A decrease in transmembrane pressure in a high flux dialyzer during hemodialysis is indicative of

A decrease in transmembrane pressure in a high flux dialyzer during hemodialysis is indicative of

• A. Blood leak in dialyzer
• B. Clotting of the extracorporeal circuit
• C. Air in the line
• D. Dialysate contamination

Answer: (B)

Transmembrane pressure is the driving force for ultrafiltration across the dialyzer membrane, equal to the blood-side pressure minus the dialysate-side pressure. A decrease in this gradient means the driving force is reduced. When the extracorporeal circuit starts clotting, resistance to blood flow increases and the effective blood-side pressure entering the dialyzer drops (or the flow slows), while the dialysate-side pressure remains about the same. The result is a smaller difference across the membrane, so transmembrane pressure falls. This drop is a warning sign that clotting is impairing the circuit and action is needed (adjust anticoagulation or change components). Other issues, like a blood leak, air in the line, or dialysate contamination, affect the system in different ways and do not produce the characteristic TMP decrease described here.

Transmembrane pressure is the driving force for ultrafiltration across the dialyzer membrane, equal to the blood-side pressure minus the dialysate-side pressure. A decrease in this gradient means the driving force is reduced. When the extracorporeal circuit starts clotting, resistance to blood flow increases and the effective blood-side pressure entering the dialyzer drops (or the flow slows), while the dialysate-side pressure remains about the same. The result is a smaller difference across the membrane, so transmembrane pressure falls. This drop is a warning sign that clotting is impairing the circuit and action is needed (adjust anticoagulation or change components). Other issues, like a blood leak, air in the line, or dialysate contamination, affect the system in different ways and do not produce the characteristic TMP decrease described here.