I have not heard of these so did a search:
Redsense is an alarm system for monitoring the vein needle during hemodialysis by detecting blood loss from the human body.
During hemodialysis, blood is drawn and cleaned from the patient's artery and circulated in a dialysis machine. Clean blood is returned to the body via the venous needle.
Redsense was initiated when nurses at the Swedish county hospital in Halmstad in 2004 witnessed occasional venous needle dislodgement during hemodialysis. Realizing that these incidents were not unique, the hospital asked medical innovation consultants to address the problem. This led to the creation of the company Redsense Medical and the development of the Redsense Medical device for blood loss detection.
"If the venous needle becomes dislodged, the dialysis machine will continue to draw blood from the patient's artery vein but returns no clean blood to the body. It takes only a few minutes before the dislodgement can have serious, even fatal consequences. The needle dislodgement can result in heavy blood loss, hypo-volemic shock, and death," said the representatives from Redsense.
"The design team took a user-centric approach to design and developed a blood loss detection device."
The device comprises of two parts: a sensor patch and an alarm unit. An infrared signal is transmitted from the alarm unit to a single use sensor patch, which continuously monitors the venous needle access point. If vein needle dislodgement occurs, the sensor triggers an alarm.
The alarm unit clips onto the patient's clothing and an infrared signal is transmitted through a fiber-optic cable to a single-use sensor patch, which continuously monitors the venous needle access point. If bleeding occurs, the sensor triggers an alarm.
"Approximately 1.7 million dialysis patients worldwide are given more than 200 million dialysis treatments every year. An aging demographic and type II diabetes will cause patient numbers to grow. Patients can now sleep and move safely in the knowledge that dislodgement of their venous needle, if it occurs, will be detected. Nurses can move freely around the unit with peace of mind. REDSENSE