Lung Ultrasound Performed by Primary Care Physicians for Clinically Suspected Community-Acquired Pneumonia: A Multicenter Prospective Study.

PURPOSE: We investigated whether lung ultrasound (US) performed in primary care is useful and feasible for diagnosing community-acquired pneumonia (CAP) compared with chest radiography, as most previous research has been conducted in hospital settings. METHODS: We undertook a prospective observational cohort study of lung US performed in 12 primary care centers. Patients aged 5 years and older with symptoms suggesting CAP were examined with lung US (by 21 family physicians and 7 primary care pediatricians) and chest radiograph on the same day. We compared lung US findings with the radiologist's chest radiograph report as the reference standard, given that the latter is the most common imaging test performed for suspected CAP in primary care. The physicians had varied previous US experience, but all received a 5-hour lung US training program. RESULTS: The study included 82 patients. Compared with chest radiography, positive lung US findings (consolidation measuring >1 cm or a focal/asymmetrical B-lines pattern) showed a sensitivity of 87.8%, a specificity of 58.5%, a positive likelihood-ratio of 2.12, and a negative likelihood-ratio of 0.21. Findings were similar regardless of the physicians' previous US training or experience. We propose a practical algorithm whereby patients having consolidation measuring greater than 1 cm or normal findings on lung US could skip chest radiography, whereas patients with a B-lines pattern without consolidation (given its low specificity) would need chest radiography to ensure appropriate management. Lung US was generally performed in 10 minutes or less. CONCLUSION: Point-of-care lung US in primary care could be useful for investigating suspected CAP (avoiding chest radiography in most cases) and is likely feasible in daily practice, as short training programs appear sufficient and little time is needed to perform the scan.

Usefulness of Lung Ultrasound Examinations Performed by Primary Care Physicians in Patients With Suspected COVID-19.

OBJECTIVES: In patients with suspected coronavirus disease 2019 (COVID-19) consulting primary care (PC) centers, clinical criteria may not be sensitive enough to detect many cases in which complications first occur. We intended to assess whether lung ultrasound (LUS) examinations performed by PC physicians are a useful tool to detect lung injury and may help in decisions about hospital referral. METHODS: This study included 61 patients with moderate symptoms suggesting COVID-19 who were evaluated with LUS by PC physicians and then referred to a hospital during the current pandemic peak in Madrid. We analyzed association of a simple self-designed LUS severity scale (grade 0, normal; grade 1, multiple separated B-lines, pleural irregularity, or both; and grade 2, coalescent B-lines, consolidations, pleural effusion, or a combination thereof) with the main outcome indicating adequacy of hospital referral, and also with chest x-ray (CXR) findings. RESULTS: The proposed LUS severity scale was significantly associated with the main outcome of appropriate referral (P = 0.001): the higher the scale, the higher the percentage of adequate referrals. The LUS scale was also associated with a CXR severity scale (P = 0.034). The presence of coalescent B-lines was the only independent LUS finding significantly associated with the appropriate-referral outcome (P =0 .008) and also with a higher probability of hospital admission (P = 0.02) and with several CXR findings. CONCLUSIONS: This study supports the use of LUS in PC as a tool to assess patients with suspected COVID-19. Its use can reduce uncertainty during clinical evaluations of moderate patients, facilitate early detection of lung involvement, allow early appropriate referral, and avoid unnecessary referral.

[Point of Care Ultrasound in Primary Care. Is it a high resolution tool?] / Modelo Point-of-Care Ultrasound en Atención Primaria: ¿herramienta de alta resolución?

Point-of-Care Ultrasound is a method of performing a rapid clinical ultrasound, with the aim of responding to a clinical question immediately. This is not an ultrasound performed systematically as the radiologists do, nor does it pretend to replace it. It is useful in some kind of screening (abdominal aortic aneurysm) and is of special interest in ultrasound-guided procedures (joint infiltration by injection). It allows to adapt the derivations, minimising the uncertainty, ruling out certain pathologies due to its high diagnostic precision. It can also lead to overdiagnosis, if the examinations carried out are not limited to the organs on which our clinical suspicion is based. Ultrasound is one tool more in the diagnostic process, but its use must be limited to certain clinical situations. Its use in early detection of prevalent diseases in Primary Care should be properly evaluated. On the other hand with more evidence of a high diagnostic accuracy in a large list of pathological conditions.

Diagnostic Accuracy of Abdominal Point of Care Ultrasound in Primary Care: Study Design and Protocol.

The aim of this study is to estimate the diagnostic accuracy of abdominal point of care ultrasound (POCUS) performed by family physicians (FPs) in primary care (PC), in comparison with the findings in the medical record (MR) at 12 months of follow-up. This study is conducted entirely in PC healthcare centers in Spain. Abdominal ultrasound scans performed by FPs (selected on the basis of their ultrasound knowledge and experience) are compared with the findings, or not, in the patient's MR after a 12-month follow-up period. The study will involve 100 FPs in Spain and an estimated sample size of 1334 patients who are to undergo abdominal POCUS at the indication of their physician. The results of the abdominal POCUS will be collected and compared with the findings of the MR. This comparison will be performed by another physician of the research team, different from their FP after one year of follow-up. The diagnostic accuracy of abdominal POCUS has been addressed in the hospital setting but not in PC. This lack of evidence can begin to be resolved with studies such as the one we present, designed for unselected populations such as those treated in PC and taking the patient's MR as the gold standard, which will allow us to make comparisons with the patient's clinical course.

Mini Peltier Cell Array System for the Generation of Controlled Local Epicardial Heterogeneities.

The present study aims to design and fabricate a system capable of generating heterogeneities on the epicardial surface of an isolated rabbit heart perfused in a Langendorff system. The system consists of thermoelectric modules that can be independently controlled by the developed hardware, thereby allowing for the generation of temperature gradients on the epicardial surface, resulting in conduction slowing akin to heterogeneities of pathological origin. A comprehensive analysis of the system's viability was performed through modeling and thermal simulation, and its practicality was validated through preliminary tests conducted at the experimental cardiac electrophysiology laboratory of the University of Valencia. The design process involved the use of Fusion 360 for 3D designs, MATLAB/Simulink for algorithms and block diagrams, LTSpice and Altium Designer for schematic captures and PCB design, and the integration of specialized equipment for animal experimentation. The objective of the study was to efficiently capture epicardial recordings under varying conditions.Clinical relevance- The proposed system aims to induce local epicardial heterogeneities to generate labeled correct signals that can serve as a golden standard for improving algorithms that identify and characterize fibrotic substrates. This improvement will enhance the efficacy of ablation processes and potentially reduce the ablated surface area.

Evaluation and assessment of clique arrangements for the estimation of omnipolar electrograms in high density electrode arrays: an experimental animal model study.

High-density catheters combined with Orientation Independent Sensing (OIS) methods have emerged as a groundbreaking technology for cardiac substrate characterisation. In this study, we aim to assess the arrangements and constraints to reliably estimate the so-called omnipolar electrogram (oEGM). Performance was evaluated using an experimental animal model. Thirty-eight recordings from nine retrospective experiments on isolated perfused rabbit hearts with an epicardial HD multielectrode were used. We estimated oEGMs according to the classic triangular clique (4 possible orientations) and a novel cross-orientation clique arrangement. Furthermore, we tested the effects of interelectrode spacing from 1 to 4 mm. Performance was evaluated by means of several parameters that measured amplitude rejection ratios, electric field loop area, activation pulse width and morphology distortion. Most reliable oEGM estimations were obtained with cross-configurations and interelectrode spacings [Formula: see text] mm. Estimations from triangular cliques resulted in wider electric field loops and unreliable detection of the direction of the propagation wavefront. Moreover, increasing interelectrode distance resulted in increased pulse width and morphology distortion. The results prove that current oEGM estimation techniques are insufficiently accurate. This study opens a new standpoint for the design of new-generation HD catheters and mapping software.

Virtual Scoliosis Surgery Using a 3D-Printed Model Based on Biplanar Radiographs.

The aim of this paper is to describe a protocol that simulates the spinal surgery undergone by adolescents with idiopathic scoliosis (AIS) by using a 3D-printed spine model. Patients with AIS underwent pre- and postoperative bi-planar low-dose X-rays from which a numerical 3D model of their spine was generated. The preoperative numerical spine model was subsequently 3D printed to virtually reproduce the spine surgery. Special consideration was given to the printing materials for the 3D-printed elements in order to reflect the radiopaque and mechanical properties of typical bones most accurately. Two patients with AIS were recruited and operated. During the virtual surgery, both pre- and postoperative images of the 3D-printed spine model were acquired. The proposed 3D-printing workflow used to create a realistic 3D-printed spine suitable for virtual surgery appears to be feasible and reliable. This method could be used for virtual-reality scoliosis surgery training incorporating 3D-printed models, and to test surgical instruments and implants.

Left ventricular myocardial dysfunction in arrhythmogenic cardiomyopathy with left ventricular involvement: A door to improving diagnosis.

BACKGROUND: Diagnostic Task Force Criteria (TFC) for arrhythmogenic cardiomyopathy (AC) exhibit poor performance for left dominant forms. TFC only include right ventricular (RV) dysfunction (akinesia, dyssynchrony, volumes and ejection fraction). Moreover, cardiac magnetic resonance imaging (CMRI) assessment of left ventricular (LV) dyssynchrony has hitherto not been described. Thus, we aimed to comprehensively characterize LV CMRI behavior in AC patients. METHODS: Thirty-five AC patients with LV involvement and twenty-three non-affected family members (controls) were enrolled. Feature-tracking analysis was applied to cine CMRI to assess LV ejection fraction (LVEF), LV end-systolic and end-diastolic volume indexes, strain values and dyssynchrony. Regions with more frequent strain and dyssynchrony impairment were also studied. RESULTS: Radial dyssynchrony and LVEF were selected (sensitivities 54.3% and 48.6%, respectively at 100% specificity), with a threshold of 70 ms for radial dyssynchrony and 48.5% for LVEF. 71.4% of patients exceeded these thresholds (31.4% both, 22.9% only dyssynchrony and 17.1% only LVEF). Considering these cut-off values as a novel combined criterion, 30% of patients with 'borderline' or 'possible' AC following 2010 TFC would move to a 'definite' AC diagnosis. Strain was globally impaired whereas dyssynchronous regions were more often apical and located at the inferolateral wall. CONCLUSIONS: Mirroring the RV evaluation, we suggest including LVEF and LV dyssynchrony to improve the diagnosis of AC. Two independent mechanisms can be claimed in AC patients with LV involvement: 1) decreased myocardial deformation with global LV affectation and 2) delayed myocardial contraction at localized regions.

Do Postoperative Hallux Angles Correlate With Outcome in MP1 Fusion? Our Experience With 71 Cases.

PURPOSE: To determine if the postoperative alignment of the hallux influences the final clinical outcome of hallux metatarsophalangeal joint (first MTPJ) arthrodesis. METHODS: A total of 71 consecutive cases (hallux rigidus) were studied in stages 3 and 4. They were operated through arthrodesis between 2008 and 2014. The follow-up mean was 7.3 years. The AOFAS (American Orthopaedic Foot and Ankle Society) test was performed preintervention and per annum. In radiology, both the hallux valgus angle and the dorsiflexion angle of the first MTPJ were studied. Furthermore, clinical outcomes were evaluated according to the type of implant used. RESULTS: Preoperative AOFAS score was 27.5, rising to 91.3 after the intervention ( P < .01). The improvement test average was 63.6. There were 17 local complications (23%), 7 of them were considered to be major complications (9%), 6 of which needed reoperation (8.5%). The dorsiflexion angle postoperative mean was 21.7°. The hallux valgus angle postoperative mean was 10.9°. No correlations between both angles, and improved AOFAS score or complications ( P > .4 and P > .5, respectively), were found. Patients who had a dorsiflexion angle higher than 20° had greater improvement in the AOFAS score compared with those who had angles lower than 20° (64.5 vs 59.6 points). Nevertheless, this result was not statistically significant ( P = .059). No differences in AOFAS score improvement regarding arthrodesis plate ( P > .1) were found. CONCLUSION: First MTPJ arthrodesis is a good alternative for patients in advanced hallux rigidus stages when conservative treatment fails. We could not confirm if a better postoperative alignment may influence in clinical outcomes. However, better results are obtained with dorsiflexion angle greater than 20° than with those with less than 20°. Likewise, any differences between the 2 arthrodesis plates have been able to confirm. LEVELS OF EVIDENCE: Level III: Retrospective cohort study.

The role of independent component analysis in the signal processing of ECG recordings.

Independent component analysis (ICA) is an emerging technique for multidimensional signal processing. In recent years, these techniques have been proposed for solving a large number of biomedical applications. This work reviews current knowledge on ICA in electrocardiographic (ECG) analysis. The benefits that ICA can bring to clinical practice are illustrated with four relevant clinical applications: foetal ECG extraction from maternal ECG recordings, analysis of atrial fibrillation, ECG denoising and removal of pacemaker artefacts.

Implantable cardioverter defibrillator algorithms: status review in terms of computational cost.

In recent decades, implantable cardioverter defibrillators (ICDs) have improved substantially, becoming the treatment of choice for patients at high risk of life-threatening arrhythmias. Nevertheless, inappropriate shock therapy for non-ventricular arrhythmias is still a problem. Extending the ICD battery lifetime demands very low power consumption, which is obtained at very low microprocessor clock frequencies. Currently, some high-performance algorithms remain beyond the computational capabilities of ICDs. Future ICDs with higher computing power will permit the implementation of computationally intensive algorithms, enhancing the discrimination performance and preventing inappropriate shock therapies. An ICD algorithm status review is presented from the point of view of signal processing techniques and their computational costs. Several examples of discrimination algorithms with increasing computational cost are analyzed. Whereas some of them are already used in commercial ICDs, other algorithms cannot be implemented yet in current ICDs. A solution based on dynamic adaptation of microprocessor power consumption to meet algorithm computational requirements is proposed. This solution allows implementation of complex discrimination algorithms in ICDs without significantly increasing the power consumption.

[Effects of myocardial stretching on excitation frequencies determined by spectral analysis during ventricular fibrillation]. / Efecto del estiramiento micárdico sobre las frecuencias de activación determinadas mediante análisis espectral durante la fibrilación ventricular.

INTRODUCTION AND OBJECTIVES: The aim of this study was to analyze the effects of myocardial stretching on excitation frequencies, as determined by spectral analysis, during ventricular fibrillation. METHODS: In 12 isolated rabbit heart preparations, ventricular activation during ventricular fibrillation was recorded with multiple electrodes. Recordings were obtained before, during and after ventricular dilatation produced with an intraventricular balloon. The dominant frequency of the signals obtained with each of the electrodes was determined by spectral analysis. RESULTS: During the control phase, the mean, minimum and maximum dominant frequencies were, respectively, 14.3 1.7, 12.5 1.7, and 16.2 1.4 Hz, and the average difference between the maximum and minimum frequencies was 3.6 2.1 Hz. This difference was over 4 Hz in four cases, and in no case did it exceed 8 Hz. During ventricular stretching, the mean dominant frequency increased significantly (21.1 6.1 Hz; p < 0.0001), as did the minimum values (14 2.6 Hz; p < 0.05) and especially the maximum values (26.6 7.7 Hz; p < 0.0001). The difference between the maximum and minimum frequencies (12.6 6.4 Hz; p < 0.001) was over 4 Hz in all cases except one, and over 8 Hz in 9 cases. The maximum values were distributed heterogeneously during ventricular stretching. Upon suppressing ventricular stretching, the dominant frequency did not differ from controls. CONCLUSIONS: Myocardial frequency maps during ventricular fibrillation show limited variations in the dominant frequency of the signals recorded in the lateral wall of the left ventricle. During stretching, the patterns were heterogeneous, due mainly to the marked increase in the maximum dominant frequency. In the experimental model used, the effects of stretching remitted after suppressing ventricular dilatation.

QT interval heterogeneities induced through local epicardial warming/cooling. An experimental study.

INTRODUCTION AND OBJECTIVES: Abnormal QT interval durations and dispersions have been associated with increased risk of ventricular arrhythmias. The present study examines the possible arrhythmogenic effect of inducing QT interval variations through local epicardial cooling and warming. METHODS: In 10 isolated rabbit hearts, the temperatures of epicardial regions of the left ventricle were modified in a stepwise manner (from 22°C to 42°C) with simultaneous electrogram recording in these regions and in others of the same ventricle. QT and activation-recovery intervals were determined during sinus rhythm, whereas conduction velocity and ventricular arrhythmia induction were determined during programmed stimulation. RESULTS: In the area modified from baseline temperature (37°C), the QT (standard deviation) was prolonged with maximum hypothermia (195 [47] vs 149 [12] ms; P<.05) and shortened with hyperthermia (143 [18] vs 152 [27] ms; P<.05). The same behavior was displayed for the activation-recovery interval. The conduction velocity decreased with hypothermia and increased with hyperthermia. No changes were seen in the other unmodified area. Repetitive responses were seen in 5 experiments, but no relationship was found between their occurrence and hypothermia or hyperthermia (P>.34). CONCLUSIONS: In the experimental model employed, local variations in the epicardial temperature modulate the QT interval, activation-recovery interval, and conduction velocity. Induction of heterogeneities did not promote ventricular arrhythmia occurrence.

Serum selenium levels in cirrhotic patients are not influenced by the disease severity index.

Selenium (Se) is an antioxidant element that protects against cellular damage by reactive oxygen species. Therefore, total serum Se concentration may reflect protection during the development of cirrhosis, an oxidative stress-related disease. We hypothesized that serum Se levels are diminished in cirrhotic patients due to their enhanced oxidative stress, and serum Se levels are reduced the most in patients with the highest severity of cirrhosis. A case-control study was performed to determine whether cirrhosis is associated with changes in serum Se levels. Blood samples from 30 healthy controls and 93 cirrhotic patients were analyzed for total serum Se by hydride generation atomic absorption spectrometry. The Child-Pugh index score was used to evaluate the severity of liver disease. The mean serum Se concentration was significantly lower in patients vs controls (0.721 ± 0.239 vs 0.926 ± 0.241 µmol/L; P = .001). Mean serum Se levels were not significantly lower in patients with higher severity of cirrhosis (0.691 ± 0.229 vs 0.755 ± 0.255 µmol/L; P = .144). A positive and significant correlation was found between age and serum Se levels in patients (r = 0.277, P = .007). Patients showed significant sex differences in serum Se level (higher in male) and severity index (higher in female). The significantly decreased serum Se level in patients indicates that the Se component of the antioxidant system is severely impaired in cirrhosis. However, serum Se levels were not influenced by the severity of the disease.