Telehealth: Can You Hear My Heart Now?

Telehealth - Laennec Stethoscope from 1820

The stethoscope was invented 201 years ago in 1816 by René Laennec in Paris, or possibly thousands of years earlier by the ancient Egyptians! We all know from any visit to a nurse or doctor that the simple “analog” stethoscope remains today a key tool for healthcare professionals who can quickly interpret anomalies from listening to heart, lung, abdominal and other body sounds. So, what happens in Telehealth systems when the doctor is remote and is connected digitally over the Internet by video and audio to the patient?

Listening to Heartbeats … Remotely

Telehealth - Thinklabs One Digital StethoscopeThe availability of remote diagnostic devices has been pushing remote healthcare to new levels. Remote temperature readings, blood pressure readings, heart monitors and many other measuring devices are now commonly integrated into remote telehealth apps. These devices all generate discrete digital results that can be easily captured by an app and then presented through tables and charts to a remote healthcare professional. The numbers tell the story.

However, a stethoscope is different – it relies on the skills of a trained nurse or doctor listening to sounds over an interval of time and then interpreting what they are hearing based on their understanding of the patient and their other conditions. The stethoscope is moved around to listen to different areas of the body based on what they have heard so far. There is no “number” to be captured and shared – using a stethoscope is a real-time skilled experience. There are several challenges to making this a robust remote Telehealth experience:

  • Stethoscope sounds are typically low-frequency which are negatively impacted by normal audio tuning for conversational speech streams over the Internet.
  • The sound of the stethoscope can be easily obscured by patient and surrounding noise – it is more difficult to keep a patient quiet remotely! This may be especially difficult in emergency and non-medical remote environments.
  • For most uses a local assistant, with some training, will be required to ensure the device is used correctly, which requires simultaneous communication between the remote nurse or doctor and the local assistant.

OpenTok Telehealth Digital Stethoscope DemoThe OpenTok platform meets these challenges in using remote digital stethoscopes as follows:

  1. OpenTok allows applications to publish multiple separate streams that can then be separately managed by subscribing applications. On the patient side we publish a separate audio stream just for the stethoscope audio, where the stethoscope is independently connected to the audio port or a USB port of the patient device.
  2. The Thinklabs One digital stethoscope we tested (see here) comes with a simple switching connector allowing a local headset to be used by the local assistant so they also hear the stethoscope to better position the device. This functionality could also be incorporated into the application, making the stethoscope audio available locally.
  3. The digital device also provides easy adjustment to different frequency ranges, for different heart, lung and abdominal uses, which would be changed by the assistant based on nurse or doctor requests.
  4. The new OpenTok Audio Tuning API is then used to tune the stethoscope channel differently from the regular speech channel – see the API details below. Because the stethoscope audio is separated from the conversational audio we can easily maintain separate audio tuning for each channel.
  5. On the nurse/doctor end of the connection, the Telehealth application can now allow the stethoscope and the regular audio channel to be separately turned on and off, so that the stethoscope can be listened to without the background patient noise or conversation, or vice versa, or both can be heard together where appropriate. The video stream from the patient remains visible so the placement of the digital stethoscope can be seen along with the rest of the patient situation.
  6. The audio channel back to the patient side remains active, or can be easily toggled within an application, so that the nurse/doctor can request different stethoscope placement and settings during their examination.

By integrating these OpenTok capabilities, Telehealth application vendors can provide simple user experiences for nurses, doctors and their remote assistants that incorporate remote stethoscope use into their diagnostic sessions.

The OpenTok Audio Tuning API

The audio carried on an OpenTok session is typically conversational voice where a range of voice optimizations normally take place on the client. These include Acoustic Echo Cancellation (AEC), Automatic Gain Control (AGC), noise suppression and potentially some frequency compression. In a typical person to person video chat these optimizations improve the overall quality of experience for users. However if a developer wants to transmit music or the unusual bass-heavy audio from a digital stethoscope, then these standard optimizations will distort the audio.

To address the need to carry “enhanced” audio, TokBox has introduced our Audio Tuning API. This allows developers to disable standard audio processing options and increase the audio bitrate from a default of 40 kbps to a maximum of 510 kbps. These settings are applied when the client audio stream is created (see the expanded options for the initPublisher() method in the documentation, and sample code is available on request).

As discussed for the stethoscope example, OpenTok clients can create multiple audio streams, so that one stream can carry regular conversational voice audio and a second stream can carry the “enhanced” specially tuned audio. On the receiving end the client application can toggle between audio streams or mix them together as required. The digital stethoscope example shows the importance of being able to handle these different channels separately.

TokBox at ATA 2017

At the American Telemedicine Association (ATA) 2017 conference last week in Orlando Florida, TokBox was pleased to demonstrate the use of a Thinklabs One digital stethoscope (details) on the patient side connected to a remote medical professional over the Internet, where the nurse or doctor could hear the precise sounds from the stethoscope while directing a local assistant to listen to different parts of the body in different ways. We used good-quality wireless headphones in our demo to make the audio easy to hear in a noisy show environment.

The response to our demo at ATA 2017 was very positive and we are keen to help our Telehealth application partners who provide remote diagnosis capabilities to quickly incorporate this feature. We will also be working with other digital stethoscope manufacturers to test their use with OpenTok.

Conclusions for Telehealth

The simple use of a stethoscope remains a fundamental diagnostic tool for nurses and doctors, despite the huge technology advances in the many complex diagnostic devices found in a modern medical setting. TokBox is pleased to show how remote digital stethoscopes can be properly supported over the Internet within our OpenTok live video and audio platform.

To read more about the use of TokBox in Telehealth, please see our white paper A Guide To Interactive Live Video In Healthcare & The Telehealth Revolution.