Message integrity for secure communication of wireless medical devices

• US 7,777,622 B2
• Filed: 11/04/2005
• Issued: 08/17/2010
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Sanchez Sanchez, David, Baldus, Heribert
• Primary Examiner(s): Crosland; Donnie L
• Application Number:
  US11/719,099
• Publication Number:
  US 20090082635A1
• Time in Patent Office: 1,747 Days
• Field of Search: 340/539.12
• US Class Current: 340/539.12
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• 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 5/145 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 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: G16H 10/20 for electronic clinical trials or questionnaires
• CPC Class Codes: Y10S 128/903 Radio telemetry
• CPC Class Codes: Y10S 128/904 Telephone telemetry

Abstract

A system for securely synchronizing medical devices and providing message integrity with timeliness and uniqueness (10) includes a plurality of medical wireless devices (12₁, 12₂, . . . , 12_n). The medical devices (12₁, 12₂, . . . , 12_n) communicate wirelessly with one another. Each message (M) includes a data portion and a timestamp. Each medical device (12₁, 12₂, . . . , 12_n) includes a sensor (14) which is attached to a patient to monitor a common vital sign. The medical devices (12₁, 12₂, . . . , 12_n) are synchronized when the sensor (16) of each medical device detects a peak of the vital sign function. At this moment, internal clocks of each medical device (12₁, 12₂, . . . , 12_n) are zeroed and each internal timer starts counting time. Thus, the medical devices are loosely synchronized at approximately the same time. Each generated message (M) is timestamped with a send time (T_SEND) generated by a time count. The generated timestamp (T_SEND) of the message (M) is validated against a receive time (T_RECEIVE) of the receiving medical device internal clock count. If the message (M) arrives out of the prespecified acceptance window, the message (M) is rejected by the receiving medical device.

Claims

1. A network system comprising:

a plurality of medical devices for sending or receiving messages to one another, each message including a data portion and a recurring vital sign based timestamp, each medical device including;

a sensor which is attached to a patient to at least confidentially monitor a recurring vital sign; and

a timestamp generating means for generating the recurring vital sign based timestamp;

synchronizing means for synchronizing at least first and second medical devices;

wherein each synchronizing means includes;

first and second peak detecting means for detecting a peak of the monitored recurring vital sign which is common to at least first and second medical devices.

2. A network system comprising:

a plurality of medical devices for sending or receiving messages to one another, each message including a data portion and a recurring vital sign based timestamp, each medical device including;

a sensor which is attached to a patient to at least confidentially monitor a recurring vital sign;

a timestamp generating means for generating the recurring vital sign based timestamp; and

a synchronizing means for synchronizing at least first and second communicating medical devices to evaluate a difference between a send time at which a message departs from the first medical device and a receive time at which the message arrives at the second medical device.

3. The system as set forth in claim 2, wherein each synchronizing means further includes:

a timer zeroing means which initializes first and second internal timers of each associated medical device when a peak is detected by corresponding first and second peak detecting means, at which instance each initialized internal timer starts a new time count.

4. The system as set forth in claim 3, wherein the timestamp is indicative of the send time at about which the message leaves the first medical device and corresponds to a time gauge of the first internal timer measured from a last peak detected by the first detecting means.

5. The system as set forth in claim 4, wherein the first medical device further includes:

an encrypting means for encrypting the message before sending it to the second medical device.

6. The system as set forth in claim 5, wherein the second medical device includes:

a timestamp validating means for comparing the affixed timestamp, which is indicative of the send time, to the receive time at which the message arrives at the second medical device, which receive time corresponds to a time gauge of the second internal timer measured from a last peak detected by the second detecting means.

7. The system as set forth in claim 2, wherein the synchronizing is performed automatically.

8. The system as set forth in claim 2, wherein the synchronizing is performed at a request of one of the medical devices.

9. A network system comprising:

a plurality of medical devices for sending or receiving messages to one another, each message including a data portion and a recurring vital sign based timestamp, each medical device including;

a sensor which is attached to a patient to at least confidentially monitor a recurring vital sign; and

a timestamp generating means for generating the recurring vital sign based timestamp, wherein the timestamp is indicative of a number of repetitions of the recurring vital sign function since a common reset time.

10. A method of networking among medical devices, which each includes a sensor, the method comprising:

attaching the sensors to a patient body;

at least monitoring a recurring vital sign of the patient;

generating a recurring vital sign based timestamp;

sending and receiving messages from one medical device to another, each message including a data portion and the timestamp;

synchronizing at least first and second communicating medical devices; and

detecting a peak of the recurring monitored common vital sign by the first and second medical devices which vital sign is common to at least first and second medical devices, and wherein the step of synchronizing includes;

automatically synchronizing the first and second medical devices to the detected peak.

11. The method as set forth in claim 10, wherein the step of synchronizing further includes:

initializing corresponding internal timers when the peak is detected by an associated first and second medical device; and

initiating a new time count in each internal timer of each associated medical device.

12. The method as set forth in claim 11, further including:

encrypting the message at the first medical device before sending the message to the second medical device;

affixing a timestamp to the message before encryption, which timestamp is indicative of the send time at about which the message leaves the first medical device and corresponds to a time gauge of the first internal timer measured from a last peak detected by the first medical device;

receiving the message at the second medical device; and

comparing the affixed timestamp to the receive time at which the message arrives at the second medical device, which receive time corresponds to a time gauge of the second internal timer measured from the last peak detected by the second medical device.

13. The method as set forth in claim 12, further including:

evaluating a difference between a send time at which a message departs from the first medical device and a receive time at which the message arrives at the second medical device.

14. The method as set forth in claim 13, further including one of:

accepting the message at the second medical device wherein the affixed timestamp substantially equals to the time gauge of the second internal timer measured from the last peak detected by the second medical device; and

rejecting the message at the second medical device wherein the affixed timestamp substantially differs from the time gauge of the second internal timer measured from a last peak detected by the second medical device.

15. A method of networking among medical devices, which each includes a sensor, the method comprising:

attaching the sensors to a patient body;

at least monitoring a recurring vital sign of the patient;

generating a recurring vital sign based timestamp;

sending and receiving messages from one medical device to another, each message including a data portion and the timestamp; and

synchronizing at least first and second communicating medical devices, wherein the step of synchronizing includes;

initiating detection of a peak of a monitored common vital sign by the first and second medical devices; and

synchronizing associated first and second internal timers when the peak is detected.

16. A method of networking among medical devices, which each includes a sensor, the method comprising:

attaching the sensors to a patient body;

at least monitoring a recurring vital sign of the patient;

generating a recurring vital sign based timestamp;

sending and receiving messages from one medical device to another, each message including a data portion and the timestamp;

synchronizing at least first and second communicating medical devices, wherein the step of synchronizing includes sending a signal to reset both the first and second medical devices and further including;

counting a number of repetitions of a common recurring vital sign; and

incorporating the count into the timestamp.

17. The method as set forth in claim 16, further including:

measuring time since a last repetition of the recurring vital sign; and

incorporating the measured time into the timestamp.