Validation of an effective, low cost, Free/open access 3D-printed stethoscope.

The modern acoustic stethoscope is a useful clinical tool used to detect subtle, pathological changes in cardiac, pulmonary and vascular sounds. Currently, brand-name stethoscopes are expensive despite limited innovations in design or fabrication in recent decades. Consequently, the high cost of high quality, brand name models serves as a barrier to clinicians practicing in various settings, especially in low- and middle-income countries. In this publication, we describe the design and validation of a low-cost open-access (Free/Libre) 3D-printed stethoscope which is comparable to the Littmann Cardiology III for use in low-access clinics.

A low-cost 3-D printed stethoscope connected to a smartphone.

We demonstrate the fabrication of a digital stethoscope using a 3D printer and commercial off-the-shelf electronics. A chestpiece consists of an electret microphone embedded into the drum of a 3D printed chestpiece. An electronic dongle amplifies the signal from the microphone and reduces any external noise. It also adjusts the signal to the voltages accepted by the smartphones headset jack. A graphical user interface programmed in Android displays the signals processed by the dongle. The application also saves the processed signal and sends it to a physician.

Choosing the best stethoscope.

Go beyond the bells and whistles to learn how to select this important assessment tool.

Choosing the best stethoscope.

Go beyond the bells and whistles to learn how to select this important assessment tool.

Accuracy of analog telephonic stethoscopy for pediatric telecardiology.

OBJECTIVE: Wide-bandwidth electronic stethoscopy is reliable and accurate for pediatric telecardiology. We tested a much less expensive and more convenient system for the same purpose, a narrow-bandwidth telephonic stethoscope (TS). METHODS: Seventy-six consecutive patients (mean age: 10.0; standard deviation: 6.5 years) in a pediatric cardiology outpatient clinic were studied. One pediatric cardiologist examined the patients with his acoustic stethoscope (AS); a second examined them within a few minutes using a remote TS. A nurse placed the TS chest piece as directed by the remote examiner via intercom, but neither video examination nor conversation with the parent/patient were permitted. Examiners independently recorded the stethoscope findings for all heart sounds, all murmurs, and heart disease (present/absent). TS accuracy was indexed using the kappa statistic for TS/AS agreement and for TS agreement with auscultatory findings predicted from echocardiographic (echo) studies (N = 49). RESULTS: TS/AS agreement was satisfactory for presence/absence of heart disease (kappa = 0.63) and for organic, functional, vibratory, diastolic aortic, and diastolic pulmonic murmurs (kappa range: 0.65-0.75). For other specific murmurs and all heart sounds, TS/AS agreement was either unsatisfactory (kappa < or = 0.60) or indeterminate because prevalence was 0. TS-AS agreement improved when the TS was used by the more-experienced TS examiner and with patients at least 5 years of age. When the older children were examined by the more TS-experienced examiner, the TS-echo comparison yielded kappa = 0.90, raw agreement = 0.96, sensitivity = 0.94, and specificity = 1.00. CONCLUSIONS: In pediatric patients, a narrow-bandwidth telephonic stethoscope can accurately distinguish between functional and organic murmurs and thus can detect heart disease. Accuracy is greatest when the instrument is used by an experienced examiner with patients at least 5 years of age.

Use of esophageal or precordial stethoscopes by anesthesia providers: are we listening to our patients?

STUDY OBJECTIVE: To ascertain current anesthesia utilization of esophageal and precordial stethoscopes in U.S. anesthesia training programs. DESIGN: Prospective, single-blind, incidence study. SETTING: Operating rooms of three tertiary care hospitals with major academic anesthesiology departments. SUBJECTS: Anesthesia faculty [MD and certified registered nurse-anesthetist (CRNA) staff] and anesthesia trainees (anesthesiology residents and student nurse-anesthetists). INTERVENTIONS: observe and record the placement (stethoscope device appropriately positioned) and utilization (stethoscope in place and connected to the ear piece of the anesthesia provider) of the esophageal or precordial stethoscope during general, regional, and monitored anesthesia care. MEASUREMENTS AND MAIN RESULTS: During 520 anesthetics, an esophageal stethoscope was inserted in 68% of subjects, a precordial stethoscope was positioned in 16%, and an anesthetic stethoscope was absent in 16% of cases. Utilization (stethoscope connected to earpiece) ranged from a low of 11% of cases to a high of 45%, depending on the institution. Overall, providers were listening via an anesthetic stethoscope in only 28% of anesthetics. CONCLUSIONS: Our data suggest infrequent utilization of esophageal and precordial stethoscopes in anesthesia training institutions. Thus, current anesthesia training may be fostering an environment where providers overlook a valuable minimally invasive, and cost-effective continuous monitor of patients' dynamic vital organ function.