20Q: Amplified Stethoscopes for Medical Practitioners

From the Desk of Gus Mueller

The fitting of amplification devices can become routine. The patients usually have a bilateral downward sloping presbycusic-pattern hearing loss. You have your go-to RIC products, from your go-to manufacturer, fitted with your go-to ear tips and domes. You might even have a go-to color. And during the post-fitting counseling, you think . . . how many times have I said this same thing before?       

But then, just when things are becoming so routine that they are almost boring, you get a phone call. It’s the physician you fit with hearing aids a couple years ago. She says she has been reading about amplified stethoscopes, and would like to stop by to hear what you recommend. Oh, oh. You haven’t thought about amplified stethoscopes for several years. What’s your go-to source for this? Well, as of today—it's a 20Q article written by A.U. Bankaitis!

If you have had questions about infection control, cerumen management, PSAPs, or ALDs, you probably have reached out to or been referred to Dr. Bankaitis. And, she just happens to be an expert on amplified stethoscopes, too. A.U. Bankaitis, PhD, is Vice President, Oaktree Products. Early in her career, Dr. Bankaitis’ published research on the effects of HIV on the auditory system, which led to a niche expertise on infection control, which has led to her co-authoring two books regarding infection control in the clinic. She has served on the Academy of Audiology’s Foundation Board, and is a past president of the Missouri Academy of Audiology. Many of you are aware of her very popular blog, www.aubankaitis.com, which contains a wealth of information on a variety of audiology topics.

A.U. has extensive clinical experience as an audiologist, ranging from adult diagnostics, intraoperative monitoring, to hearing aids, cochlear and other implants. These professional experiences allow her to provide straightforward answers to busy practitioners seeking practical, technical or business-oriented information. This is very evident in her 20Q article on amplified stethoscopes.

Gus Mueller, PhD
Contributing Editor

Browse the complete collection of 20Q with Gus Mueller CEU articles at www.audiologyonline.com/20Q

20Q: Amplified Stethoscopes for Medical Practitioners

Learning Outcomes 

After this course, readers will be able to:

• Discuss challenges that medical practitioners with hearing loss may have when performing auscultation.
• Describe solutions an audiologist may recommend for medical practitioners with hearing loss who do not use hearing aids who have challenges performing auscultation.
• Describe solutions an audiologist may recommend for medical practitioners with hearing loss who use hearing aids and have challenges performing auscultation.
• List resources that audiologists can access for more information on amplified stethoscopes and related accessories. 

      A.U. Bankaitis Smith   

1. I’m just starting to learn about amplified stethoscopes. Are these products complicated?

Not at all. Apart from a battery requirement, most amplified stethoscopes on the market operate in the same manner as traditional stethoscopes, allowing medical practitioners with hearing loss to perform auscultation during routine examinations. There are a few exceptions as newer technology has been introduced but they are not complicated. Having said that, finding a satisfactory solution for hearing instrument users poses inherent challenges that often complicates things, creating frustration for both the practitioner and the audiologist.      

2. Auscultation?

Auscultation is the medical term for using a stethoscope to listen to internal sounds of the body (Bankaitis, 2010). It allows physicians, nurses, EMTs and other practitioners to listen for and analyze heart and lung sounds for differential diagnosis, representing an essential component in the delivery of health care services.

3. If a practitioner has a hearing loss but doesn’t wear hearing aids, is an amplified stethoscope the solution?

Yes. Practitioners having trouble hearing necessary body sounds can quickly achieve success by switching to an amplified stethoscope. There are quite a few amplified stethoscopes available, with the E-Scope II (Cardionics), Thinklabs One or TL-One (Thinklabs), and Littmann Model 320 (3M) most popular and the newer Core (Eko) gaining some interesting ground. Each is designed to compensate for hearing loss by amplifying body sound, although it is difficult to make comparisons among devices. There are no specification standards with amplified stethoscopes and much of the product capability information has been reduced to marketing claims of providing “up to 24, 30, 40 or 100x amplification”, whatever that’s supposed to mean. Nevertheless, these devices do offer practitioners with hearing loss, who are not regular hearing aid wearers, a straightforward solution, if their hearing loss isn’t “too severe”.  

4. What about the practitioners who wear hearing aids while seeing patients? 

The solution isn’t simple. Stethoscope earpieces were designed with the unoccluded ear canal in mind and end up competing for real estate occupied by the hearing aid. As a result, this scenario calls for reconfiguration that is not only influenced by the hearing aid style, but the amplified stethoscope of choice. Not every commercially available amplified stethoscope will be an option for hearing aid wearers. There are, however, more pressing obstacles that often preclude the successful use of an amplified stethoscope in these cases.

5. What types of obstacles?

Heart and lung sounds are very soft, low frequency sounds. For the medical practitioner with hearing loss, audiologists will need to create a separate hearing aid program with low frequency emphasis and necessary compression ratios that may be counterintuitive based on the face value of the audiogram.     

6. Low-frequency emphasis? What exactly are we talking about?

A few years back, I worked with a couple of colleagues from Washington University School of Medicine to spectrally analyze standard auscultation recordings provided by a manufacturer of a commercially available amplified stethoscope. Most of spectral energy for a normal breath cycle fell below 2000 Hz, the normal heart beat fell below 200 Hz. According to the literature, the most important auscultation sounds for differential diagnosis fall well below 1000 Hz, where critical lung sounds fall in the 200 – 600 Hz range versus critical heart sounds that fall in the 70 to 120 Hz range (Rennert, Morris, & Barrere, 2004; Atcherson, 2010).

7. I am beginning to appreciate the need for a separate auscultation hearing aid program. Is that the end game?

Unfortunately, no.  Even in the presence of a low-frequency emphasis “auscultation” program, the low frequency tolerances of hearing aids remain a fundamental hardware/software problem.  It’s uncertain what a hearing aid can truly amplify below about 200 Hz.  For the seasoned practitioner with auscultation experience prior to their hearing loss, it ends up being a counseling issue and working with the patient to re-learn what they need to listen for via practice and patience (Bankaitis & Ison, 2015).  For students with hearing loss in the process of learning auscultation techniques, it may require a teacher to simultaneously listen and teach the student what to listen for and/or to rely on visual cues in the form of available apps offered by some amplified stethoscope manufacturers to facilitate the learning process. 

8. It seems like it would just be easier to tell the practitioner to take their hearing out when performing auscultation, and then use the amplified stethoscope?

Yes, that would be easier and represents an option but usually one of last resort. In these situations, the practitioner is highly motivated to find a solution to a critical job-related listening need and typically persistent in exhausting every viable option before conceding to taking their hearing aids out.   

9. Is there a universal amplified stethoscope solution for hearing aids wearers?

The closest thing to a universal solution would involve using an amplified stethoscope with headphones. This is an option with the previously mentioned E-Scope II, TL-One, and Core amplified stethoscopes, but it is not a configuration supported by the Littmann devices. Regardless of hearing aid style, headphones offer the greatest potential of success in allowing the hearing aids to remain in the ears during auscultation. Unfortunately, this option is typically unappealing to most medical practitioners who are used to using a traditional stethoscope or motivated to use something that resembles one; they will often reject headphones for aesthetic reasons.

10. If headphones are a no go, what other options are there for these hearing aid wearers?

It depends on the hearing aid style and available features.  For BTE wearers, one option is to connect the hearing aids to the amplified stethoscope via direct audio input (DAI). This will require an audio shoe or boot from the hearing aid manufacturer along with an accessory cable from the amplified stethoscope manufacturer.  If the BTE’s are equipped with telecoils, you could try to use an induction earhook to route signals to the BTE although this introduced new variables for consideration.  For a telecoil to provide maximum benefit, however, audiologists need to pay attention to the sound pressure level for an inductive telephone simulator (SPLITS) (Valente, 2013). Unfortunately, very few audiologists verify the hearing aid’s microphone frequency response to matched prescriptive targets and its pretty safe to assume that most leave the telecoil to manufacturer’s default. This may partially explain why outcomes tend to be poor with DAI, subsequently leading amplified stethoscope manufacturers to communicate that it isn’t a viable option. Aside from this, seems like many of the earhooks are being discontinued, as we are having a harder time sourcing them.  Finally, for RICs, if enough ear canal real estate is available, some hearing aid users may be able to use an amplified stethoscope with traditional earpieces without needing to take the ear coupling out of the ear canal, although that doesn’t happen that often.

11. What options will work with custom hearing aids?

The most straightforward solution is to use an amplified stethoscope with a pair of headphones. Beyond that, you could try stethomate tips in the off chance they end up working out. These are rubber adapters resembling a listening bell designed to replace the original eartips of an amplified stethoscope for CIC or ITC wearers. When the stethoscope earpieces are inserted into the ears, the stethomate tips will cup the hearing instrument, including the microphone port, making contact mainly with the outer portions of the faceplate. Theoretically, this allows auscultation sounds to be directed to the hearing aid microphone.

12. Do these stethomate tips work?

Not really. The cupped portion of the stethomate must reside over the hearing aid microphone. If the microphone port is located too close to the outer edge of the hearing instrument’s faceplate, the stethomate tip ends up covering the microphone port, precluding the hearing instrument from picking up sounds from the amplified stethoscope. Even with proper alignment, the bigger problem is most individuals can’t tolerate the pressure transferred to the hearing aid by stethomate tips from the spring-loaded ear pieces of the amplified stethoscope. At best, chances of success are no more than 20%.   

13. Is it possible to have a special earmold made for CIC and ITC wearers?  

Literature does make mention of this option (Applebaum, 2003; Morris, 2003) although it seems like every earmold lab I have reached out to in the past year is unwilling to customize a special earmold for this configuration due to low satisfaction rates. They typically recommend the use of headphones instead.

14. What if my patient uses a streamer?

Except for open-fit BTE’s, the most straightforward option is the TL-One because it will connect to most streamers via a cord that already comes packaged with the stethoscope.  If the streamer has a 2.5mm input jack, a separate adapter will need to be purchased. The E-Scope is an option too although it requires both a patch cord accessory cable from E-Scope as well as an audio accessory cable that may or may not come packaged with the streamer. This configuration is not recommended in cases of open-fit BTEs because the low frequency heart and lung sounds will leak out of the unoccluded ear, making it impossible to hear what needs to be heard during auscultation.

15. Do the same options apply with Bluetooth hearing aids where the smartphone serves as the streamer?

Great question, because the answer is no. Neither the TL-One or E-Scope II are Bluetooth enabled devices, therefore, they cannot stream to an iOS or Android smartphone. The TL-One can connect to an external Bluetooth transmitter and wirelessly stream to Bluetooth devices, including headphones, but this configuration does not translate to Bluetooth hearing aids because the hearing aids are tied to a specific iOS or Android platform. For the TL-One, this configuration would require recording auscultation with a recording app like Garage Band (iOS) or Tape Machine (Android) and then streaming the play back via the smartphone to the hearing aids. It’s a cumbersome set up, although there have been some limited anecdotal reports of success.

16. Are there any Bluetooth stethoscopes currently available that can pair directly with a hearing aid?

Not currently. However, there are Bluetooth stethoscopes capable of streaming auscultation recordings directly to Bluetooth hearing aids - the operative word here being “recordings”.  The Core is an amplified stethoscope that can pair to an iPhone, iPad, or Android device. You can record, visualize, and save all data with their app and then listen to recorded heart and lung sounds with Bluetooth hearing aids by playing back the recorded audio via the Eko App.

17. Is there any way to listen to auscultation with hearing aids in real time while using a Bluetooth stethoscope?

Yes, but it requires headphones. The Core is capable of streaming live audio to a smartphone from the chest piece of the stethoscope to a pair of Bluetooth headphones. Plug either a standard or Bluetooth headset into the smartphone and place the headphones over the hearing aids during auscultation to hear heart and lung sounds in real time. A similar device by a European company called the eKuore is also available we are in the process of having some of our audiology colleague evaluate it.

Since we are on the subject, the 3M Littmann Amplified Electronic Stethoscope is equipped with Bluetooth capabilities but limited to wireless transmission of recorded data to a Bluetooth enabled PC or another user’s Littman stethoscope.  A lot of time, patients see Bluetooth and assume it will pair with their hearing aids.

18. What do you foresee in the future for amplified stethoscopes?

As an audiologist, my hope is that one day the hearing industry will figure out a way to stream auscultation directly to hearing instruments without the need for headphones because most practitioners reject this configuration. It will be interesting to see if hearing aids utilizing Bluetooth Classic (as opposed to low energy Bluetooth) offer any headway in terms of more aesthetically appealing interfaces than headphones.

Having said that, my gut tells me that even if a solution like this becomes available, it may be a moot point because the traditional stethoscope seems to be at a crossroads. The recent commercial availability of the Core and similar products may be indicators that auscultation is moving toward digitally recording body sounds with smartphones. The recording capabilities are quite remarkable, faithfully reproducing heart, lung, and other sounds with a mobile app thousands of miles away (Berstein, 2018; Kang et al, 2018).  In addition, these devices allow practitioners to send recordings directly to a patient’s electronic medical record securely and in accordance with HIPAA compliance policies. Given all the disruption going on in healthcare and the growing need for telemedicine, this seems entirely plausible in my mind. 

19. Any final advice to audiologists when it comes to amplified stethoscopes?

There is no “one size fits all” solution when it comes to amplified stethoscopes and hearing aid. The two options associated with the most success are either undesirable (i.e. remove hearing instruments during auscultation) or often rejected (i.e. use of headphones). Access to the full scope of potential options at the time of the initial consultation is key in establishing expectations while consolidating the pursuit of a viable solution to one appointment time. This involves investing in one or two amplified stethoscope demos and any necessary accessories (e.g. headphone, stethomate tip, patch cords) to have on hand in the clinic. The investment in demos is not a bad idea because it streamlines the decision-making process, saving you and your patient a lot of time.

20. Where can I find more information?

• Oaktree Products offers a very practical resource page dedicated to amplified stethoscopes that I created several years ago based on the number on inquiries we get on this topic. Covered content included background information on auscultation, a breakdown of stethoscope options as a function of hearing aid style, hearing aid programming and patient considerations. If you go company home page, just click the amplified stethoscope box located immediately below the main banner or use the direct link www.oaktreeproducts.com/amp-steth-solutions.
• The Association of Medical Professionals with Hearing Loss (AMPHL) has a dedicated Stethoscope Section on their website (www.amphl.org) with comparison tables, a few articles, and a FAQ section that is very helpful.
• Thinklabs One, maker of the TL-One amplified, has a hearing aid section in the FAQ portion of their website too.
• Periodic updates appear in the amplified stethoscope section of my blog at www.aubankaitis.com. 

References

Applebaum, S. (2003). Stethoscope use without behind-the-ear hearing aid removal. Journal of the Association of Medical Professionals with Hearing Losses,1(3). Retrieved from www. amphl.org

Atcherson, S.R. (2010). Technical considerations in using stethoscopes with hearing aids and cochlear implants. Association of Medical Professions with Hearing Losses. Retrieved from www. amphl.org

Bankaitis, A.U. (2010). Amplified stethoscope options for professionals with hearing loss. AudiologyOnline, Article 860. Retrieved from www.audiologyonline.com

Bankaitis, A.U., & Ison, P. (2015). Medical professional with hearing loss seeking amplified stethoscope. In M. Valente & L. Valente (Eds.). Adult audiology casebook. New York: Thieme Medical Publishers.

Bernstein, L. (2016). Heart doctors are listening for clues to the future of their stethoscopes. Washington Post Online. Available at www.washingtonpost.com

Kang, S., Joe, B., Yoon, Y., Cho, G., Shin, I., & Suh, J. (2018). Cardiac Auscultation Using Smartphones: Pilot Study. Journal of Medical Internet Research Mhealth Uhealth; 6(2),e39.

Morris, R. (2003, August 4). Cope with scopes: stethoscopes and hearing aids – what are the options? AudiologyOnline, Article 439. Retrieved from www.audiologyonline.com.

Rennert, N., Morris, F., & Barrere, C. (2004, February). How to cope with scopes: stethoscope selection and use with hearing aids and CIs. Hearing Review, 34-38.

Valente, M. (2013). The telecoil: the lonely transducer that could be a bigger producer. AudiologyOnline, Article 11911. Retrieved from www.audiologyonline.com