Patent ID: 11957890
Assignee: GAMBRO LUNDIA AB
Field: Medical technology (Instruments)
Classification: CPC A  H | IPC A

Claim 16:
17. A medical device for introduction of a fluid into a blood circulation system of a patient, the medical device comprising:
at least one fluid circuit configured to be coupled to a vascular access of the patient to introduce the fluid into the patient, wherein the at least one fluid circuit comprises a heated portion; and
a warming unit coupled to the heated portion, the warming unit configured to warm the fluid before the fluid passes to the blood circulation system of the patient;
wherein the warming unit comprises:
at least one electrical heater element connected to a main electrical source providing a mains voltage,
at least one heat transfer element in contact with the heated portion,
an electrical safety insulation interposed between the at least one electrical heater element and the at least one heat transfer element,
a ground connection connected to the at least one heat transfer element, and
a leakage current reduction circuit operatively interposed between the at least one heat transfer element and the ground connection;

wherein the leakage current reduction circuit comprises:
a resistance element placed between the at least one heat transfer element and the ground connection, and
a current sense circuitry configured to sense a current through the ground connection;

wherein the leakage current reduction circuit is configured to:
keep leakage currents below a first limit value under normal working conditions of the warming unit in which the at least one electrical heater element is connected to the main electrical source to warm the fluid;
keep leakage currents below a second limit value, higher than the first limit value, under a fault condition of the warming unit in which the patient is connected to the mains voltage;

wherein keeping the leakage currents below the first limit value comprises: connecting the main electrical source to the ground connection through the resistance element placed between the at least one heat transfer element and the ground connection; and
wherein keeping the leakage currents below the second limit value comprises: disconnecting the ground connection from the at least one heat transfer element while keeping the at least one electrical heater element connected to the main electrical source to continue warming the fluid.