Method for detection of leakage of blood

A method of detecting the presence of blood during dialysis treatment of a patient in a dialysate solution, said solution having been passed through a dialyzer during dialysis of a patient's blood, comprising the steps of:

• (a) prior to said dialysis treatment
• conducting a first measurement of the intensity of light impinging on a photosensitive detector aligned with a light source, said light passing through a chamber containing a control dialysate solution that is free of blood, with said light source in a first condition emitting light of intensity P.sub.0, where P.sub.0 is greater than or equal to zero;
• changing the state of said light source from a first condition to a second condition different from said first condition;
• conducting a second measurement with said photosensitive detector of the intensity of light from said light source that passes through said chamber containing said control dialysate solution, with said light source in said second condition emitting light at an intensity P.sub.1 .noteq.P.sub.0, and
• (b) during dialysis,
• conducting a third measurement with said photosensitive detector of the intensity of light, said light passing through said chamber, said chamber containing dialysate solution that may contain the patient's blood is said dialzyer is in a defective condition allowing said patient's blood to pass through said dialzyer into said dialysate solution, said light source in said first condition;
• changing the state of said light source from said first condition to said second condition;
• conducting a third measurement with said photosensitive detector of the intensity of light of said light source that passes through said chamber, said chamber containing dialysate solution that may contain the patient's blood is said dialyzer is in a defective condition allowing said patient's blood to pass through said dialzyer into said dialysate solution, said light source in said second condition;
• and
• calculating an attenuation coefficient of said intensity of light passing through said chamber indicative of the presence of blood in said dialysate solution during dialysis from said first, second, third and fourth measurements.