scholarly journals Heart and Lung Sound Measurement Using an Esophageal Stethoscope with Adaptive Noise Cancellation

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6757
Author(s):  
Nourelhuda Mohamed ◽  
Hyun-Seok Kim ◽  
Kyu-Min Kang ◽  
Manal Mohamed ◽  
Sung-Hoon Kim ◽  
...  
Keyword(s):  
Operating Room ◽  
Coming Out ◽  
Background Noise ◽  
Lung Sounds ◽  
Adaptive Noise Cancellation ◽  
Lung Sound ◽  
Cardiorespiratory System ◽  
Software Application ◽  
3D Printed ◽  
Adaptive Noise

In surgeries where general anesthesia is required, the auscultation of heart and lung sounds is essential to provide information on the patient’s cardiorespiratory system. Heart and lung sounds can be recorded using an esophageal stethoscope; however, there is huge background noise when this device is used in an operating room. In this study, a digital esophageal stethoscope system was designed. A 3D-printed case filled with Polydimethylsiloxane material was designed to hold two electret-type microphones. One of the microphones was placed inside the printed case to collect the heart and lung sound signals coming out from the patient through the esophageal catheter, the other was mounted on the surface of the case to collect the operating room sounds. A developed adaptive noise canceling algorithm was implemented to remove the operating room noise corrupted with the main heart and lung sound signals and the output signal was displayed on software application developed especially for this study. Using the designed case, the noise level of the signal was reduced to some extent, and by adding the adaptive filter, further noise reduction was achieved. The designed system is lightweight and can provide noise-free heart and lung sound signals.

scholarly journals Crackle Pitch Rises Progressively during Inspiration in Pneumonia, CHF, and IPF Patients

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Andrey Vyshedskiy ◽  
Raymond Murphy
Keyword(s):  
Heart Failure ◽  
Lung Volume ◽  
Interstitial Fibrosis ◽  
Lung Sounds ◽  
Lung Sound ◽  
Lung Volumes ◽  
Alternate Explanation ◽  
40 Hz

Objective. It is generally accepted that crackles are due to sudden opening of airways and that larger airways produce crackles of lower pitch than smaller airways do. As larger airways are likely to open earlier in inspiration than smaller airways and the reverse is likely to be true in expiration, we studied crackle pitch as a function of crackle timing in inspiration and expiration. Our goal was to see if the measurement of crackle pitch was consistent with this theory.Methods. Patients with a significant number of crackles were examined using a multichannel lung sound analyzer. These patients included 34 with pneumonia, 38 with heart failure, and 28 with interstitial fibrosis.Results. Crackle pitch progressively increased during inspirations in 79% of all patients. In these patients crackle pitch increased by approximately 40 Hz from the early to midinspiration and by another 40 Hz from mid to late-inspiration. In 10% of patients, crackle pitch did not change and in 11% of patients crackle pitch decreased. During expiration crackle pitch progressively decreased in 72% of patients and did not change in 28% of patients.Conclusion. In the majority of patients, we observed progressive crackle pitch increase during inspiration and decrease during expiration. Increased crackle pitch at larger lung volumes is likely a result of recruitment of smaller diameter airways. An alternate explanation is that crackle pitch may be influenced by airway tension that increases at greater lung volume. In any case improved understanding of the mechanism of production of these common lung sounds may help improve our understanding of pathophysiology of these disorders.

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