System for monitoring patient location and data

• US 5,458,123 A
• Filed: 04/29/1994
• Issued: 10/17/1995
• Est. Priority Date: 12/16/1992
• Status: Expired due to Fees

• Current Assignee: Draeger Medical Systems Incorporated (Dragerwerk AG)
• Original Assignee: Siemens Medical Systems, Inc. (Siemens AG)
• Inventors: Unger, John D.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Parker, Marianne
• Application Number:
  US08/235,208
• Time in Patent Office: 536 Days
• Field of Search: 340/573, 340/870.41, 340/825.36, 340/825.54, 128/630, 128/637, 128/671, 128/680, 128/687, 128/696, 128/, 128/776, 128/903, 181/125, 329/370, 367/117
• US Class Current: 600/509
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/1113 Local tracking of patients, e.g. in a hospital or private home
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: Y10S 128/903 Radio telemetry

Abstract

A patient monitoring system utilizes a transmitter associated with each patient. The transmitter is worn by a patient and includes sensors operative to monitor vital signs of the patient. The transmitter transmits an allocated RF frequency which is particularly associated with that patient. A series of antennas are incorporated in a building, each antenna having its own signature signal. As the patient moves throughout the building, the antennas pick up the signals from the patient'"'"'s transmitter and combines the antenna signature signal with the transmitted patient signal. This combined signal is then analyzed at a central location to determine the exact location of the patient due to the antenna signature signal which is modulated on the transmitted patient signal. Transmitted patient data is also decoded at the central station to provide a signal indicative of the vital signs of the patient.

Claims

1. A telemetry system for monitoring at least one vital sign of each one of a plurality of patients, as well as a physical location within an operating area for each patient being so monitored, comprising:

a plurality of patient monitoring transmitters, each transmitter adapted for being worn by a different one of said plurality of patients and for transmitting as a patient signal an RF signal which has a different RF carrier frequency allocated to each of said plurality of patients, each patient signal containing data indicative of at least one monitored vital sign of the patient wearing the transmitter,

a plurality of antennas located in fixed positions throughout the operating area, each of the antennas having an input operative for receiving the patient signal transmitted by each transmitter and an output for directing the patient signal so received to a central location, which central location analyzes the patient signal for providing data indicative of the at least one monitored vital sign of the patient wearing the transmitter; and

a plurality of antenna signature means, a different one of each of said antenna signature means being coupled to a respective different one of each of said plurality of antennas for generating a unique antenna identification signal for each antenna it is coupled to, which unique antenna identification signal is combined by said antenna signature means with each patient signal received by said antenna for forming a combined patient signal which is sent to said central location, said central location analyzing the combined patient signal so as to determine which unique antenna identification signal was combined with the patient signal, said determination indicating which antenna of said plurality of antennas located in fixed positions throughout the operating area transmitted the combined patient signal, thereby indicating the location within said operating area of the patient transmitter which transmitted the patient signal.

2. The system according to claim 1, wherein:

each one of said plurality of antenna signature means includes a modulator means having an input coupled to a respective one of each antenna output for applying a modulation to any patient signal received thereby, and a separate local oscillator coupled to a respective one of each modulator means and operative for causing each modulator means to apply a separate modulation frequency to any patient signal received thereby, which modulation frequency is indicative of a unique signature for each antenna; and

each said modulator means having an output for providing as the combined patient signal any received patient signal modulated by said modulation frequency.

3. The system according to claim 2, wherein said modulation frequencies are in a range between 100 and 300 Hz.

4. The system according to claim 2, wherein said modulator means includes an amplitude modulator.

5. The system according to claim 2, wherein said modulator means includes a frequency modulator.

6. The system according to claim 1 further including:

receiving means for receiving said combined signal,

said receiving means including means for bandpass filtering said combined signal to determine an RF carrier frequency of the patient signal and therefore a patient allocated to said RF carrier frequency, and

means for detecting the unique antenna identification signal of said combined signal to determine a given one antenna of said plurality of antennas and therefore an indication of a patient location.

7. The system according to claim 6, wherein said means for bandpass filtering said signal includes a hetrodyning means for translating the RF carrier frequency to a lower frequency.

8. The system according to claim 1, wherein:

said antenna signature means includes a location code generator means coupled to each antenna, for combining a given location code with signals received by said antenna, where said location code provides an indication of location for each antenna.

9. In a patient monitoring telemetry system employing a plurality of antennas located in fixed positions throughout an operating area and where a mobile patient wears a transmitter capable of transmitting a patient signal containing data indicative of at least one monitored vital sign of said patient being monitored, said antennas adapted to receive said transmitted patient signal for directing the transmitted patient signal to a central location to provide data indicative of the at least one monitored vital sign of said patient, the improvement in combination therewith of apparatus for providing said central location with information indicative of a location of said patient within said operating area as determined by said patient being located near a given one antenna in said plurality, said apparatus comprising:

antenna signature means coupled to each antenna and operative for providing a unique signal for each antenna coupled thereto, which unique signal is combined with a received patient signal by said antenna for forming a combined signal, whereby each antenna of said plurality has a unique signal which is impressed upon any received patient signal to enable said central location to determine which antenna in said plurality transmitted the combined signal and therefore indicative of a location for said patient within said operating area; and

threshold detection means coupled to said antenna signature means for detecting an amplitude of said combined signal so as to only direct combined signals exceeding a predetermined amplitude threshold to said central location.

10. A patient monitoring telemetry system for remotely and continuously monitoring patients within a given area, said system comprising:

a plurality of patient transmitters, each transmitter adapted to be mounted on a patient and including means for collecting patient data and each transmitter having an antenna for continuously radiating a patient signal indicative of said patient data,

a plurality of antennas each positioned apart from one another and located at predetermined positions throughout said given area,

a plurality of antenna signature meant, each one associated with one of said antennas and operative for combining an antenna signature signal with any patient signal received by said associated antenna for generating a combined signal, said signature signal being different for each antenna and thereby each being indicative of a specific one of said antennas which is located at a predetermined position in said given area, and

receiving means coupled to said antennas for continuously receiving the combined signal from said antennas, and including means for detecting said antenna signature signal and said patient signal to simultaneously and continuously provide an output indicative of a location of said patient with regard to any one of said antennas and patient data of said patient.

11. The system according to claim 10, wherein said antenna signature means includes modulator means for applying a modulation to any patient signal received thereby, one modulator means for each antenna, and a separate local oscillator associated with each modulator means and operative to provide a separate modulation frequency for each modulator means and therefore for each antenna, said modulator means having one input for receiving said associated antenna signal and for providing at an output the combined signal which is said received patient signal modulated by said separate modulation frequency for said antenna.

12. The system according to claim 11, where said modulator means includes an amplitude modulator.

13. The system according to claim 11, wherein said modulator means includes a frequency modulator.

14. The system according to claim 11, wherein said modulation frequency is between 100 and 300 Hz.

15. The system according to claim 10, wherein each patient transmitter is allocated a unique frequency different from another patient transmitter frequency whereby said allocated frequency is definitive of a given patient.

16. The system according to claim 15, wherein said unique frequencies are RF frequencies selected in a range between 70 and 500 MHz.

17. The system according to claim 10 including:

threshold detecting means responsive to the combined signals from said antennas for selecting only those combined signals which have a magnitude which exceeds a predetermined threshold, whereby a greatest magnitude combined signal for a given patient will be selected from only one antenna of a plurality of antennas receiving said patient signal.