What is AUSCULTO?

AUSCULTO produces a patent-pending medical device for monitoring arteriovenous fistulas (AVF) in patients beginning in hemodialysis treatment. The medical patch monitors the sound produced by blood flow in the AVF and automatically notify the patient and healthcare personnel at the hospital in case of dysfunction of the AVF.

AUSCULTO is developing a patent-pending medical device for remote monitoring of arteriovenous fistulas (AVF) in patients beginning in hemodialysis treatment. The medical sensor monitors the vibrations produced by the blood flow in the AVF and automatically notify the healthcare personnel at the hospital in case of dysfunction of the AVF to decide on next steps.

The remote sensor can ease the already heavily burdened patients from the responsibility of monitoring AVF progression, a task many feel uneasy about performing themselves. The solution could potentially result in significantly fewer chronic AVF damages for about 150.000 new patients [1] who are to initiate hemodialysis treatment on an AVF, every year in Europe and USA.

What is the problem?

AUSCULTO addresses an unmet need for end-stage renal disease (ESRD) patients planned to initiate hemodialysis treatment within a timeframe of 6 months. In order to enable the vital hemodialysis treatment the patients need a high flow access point to the vascular system. This can be achieved in different ways, but more than 80% of patients [1] achieve this access through surgically constructing an arteriovenous fistula (AVF), basically by creating a direct connection from an artery to a vein.

When the AVF is constructed the high blood pressure from the artery flows to the low pressure in the vein, exerting stress on the walls of the vein. This causes the vein walls to expand and thicken and thereby increasing the blood flow. The AVF will mature over the next weeks until it is ready for use in hemodialysis treatment.

It is in the timespan from AVF-surgery to maturation of the vein, potential problems can arise. It is expected that the AVF should mature in 4-8 weeks, but many patients will experience that it takes longer.

Different studies report different maturation durations; Huber et. al [2] reports between 15 and 24 weeks, with 34-37% of patients requiring intervention to help the maturation process. Richards et. al [3] reports that only 65% of AVFs will have matured by week 10.
Other studies reports AVF survival within the first year to be between 40% and 60% [4-6].

If a dysfunction is left unnoticed the AVF will be permanently damaged and the patient will need a new AVF-surgery, or alternative method of renal replacement therapy.

A main reason for unnoticed dysfunctions in the method of monitoring.

Currently, two options exist for monitoring the health of the AVF; either the patient is called into the hospital or clinic for frequent check-ups where the AVF is ultrasound scanned to control the condition of the AVF. The transportation to and from the hospital can be burdensome for the patient, and in the cases where the AVF is perfectly healthy, largely an unnecessary trip.

Alternatively, the responsibility to monitor the condition of the AVF is placed upon the patient themselves, by listening to the blood flow in the AVF with a stethoscope. This can be a difficult task, and many patients feel uneasy about this responsibility.

What is the solution?

Our solution to the problem of monitoring is producing a medical sensor that can perform the monitoring of the AVF without needing active involvement by the patient. This removes both a burden and responsibility from the patients, and in turn secures a regular autonomous monitoring of the AVF. In case of dysfunction the healthcare personnel at the hospital will be notified of the faulty AVF and can contact the patient to call them in for further assessment.

Sound produced at a functioning AVF
(Headphones might be necessary to clearly hear the difference)

funcavf.webm

Sound produced at a non-functioning AVF

nonfuncavf.webm

How is this possible?

The medical sensor records the vibrations caused by the blood flow through the AVF. This is the same sound a physician will listen for with a stethoscope when assessing the health of the AVF at the hospital. The sound recordings are transmitted to a cloud computer where the recordings are analyzed by an advanced machine learning algorithm. The algorithm can recognize if the AVF is functional or not by the sound of the blood flow in the AVF. In case of dysfunction an alarm is sent to the healthcare personnel at the hospital which will call the patient in for assessment, resulting in the AVF being saved.

[1]: Kramer et. al, A comparison of the epidemiology of kidney replacement therapy between Europe and the United States: 2021 data of the ERA Registry and the USRDS, Nephrology Dialysis Transplantation, Volume 39, Issue 10, October 2024, Pages 1593–1603, https://doi.org/10.1093/ndt/gfae040
[2] Huber TS, Berceli SA, Scali ST, et al. Arteriovenous Fistula Maturation, Functional Patency, and Intervention Rates. JAMA Surg. 2021;156(12):1111–1119. doi:10.1001/jamasurg.2021.4527
[3] Richards, James, et al., Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula. Kidney International Reports, Volume 9, Issue 4, 1005 - 1019
[4] Lindhard, K., Rix, M., Heaf, J.G. et al. Effect of far infrared therapy on arteriovenous fistula maturation, survival and stenosis in hemodialysis patients, a randomized, controlled clinical trial: the FAITH on fistula trial. BMC Nephrol 22, 283 (2021). https://doi.org/10.1186/s12882-021-02476-x
[5] Almasri, Jehad et al., Outcomes of vascular access for hemodialysis: A systematic review and meta-analysis. Journal of Vascular Surgery, Volume 64, Issue 1, 236 - 243
[6] Al-Jaishi, Ahmed A. et al., Patency Rates of the Arteriovenous Fistula for Hemodialysis: A Systematic Review and Meta-analysis. American Journal of Kidney Diseases, Volume 63, Issue 3, 464 - 478

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