicerina (NTG) lo cual produce, respectivamente, un incremento o decremento de la presión arterial (PA). Ello induce, como respuesta refleja, una prolongación o un acortamiento del intervalo RR electrocardiográfico. La pendiente de la correlación entre las variaciones del espacio RR en función de la variación de la PA representa la ganancia o sensibilidad del control barorreflejo de la FC (SBR). Por otro lado, la cuantificación de la variabilidad de la PA se realiza mediante el cálculo de la desviación estándar del período de registro contínuo de la PA. El objetivo del presente trabajo fue: 1) Evaluar un programa de análisis computarizado que permite no sólo la cuantificación de la variabilidad de la PA y FC sino también de la sensibilidad barorrefleja. 2) Evaluar las relaciones entre la SBR y la Var. 3) Evaluar las diferencias entre normotensos e hipertensos. Se estudiaron 143 sujetos que fueron separados en dos grupos: 35 normotensos (NT) con valores de PA de consultorio por debajo de los 140/90 mmHg (OMS/ISH) y 93 hipertensos (HT) con valores por sobre lo anteriormente mencionado. A cada uno de ellos se les realizó un registro contínuo de PA (Finapres, 1 hora) y la señal fue digitalizada (PC 486). Las señales fueron analizadas a posteriori mediante un programa especialmente diseñado por nuestro grupo de trabajo. La SBR se evaluó a través 1) del método farmacológico, como fuera descripto anteriormente, y 2) por medio del análisis computarizado, se identifican en el trazado adquirido (Finapres) las secuencias de 3 o más latidos en las cuales la PA aumenta (Fe comp: tipo Fe) o disminuye (NTG comp: tipo NTG). El promedio de las pendientes de la correlación entre los cambios de la PA y del intervalo RR de las secuencias analizadas representa la SBR. A posteriori y mediante el análisis computarizado se obtiene el valor promedio de la PA y su respectiva desviación estándar, índice de la Var. Los valores de la Var de los pacientes NT fue de 8,78 ñ 0,7 mmHg con un rango de normalidad (intervalo de confianza al 95 por ciento) comprendido entre los 7,3422 y 10,28 mmHg. Los sujetos HT tuvieron una mayor Var de la PA (11,52 ñ 1,32 mmHg; p< 0,025)... (AU)

Control barorreflejo de la frecuencia cardíaca y la variabilidad de la presión arterial: medición a través del análisis computarizado de la señal de presión arterial en sujetos normotensos y pacientes hipertensos / Heart rate baroreflex control and blood pressure variability: computarized analysis in normotensive and hypertensive subjects

La evaluación farmacológica del control barorreflejo de la frecuencia cardíaca (FC) se realiza mediante la administración de un bolo de fenilefrina (Fe) o nitroglicerina (NTG) lo cual produce, respectivamente, un incremento o decremento de la presión arterial (PA). Ello induce, como respuesta refleja, una prolongación o un acortamiento del intervalo RR electrocardiográfico. La pendiente de la correlación entre las variaciones del espacio RR en función de la variación de la PA representa la ganancia o sensibilidad del control barorreflejo de la FC (SBR). Por otro lado, la cuantificación de la variabilidad de la PA se realiza mediante el cálculo de la desviación estándar del período de registro contínuo de la PA. El objetivo del presente trabajo fue: 1) Evaluar un programa de análisis computarizado que permite no sólo la cuantificación de la variabilidad de la PA y FC sino también de la sensibilidad barorrefleja. 2) Evaluar las relaciones entre la SBR y la Var. 3) Evaluar las diferencias entre normotensos e hipertensos. Se estudiaron 143 sujetos que fueron separados en dos grupos: 35 normotensos (NT) con valores de PA de consultorio por debajo de los 140/90 mmHg (OMS/ISH) y 93 hipertensos (HT) con valores por sobre lo anteriormente mencionado. A cada uno de ellos se les realizó un registro contínuo de PA (Finapres, 1 hora) y la señal fue digitalizada (PC 486). Las señales fueron analizadas a posteriori mediante un programa especialmente diseñado por nuestro grupo de trabajo. La SBR se evaluó a través 1) del método farmacológico, como fuera descripto anteriormente, y 2) por medio del análisis computarizado, se identifican en el trazado adquirido (Finapres) las secuencias de 3 o más latidos en las cuales la PA aumenta (Fe comp: tipo Fe) o disminuye (NTG comp: tipo NTG). El promedio de las pendientes de la correlación entre los cambios de la PA y del intervalo RR de las secuencias analizadas representa la SBR. A posteriori y mediante el análisis computarizado se obtiene el valor promedio de la PA y su respectiva desviación estándar, índice de la Var. Los valores de la Var de los pacientes NT fue de 8,78 ñ 0,7 mmHg con un rango de normalidad (intervalo de confianza al 95 por ciento) comprendido entre los 7,3422 y 10,28 mmHg. Los sujetos HT tuvieron una mayor Var de la PA (11,52 ñ 1,32 mmHg; p< 0,025)...

Hemodynamic effects of cardiomyoplasty in an experimental model of acute heart failure and atrial fibrillation.

The aim of our work was to study the hemodynamic effects of dynamic cardiomyoplasty on an acute animal model of atrial fibrillated heart failure. Eight anesthetized open chest dogs suffering from atrial fibrillation and heart failure, obtained by topic acetylcholine and propranolol, were treated by a cardiomyoplasty procedure performed with an electrostimulated latissimus dorsi muscle flap (LDMF). Values considered for analysis during LDMF stimulation were selected from cardiac cycles with R-R intervals similar to those when the LDMF was not stimulated (+/- 20 ms). Atrial fibrillated heart failure showed a significant increase of systemic vascular resistance, end diastolic left ventricular pressure (EDLVP) and right atrial pressure (p < 0.05), and a significant decrease in cardiac output, systolic left ventricular pressure (SLVP), and mean aortic pressure (p < 0.05) compared with control values. LDMF stimulation in atrial fibrillated heart failure resulted in a significant increase of SLVP, cardiac output, and mean aortic pressure (p < 0.05) and a significant decrease of systemic vascular resistance, EDLVP, and right atrial pressure (p < 0.05) compared with nonstimulated values. The highest LVP values were obtained with R-R intervals long enough to allow an adequate LV filling. We conclude that dynamic cardiomyoplasty provides an appropriate recovery in this animal model of atrial fibrillated heart failure. Cardiomyoplasty is an appropriate procedure for cardiac assist when R-R intervals allow an adequate LV filling.

Benefits of aortic and pulmonary counterpulsation using dynamic latissimus dorsi myoplasty.

BACKGROUND: Intraaortic and pulmonary artery counterpulsation are useful techniques to support circulation during either left or right ventricular dysfunction. Electrically stimulated skeletal muscles wrapped around the aorta, used as means of cardiac failure treatment, have proved to be an effective method of handling experimental left ventricular failure. In this article we report an induced cardiac failure model in acute open chest dogs and describe the hemodynamic improvement of simultaneous aortic and pulmonary artery counterpulsation. METHODS: This was achieved with a bilateral latissimus dorsi muscle flap, stimulated with a software written in C++ for Windows. Dynamic aortomyoplasty was performed using the left latissimus dorsi muscle flap around the descending aorta, and dynamic pulmonaromyoplasty was achieved wrapping the pulmonary trunk with the right latissimus dorsi muscle flap. In all animals blood pressures and cardiac output were measured after cardiac failure induced by a high-dose of propranolol hydrochloride (3 mg/kg intravenously) before and after latissimus dorsi muscle flap stimulation. RESULTS: Aortopulmonary counterpulsation resulted in a significant increase in mean aortic pressure, mean pulmonary pressure, and cardiac output. In addition, a significant decrease was observed in end-diastolic left ventricular pressure, systemic vascular resistance, and pulmonary vascular resistance. Subendocardial viability index (diastolic pressure-time index/systolic tension-time index) in aortomyoplasty and tension time index in pulmonaromyoplasty showed significant improvement when cardiac assistance was performed by electrical stimulation of both muscles (p = 0.037 and p = 0.001, respectively). CONCLUSIONS: Treatment of experimentally induced cardiac failure using aortopulmonary counterpulsation allows effective hemodynamic improvement in open-chest dogs.