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.

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.  

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.