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8th Dutch Bio-Medical Engineering Conference
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13:40   Lung & Respiration - II
Chair: Natasha Maurits
13:40
15 mins
Adjustable breathing resistance for laryngectomized patients: proof of principle in a novel heat and moisture exchanger cassette
Maartje Leemans, Saar Muller, Maarten van Alphen, Wim Vallenduuk, Richard Dirven, Michiel van den Brekel
Abstract: ABSTRACT Background: Heat and Moisture Exchangers (HMEs) are used as a standard treatment for pulmonary rehabilitation after a total laryngectomy. Normally the upper airways condition (heat and humidify) the inhaled air, but in laryngectomized patients their lungs are exposed to the dry and cold air when breathing through the open stoma in their neck. An HME covering the stoma can to some extent improve the pulmonary condition. However, as a result of the HME’s breathing resistance, laryngectomized patients cannot always use an (optimal) HME during physical exercise. We propose a novel HME cassette concept with adjustable ‘bypass’, to provide adjustment between different breathing resistances within a single device. Methods: Under standardized conditions, the resistance and humidification performance of a high resistance/high humidification HME (XM) foam in a cassette with and without bypass were compared to a lower resistance/lesser humidification HME (XF) foam in a closed cassette. Results: With a bypass in the cassette, the resistance and humidification performance of the XM foam were similar to those of the XF foam in the closed cassette. Compared to the XM foam in the closed cassette, the introduction of the bypass resulted in a 40% decrease in resistance, whereas the humidification performance was maintained at 80% of the original value. Conclusions: This HME cassette prototype allows adjustment between substantially different breathing resistances while maintaining appropriate humidification performances. This could facilitate physical exercise without changing or removing the HME and potentially increase compliance.
13:55
15 mins
Respiratory rate estimation from functional near infrared spectroscopy signals
M. Sofia Sappia, Naser Hakimi, Jörn M. Horschig, Willy J. N. M. Colier
Abstract: Changes in respiratory activity provide important markers of health and fitness. Respiratory rate (RR) is a key physiological indicator of a variety of chronic diseases, often used in clinical settings for the identification of abnormalities. RR monitoring at home and hospitals can help clinicians to diagnose and make medical prognoses. In addition, it provides information about respiratory fitness, which can be desirable for athletes in sports applications. Functional near infrared spectroscopy (fNIRS) signals include spontaneous hemodynamic oscillations due to systemic changes caused by respiration, in addition to brain hemodynamics. This respiratory information in fNIRS signals makes it possible to estimate RR without using direct respiratory sensors. In this study we propose an algorithm to estimate RR from fNIRS signals, which consists of four consecutive stages: signal quality assessment, preprocessing, respiratory signal extraction, and respiratory rate estimation. In the proposed algorithm, we firstly exclude signals with insufficient quality (first stage) and filter the remaining ones to keep the respiratory information (second stage). For respiratory signal extraction (third stage), we detect the peaks and troughs in the signal using a real-time peak detection algorithm. We then extract three respiratory signals representing respiratory modulation in amplitude, intensity, and frequency of the fNIRS signals. These three respiratory signals are combined using Hilbert transform to reconstruct one respiratory signal with an enhanced spectrum. In the fourth stage, we use this reconstructed signal to estimate the RR by finding the maximal peak in the spectrum of the signal. The algorithm proposed in this study makes it possible to estimate RR besides brain hemodynamics without the need for two separate devices. This allows for a wide range of applications in both home-based and clinical settings, such as brain and respiratory fitness assessment as well as the prognosis of a variety of chronic diseases, especially in neonates.
14:10
15 mins
Evaluation of a novel DCT-based EIT algorithm for pulmonary ventilation
Rongqing Chen, Knut Möller
Abstract: Background: Electrical impedance tomography (EIT) is a functional radiation-free imaging technique which measures regional lung ventilation and aeration distribution by means of changes in electrical potentials at the skin surface. EIT has shown the potential to continuously monitor lung status and guide mechanical ventilation. However, the fact that traditional EIT algorithms usually reconstruct conductivity within whole domain instead of lung area, together with artefacts, hinders the interpretation of EIT images in clinical circumstances. Aiming to overcome this hindrance, our team proposed a CT-infused EIT algorithm [1], which implements the discrete cosine transformation (DCT) on CT-derived lung areas to restrain the reconstruction. The question remains whether the novel algorithm reconstructed images accurately represent patient status. Purpose: To evaluate the feasibility and accuracy of the novel DCT-based EIT algorithm for further clinical implementation. Method: We adopted both simulation and retrospective patient research for the evaluation of the novel algorithm by comparison with the up-to-date GREIT algorithm. Lungs with five different conductivity distributions were used in simulation models to generate reconstructions of both algorithms. Wildly adopted evaluation indexes, inhomogeneity index (GI) and Centre of Ventilation (CoV), were adopted for the comparison. The same indexes were also used to analyse retrospective patient data. Results: Firstly, DCT-based EIT restrained the artefacts and only reconstructed within lung areas that improved interpretability; Secondly, in the simulation research, the difference between GI indexes of DCT-based EIT and GI of the ground truth is smaller than the GREIT’s, which implies that reconstructed distribution of conductivity is more accurate in DCT-based EIT images. The CoV indexes did not vary much in both algorithms, and were similar to the CoV of ground truth; thirdly, in the retrospective patient research, the GI indexes showed different trends in two different algorithms within the same ventilation cycle, yet the CoV showed similar results. Conclusion: The DCT-based EIT algorithm has advantages over traditional EIT algorithm by reconstructing more accurate conductivity distribution in a restrained lung area, promising a better interpretation in medical settings. However, an influence on the distribution of regional gas allocation is possible in the novel algorithm, which needs further investigation.
14:25
15 mins
Translation of third and second harmonic generation microscopy into the clinic for the assessment of fresh lung tumor tissue
Laura van Huizen, Teodora Radonic, Frank van Mourik, Daniëlle Seinstra, Chris Dickhoff, Johannes Daniels, Idris Bahce, Jouke Annema, Marloes Groot
Abstract: Background - Third and second harmonic generation (THG/SHG) microscopy is a novel imaging technique that has been suggested as a promising clinical tool, mainly for cancer diagnosis. In lung surgery, immediate feedback on the nature of the excised tissue is important. During the operation a ‘fast’ diagnosis can be made using frozen section analysis, which takes up to 30 minutes. Alternative techniques are therefore required that can assess lung tissue with a speed that enables ‘live’ feedback to surgeons while they operate. THG/SHG/2PEF microscopy - A technique that meets these requirements is the combined THG/SHG and two-photon excited autofluorescence (2PEF) microscopy, which is non-invasive, label-free and provides 3D images with a high, sub-cellular resolution, within seconds. Before, we demonstrated on lung tissue that THG/SHG/2PEF microscopy can generate high quality images of freshly excised unprocessed tissue, in less than a minute with information content comparable to that of the gold standard, histopathology [1]. We could successfully reveal alveolar structures and histopathology hallmarks, including cell morphology and general tissue architecture (collagen and elastin organization). Goal of ongoing study - Here, we elaborate on this previous study by imaging a larger number of patients with lung cancer, comparing the THG/SHG/2PEF images with the histopathology, assessing the quality of diagnoses by independent pathologists, and examining the clinical impact of the portable THG/SHG/2PEF microscope. In addition, we investigate whether THG/SHG/2PEF microscopy is able to distinguish different immune cells, which is important for the pathological assessment of lung tumor tissue. [1] L.M.G. van Huizen, et al. Translational Biophotonics, 4, (2020)


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