Improved filtering methods to suppress cardiovascular contamination in electrical impedance tomography recordings

OBJECTIVE

Electrical Impedance Tomography (EIT) produces clinical useful visualization of the distribution of ventilation inside the lungs. The accuracy of EIT-derived parameters can be compromised by the cardiovascular signal. Removal of these artefacts is challenging due to spectral overlapping of the ventilatory and cardiovascular signal components and their time-varying frequencies. We designed and evaluated advanced filtering techniques and hypothesized that these would outperform traditional low-pass filters. Approach: Three filter techniques were developed and compared against traditional low-pass filtering: multiple digital notch filtering (MDN), empirical mode decomposition (EMD) and the maximal overlap discrete wavelet transform (MODWT). The performance of the filtering techniques was evaluated 1) in the time domain 2) in the frequency domain 3) by visual inspection. We evaluated the performance using simulated contaminated EIT data and data from fifteen adult and neonatal ICU patients. Main result: Each filter technique exhibited varying degrees of effectiveness and limitations. Quality measures in the time domain showed the best performance for MDN filtering. The signal to noise ratio was best for DLP, but at the cost of a high relative and removal error. MDN outbalanced the performance resulting in a good SNR with a low relative and removal error. MDN, EMD and MODWT performed similar in the frequency domain and were successful in removing the high frequency components of the data. Significance: Advanced filtering techniques have benefits compared to traditional filters but are not always better. MDN filtering outperformed EMD and MODWT regarding quality measures in the time domain. This study emphasizes the need for careful consideration when choosing a filtering approach, depending on the dataset and the clinical/research question. .

Design of percutaneous transluminal coronary angioplasty balloon catheters

BACKGROUND

Eight commercially available percutaneous transluminal coronary angioplasty (PTCA), including semi-compliant and non-compliant balloons, have been assessed in detail on their tip, balloon, shaft, RX-Port, and hypotube design. Important performance characteristics such as tip deformation, balloon elongation, and deflation rate have been quantified.

METHODS

Five catheters of each model were evaluated during various tests. The robustness of the tips was evaluated through compression, measuring any occurrence of damage. The longitudinal growth of the balloons was recorded during inflation up to Rated Burst Pressure (RBP). The forces required to move the catheter forward and retract it into the guide catheter were measured in a simulated use test setup. The deflation behavior was studied by measuring extracted contrast media over time. Furthermore, balloon compliance and catheter dimensions were investigated.

RESULTS

The outer dimensions of the catheter were found to be smallest at the hypotube (0.59-0.69 mm) and highest at the balloon, respectively, the crossing profile (0.9-1.2 mm). The tip diameter increased after compression by 1.7-22%. Cross-sections of the folded balloons revealed a tri- and two-fold, respectively. The measured balloon elongation ranged from 0.6 to 2.0 mm. After the inflation of the balloon, an increase in friction between the guide wire and the catheter was observed on four catheters. A maximum increase of 0.12 N to 1.07 N was found. Cross-sections of the RX-Port revealed a semicircular-shaped inflation lumen and a circular guide wire lumen. The measured deflation rate ranged from 0.004 to 0.013 µL/s, resulting in an estimated balloon deflation time of 10.2-28.1 s.

CONCLUSION

This study provides valuable insights into the design characteristics of RX PTCA balloon catheters, which can contribute to facilitating the development of improved catheter designs and enhancing clinical outcomes. Distinctions between SC and NC catheters, such as balloon performance and dimensions, are evident. It is important to note that no single catheter excels in all aspects, as each possesses unique strengths. Therefore, it is essential to consider individual intervention requirements when selecting a catheter. The research also identifies specific catheter weaknesses, such as reduced wall thickness, fringes at the tip, and reduced performance characteristics.

[Linguistic Validation of the "German Lung Fibrosis Health Related Quality of Life Questionnaire"]

Health status and quality of life are impaired in patients with idiopathic pulmonary fibrosis (IPF) and idiopathic non-specific interstitial fibrosis (iNSIP). In Germany exists only the K-BILD questionnaire for patients with ILD 1 in a professional translation by Kreuter et al. 2 This questionnaire focuses on the main problems in patients with progressive lung fibrosis in a limited manner. Therefore a new quality of life questionnaire for patients with idiopathic pulmonary fibrosis was developed and linguistically validated.

METHODS

 The linguistic validation of our questionnaire was carried out in a multistage process in collaboration with the developer of the questionnaire and bilingual, professional translators. Review by the developers and back translations as well as clinical assessment by IPF- and iNSIP-patients ensured that the translated questionnaire reflected the intention of the original English version of our questionnaire.Cross-validation was carried out with the St. Georges Respiratory Questionnaire (SGRQ).

RESULTS

 The new questionnaire concerning the health status was composed in English and German language. The questions cover five scales (sensitivity, selectivity and symptoms like breathlessness and cough and a visual analog scale on general health status) with 23 items.

CONCLUSIONS

 The results show that the FFB maps the special needs of the patients with IPF and iNSIP well and can support clinical and scientific questions and can be helpful in monitoring the clinical course.

Artificial intelligence solution to classify pulmonary nodules on CT

PURPOSE

The purpose of this study was to create an algorithm to detect and classify pulmonary nodules in two categories based on their volume greater than 100 mm³ or not, using machine learning and deep learning techniques.

MATERIALS AND METHOD

The dataset used to train the model was provided by the organization team of the SFR (French Radiological Society) Data Challenge 2019. An asynchronous and parallel 3-stages pipeline was developed to process all the data (a data "pre-processing" stage; a "nodule detection" stage; a "classifier" stage). Lung segmentation was achieved using 3D U-NET algorithm; nodule detection was done using 3D Retina-UNET and classifier stage with a support vector machine algorithm on selected features. Performances were assessed using area under receiver operating characteristics curve (AUROC).

RESULTS

The pipeline showed good performance for pathological nodule detection and patient diagnosis. With the preparation dataset, an AUROC of 0.9058 (95% confidence interval [CI]: 0.8746-0.9362) was obtained, 87% yielding accuracy (95% CI: 84.83%-91.03%) for the "nodule detection" stage, corresponding to 86% specificity (95% CI: 82%-92%) and 89% sensitivity (95% CI: 84.83%-91.03%).

CONCLUSION

A fully functional pipeline using 3D U-NET, 3D Retina-UNET and classifier stage with a support vector machine algorithm was developed, resulting in high capabilities for pulmonary nodule classification.

[German Guideline for Idiopathic Pulmonary Fibrosis]

Idiopathic pulmonary fibrosis (IPF) is a severe and often fatal disease. Diagnosis of IPF requires considerable expertise and experience. Since publication of the international IPF guideline in the year 2011 and Update 2018 several studies and technical advances occurred, which made a new assessment of the diagnostic process mandatory. In view of the antifibrotic drugs which have been approved for the treatment of IPF patients, the goal of this guideline is to foster early, confident and effective diagnosis of IPF. The guideline focusses on the typical clinical setting of an IPF patient and provides tools to exclude known causes of interstitial lung disease including standardised questionnaires, serologic testing and cellular analysis of bronchoalveolar lavage. High resolution computed tomography remains crucial in the diagnostic work-up. If it is necessary to obtain specimen for histology transbronchial lung cryobiopsy is the primary approach, while surgical lung biopsy is reserved for patients who are fit for it and in whom bronchoscopic diagnosis did not provide the information needed. Despite considerable progress, IPF remains a diagnosis of exclusion and multidisciplinary discussion remains the golden standard of diagnosis.

The impact of COPD on polyneuropathy: results from the German COPD cohort COSYCONET

Background

Peripheral neuropathy is a common comorbidity in COPD. We aimed to investigate associations between alterations commonly found in COPD and peripheral neuropathy, with particular emphasize on the distinction between direct and indirect effects.

Methods

We used visit 4 data of the COPD cohort COSYCONET, which included indicators of polyneuropathy (repeated tuning fork and monofilament testing), excluding patients with diabetes a/o increased HbA1c. These indicators were analysed for the association with COPD characteristics, including lung function, blood gases, 6-min walk distance (6-MWD), timed-up-and-go-test (TUG), exacerbation risk according to GOLD, C-reactive protein (CRP), and ankle-brachial index (ABI). Based on the results of conventional regression analyses adjusted for age, BMI, packyears and gender, we utilized structural equation modelling (SEM) to quantify the network of direct and indirect relationships between parameters.

Results

606 patients were eligible for analysis. The indices of polyneuropathy were highly correlated with each other and related to base excess (BE), ABI and TUG. ABI was linked to neuropathy and 6-MWD, exacerbations depended on FEV₁, 6-MWD and CRP. The associations could be summarized into a SEM comprising polyneuropathy as a latent variable (PNP) with three measured indicator variables. Importantly, PNP was directly dependent on ABI and particularly on BE. When also including patients with diabetes and/or elevated values of HbA1c (n = 742) the SEM remained virtually the same.

Conclusion

We identified BE and ABI as major determinants of peripheral neuropathy in patients with COPD. All other associations, particularly those with lung function and physical capacity, were indirect. These findings underline the importance of alterations of the micromilieu in COPD, in particular the degree of metabolic compensation and vascular status.

Patientenfragebogen zur Erfassung der Ursachen interstitieller und seltener Lungenerkrankungen – klinische Sektion der DGP

Hintergrund Interstitielle Lungenerkrankungen (ILD) umfassen verschiedenste heterogene, zumeist chronische Erkrankungen des Interstitiums und/oder der Alveolen mit bekannten und unbekannten Ursachen. Die Diagnostik der ILD ist sehr komplex und sollte interdisziplinär erfolgen. Eine der wesentlichen Basisuntersuchungen ist eine umfangreiche Anamnese. Hierzu kam im deutschsprachigen Raum bisher der Frankfurter Bogen von 1985 zur Anwendung, der mittlerweile jedoch sprachlich und inhaltlich einer Überarbeitung bedurfte.

Methode Unter Schirmherrschaft der klinischen Sektion der DGP erfolgte die Erstellung eines neuen Patientenfragebogens zur Diagnostik interstitieller und seltener Lungenerkrankungen. Der Fragebogen entstand unter Mitarbeit von Pneumologen mit ILD-Expertise, Arbeitsmedizinern und Psychologen sowie der Unterstützung von Selbsthilfegruppen. Abschließend wurde der Fragebogen mithilfe von Patienten sprachlich optimiert.

Ergebnisse Der neu erstellte Patientenfragebogen zur Diagnostik interstitieller und seltener Lungenerkrankungen umfasst mehrere Bereiche: Initiale und aktuelle Symptome, Fragen zur Vorgeschichte inklusive Medikation, pulmonale und extrapulmonale Vorerkrankungen, mögliche Expositionen im häuslichen, privatem und beruflichem Umfeld sowie Familienanamnese und Reisetätigkeiten.

Schlussfolgerung Der neu erstellte Fragebogen kann in der klinischen Routine die Diagnostik bei Patienten mit Verdacht auf eine interstitielle Lungenerkrankung wesentlich erleichtern.

Airway-centered interstitial fibrosis - an under-recognized subtype of diffuse parenchymal lung diseases

Airway centered interstitial fibrosis (ACIF) has been recently suggesed as a rare histological pattern of interstitial lung disease of variable etiology and outcome. It is characterized by fibrosis of the respiratory bronchioles and the peribronchiolar interstitium. We describe the clinical features of 13 patients (7 female, mean age 55 years) with histologically proven ACIF in 12 cases and long-term follow up. In ten patients, exogenous agents could be detected (mould n=5, wood n=2, leather exposure n=1, occupational exposure n=2). Two patients had rheumatoid arthritis and 1 patient suffered from recurrent aspiration. In three patients no associated exposure could be detected. Eight patients were never-smokers, while five were ex- smokers. At time of diagnosis patients presented with a moderate restrictive ventilation impairment and sever reduction in diffusion capacity (VC 61%, TLC 66%, DLCOc-SB 38% pred.). All patients were started on immunosuppressive therapy with steroids which were combined with azathioprine in seven and with mycophenolate mofetil in one patient. Median time of follow up was 52 months (2-127 months). Patients with ACIF due to exogenous agents or associated with RA were stable with immunosuppressive therapy. One patient with idiopathic ACIF showed a progressive deterioration within 29 months despite immunosuppression and died while on a waiting-list for lung transplantation. In our experience ACIF is a rare finding, which is relatively frequently observed in the context of hypersensitivity pneumonitis, aspiration and rheumatoid arthritis, while idiopathic ACIF was a minority. In the majority of patients, ACIF showed a favorable long-term outcome with immunosuppressive therapy. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 218-229).

Identification of a plasma miRNA biomarker signature for allergic asthma: A translational approach

BACKGROUND

Asthma is a heterogeneous chronic disease with different phenotypes and treatment responses. Thus, there is a high clinical need for molecular disease biomarkers to aid in differentiating these distinct phenotypes. As MicroRNAs (miRNAs), that regulate gene expression at the post-transcriptional level, are altered in experimental and human asthma, circulating miRNAs are attractive candidates for the identification of novel biomarkers. This study aimed to identify plasmatic miRNA-based biomarkers of asthma, through a translational approach.

METHODS

We prescreened miRNAs in plasma samples from two different murine models of experimental asthma (ovalbumin and house dust mite); miRNAs deregulated in both models were further tested in a human training cohort of 20 asthma patients and 9 healthy controls. Candidate miRNAs were then validated in a second, independent group of 26 asthma patients and 12 healthy controls.

RESULTS

Ten miRNA ratios consisting of 13 miRNAs were differentially regulated in both murine models. Measuring these miRNAs in the training cohort identified a biomarker signature consisting of five miRNA ratios (7 miRNAs). This signature showed a good sensitivity and specificity in the test cohort with an area under the receiver operating characteristic curve (AUC) of 0.92. Correlation of miRNA ratios with clinical characteristics further revealed associations with FVC % predicted, and oral corticosteroid or antileukotriene use.

CONCLUSION

Distinct plasma miRNAs are differentially regulated both in murine and in human allergic asthma and were associated with clinical characteristics of patients. Thus, we suggest that miRNA levels in plasma might have future potential to subphenotype patients with asthma.

[Expert Knowledge and Supporting Advice for the Clinical Use of Nintedanib in Patients with Idiopathic Pulmonary Fibrosis]

In October 2016, a group of German IPF experts were invited by Boehringer Ingelheim to meet in Frankfurt with the aim, (a) to discuss relevant aspects of the management and treatment of idiopathic pulmonary fibrosis (IPF) using nintedanib; and, (b) to provide supportive advice for daily clinical practice with nintedanib. The resulting information compiled in this document is confined to practical issues regarding the use of nintedanib in patients with IPF. Where different therapeutic options were available, the choice of IPF medication was not discussed and the experts alluded to current guidelines for the diagnosis and treatment of IPF.The participants discussed a comprehensive spectrum of clinical questions related to 10 different topics, including patient-related aspects at initiation of IPF therapy, the treatment of anticoagulated IPF patients, and the handling of nintedanib-related adverse events such as gastrointestinal side effects and elevated liver enzymes. In addition, the experts evaluated therapeutic options for IPF patients with continuous disease progression, clinical scenarios that justify discontinuation of nintedanib treatment, and therapeutic options for IPF patients with an acute exacerbation or severe infection. Finally, the participants discussed the handling of nintendanib before/after elective surgical intervention (e. g. lung transplantation) and the current evidence for antifibrotic combination therapy in patients with IPF.For each topic discussed, the resulting information incorporates published evidence from clinical trials. In case of insufficient or lacking evidence, the experts have formulated recommendations based on their personal clinical experience and evaluation.