PREVENTION OF SAFETY HAZARDS DUE TO LEAKAGE CURRENT

• US 20120195078A1
• Filed: 02/01/2011
• Published: 08/02/2012
• Est. Priority Date: 02/01/2011
• Status: Abandoned Application

• Current Assignee: Biosense Webster Israel Ltd. (Johnson & Johnson)
• Original Assignee: Biosense Webster Israel Ltd. (Johnson & Johnson)
• Inventors: Levin, Michael, Govari, Assaf, Ephrath, Yaron, Altmann, Andres Claudio
• Application Number:
  US13/018,773
• Publication Number:
  US 20120195078A1
• Time in Patent Office: Days
• US Class Current: 363/50
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00708 switching the power on or off
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/1273 including multiple generators in one device

Abstract

Medical apparatus includes an electrical power supply, which is configured for connection to an electrical medical device that is coupled to a body of a patient. In one embodiment, the apparatus includes alternating current (AC) lines that include a ground line. A switch is coupled to connect and disconnect the AC lines from an AC power source. A current sensor is coupled to sense a current flowing in the ground line and to actuate the switch to disconnect the AC lines when the current exceeds a predetermined threshold. In another embodiment, a plurality of electrocardiogram (ECG) leads, including a common lead, are coupled to the body of the patient. An auxiliary current sensor is coupled to monitor a current flowing through the common lead and to actuate the switch to disconnect the power connection when the current exceeds a predetermined limit.

Claims

1. Medical apparatus, comprising:

an electrical power supply, which is configured for connection to an electrical medical device that is coupled to a body of a patient and which comprises alternating current (AC) lines that include a ground line;

a switch, which is coupled to connect and disconnect the AC lines from an AC power source; and

a current sensor, which is coupled to sense a current flowing in the ground line and to actuate the switch to disconnect the AC lines when the current exceeds a predetermined threshold.

2. The apparatus according to claim 1, wherein the electrical power supply comprises a plurality of power supplies arranged in parallel to supply power to the medical device.

3. The apparatus according to claim 2, wherein the plurality of the power supplies are configured to supply radio frequency (RF) power to an electrode on the medical device for ablation of tissue from the body.

4. The apparatus according to claim 2, wherein each of the plurality of the power supplies individually has a level of isolation sufficient so that a leakage current in the ground line due to application of an AC lines voltage to the medical device will be less than a limit provided by an applicable safety standard, while the sum of the leakage current over all of the power supplies exceeds the limit.

5. The apparatus according to claim 1, and comprising:

a plurality of electrocardiogram (ECG) leads for coupling to the body of the patient, including a common lead; and

an auxiliary current sensor, which is coupled to monitor a current flowing through the common lead and to actuate the switch to disconnect the AC lines when the current exceeds a predetermined limit.

6. Medical apparatus, comprising:

an electrical power supply, which is configured for connection to an electrical medical device that is coupled to a body of a patient and which comprises a power connection;

a switch, which is coupled to connect and disconnect the power connection;

a plurality of electrocardiogram (ECG) leads, including a common lead, for coupling to the body of the patient; and

an auxiliary current sensor, which is coupled to monitor a current flowing through the common lead and to actuate the switch to disconnect the power connection when the current exceeds a predetermined limit.

7. The apparatus according to claim 6, wherein the common lead is connected to a right leg of the patient.

8. The apparatus according to claim 6, wherein the auxiliary current sensor comprises a resistor connected between the common lead and a reference point, and a sensing circuit coupled to measure a voltage drop across the resistor.

9. A method for operating an electrical medical device that is coupled to a body of a patient, the method comprising:

providing an electrical power supply for connection to the electrical medical device, the supply comprising alternating current (AC) lines that include a ground line for connection to an AC power source;

sensing a current flowing in the ground line; and

actuating a switch to disconnect the AC lines when the current flowing in the ground line exceeds a predetermined threshold.

10. The method according to claim 9, wherein the electrical power supply comprises a plurality of power supplies arranged in parallel to supply power to the medical device.

11. The method according to claim 10, and comprising supplying radio frequency (RF) power from the plurality of the power supplies to an electrode on the medical device for ablation of tissue from the body.

12. The method according to claim 10, wherein each of the plurality of the power supplies individually has a level of isolation sufficient so that a leakage current in the ground line due to application of an AC lines voltage to the medical device will be less than a limit provided by an applicable safety standard, while the sum of the leakage current over all of the power supplies exceeds the limit.

13. The method according to claim 9, and comprising:

coupling a plurality of electrocardiogram (ECG) leads for coupling to the body of the patient, including a common lead;

monitoring a current flowing through the common lead; and

actuating the switch to disconnect the AC lines when the current exceeds a predetermined limit.

14. A method for operating an electrical medical device that is coupled to a body of a patient, the method comprising:

providing an electrical power supply for connection to the electrical medical device, the supply comprising a power connection;

coupling a plurality of electrocardiogram (ECG) leads, including a common lead, to the body of the patient;

monitoring a current flowing through the common lead; and

actuating a switch to disconnect the power connection when the current exceeds a predetermined limit.

15. The method according to claim 14, wherein the coupling the plurality of the ECG leads comprises connecting the common lead to a right leg of the patient.

16. The method according to claim 14, wherein monitoring the current comprises connecting a resistor connected between the common lead and a reference point, and measuring a voltage drop across the resistor.