Post-spinal Anesthesia Low Back Pain in Obese Female Patients: Comparison of the Median Versus Paramedian Approach.

BACKGROUND: A side effect of spinal anesthesia is post-dural puncture backache (PDPB), which is characterized by ongoing discomfort at the location of the spinal puncture without any radicular pain. This study aims to compare the incidence and severity of post-dural puncture back pain following spinal anesthesia by median versus paramedian technique in obese female patients. METHODS:  A prospective randomized comparative study on 120 female patients, aged 20-50 years with a BMI of 30-40 kg/m2 and American Society of Anesthesiologists physical status II, scheduled for elective surgery under spinal anesthesia, was included in the study. Patients were randomly divided into two groups, with 60 patients in each group. Group P uses the paramedian approach for spinal anesthesia, and group M uses the midline approach for spinal anesthesia. RESULTS: Low back pain incidence was lower in group P than in group M at seven days, but at one month and after, its incidence remained the same in both groups. No difference in the severity of pain was observed. CONCLUSIONS: The occurrence of back pain in the first seven days of surgery was significantly more frequent with the median approach. The pain severity decreased as the time passed from day seven to three months of follow-up. There is no difference in the severity of pain with either approach at different intervals.

Chronic Suppurative Lung Disease in Children: A Case Based Approach.

Bronchiectasis is a pathologic state of conducting airways manifested radiographically by evidence of bronchial dilation and clinically by chronic productive cough. Considered an "orphan disease" for long, it remains a major contributor to morbidity and mortality in both developed and underdeveloped countries. With the advances in the medical field accompanied by widespread access to vaccines and antibiotics, improved health services and better access to nutrition, the incidences of bronchiectasis have markedly decreased, particularly in developed countries. This review summarizes the current knowledge pertaining to the clinical definition, etiology, clinical approach and management related to pediatric bronchiectasis.

HeartMate 3: new challenges in ventricular tachycardia ablation.

AIM: To describe clinical characteristics, procedural details, specific challenges, and outcomes in patients with HeartMate3™ (HM3), a left ventricular assist device system with a magnetically levitated pump, undergoing ventricular tachycardia ablation (VTA). METHODS AND RESULTS: Data were collected from patients with an HM3 system who underwent VTA in seven tertiary centres. Data included baseline patient characteristics, procedural data, mortality, and arrhythmia-free survival. The study cohort included 19 patients with cardiomyopathy presenting with ventricular tachycardia (VT) (53% with VT storm). Ventricular tachycardias were induced in 89% of patients and a total of 41 VTs were observed. Severe electromagnetic interference was present on the surface electrocardiogram. Hence, VT localization required analysis of intra-cardiac signals or the use of filter in the 40-20 Hz range. The large house pump HM3 design obscured the cannula inflow and therefore multi imaging modalities were necessary to avoid catheter entrapment in the cannula. A total of 32 VTs were mapped and were successfully ablated (31% to the anterior wall, 38% to the septum and only 9% to the inflow cannula region). Non-inducibility of any VT was reached in 11 patients (58%). Over a follow-up of 429 (interquartile range 101-692) days, 5 (26%) patients underwent a redo VT ablation due to recurrent VTA and 2 (11%) patients died. CONCLUSIONS: Ventricular tachycardia ablation in patients with HM3 is feasible and safe when done in the appropriate setup. Long-term arrhythmia-free survival is acceptable but not well predicted by non-inducibility at the end of the procedure.

Inverse design of photonic meta-structure for beam collimation in on-chip sensing.

Designed or patterned structured surfaces, metasurfaces, enable the miniaturization of complex arrangements of optical elements on a plane. Most of the existing literature focuses on miniaturizing the optical detection; little attention is directed to on-chip optical excitation. In this work, we design a metasurface to create a planar integrated photonic source beam collimator for use in on-chip optofluidic sensing applications. We use an iterative inverse design approach in order to optimize the metasurface to achieve a target performance using gradient descent method. We then fabricate beam collimators and experimentally compare performance characteristics with conventional uniform binary grating-based photonic beam diffractors. The optimal design enhances the illumination power by a factor of 5. The reinforced beam is more uniform with 3 dB beam spot increased almost ~ 3 times for the same device footprint area. The design approach will be useful in on-chip applications of fluorescence imaging, Raman, and IR spectroscopy and will enable better multiplexing of light sources for high throughput biosensing.

Design of optical meta-structures with applications to beam engineering using deep learning.

Nanophotonics is a rapidly emerging field in which complex on-chip components are required to manipulate light waves. The design space of on-chip nanophotonic components, such as an optical meta surface which uses sub-wavelength meta-atoms, is often a high dimensional one. As such conventional optimization methods fail to capture the global optimum within the feasible search space. In this manuscript, we explore a Machine Learning (ML)-based method for the inverse design of the meta-optical structure. We present a data-driven approach for modeling a grating meta-structure which performs photonic beam engineering. On-chip planar photonic waveguide-based beam engineering offers the potential to efficiently manipulate photons to create excitation beams (Gaussian, focused and collimated) for lab-on-chip applications of Infrared, Raman and fluorescence spectroscopic analysis. Inverse modeling predicts meta surface design parameters based on a desired electromagnetic field outcome. Starting with the desired diffraction beam profile, we apply an inverse model to evaluate the optimal design parameters of the meta surface. Parameters such as the repetition period (in 2D axis), height and size of scatterers are calculated using a feedforward deep neural network (DNN) and convolutional neural network (CNN) architecture. A qualitative analysis of the trained neural network, working in tandem with the forward model, predicts the diffraction profile with a correlation coefficient as high as 0.996. The developed model allows us to rapidly estimate the desired design parameters, in contrast to conventional (gradient descent based or genetic optimization) time-intensive optimization approaches.

Mapping the design space of photonic topological states via deep learning.

Topological states in photonics offer novel prospects for guiding and manipulating photons and facilitate the development of modern optical components for a variety of applications. Over the past few years, photonic topology physics has evolved and unveiled various unconventional optical properties in these topological materials, such as silicon photonic crystals. However, the design of such topological states still poses a significant challenge. Conventional optimization schemes often fail to capture their complex high dimensional design space. In this manuscript, we develop a deep learning framework to map the design space of topological states in the photonic crystals. This framework overcomes the limitations of existing deep learning implementations. Specifically, it reconciles the dimension mismatch between the input (topological properties) and output (design parameters) vector spaces and the non-uniqueness that arises from one-to-many function mappings. We use a fully connected deep neural network (DNN) architecture for the forward model and a cyclic convolutional neural network (cCNN) for the inverse model. The inverse architecture contains the pre-trained forward model in tandem, thereby reducing the prediction error significantly.

Electroanatomical Voltage Mapping to Distinguish Right-Sided Cardiac Sarcoidosis From Arrhythmogenic Right Ventricular Cardiomyopathy.

OBJECTIVES: This study sought to investigate the value of electroanatomical voltage mapping (EAVM) to distinguish cardiac sarcoidosis (CS) from arrhythmogenic right ventricular cardiomyopathy (ARVC) in patients with ventricular tachycardia from the right ventricle (RV). BACKGROUND: CS can mimic ARVC. Because scar in ARVC is predominantly subepicardial, this study hypothesized that the relative sizes of endocardial low bipolar voltage (BV) to low unipolar voltage (UV) areas may distinguish CS from ARVC. METHODS: Patients with CS affecting the RV (n = 14), patients with gene-positive ARVC (n = 13), and a reference group of patients without structural heart disease (n = 9) who underwent RV endocardial EAVM were included. RV region-specific BV and UV cutoffs were derived from control subjects. In CS and ARVC, segmental involvement was determined and low-voltage areas were measured, using <1.5 mV for BV and <3.9 mV, <4.4 mV, and <5.5 mV for UV. The ratio between low BV and low UV area was calculated generating 3 parameters: Ratio3.9, Ratio4.4 and Ratio5.5, respectively. RESULTS: In control subjects, BV and UV varied significantly among RV regions. The basal septum was involved in 71% of CS patients and in none of ARVC patients. Ratio5.5 discriminated CS from ARVC the best. An algorithm including Ratio5.5 ≥0.45 and basal septal involvement identified CS with 93% sensitivity and 85% specificity. This was validated in a separate population (CS [n = 6], ARVC [n = 10]) with 100% sensitivity and 100% specificity. CONCLUSIONS: EAVM provides detailed information about scar characteristics and scar distribution in the RV. An algorithm combining Ratio5.5 (area BV <1.5 mV/area UV <5.5 mV) and bipolar basal septal involvement allows accurate diagnosis of (isolated) CS in patients presenting with monomorphic ventricular tachycardia from the RV.

Chemical Characterization of Aerosol Particles Using On-Chip Photonic Cavity Enhanced Spectroscopy.

We demonstrate the chemical characterization of aerosol particles with on-chip spectroscopy using a photonic cavity enhanced silicon nitride (Si3N4) racetrack resonator-based sensor. The sensor operates over a broad and continuous wavelength range, showing cavity enhanced sensitivity at specific resonant wavelengths. Analysis of the relative change in the quality factor of the cavity resonances successfully yields the absorption spectrum of the aerosol particles deposited on the resonators. Detection of N-methyl aniline-based aerosol in the near infrared (NIR) range of 1500 to 1600 nm is demonstrated. Our aerosol sensor spectral data compares favorably with that from a commercial spectrometer, indicating good accuracy. The small size of the device is advantageous in remote, environmental, medical, and body-wearable sensing applications.

Multistimuli-Responsive Foams Using an Anionic Surfactant.

In this work, we report a novel class of a commercially available surfactant which shows a multistimuli-responsive behavior toward foam stability. It comprises three components-a hydrophobe (tristyrylphenol), a temperature-sensitive block (polypropylene oxide, PO), and a pH-sensitive moiety (carboxyl group). The hydrophobicity-hydrophilicity balance of the surfactant can be tuned by changing either the pH or temperature of the system. At or below pH 4, the carboxyl functional group is dominantly protonated, resulting in zero foamability. At higher pH, the surfactant exhibits good foamability and foam stability marked with a fine bubble texture (∼200 µm). Foam destabilization could be achieved rapidly by either lowering the pH or bubbling CO2 gas. At a fixed pH in the presence of salt, increasing the temperature to 65 °C resulted in rapid defoaming because of the increased hydrophobicity of the PO chain. This stimuli-induced stabilization and destabilization of foam were found to be reversible. We envisage the use of such a multi-responsive foaming system in diverse applications such as foam-enhanced oil recovery and environmental remediation where spatial and temporal control over foam stability is desirable. The low-cost commercial availability of the surfactant further makes it lucrative.

Development of low-cost non-contact structural health monitoring system for rotating machinery.

Condition monitoring systems are increasingly being employed in industrial applications to improve the availability of equipment to increase the overall equipment efficiency. Condition monitoring of gearboxes, a key element of rotating machines, ensures to continuously reduce and eliminate costs, unscheduled downtime and unexpected breakdowns. This study demonstrates a low-cost microcontroller-based non-contact data acquisition system for condition monitoring of rotating machinery. Experimental validation of the proposed system was carried out by performing examination tests on a gearbox test rig. A user-friendly graphical user interface was also developed which facilitates users to perform signal processing in both real-time and offline mode. The proposed system can perform most of the functions available in complex, stand-alone vibration analysers. The use of a general-purpose PC and standard programing language makes the system simple, economical and adaptable to a variety of problems. The tests show the developed system can perform properly as proposed.

Noninvasive Assessment of Jugular Venous Pressure via Force-Coupled Single Crystal Ultrasound.

OBJECTIVE: we have developed a handheld device for noninvasive quantitative assessment of jugular venous pressure (JVP). METHODS: we used a single crystal ultrasound coupled to a force-sensing load cell to measure JVP based on the force necessary to collapse the internal jugular vein (IJV) walls. We used a gelatin-based model system of the IJV to test the ability of single crystal ultrasound to identify the IJV and verified the cross-sectional position and diameter of the vessels with conventional imaging ultrasound. We also tested our prototype device on healthy human volunteers. RESULTS: experiments on model system demonstrated that vessel diameters determined with single crystal ultrasound were in close agreement with the diameters derived from conventional 2-D ultrasound. Proof-of-concept human experiments demonstrate that single crystal ultrasound can detect the IJV in basal and collapsed states, as compared to gold-standard sonography (insert stats). Assessment of JVP in human volunteers was physiologically consistent with and sensitive to postural changes (supine JVP 6.6 ± 2.4 mmHg; standing JVP 4.2 ± 1.9 mmHg (p < 0.0001). CONCLUSION: noninvasive assessment of JVP could prove valuable in informing rapid clinical decision-making across various pathologies and conditions leading to derangements in intravascular volume status.

Microencapsulation and Stimuli-Responsive Controlled Release of Particles Using Water-in-Air Powders.

In this work, we report a facile, one-step method to encapsulate hydrophilic particles (HP) (micro- or nanosize) using water-in-air powders. Hydrophobic silica nanoparticles were mixed with an aqueous phase containing HP in the presence of air under high shear, resulting in the self-assembly of silica nanoparticles on water droplets to make water-in-air powders with HP encapsulated in the aqueous phase within the silica shell. The encapsulated HP can be released on the basis of an external stimulus such as adding an external aqueous phase of a certain pH or a surfactant solution that alters the wettability of the encapsulating silica nanoparticles. A contact angle study was performed using surface-hydrophobized glass slides, which acted as a proxy for hydrophobic silica nanoparticles, to investigate the effect of these stimuli on surface hydrophobicity. Such encapsulation and a stimuli-responsive controlled release system has promising potential in subsurface petroleum engineering such as the delayed swelling of particles for conformance control and delayed acid stimulation.

Arrhythmias and Other Electrophysiology Issues in Cancer Patients Receiving Chemotherapy or Radiation.

Enhanced understanding of cancer biology has significantly increased treatment options and dramatically improved outcomes for patients with malignancies. Despite these advances, many therapies have cardiovascular toxicities which can affect morbidity and mortality independent of the oncologic prognosis. Arrhythmias and other electrophysiology issues are increasingly identified as common complications of cancer therapy. Atrial fibrillation and other supraventricular arrhythmias are frequently observed in cancer patients receiving chemotherapy, often due to their effects on intracellular signaling pathways. Similarly, many oncologic pharmaceuticals can lead to QT prolongation and possible ventricular arrhythmias including torsades do pointes. Management of these arrhythmias can be challenging as typical treatment strategies may not be feasible in cancer patients. Finally, a proportion of individuals with cancer will present with an implantable cardiac device (pacemaker or defibrillator) which poses unique challenges should radiation be necessary in the region of the device. Given the frequency of electrophysiology complications in cancer patients, it is essential for cardio-oncologists to possess knowledge of these issues in order to provide optimal care.

Cardiac resynchronization therapy is appropriate for all patients requiring chronic right ventricular pacing: the pro perspective.

Long-term right ventricular pacing has deleterious effects on the left ventricle (LV). The risk of pacemaker-induced cardiomyopathy (PICM) seems to be lower in patients with a normal LV ejection fraction (LVEF). Patients developing PICM respond favorably to a cardiac resynchronization therapy upgrade, suggesting that the dysfunction is partially reversible. Biventricular pacing has emerged as a treatment and/or prevention of PICM. Cumulative pacing greater than 40% of the time is considered the most important risk factor for PICM. No organizational guidelines exist for preventive biventricular pacing. The decision to pursue biventricular pacing should be individualized.

Role of cardiac CTA in estimating left ventricular volumes and ejection fraction.

Left ventricular ejection fraction (LVEF) is an important predictor of cardiac outcome and helps in making important diagnostic and therapeutic decisions such as the treatment of different types of congestive heart failure or implantation of devices like cardiac resynchronization therapy-defibrillator. LVEF can be measured by various techniques such as transthoracic echocardiography, contrast ventriculography, radionuclide techniques, cardiac magnetic resonance imaging and cardiac computed tomographic angiography (CTA). The development of cardiac CTA using multi-detector row CT (MDCT) has seen a very rapid improvement in the technology for identifying coronary artery stenosis and coronary artery disease in the last decade. During the acquisition, processing and analysis of data to study coronary anatomy, MDCT provides a unique opportunity to measure left ventricular volumes and LVEF simultaneously with the same data set without the need for additional contrast or radiation exposure. The development of semi-automated and automated software to measure LVEF has now added uniformity, efficiency and reproducibility of practical value in clinical practice rather than just being a research tool. This article will address the feasibility, the accuracy and the limitations of MDCT in measuring LVEF.

Fragmented ECG as a risk marker in cardiovascular diseases.

Various noninvasive tests for risk stratification of sudden cardiac death (SCD) were studied, mostly in the context of structural heart disease such as coronary artery disease (CAD), cardiomyopathy and heart failure but have low positive predictive value for SCD. Fragmented QRS complexes (fQRS) on a 12-lead ECG is a marker of depolarization abnormality. fQRS include presence of various morphologies of the QRS wave with or without a Q wave and includes the presence of an additional R wave (R') or notching in the nadir of the R' (fragmentation) in two contiguous leads, corresponding to a major coronary artery territory. fQRS represents conduction delay from inhomogeneous activation of the ventricles due to myocardial scar. It has a high predictive value for myocardial scar and mortality in patients CAD. fQRS also predicts arrhythmic events and mortality in patients with implantable cardioverter defibrillator. It also signifies poor prognosis in patients with nonischemic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and Brugada syndrome. However, fQRS is a nonspecific finding and its diagnostic prognostic should only be interpreted in the presence of pertinent clinical evidence and type of myocardial involvement (structural vs. structurally normal heart).

Assessment of left ventricular function: comparison of cardiac multidetector-row computed tomography with two-dimension standard echocardiography for assessment of left ventricular function.

OBJECTIVE: To compare global Left Ventricular (LV) systolic function assessment by 16-detector row Computed Tomography (MDCT) with Two-Dimensional Standard Echocardiography (2DSE) in a routine cardiology practice setting and to ascertain the degree of correlation between LV volumes and measurements obtained by 2DSE with those measured by MDCT. METHODS: In 52 patients with suspected coronary artery disease, a contrast enhanced MDCT study was performed using retrospective gating without dose modulation for better endocardial delineation. Eight phases of the cardiac cycle were analyzed to identify the end-diastolic and end-systolic phases. 2DSE was performed on the same day. Left ventricular systolic and diastolic volumes and ejection fraction were calculated in 4-chamber, 2-chamber and biplane (average of the two) views. Endocardial tracing was used to measure ventricular volumes by area length method for CT and Simpson's method for echocardiography. RESULTS: On MDCT, mean LV ejection fraction (LVEF) in 4-chamber, 2-chamber and biplane views were 58.4 +/- 12, 59.3 +/- 12 and 59.7 +/- 12% respectively. On 2DSE, mean LVEF in 4-chamber, 2-chamber and biplane views were 58 +/- 14, 57 +/- 16 and 58 +/- 13% respectively. LVEF correlated best using the biplane views (r = 0.59 and P < 0.01) compared to 2-chamber (r = 0.57 and P < 0.01) and 4-chamber views (r = 0.32 and P = 0.02). Biplane measurement by these two techniques correlated well for LV volumes in both diastole (r = 0.69 and P < 0.01) and systole (r = 0.73 and P < 0.01), although MDCT consistently gave higher values. CONCLUSIONS: MDCT can be a useful tool to measure LVEF while patients are undergoing CT coronary angiography.

Ischemic colitis revisited: a prospective study identifying hypercoagulability as a risk factor.

BACKGROUND: Although causes for ischemic colitis have been identified, many cases are deemed idiopathic. Some reports suggest an association between ischemic colitis and coagulation disorders. Our purpose was to explore the relationship of ischemic colitis and clotting abnormalities. METHODS: Eighteen patients consented to undergo a hypercoagulability evaluation. Tests included protein C, protein S, activated protein C resistance, factor V Leiden, anticardiolipin antibodies, antineutrophil cytoplasmic antibodies, rheumatoid factor, antithrombin III, anti-smooth muscle antibody, lupus anticoagulant panel, and prothrombin 20210G/A mutation (in women undergoing hormone replacement therapy). RESULTS: Five of 18 patients tested positive for coagulation abnormalities, including factor V and activated protein C resistance, protein S deficiency, prothrombin 20210G/A mutation, and anticardiolipin antibody. CONCLUSION: To our knowledge, this is the largest series of patients with ischemic colitis studied for coagulation defects in the United States. The prevalence of clotting disorders in our study (28%) was higher than that in the general population (8.4%). Coagulation disorders should be considered in some cases of ischemic colitis that are thought to be idiopathic.