Conventional Stethoscope Research Articles

Auscultation in high-noise environments using hybrid electromechanical and ultrasound-Doppler techniques

Medical evacuation of battlefield casualties or traffic accident victims by air typically takes place in very noisy environments. Auscultation of patients, e.g., to support chest intubation or to detect a pneumothorax, is therefore difficult or impossible to perform. A conventional acoustic stethoscope will not function very well in background noise levels beyond 80 dB. Electronic stethoscopes, in combination with mechanical impedance-matched transducer designs, can extend this range to about 90 dB, but this is not enough for helicopter noise levels that can reach 110 dB. The use of an ultrasound transmitter and receiver, however, provides an essentially noise-free auscultation channel since transportation vehicles do not produce acoustic energy at ultrasound carrier frequencies of 2–3 MHz. Clean and noise-free heart and breath sounds have been obtained in broadband noise fields of intensities as high as 120 dB. A hybrid stethoscope has been developed that allows auscultation by ultrasound-Doppler as well as electromechanical means. Pros and cons of making Doppler sounds subjectively similar to conventional sounds by nonlinear signal processing will be discussed, as well as potentially functional and meaningful aspects of Doppler signals that are not found in conventional stethoscope sounds.

A fuzzy expert system design for analysis of body sounds and design of an unique electronic stethoscope (development of HILSA kit)

In this paper we have developed a fuzzy expert system (FES) for different sounds produced by different organs in the human body. We have also constructed a unique electronic stethoscope. The human body sounds produced by different organs like heart, lungs and intestine were analyzed. The doctor provided the data and relation between variables chosen for each organ sound. Using this information a rule base for fuzzy expert system was built. Such FES helps the medical doctor in arriving at appropriate decision in different difficult clinical situations. The examination of body sounds was done using conventional stethoscope (CS) and electronic stethoscope (ES), which was uniquely designed for this study. We have found that unique stethoscope developed by us is far superior to conventional stethoscope by its overall performance.

A randomized trial comparing electronic and conventional stethoscopes

A randomized trial comparing electronic and conventional stethoscopes

Cardiac auscultation training of medical students: a comparison of electronic sensor-based and acoustic stethoscopes

BackgroundTo determine whether the use of an electronic, sensor based stethoscope affects the cardiac auscultation skills of undergraduate medical students.MethodsForty eight third year medical students were randomized to use either an electronic stethoscope, or a conventional acoustic stethoscope during clinical auscultation training. After a training period of four months, cardiac auscultation skills were evaluated using four patients with different cardiac murmurs. Two experienced cardiologists determined correct answers. The students completed a questionnaire for each patient. The thirteen questions were weighted according to their relative importance, and a correct answer was credited from one to six points.ResultsNo difference in mean score was found between the two groups (p = 0.65). Grading and characterisation of murmurs and, if present, report of non existing murmurs were also rated. None of these yielded any significant differences between the groups.ConclusionWhether an electronic or a conventional stethoscope was used during training and testing did not affect the students' performance on a cardiac auscultation test.

Preadmission anesthesia consultation using telemedicine technology: a pilot study.

TELEMEDICINE has been defined as the delivery of healthcare and sharing of medical knowledge over a distance using telecommunications systems. 1 It uses modern high-speed telecommunication systems that allow interactive video-mediated clinical consultations. Telemedicine enables the delivery of healthcare irrespective of geographic location or ability to travel to tertiary healthcare centers. 2 In Canada, a significant population lives in remote regions away from tertiary care centers. At Toronto Western Hospital, 15% of patients are referred from remote regions. Telemedicine can potentially reduce travel costs and improve accessibility to health care. Although telemedicine has been used by other medical and surgical specialties, there have been no reports in the literature evaluating telemedicine technology for anesthesia consultations. 3-5 We report the technical aspects and implementation of telemedicine anesthesia consultation, the first 10 patients interviewed, and their satisfaction regarding telemedicine consultations.

Validation of heart and lung teleauscultation on an Internet-Based system

The feasibility and accuracy of an Internet-based system for teleauscultation was evaluated in 103 cardiac patients, who were auscultated by the same cardiologist with a conventional stethoscope and with an Internet-based method, using an electronic stethoscope and transmitting heart and lung sounds between computer work stations. In 92% of patients, the results of electronic and acoustic auscultation coincided, indicating that teleauscultation may be considered a reliable method for assessing cardiac patients and could, therefore, be adopted in the context of comprehensive telecare programs.

Disposable stethoscope diaphragm and dispenser

A disposable diaphragm assembly for use with al types of conventional stethoscopes and a universal retainer ring for retro-fitting conventional stethoscopes to accept the disposable diaphragm assembly. A novel stethoscope for use with the disposable diaphragm assemblies. A stationary dispenser for the disposable diaphragm assemblies from which the assemblies may be loaded onto either retrofitted conventional stethoscopes or the novel stethoscope of this invention without the assembly being contaminated by the hands of medical personnel. Portable and disposable dispensers which also provide for the loading of the disposable diaphragm assembly in a manner which prevents the assembly from becoming contaminated by the hands of medical personnel.

Sensor system for heart sound biomonitor

Heart sounds can be utilised more efficiently by medical doctors when they are displayed visually, rather than through a conventional stethoscope. A system whereby a digital stethoscope interfaces directly to a PC will be described along with signal processing algorithms adopted. The sensor is based on a noise cancellation microphone, with a 450Hz bandwidth and is sampled at 2250 samples per second with 12-bit resolution. Further to this, we discuss for comparison a piezo-based sensor with a 1kHz bandwidth. A major problem is that the recording of the heart sound into these devices is subject to unwanted background noise, which can override the heart sound and results in a poor visual representation. This noise originates from various sources such as skin contact with the stethoscope diaphragm, lung sounds (patient breathing), and other surrounding sounds such as speech. Furthermore we demonstrate a solution using ‘wavelet denoising.’ The wavelet transform is used because of the similarity between the shape of wavelets and the time-domain shape of a heartbeat sound. Thus coding of the waveform into the wavelet domain is achieved with relatively few wavelet coefficients, in contrast to the many Fourier components that would result from conventional decomposition. We show that the background noise can be dramatically reduced by a thresholding operation in the wavelet domain. The principle is that the background noise codes into many small broadband wavelet coefficients that can be removed without significant degradation of the signal of interest. Also explored is the use of a phase space representation of the heart sound to exploit different properties of the signal.

An active noise control stethoscope

A prototype of an active noise control stethoscope has been developed. The device enables medical personnel to clearly hear sound from a stethoscope device while working in a noisy environment. Using a conventional stethoscope to detect lung noises and blood pressure is difficult in many emergency medical environments, such as helicopters. An electronic stethoscope device is to be designed that will make use of digital signal processing technology to remove unwanted noise. Acoustical noise and vibrations that are detected by the stethoscope are digitally subtracted out of the stethoscope signal. The stethoscope signal is then amplified and broadcast into the earcup of an an antinoise headset. Unwanted noise penetrating the shell of the earcup is eliminated by broadcasting counteracting ‘‘antinoise’’ in addition to the amplified stethoscope signal.

Devices for the diagnosis and treatment of temporomandibular disorders. Part II: Electromyography and sonography

This second article in the three-part series on temporomandibular disorder (TMD) devices compares the claimed diagnostic usefulness of electromyography and sonography with the present scientific evidence. This review concludes that there is no evidence to support the use of either surface electromyography or silent period duration for the evaluation or diagnosis of TMD. Furthermore, in view of the available evidence, sonography and Doppler ultrasound have no particular advantage over a conventional stethoscope or direct auscultation.

An inexpensive transducer for remote determination of arterial blood pressure.

ABSTRACTA low‐cost transducer for monitoring arterial blood pressure by remote auscultation is described. It employs a miniature earphone attached to the diaphragm of a conventional stethoscope. The Korotkov sounds picked up by the diaphragm are converted to electrical signals by the earphone. These are amplified and monitored over a loudspeaker or headphones.

A quantitative stethoscope and its clinical applications

A simple stethoscope is described. It allows the measurement of the intensity of cardiac sounds and murmurs in decibels above the normal hearing threshold. The size of the instrument does not exceed that of the conventional stethoscope. The acoustic characteristics of the stethoscope and methods of minimizing sources of error during measurement are described. The practical value of the stethoscope lies in the possibility of quantitative measurement of the loudness of the heart murmurs and sounds (especially that of the systolic murmurs and of the first heart sound), which in turn may give aid in the differentiation between functional and organic murmurs and in the early recognition of valvular heart disease. To facilitate this differentiation, further correlations to the conductivity for sound of the thorax, the heart rate, and blood velocity as well as the P-R interval of the electrocardiogram are proposed.