Electrical Isolation Devices, Methods and Systems
AssigneeNxStage Medical, Inc.
InventorGoetz FRIEDERICHS
Life of this patent
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Abstract
A method of reducing leakage current from a patient to a ground potential through an applied part of a medical device includes defining a maximum permissible leakage current Amax from the patient to the ground potential when the patient is energized to an electric potential V and supplying the medical device with water having a resistivity value p through a fluid line having a length L and an inner diameter ID. The value of L and ID is selected to cause the fluid conduit filled with water of resistivity ρ to have a resistance of R high enough to maintain the leakage current from the patient to the ground potential below Amax.
Claims14
A medical treatment system, comprising:
- medical treatment device connectable to an object by an applied part that creates a conductive connection between the object and the medical treatment device when the object and the medical device are physically connected;
- a water purification device that is fluidly connected to the medical treatment device with a fluid conduit and fluidly connected to a water source with an input conduit, the water purification device receiving source water having a first resistivity value from the water source and purifying the source water into purified water having a second resistivity value that is greater than the first resistivity value, and conveying the purified water to the medical treatment device, the water source being at ground potential;
- and
- the fluid conduit being a tube having a uniform cross-section of its flow channel with area A and a length L measured from the medical treatment device to the water purification device, with the length L greater than or equal to (V) (A)/(I) (ρ), where
- V is a maximum expected voltage applied to the object, A is a cross-sectional area of the flow channel, I is a maximum permitted leakage current from the object to the ground potential when the object is connected to the medical treatment device, and ρ is the resistivity of the purified water output by the water purification device.
Dependencies are inferred from the claim text.