Battery system for MRI compatible wireless patient monitor

• US 8,294,588 B2
• Filed: 05/10/2007
• Issued: 10/23/2012
• Est. Priority Date: 05/12/2006
• Status: Active Grant

• Current Assignee: Invivo Corporation (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Fisher, Stephen Douglas, Harwell, Robert A., Van Arsdel, Kenneth
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): WANG, JACK K
• Application Number:
  US12/440,027
• Publication Number:
  US 20100191069A1
• Time in Patent Office: 1,993 Days
• Field of Search: 340/636.1
• US Class Current: 340/636.1
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: G01R 33/28 Details of apparatus provided for in groups G01R33/44 - G01R33/64
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

A patient monitoring system detects physiological signals from a patient during an MRI examination. The patient monitoring system wirelessly transmits data associated with the physiological signals to a remote base unit. The wireless transmission of data is carried out in a manner to not be disruptive to the MRI examination. The patient monitoring system has a removable, MRI magnet compatible battery.

Claims

1. A wireless patient monitoring system for acquiring and wirelessly transmitting physiological data from a patient undergoing an MRI examination in an MRI machine, comprising:

a housing;

leads which acquire the physiological data from the patient during the MRI examination, the leads extending from the housing;

an antenna which wirelessly transmits physiological data acquired from the patient during an MRI examination, the antenna supported by the housing;

first and second interior portions defined within the housing, wherein the first interior portion is open to receive outside electrical interference including RF signals from the MRI machine and electrically isolated from the second interior portion;

RF shielding which RF shields the second interior portion from RF signals from the MRI machine, a portion of the RF shielding extending between the first and second interior portions to RF shield the second interior portion from RF signals received via the first interior portion;

circuitry disposed in the second interior portion, the circuitry including transmitter circuitry configured to transmit the physiological data wirelessly via the antenna to a remote base station; and

a battery substantially free from ferromagnetic components and disposed in the first interior portion.

2. The wireless patient monitoring system of claim 1 wherein the battery is a rechargeable battery.

3. The wireless patient monitoring system of claim 2 wherein the rechargeable battery is a lithium ion battery.

4. The wireless patient monitoring system of claim 2 wherein the battery includes integrated circuitry monitoring battery status information that includes at least one of battery type, battery capacity, remaining battery charge, and charge time.

5. The wireless patient monitoring system of claim 4 further comprising:

an electrical connector formed in the RF shielding portion between the first interior portion and the second interior portion to pass power and battery status from the battery disposed in the first interior portion to the circuitry disposed in the second interior portion;

wherein the battery has at least two terminals that electrically connect with the connector; and

an interface having a band pass filter through which the battery status information passes from the connector to the circuitry and a low pass filter through which power passes from the connector to the circuitry.

6. The wireless patient monitoring system of claim 1 further including:

a connector extending through the RF shielding, the circuit being connected with the connector; and

an interface between the connector and the circuit, the interface blocking RF energy present on terminals of the battery.

7. The wireless patient monitoring system of claim 6 wherein the housing further includes a chamber RF shielded from the first and second interior portions, the chamber holding the interface.

8. A wireless patient sensor operative within an MRI machine to sense physiological data indicative of at least one of heartbeat, respiration, temperature, and blood oxygen of a patient during an MRI examination, comprising:

a battery pocket containing a battery, the battery pocket being defined in the housing and open to receive the RF signals generated during the MRI examination;

an RF shielded circuitry housing portion containing circuitry disposed within an interior volume of the RF shielded circuitry housing such that the circuitry is shielded from receiving RF signals generated during the MRI examination, including RF signals received in the battery pocket; and

RF signal blocking electrical connections through the RF shielded circuitry housing to electrically connect a ferromagnetic component free battery received in the battery pocket with the circuitry.

9. The wireless patient sensor of claim 8 wherein the housing includes an RF shield.

10. The wireless patient sensor of claim 9 wherein a portion of the RF shield extends between the battery pocket and the housing portion.

11. The wireless patient sensor of claim 8 wherein the circuitry acquires physiological data from the patient during the MRI examination.

12. The wireless patient sensor of claim 11 wherein the circuitry acquires status information of the battery.

13. The wireless patient monitoring system of claim 12 wherein the circuitry includes transmitter circuitry for transmitting the physiological data and the battery status information wirelessly via an antenna exterior to the housing to a remote base station.

14. The wireless patient sensor of claim 12 further including:

at least one filter that filters a data signal and a power signal provided by the battery to the circuitry.

15. The wireless patient sensor of claim 14 wherein the at least one filter includes filter elements that provide low pass filtering on the power signal from the battery and that provide band pass or lowpass filtering on the data signal from the battery.

16. The wireless patient sensor of claim 15 wherein the at least one filter is contained in a chamber, the chamber including a first electrically conductive interior wall and a second electrically conductive interior wall, a first set of feed through capacitors formed in the first electrically conductive interior wall, and a second set of feed through capacitors formed in the second electrically conductive interior wall, and wherein the at least one filter includes RF chokes disposed between the first set of feed through capacitors and the second set of feed through capacitors.

17. A wireless patient sensor operative with an MRI machine during an MRI examination, comprising:

a housing having an interior volume;

a chamber disposed within a first portion of the interior volume and defined by electrically conductive walls;

a shielded circuitry housing containing circuitry within a second portion of the interior volume;

a battery pocket containing a battery, the battery pocket being disposed within a third portion of the interior volume, electrically isolated from the chamber, and open to outside electrical interference; and

electrical connections between the shielded circuitry and the battery pocket through the chamber;

wherein the circuitry includes transmitter circuitry that wirelessly transmits data to a remote base unit.

18. A method comprising:

at a commissioned patient sensor having circuitry to acquire physiological signals from a patient during an MRI examination and further having a battery to supply power to the circuitry, determining a charge of the battery;

performing a communication synchronization of the patient sensor with a base station prior to use of the patient sensor in a scheduled MRI examination;

with a processor at the base station, determining a minimal charge value required to complete the scheduled MRI examination based on particulars of the scheduled MRI examination;

with the processor, comparing the determined battery charge of the patient sensor to the minimal charge value for the scheduled MRI examination; and

wirelessly signaling that the commissioned patient sensor lacks the battery charge required to perform the scheduled MRI examination if the battery charge of the patient sensor is less than the determined minimal charge value.

19. The method of claim 18 further comprising:

monitoring the battery charge of the patient sensor during the acquisition of physiological signals during the scheduled MRI examination; and

if the charge of the battery falls below the minimal charge value, wirelessly transmitting a low battery charge signal to the base station.

20. The method of claim 19 further comprising:

wirelessly transmitting data to the base station associated with physiological signals acquired from the patient.

21. The method of claim 19 further comprising:

storing battery usage data and determining maintenance needs for the battery from the stored battery usage data.

22. The method of claim 19 further comprising:

preventing the acquisition of physiological signals if the charge of the battery is below the minimal charge value.