What is a common cause of a blood leak detector alarm during recirculation?

A blood leak detector alarm is designed to identify the presence of blood where it shouldn't be, particularly during the recirculation phase of dialysis. A common reason for this alarm to trigger is the presence of air bubbles in the dialysate or a dirty sensor.

When air bubbles are present, they can create false readings that are interpreted as a blood leak, because the sensor can confuse the characteristics of the bubbles with that of blood. Similarly, a dirty sensor may fail to accurately detect the differences between blood and the fluid being measured, ultimately causing the alarm to sound.

During recirculation, the system is closely monitoring the return of blood to ensure that there is no leak or unintended presence of air. Therefore, the combination of air bubbles in the dialysate or a malfunctioning sensor is a typical reason for a blood leak detector alarm to activate.