I ordered a couple of blood leak alarms from Anza Care some time back and had them delivered to a friend who was coming to India. I should get the alarms in a few days from now.
The alarms are designed to detect any blood that leaks. The way it works is they have a sensor that is connected to an alarm. If any blood touches the sensor, the device sounds an alarm. One sensor is placed close to the site where the needles are inserted into the arm. So, if there is any oozing of blood from the needle site, as it trickles down the arm, it touches the sensor and the alarm sounds so that you wake up and fix whatever is causing the ooze.
The other sensor is placed below the dialyzer. Sometimes, if the dialyzer is defective, if you haven't closed the two covers properly or if you haven't screwed the blood lines on the two sides properly, there is a possibility that blood may leak out of the dialyzer. The sensor will cause the alarm to sound in that case and you can fix the problem.
The sensors from Anza Care were initially designed to help children who wet their bed at night to get rid of this problem. It started being used for home dialysis especially nocturnal to detect blood leaks. Now Anza Care has a specially designed sensors that detect blood more accurately.
This device is really great for nocturnal dialysis as blood leaks, as I have found, can occur and an alarm such as this can prevent a lot of blood loss if detected early enough.