Study Design, Setting, and Participants
This study was an open-label randomized controlled trial to assess the utility of real-time remote auscultation using an electronic stethoscope and an Internet-connected online medical care program. We conducted a pilot study because the protocol for real-time remote auscultation using an Internet connection has not yet been established. We used a lung simulator for lung auscultation and a cardiology patient simulator for cardiac auscultation to ensure standardized assessment . Simulators also represent a convenient, reliable, and objective method for auscultation skill assessment . The simulators used in this study were located in the skills laboratory at Dokkyo Medical University, while real-time remote auscultation was conducted at the Doctor’s Office of General Medicine of Dokkyo Medical University. In the control group, the participants performed direct auscultation with a classic stethoscope in the skills laboratory at Dokkyo Medical University. The straight-line distance between the skills lab and the doctor's office is approximately 220 m.
We recruited senior residents and faculty members from the Department of Diagnostic and Generalist Medicine. The exclusion criteria were refusal to participate in this study or the presence of hearing loss. The study was performed in accordance with the standards of the Declaration of Helsinki. The Institutional Ethics Committee of Dokkyo Medical University, Tochigi, Japan approved the study protocols (No. R-42-16J). This study was registered in UMIN-CTR (UMIN000043153; https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000049259). The date of first registration was 28/01/2021. Written informed consent was obtained from all participants after a detailed explanation of the study before participation.
Study Flow and Randomization
The group allocation was conducted by using a computer-generated allocation table. Before all sessions, participants were randomly assigned to either the real-time remote auscultation group (intervention group) or the classical auscultation group (control group). After assignment to each group, the participants performed a training session, followed by a test session.
In the intervention group, participants performed real-time remote auscultation using an electronic stethoscope and an Internet-connected online medical care program. In the control group, participants auscultated all sounds directly using a classical stethoscope (3M Littmann Cardiology III), placing it on the lung simulator and the cardiac patient simulator by themselves. The participant listened to five different lung sounds and five different cardiac sounds in a previously determined order, with the correct classification provided for each sound. In the training session for lung auscultation, the following five sounds were played: normal lung sounds, wheezes, rhonchi, stridor, coarse crackles, and fine crackles. In the training session for cardiac auscultation, the following five sounds were played: normal cardiac sounds, third cardiac sound (S3 gallop enhanced), aortic stenosis, aortic regurgitation, and mitral regurgitation. Each participant was instructed to auscultate the simulators at standardized positions: two times each on the anterior and posterior sides of the lung simulator, and four times on the cardiology patient simulator (Figure 1). Each sound was played for a maximum of one minute.
In the test session, the researchers changed the settings of the cardiology patient simulator to ensure that the monitoring screen of the cardiology patient simulator displayed only a heartbeat icon. In this session, all participants auscultated the five different lung sounds and five different heart sounds from the training session in a random order and filled in the types of sounds they recognized in a formatted questionnaire (Supplemental Figure).
For lung auscultation, the same lung simulator (MW28; Kyoto Kagaku Co., Ltd.) was used in all sessions. This simulator has been designed for medical education training using 34 samples of lung sounds, which were classified as continuous (wheezes or rhonchi) or discontinuous (fine or coarse crackles), according to the classification of the American Thoracic Society. In the lung simulator, the light-emitting diode (LED) panel on the simulator side indicates the inspiration or expiration phase.
For cardiac auscultation, the same cardiology patient simulator (MW41; Kyoto Kagaku Co., Ltd.) was used in all sessions. This simulator has been designed for medical education training and includes 88 cardiac sounds recorded from actual patients and reproduced using a high-quality sound system. Cardiology patient simulators can present data for vital signs (heartbeat, blood pressure, respiratory rate, and body temperature), electrocardiogram (ECG), carotid artery pulse, jugular vein pulse, and apex cardiogram. In the test session for the control group, the cardiology patient simulator's monitoring screen was modified to display only a heartbeat icon. In the intervention group, the participants were not allowed to see the monitor.
Real-time remote auscultation
Participants auscultated all sounds remotely using an electronic stethoscope (JPES-01; MEMS CORE Co., Ltd.), a wireless module for the electronic stethoscope option (BioCMOS Co., Ltd.), a noise-canceling stereo headset (WH-1000XM3; Sony Corp.), and an online medical care program (Smart Cure, Smart Gate Inc.) (Figure 2). Researchers placed the electronic stethoscope on the simulator, and participants could monitor the placement of the electronic stethoscope in real time through the online medical care program (Figure 3).
The electronic stethoscope is equipped with an ultra-sensitive piezoelectric sensor film and an electrical amplifier, and the signals are converted into sound waves. It is also equipped with a volume regulator and a frequency filter to enable high-quality hearing. The filter has the following modes: a bell mode (20–100 Hz), diaphragm mode (200–2,000 Hz), and a wide mode (20–2,000 Hz). In the lung and cardiac parts, we used the diaphragm mode (200–2,000 Hz) and bell mode (20–100 Hz), respectively. The transmitter transferred the lung and cardiac sounds to the wireless module for the electronic stethoscope option (BioCMOS Co., Ltd) and the online medical care program via an internet connection.
The online medical care program supports full high-definition videos and 4 K still images, incorporating an online conferencing system (Cisco Webex Meetings, Cisco Systems G.K.). The online medical care program can easily share medical record information, such as medical interview sheets, sounds, and images with doctors. Therefore, in real-time auscultation, multiple doctors can simultaneously hear, record, and share data.
Data collection and Outcome Measures
We collected data on age, sex, and years since obtaining a degree in medicine from all participants as baseline demographic data. All participants’ answers for each sound in the test session were collected. The primary outcome measure was the test score of each group. The secondary outcome measures were the rates of correct answers for each sound.
Results were analyzed with R 4.0.5 for Windows (The R Foundation for Statistical Computing, Vienna, Austria). A post-hoc power analysis was performed using the program G*power 22.214.171.124 (12). Statistical significance was set at P<.05. The correct answers in each group were compared using Fisher’s exact test for primary and secondary outcome measures. Mann–Whitney U test was used to compare the continuous variables for baseline participant characteristics, which were presented as medians (IQRs). In contrast, Fisher’s exact test was used to compare the categorical and binary variables for baseline participant characteristics, which were presented as numbers (percentages).