RBC aggregometer head as a warning monitor of flow disturbance in extracorporeal systems

A simple photoelectric apparatus is described, to monitor the flow condition of whole blood in an extracorporeal system. It can raise an immediate alarm on disturbance of flow. The apparatus comprises an RBC aggregometer head, described previously, for measuring the rate of RBC aggregation in whole blood. Its construction was modified for easy attachability and detachability without causing tube damage. In practice, the apparatus was applied by hooking it to the tube of the extracorporeal system in animals and in a clinical case of blood dialysis in a patient with renal failure, in which stoppage of blood flow elicited a dramatic change in the baseline record of light transmission of the mobile blood. The signal of the apparatus was fed to an alarm system via a voltage comparator switch. The apparatus is inexpensive, solid and durable, easy to operate by untrained personnel, and has excellent stability and reproducibility.