Medical device for introduction of a fluid into the blood circulation system of a patient and method for controlling leakage currents in a medical device provided or combined with a warming unit
Inventors
WANGEN, MICHAEL JON • Ruhland, Daniel Edward • Miller, Randy A.
Assignees
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Publication Number
US-11957890-B2
Publication Date
2024-04-16
Expiration Date
Abstract
A warming unit (21) coupled or configured to be coupled to a heated portion (19) of a fluid circuit (6, 7, 10, 11, 13, 14, 15; 107) of a medical device (1, 100). The warming unit (21) comprises a leakage current reduction circuit (35) configured to perform the following procedure: connecting a heat transfer element (22) of the warming unit (21) to a ground connection (33) through a resistance element (34), which keeps a normal condition patient leakage current below a first limit value, and disconnecting the heat transfer element (22) from the ground connection (33) if a current indicating that a patient is connected to a mains voltage is sensed through the resistance element (34), in order to keep a fault condition patient leakage current below a second limit value.
Core Innovation
The patent describes a medical device for introduction of a fluid into a blood circulation system of a patient. The medical device comprises at least one fluid circuit coupled to a vascular access to introduce the fluid into the patient, wherein the at least one fluid circuit comprises a heated portion. The device further includes a warming unit coupled to the heated portion to warm the fluid before the fluid passes to the blood circulation system of the patient.
The warming unit comprises at least one electrical heater element connected to a main electrical source providing a mains voltage, and at least one heat transfer element in contact with the heated portion. An electrical safety insulation is interposed between the at least one electrical heater element and the at least one heat transfer element. A ground connection is connected to the at least one heat transfer element, and a leakage current reduction circuit is operatively interposed between the heat transfer element and the ground connection.
The core leakage-current control uses 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. Under normal working conditions, the leakage current reduction circuit keeps leakage currents below a first limit value while the electrical heater element is connected to the main electrical source to warm the fluid. Under a fault condition in which the patient is connected to the mains voltage, the circuit keeps leakage currents below a second limit value higher than the first by disconnecting the ground connection from the heat transfer element while keeping the electrical heater element connected to continue warming the fluid.
The patent further provides fault recovery by attempting to connect the ground connection to the at least one heat transfer element at a selected time interval after disconnecting the ground connection while continuing to warm the fluid. After reconnecting, monitoring of the current in the resistance element through the current sense circuitry is returned to, and the behavior repeats based on whether the monitored current is greater than or lower than the threshold current indicating the fault condition.
Claims Coverage
The document includes three independent claims that share the same core leakage current reduction architecture and fault behavior using ground connection switching based on current sensing, with additional refinements recited in dependent claims.
Medical fluid warming device with leakage current reduction circuit using resistance and current sensing
A medical device for introduction of a fluid into a blood circulation system, comprising at least one fluid circuit with a heated portion, a warming unit with an electrical heater element connected to a main electrical source providing a mains voltage and a heat transfer element in contact with the heated portion, electrical safety insulation interposed between the heater element and the heat transfer element, a ground connection connected to the heat transfer element, and a leakage current reduction circuit interposed between the heat transfer element and the ground connection, wherein the leakage current reduction circuit comprises a resistance element between the heat transfer element and the ground connection and current sense circuitry configured to sense a current through the ground connection, and the leakage current reduction circuit monitors the current and disconnects the ground connection from the heat transfer element when the monitored current is greater than a threshold current while keeping the heater element connected to continue warming the fluid.
Two-limit leakage current control for medical fluid warming device during normal and fault conditions
A medical device for introduction of a fluid into a blood circulation system, comprising at least one fluid circuit with a heated portion and a warming unit configured to warm the fluid before it passes to the blood circulation system, wherein the warming unit comprises at least one electrical heater element connected to a mains voltage source, at least one heat transfer element in contact with the heated portion, electrical safety insulation between the heater element and the heat transfer element, a ground connection connected to the heat transfer element, and a leakage current reduction circuit between the heat transfer element and the ground connection, wherein the leakage current reduction circuit comprises a resistance element between the heat transfer element and the ground connection and current sense circuitry configured to sense a current through the ground connection, the circuit configured to keep leakage currents below a first limit value under normal working conditions and below a second limit value higher than the first limit under a fault condition in which the patient is connected to mains voltage by disconnecting the ground connection from the heat transfer element while keeping the heater element connected to continue warming the fluid.
Method for controlling leakage currents by switching ground connection while continuing heating
A method for controlling leakage currents in a medical device having at least one fluid circuit with a heated portion and a warming unit coupled to the heated portion to warm the fluid before the fluid passes to a blood circulation system, 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, electrical safety insulation between the heater element and the heat transfer element, a ground connection connected to the heat transfer element, and a leakage current reduction circuit interposed between the heat transfer element and the ground connection, the method comprising keeping leakage currents below a first limit value under normal working conditions while the heater element is connected to the main electrical source to perform heating by connecting the main electrical source to the ground connection through a resistance element placed between the heat transfer element and the ground connection, and keeping leakage currents below a second limit value higher than the first limit under a fault condition in which the patient is connected to the mains voltage by disconnecting the ground connection from the heat transfer element while keeping the heater element connected to continue warming the fluid.
Across the independent claims, the inventive concept is a warming unit with electrical safety insulation and a leakage current reduction circuit that uses a resistance element and current sense circuitry to monitor current and implement a two-limit leakage strategy, disconnecting the ground connection from the heat transfer element under a mains-voltage fault condition while keeping the electrical heater element connected to continue warming.
Stated Advantages
Keeps leakage currents below a first limit value under normal working conditions while warming the fluid.
Keeps leakage currents below a second limit value higher than the first limit value under a fault condition when the patient is connected to mains voltage.
Continues warming the fluid during the fault condition by keeping the electrical heater element connected to the main electrical source while disconnecting the ground connection.
Attempts to reconnect the ground connection to the heat transfer element at a selected time interval after disconnecting, while continuing to warm the fluid.
Documented Applications
Extracorporeal blood treatment apparatus comprising the medical device for introducing a fluid into a blood circulation system.
IV pole infusion apparatus comprising the medical device for introducing a fluid into a blood circulation system.
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