Automatic pediatric congenital heart disease classification based on heart sound signal.

Congenital heart diseases (CHD) are the most common birth defects, and the early diagnosis of CHD is crucial for CHD therapy. However, there are relatively few studies on intelligent auscultation for pediatric CHD, due to the fact that effective cooperation of the patient is required for the acquisition of useable heart sounds by electronic stethoscopes, yet the quality of heart sounds in pediatric is poor compared to adults due to the factors such as crying and breath sounds. This paper presents a novel pediatric CHD intelligent auscultation method based on electronic stethoscope. Firstly, a pediatric CHD heart sound database with a total of 941 PCG signal is established. Then a segment-based heart sound segmentation algorithm is proposed, which is based on PCG segment to achieve the segmentation of cardiac cycles, and therefore can reduce the influence of local noise to the global. Finally, the accurate classification of CHD is achieved using a majority voting classifier with Random Forest and Adaboost classifier based on 84 features containing time domain and frequency domain. Experimental results show that the performance of the proposed method is competitive, and the accuracy, sensitivity, specificity and f1-score of classification for CHD are 0.953, 0.946, 0.961 and 0.953 respectively.

An Examination and Comparison of Stethoscope Hygiene in Nursing Education Programs.

BACKGROUND: Improper stethoscope hygiene has been found to contribute to the development of health care associated infections, which affects approximately one in every 30 hospitalized patients. Various pathogens have been found on the stethoscopes of health care workers. METHOD: A correlational descriptive design was used to compare stethoscopes from 117 nursing students. Sterile swab samples were obtained from four separate areas of each stethoscope. Samples were plated and incubated for 24 to 48 hours. RESULTS: Bacteria were found on all parts of the stethoscopes from both undergraduate and graduate nursing students, with the earpiece having the highest percentage of contamination. Staphylococcus was the most prevalent microbe found on all four swab sites. CONCLUSION: Educating students about stethoscope hygiene and consistently reinforcing it in practice are essential to reduce the transmission of pathogens in the health care environment. Nurses can model best practice with students and other disciplines to increase the likelihood of adherence. [J Nurs Educ. 2021;60(5):277-280.].

Stethoscope hygiene: A call to action. Recommendations to update the CDC guidelines.

Healthcare-acquired infections are a tremendous challenge to the US medical system. Stethoscopes touch many patients, but current guidance from the Centers for Disease Control and Prevention does not support disinfection between each patient. Stethoscopes are rarely disinfected between patients by healthcare providers. When cultured, even after disinfection, stethoscopes have high rates of pathogen contamination, identical to that of unwashed hands. The consequence of these practices may bode poorly in the coronavirus 2019 disease (COVID-19) pandemic. Alternatively, the CDC recommends the use of disposable stethoscopes. However, these instruments have poor acoustic properties, and misdiagnoses have been documented. They may also serve as pathogen vectors among staff sharing them. Disposable aseptic stethoscope diaphragm barriers can provide increased safety without sacrificing stethoscope function. We recommend that the CDC consider the research regarding stethoscope hygiene and effective solutions to contemporize this guidance and elevate stethoscope hygiene to that of the hands, by requiring stethoscope disinfection or change of disposable barrier between every patient encounter.

Hemopneumothorax detection through the process of artificial evolution - a feasibility study.

BACKGROUND: Tension pneumothorax is one of the leading causes of preventable death on the battlefield. Current prehospital diagnosis relies on a subjective clinical impression complemented by a manual thoracic and respiratory examination. These techniques are not fully applicable in field conditions and on the battlefield, where situational and environmental factors may impair clinical capabilities. We aimed to assemble a device able to sample, analyze, and classify the unique acoustic signatures of pneumothorax and hemothorax. METHODS: Acoustic data was obtained with simultaneous use of two sensitive digital stethoscopes from the chest wall of an ex-vivo porcine model. Twelve second samples of acoustic data were obtained from the in-house assembled digital stethoscope system during mechanical ventilation. The thoracic cavity was injected with increasing volumes of 200, 400, 600, 800, and 1000 ml of air or saline to simulate pneumothorax and hemothorax, respectively. The data was analyzed using a multi-objective genetic algorithm that was used to develop an optimal mathematical detector through the process of artificial evolution, a cutting-edge approach in the artificial intelligence discipline. RESULTS: The in-house assembled dual digital stethoscope system and developed genetic algorithm achieved an accuracy, sensitivity and specificity ranging from 64 to 100%, 63 to 100%, and 63 to 100%, respectively, in classifying acoustic signal as associated with pneumothorax or hemothorax at fluid injection levels of 400 ml or more, and regardless of background noise. CONCLUSIONS: We present a novel, objective device for rapid diagnosis of potentially lethal thoracic injuries. With further optimization, such a device could provide real-time detection and monitoring of pneumothorax and hemothorax in battlefield conditions.

A basic investigation into the optimization of cylindrical tubes used as acoustic stethoscopes for auscultation in COVID-19 diagnosis.

During the COVID-19 outbreak, the auscultation of heart and lung sounds has played an important role in the comprehensive diagnosis and real-time monitoring of confirmed cases. With clinicians wearing protective clothing in isolation wards, a potato chip tube stethoscope, which is a secure and flexible substitute for a conventional stethoscope, has been used by Chinese medical workers in the first-line treatment of COVID-19. In this study, an optimal design for this simple cylindrical stethoscope is proposed based on the fundamental theory of acoustic waveguides. Analyses of the cutoff frequency, sound power transmission coefficient, and sound wave propagation in the uniform lossless tube provide theoretical guidance for selecting the geometric parameters for this simple cylindrical stethoscope. A basic investigation into the auscultatory performances of the original tube and the optimal tube with proposed dimensions was conducted both in a semi-anechoic chamber and in a quiet laboratory. Both experimental results and front-line doctors' clinical feedback endorse the proposed theoretical optimization.

Artificial intelligence accuracy in detecting pathological breath sounds in children using digital stethoscopes.

BACKGROUND: Manual auscultation to detect abnormal breath sounds has poor inter-observer reliability. Digital stethoscopes with artificial intelligence (AI) could improve reliable detection of these sounds. We aimed to independently test the abilities of AI developed for this purpose. METHODS: One hundred and ninety two auscultation recordings collected from children using two different digital stethoscopes (Clinicloud™ and Littman™) were each tagged as containing wheezes, crackles or neither by a pediatric respiratory physician, based on audio playback and careful spectrogram and waveform analysis, with a subset validated by a blinded second clinician. These recordings were submitted for analysis by a blinded AI algorithm (StethoMe AI) specifically trained to detect pathologic pediatric breath sounds. RESULTS: With optimized AI detection thresholds, crackle detection positive percent agreement (PPA) was 0.95 and negative percent agreement (NPA) was 0.99 for Clinicloud recordings; for Littman-collected sounds PPA was 0.82 and NPA was 0.96. Wheeze detection PPA and NPA were 0.90 and 0.97 respectively (Clinicloud auscultation), with PPA 0.80 and NPA 0.95 for Littman recordings. CONCLUSIONS: AI can detect crackles and wheeze with a reasonably high degree of accuracy from breath sounds obtained from different digital stethoscope devices, although some device-dependent differences do exist.

Should the ultrasound probe replace your stethoscope? A SICS-I sub-study comparing lung ultrasound and pulmonary auscultation in the critically ill.

BACKGROUND: In critically ill patients, auscultation might be challenging as dorsal lung fields are difficult to reach in supine-positioned patients, and the environment is often noisy. In recent years, clinicians have started to consider lung ultrasound as a useful diagnostic tool for a variety of pulmonary pathologies, including pulmonary edema. The aim of this study was to compare lung ultrasound and pulmonary auscultation for detecting pulmonary edema in critically ill patients. METHODS: This study was a planned sub-study of the Simple Intensive Care Studies-I, a single-center, prospective observational study. All acutely admitted patients who were 18 years and older with an expected ICU stay of at least 24 h were eligible for inclusion. All patients underwent clinical examination combined with lung ultrasound, conducted by researchers not involved in patient care. Clinical examination included auscultation of the bilateral regions for crepitations and rhonchi. Lung ultrasound was conducted according to the Bedside Lung Ultrasound in Emergency protocol. Pulmonary edema was defined as three or more B lines in at least two (bilateral) scan sites. An agreement was described by using the Cohen κ coefficient, sensitivity, specificity, negative predictive value, positive predictive value, and overall accuracy. Subgroup analysis were performed in patients who were not mechanically ventilated. RESULTS: The Simple Intensive Care Studies-I cohort included 1075 patients, of whom 926 (86%) were eligible for inclusion in this analysis. Three hundred seven of the 926 patients (33%) fulfilled the criteria for pulmonary edema on lung ultrasound. In 156 (51%) of these patients, auscultation was normal. A total of 302 patients (32%) had audible crepitations or rhonchi upon auscultation. From 130 patients with crepitations, 86 patients (66%) had pulmonary edema on lung ultrasound, and from 209 patients with rhonchi, 96 patients (46%) had pulmonary edema on lung ultrasound. The agreement between auscultation findings and lung ultrasound diagnosis was poor (κ statistic 0.25). Subgroup analysis showed that the diagnostic accuracy of auscultation was better in non-ventilated than in ventilated patients. CONCLUSION: The agreement between lung ultrasound and auscultation is poor. TRIAL REGISTRATION: NCT02912624. Registered on September 23, 2016.

Perceptual audio processing stethoscope.

Stethoscopes are used to transmit body sounds related to various physiological processes to ears of a physician, providing basic or supportive information for eventual diagnosis. Unfavorably, the dominant frequency components of most of the auscultation signals are localized close to the lower frequency limits of the human auditory system, restricting the achievable selectivity and specificity. The present study introduces an approach that aims at overcoming the existing limitations. A signal processing scheme utilizing knock rejection, dynamic compressor, and pseudo-stereo synthesizer blocks is described, along with hardware implementation and results of the initial subjective evaluation.

Digital Stethoscope-Improved Auscultation at the Bedside.

Electronic stethoscopes convert acoustic sound waves to electrical signals which can then be amplified and processed for optimal listening. However, amplification of stethoscope contact artifacts, and component cutoffs has led to the question of whether they are an improvement in the bedside cardiac examination. In this study, a single observer compared an analog stethoscope with the Thinklabsone electronic stethoscope in a clinical setting to determine if there was a significant difference in the diagnostic utility of the devices. Two hundred and nine patients were examined and the electronic stethoscope was felt to have superior sound quality in 65% of patients.

Developing a reference of normal lung sounds in healthy Peruvian children.

PURPOSE: Lung auscultation has long been a standard of care for the diagnosis of respiratory diseases. Recent advances in electronic auscultation and signal processing have yet to find clinical acceptance; however, computerized lung sound analysis may be ideal for pediatric populations in settings, where skilled healthcare providers are commonly unavailable. We described features of normal lung sounds in young children using a novel signal processing approach to lay a foundation for identifying pathologic respiratory sounds. METHODS: 186 healthy children with normal pulmonary exams and without respiratory complaints were enrolled at a tertiary care hospital in Lima, Peru. Lung sounds were recorded at eight thoracic sites using a digital stethoscope. 151 (81%) of the recordings were eligible for further analysis. Heavy-crying segments were automatically rejected and features extracted from spectral and temporal signal representations contributed to profiling of lung sounds. RESULTS: Mean age, height, and weight among study participants were 2.2 years (SD 1.4), 84.7 cm (SD 13.2), and 12.0 kg (SD 3.6), respectively; and, 47% were boys. We identified ten distinct spectral and spectro-temporal signal parameters and most demonstrated linear relationships with age, height, and weight, while no differences with genders were noted. Older children had a faster decaying spectrum than younger ones. Features like spectral peak width, lower-frequency Mel-frequency cepstral coefficients, and spectro-temporal modulations also showed variations with recording site. CONCLUSIONS: Lung sound extracted features varied significantly with child characteristics and lung site. A comparison with adult studies revealed differences in the extracted features for children. While sound-reduction techniques will improve analysis, we offer a novel, reproducible tool for sound analysis in real-world environments.

Performance evaluation of heart sound cancellation in FPGA hardware implementation for electronic stethoscope.

This paper presents the design and evaluation of the hardware circuit for electronic stethoscopes with heart sound cancellation capabilities using field programmable gate arrays (FPGAs). The adaptive line enhancer (ALE) was adopted as the filtering methodology to reduce heart sound attributes from the breath sounds obtained via the electronic stethoscope pickup. FPGAs were utilized to implement the ALE functions in hardware to achieve near real-time breath sound processing. We believe that such an implementation is unprecedented and crucial toward a truly useful, standalone medical device in outpatient clinic settings. The implementation evaluation with one Altera cyclone II-EP2C70F89 shows that the proposed ALE used 45% resources of the chip. Experiments with the proposed prototype were made using DE2-70 emulation board with recorded body signals obtained from online medical archives. Clear suppressions were observed in our experiments from both the frequency domain and time domain perspectives.

Comparison of conventional and sensor-based electronic stethoscopes in detecting cardiac murmurs of dogs.

BACKGROUND AND OBJECTIVE: Cardiac auscultation is one of the most important parts of the cardiological examination traditionally performed with acoustic stethoscopes. The aim of this study was to compare the sensitivities and the diagnostic capabilities of traditional and electronic stethoscopes in detecting canine heart murmurs. MATERIALS AND METHODS: The study was performed on 21 dogs referred for cardiologic examination with suspected heart murmurs. Six out of these dogs had cardiac murmurs bilaterally. Cardiac auscultation was performed independently by a final-year veterinary student (AB=I1) and by an experienced clinician (KV=I2), both using a traditional and a Welch Allyn Meditron electronic sensor-based stethoscope. Final diagnoses were established by echocardiography and by digital phonocardiography. RESULTS: Correct detection of a murmur was made by I1 with a traditional stethoscope in 20/27 (74.0%) of the suspected murmurs (p=0.30, kappa[κ] =0.2) and with the electronic stethoscope in 26/27 (96.3%), respectively (p=0.0013, κ=0.75). I2 correctly detected the murmurs with the traditional stethoscope in 25/27 (92.6%) cases (p=0.0013, κ=0.75) and with the electronic stethoscope in all 27/27 (100%) cases (p=0.00012, κ=1). Agreements of murmur intensity gradings between traditional and electronic stethoscopes were highly significant (I1: p=6.9´10⁻8; κ=0.79), (I2: p=5.2´10⁻¹¹; κ=0.92). When grading the murmurs with the traditional stethoscope, there was a significant agreement between I1 and I2 (p=2.9´10⁻7; κ=0.79), being even higher with the electronic stethoscope (p=1.1´10⁻¹¹; κ=0.92). CONCLUSION: The electronic stethoscope was more sensitive than the traditional one in detecting and grading cardiac murmurs being especially useful for I1 with less experience. However, it can be suggested to use a traditional and an electronic stethoscopes simultaneously to optimally utilize their advantages.

Auscultation in flight: comparison of conventional and electronic stethoscopes.

OBJECTIVES: The ability to auscultate during air medical transport is compromised by high ambient-noise levels. The aim of this study was to assess the capabilities of a traditional and an electronic stethoscope (which is expected to amplify sounds and reduce ambient noise) to assess heart and breath sounds during medical transport in a Boeing C135. METHODS: We tested one model of a traditional stethoscope (3MTM Littmann Cardiology IIITM) and one model of an electronic stethoscope (3MTM Littmann Stethoscope Model 3000). We studied heart and lung auscultation during real medical evacuations aboard a medically configured C135. For each device, the quality of auscultation was described using a visual rating scale (ranging from 0 to 100 mm, 0 corresponding to "I hear nothing," 100 to "I hear perfectly"). Comparisons were accomplished using a t-test for paired values. RESULTS: A total of 36 comparative evaluations were performed. For cardiac auscultation, the value of the visual rating scale was 53 ± 24 and 85 ± 11 mm, respectively, for the traditional and electronic stethoscope (paired t-test: P = .0024). For lung sounds, quality of auscultation was estimated at 27 ± 17 mm for traditional stethoscope and 68 ± 13 for electronic stethoscope (paired t-test: P = .0003). The electronic stethoscope was considered to be better than the standard model for hearing heart and lung sounds. CONCLUSION: Flight practitioners involved in air medical evacuation in the C135 aircraft are better able to practice auscultation with this electronic stethoscope than with a traditional one.

Semmelweis: de médicos: estetoscopios: corbatas y otros atuendos / Semmelweis: about physicians: athetoscopes: neckties and other garments

Por la heroica historia de Ignaz Semmelweis (1818-1865), los médicos hemos sido aconsejados a lavarnos las manos cada vez que examinamos un paciente. Deberíamos hacerlo antes y después, y estar seguros de que él nos viera… Una manifiesta y justificada cruzada a favor de la limpieza de los estetoscopios y contra del uso de batas blancas. Corbatas y otras prendas de vestir, ha venido expresándose en ambientes médicos, primero en forma tímida y ahora con mayor fuerza, al aportarse pruebas convenientes acerca de la inconveniencia de llevarlas. La consigna es la eliminación de las corbatas durante la visita o revistas médicas al considerárselas como diseminadoras de infecciones adquiridas en el hospital. Las corbatas más que un probable reservorío de gérmenes son prendas innecesarias por lo que el médico debe reconocer su eventual riesgo. Las nuevas guías de la Brithish Medical Association incluyen un mayor énfasis en el lavado de las manos y de acuerdo a ella, “es la intervención más importante en el control de las infecciones”. Igualmente, se aboga por un mejor diseño de las salas de hospitalización, mejor provisión de lavamanos o geles antisépticos, políticas más inteligentes en la prescripción de antibióticos y eliminar el uso de ítems tales como corbatas, a veces usadas continuamente y por semanas y solo por raridad enviadas a la lavandería

Since the heroic history of Ignaz Semmelweis (1818´1865), we doctors have been advised to wash our hands every time we examine a patient. We should have to do it before and sfter, and be sure that the patients is seeing us… An overt and warranted crusade in favor of cleaning stethoscopes and against the use of medical gowns, neckties and other clothing items has begun expressing itselfin medical spheres, first in timed form and now with greater force, thanks to convincing test regarding the inconvenience of their use. The main message is the alimination of neckties during examinations or medical rounds, considering that these are vehicles of infection acquired in the hospital. Neckties, more than probable reservoirs of germs, are unnecessary clothing items, reason why doctors must recognize their possible risk. The new guidelines of the Medical Brithish Association include a greater emphasis on the washing of hands and according to it, “(it) is the most important intervention in the control of infections”. Also, it pleads for a better design of hospital rooms, better provision of sink and/or antiseptic gels, more intelligent policies for antibiotic prescriptions and the elimination of the use of items such as neckties, sometimes used continuously and for weeks and only rarely washed