Communication method and medical communication system

Abstract

The invention relates to a communication method between medical devices, comprising the steps of transmitting (S1) an RF-communication request signal (10) from a first medical device (12) to a second medical device (14), wherein the RF-communication request signal (10) has a first signal range (R1), and after establishing (S2) communication between the first medical device (12) and the second medical device (14), a communication signal (15) of the first medical device (12) has a second signal range (R2), wherein the first signal range (R1) is less than the second signal range (R2). The invention further relates to a first medical device (12) and a medical communication system (1).

Description

[0001] Communication method and medical communication system

[0002] The invention relates to a communication method between medical devices. Furthermore, the invention relates to a first medical device, e.g. a patient communication device or an implantable medical device. In addition, the invention relates to a medical communication system comprising a second medical device and the first medical device.

[0003] Implants conventionally contain two telemetry systems. During follow-up care, a patient's implant is programmed. Conventionally, at the beginning, a near-field telemetry system, in particular a coil telemetry system is used, which has a range of a few centimeters due to the strongly decreasing magnetic field. This ensures that the patient is in the immediate vicinity.

[0004] Thereafter radio frequency telemetry (RF -telemetry) is used to continue follow-up at a comfortable distance from the programming device.

[0005] However, the presence of two telemetry systems in classic implants such as an implantable cardioverter-defibrillator (ICD) and implantable pulse generator (IPG) leads to higher costs and in miniaturized implants such as an implantable leadless pacer (iLP) this further leads to a considerable increase in size.

[0006] Installing a button or a display for authorization means higher production costs and possibly poorer usability.

[0007] It is therefore an object of the present invention to provide an improved communication method between medical devices that allows a simplified yet secure method of initializing communication between the second medical device, e.g. the implantable medical device, and the first medical device, e.g. the patient communication device. The object is solved by a communication method between medical devices having the features of claim 1.

[0008] Furthermore, the object is solved by a first medical device having the features of claim 12.

[0009] In addition, the object is solved by a medical communication system having the features of claim 13.

[0010] Moreover, the object is solved by a computer program having the features of claim 14 and by a computer-readable data carrier having the features of claim 15.

[0011] Further developments and advantageous embodiments are defined in the dependent claims.

[0012] The present invention provides a communication method between medical devices. The method comprises transmitting an RF-communication request signal from a first medical device to a second medical device, wherein the RF-communication request signal has a first signal range.

[0013] Furthermore, the method comprises that after establishing communication between the first medical device and the second medical device, a communication signal of the first medical device has a second signal range, wherein the first signal range is less than the second signal range.

[0014] In addition, the present invention provides a first medical device, said first medical device being configured to transmit an RF-communication request signal to a second medical device, wherein the RF-communication request signal has a first signal range, wherein the first medical device is further configured, after establishing communication with the second medical device, to emit a communication signal having a second signal range, wherein the first signal range is less than the second signal range. Moreover, the present invention provides a medical communication system comprising the first medical device and a second medical device configured to generate a response signal to the RF -communi cation request signal of the first medical device, said response signal having a third signal range, wherein the third signal range is less than the second signal range of the communication signal of the first medical device.

[0015] Within the medical communication system, the first medical device may be a patient communication device and the second medical device may be an implantable medical device, and vice versa.

[0016] In addition, the present invention provides a computer program with program code to perform the method of the present invention when the computer program is executed on a computer. Moreover, the present invention provides a computer-readable data carrier containing program code of a computer program for performing the method of the present invention when the computer program is executed on a computer.

[0017] An idea of the present invention is to provide an improved communication method between medical devices which replaces the conventional method of coil telemetry with initiation of communication by RF telemetry.

[0018] Furthermore, the invention allows the implant or the implantable medical device to check whether the patient device or the patient communication device is in the immediate vicinity. A patient can thus use the patient communication device to authorize critical operations in the implant, such as remote programming.

[0019] The invention thus provides initiation of communication by RF telemetry while maintaining the properties of coil telemetry. In particular, it is ensured that the range of RF communication during initiation requires the patient to be in the immediate vicinity. This in turn enables that the desired patient is selected, as there may be other patients in a waiting room adjacent to the treatment room. The procedure makes it possible to clearly select the patient at the beginning of the communication. At the same time, it sets an additional cybersecurity hurdle against remote attackers. Communication in the uplink, i.e. from the implant to the patient device during the initiation phase has such a short range such that an attacker must be in the immediate vicinity in order to receive the information from the implant and thus be able to communicate with the implant.

[0020] Furthermore, the present invention allows miniaturized implants such as iLP and insertable / implantable cardiac monitor (ICM) to preserve size and lifetime while maintaining the benefits of home monitoring.

[0021] According to an aspect of the invention, the first signal range of the RF -communi cation request signal of the first medical device is determined by a first signal transmission power level of the RF -communi cation request signal, and wherein the second signal range of the communication signal of the first medical device is determined by a second signal transmission power level of the communication signal.

[0022] The first signal transmission power level of the RF -communi cation request signal is thus chosen appropriately in order to ensure its short signal range, whereas the second signal range of the communication signal of the first medical device is chosen to support a longer signal range.

[0023] According to a further aspect of the invention, the signal range of the RF-communication request signal of the first medical device and the communication signal of the first medical device is further determined by a signal modulation method and / or a data transmission rate. These additional factors can thus advantageously be considered in order to design an optimal signal range.

[0024] According to a further aspect of the invention, the first signal range of the RF-communication request signal is less than 3m, in particular less than 1.5m, wherein in the first signal range, the RF-communication request signal has a signal to noise ratio that is above a first predetermined threshold value and / or a packet loss that is below a second predetermined threshold value. The respective threshold values are thus chosen to match the desired signal range such that if the signal of the first medical device is received by another second medical device for which it is not intended the signal will not be usable since either the noise or the packet loss are too high at a distance higher than intended for communication with the patient medication device.

[0025] According to a further aspect of the invention, a response signal of the second medical device to the RF -communi cation request signal of the first medical device has a third signal range, wherein the third signal range is less than the second signal range of the communication signal of the first medical device.

[0026] The third signal range is thus analogously to the first signal range of the first medical device lower than the second signal range of the communication signal of the first medical device.

[0027] According to a further aspect of the invention, the third signal range of the response signal of the second medical device is determined by a third signal transmission power level of the response signal, and wherein the third signal range of the response signal of the second medical device is further determined by a signal modulation method and / or a data transmission rate. These additional factors can thus advantageously be considered in order to design an optimal signal range.

[0028] According to a further aspect of the invention, the third signal range of the response signal of the second medical device is less than 3m, in particular less than 1.5m, wherein in the third signal range, the response signal has a signal to noise ratio that is above a third predetermined threshold value and / or a packet loss that is below a fourth predetermined threshold value. The respective threshold values are thus chosen to match the desired signal range.

[0029] According to a further aspect of the invention, the RF -communi cation request signal from the first medical device is a programming request for programming a function of the second medical device. For this reason, it is important that the programming request is transmitted only within a short range such that the patient has to be in an immediate vicinity of the first medical device.

[0030] According to a further aspect of the invention, the first signal range of the RF-communication request signal of the first medical device and the second signal range of the communication signal of the first medical device are adapted to an antenna characteristic of the first medical device, and wherein the third signal range of the response signal of the second medical device is adapted to an antenna characteristic of the second medical device. The antenna characteristic of the respective device is thus advantageously taken into account when designing the signal range.

[0031] According to a further aspect of the invention, the transmission power level of the response signal transmitted by the second medical device is higher than a transmission power level of the RF -communi cation request signal transmitted by the first medical device. This functionality thus advantageously enables short-range communication for establishing communication between the second medical device and the first medical device in a similar fashion than using coil telemetry by means of RF telemetry.

[0032] According to a further aspect of the invention, a signal attenuation used to determine the transmission power level of signals transmitted by the second medical device and the first medical device is solely a free space attenuation, in particular at a distance of Im. Since communication between the second medical device and the patient medication device is intended to take place within a short distance within the same room only free space attenuation needs to be considered when designing the appropriate transmission power level of signals transmitted by the second medical device and the first medical device.

[0033] The herein described features of the communication method between medical devices are also disclosed for the first medical device, the medical communication system and vice versa.

[0034] For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments, which are specified in the schematic figures of the drawings, in which:

[0035] Fig. 1 shows a flowchart of a communication method between medical devices according to a preferred embodiment of the invention; and

[0036] Fig. 2 shows a medical communication system according to the preferred embodiment of the invention.

[0037] The communication method between medical devices shown in Fig. 1 comprises transmitting SI an RF-communication request signal 10 from a first medical device 12 to a second medical device 14, wherein the RF-communication request signal 10 has a first signal range R1.

[0038] Furthermore, the method comprises that after establishing S2 communication between the first medical device 12 and the second medical device 14, a communication signal 15 of the first medical device 12 has a second signal range R2, wherein the first signal range R1 is less than the second signal range R2.

[0039] Hereinafter, the first medical device 12 is a patient communication device 12, and the second medical device 14 is an implantable medical device 14. However, a reverse assignment of the patient communication device 12 and the implantable medical device 14 would also be possible.

[0040] The first signal range R1 of the RF-communication request signal 10 of the patient communication device 12 is determined by a first signal transmission power level Pl of the RF-communication request signal 10. Furthermore, the second signal range R2 of the communication signal 15 of the patient communication device 12 is determined by a second signal transmission power level P2 of the communication signal 15.

[0041] The signal range of the RF-communication request signal 10 of the patient communication device 12 and the communication signal 15 of the patient communication device 12 is further determined by a signal modulation method and / or a data transmission rate. The first signal range R1 of the RF-communication request signal 10 is less than 3m, in particular less than 1.5m, wherein in the first signal range Rl, the RF-communi cation request signal 10 has a signal to noise ratio that is above a first predetermined threshold value 16 and / or a packet loss that is below a second predetermined threshold value 18.

[0042] A response signal 20 of the implantable medical device 14 to the RF-communi cation request signal 10 of the patient communication device 12 has a third signal range R3, wherein the third signal range R3 is less than the second signal range R2 of the communication signal 15 of the patient communication device 12. The third signal range R3 of the response signal 20 of the implantable medical device 14 is determined by a third signal transmission power level P3 of the response signal 20, and wherein the third signal range R3 of the response signal 20 of the implantable medical device 14 is further determined by a signal modulation method and / or a data transmission rate.

[0043] In addition, the third signal range R3 of the response signal 20 of the implantable medical device 14 is less than 3m, in particular less than 1.5m, wherein in the third signal range R3, the response signal 20 has a signal to noise ratio that is above a third predetermined threshold value 22 and / or a packet loss that is below a fourth predetermined threshold value 24. The RF-communi cation request signal 10 from the patient communication device 12 is a programming request for programming a function of the implantable medical device 14.

[0044] The first signal range Rl of the RF-communication request signal 10 of the patient communication device 12 and the second signal range R2 of the communication signal 15 of the patient communication device 12 are adapted to an antenna characteristic of the patient communication device 12, and wherein the third signal range R3 of the response signal 20 of the implantable medical device 14 is adapted to an antenna characteristic of the implantable medical device 14. Moreover, the transmission power level of the response signal 20 transmitted by the implantable medical device 14 is higher than a transmission power level of the RF-communication request signal 10 transmitted by the patient communication device 12. A signal attenuation used to determine the transmission power level of signals transmitted by the implantable medical device 14 and the patient communication device 12 is solely a free space attenuation, in particular at a distance of Im.

[0045] Fig. 2 shows a medical communication system 1 according to the preferred embodiment of the invention.

[0046] The medical communication system 1 comprises a patient communication device 12, said patient communication device 12 being configured to transmit an RF -communi cation request signal 10 to an implantable medical device 14, wherein the RF-communication request signal 10 has a first signal range Rl, wherein the patient communication device 12 is further configured, after establishing communication with the implantable medical device 14, to emit a communication signal 15 having a second signal range R2, wherein the first signal range Rl is less than the second signal range R2. As mentioned above, a reverse assignment between devices 12 and 14 is also possible.

[0047] In addition, the medical communication system 1 further comprises an implantable medical device 14 configured to generate a response signal 20 to the RF-communication request signal 10 of the patient communication device 12, said response signal 20 having a third signal range R3, wherein the third signal range R3 is less than the second signal range R2 of the communication signal 15 of the patient communication device 12.

[0048] An approximate antenna characteristic is known for each implant type (or type of implantable medical device) such as ICD, IPG, ICM and iLP. This characteristic can be used to define a combination of power, modulation method and data rate that ensures that the RF communication has only a short range. Once packets have been exchanged in this mode to initiate communication, the combination of power, modulation method and data rate is increased for the rest of the session so that communication over a greater distance is possible.

[0049] After Auto-Implant-Detect, an implant is in Home Monitoring and Quick Mode. In this mode, it sends regular Home Monitoring messages, usually once a day and listens to Quick requests at regular intervals, usually every 2 minutes. Quick requests can be QuickCheck or QuickProgramming requests.

[0050] Both Home Monitoring messages and the response (or response signal) to a QuickCheck request are sent with RF transmission power and data rates that enable communication with a range of several meters.

[0051] In contrast, the QuickProgramming request, sent by the patient communication device 12 and the response sent by the implant are sent with a combination of power, modulation method and data rate that only allows a short range, e.g. Im with ideal propagation.

[0052] Ideal propagation means optimal orientation of the antenna characteristics, no polarization mismatch, i.e. both antenna characteristics are taken into account at their maximum antenna gain, wherein only free space attenuation, no loss due to fading is considered.

[0053] In the transmission chain, the following values can be assumed for a classic implant such as an IPG and ICD in the medical implant communication system band (MICS band) 402 - 405 MHz:

[0054] - Antenna gain external device: 2 dBi

[0055] - Antenna gain of classic implant: -30 dBi

[0056] - Sum of matching losses and surface acoustic wave filter (SAW filter): -10 dB

[0057] - Free space attenuation at a distance of r=lm: F = -24 dB.

[0058] This means that the entire transmission chain has an attenuation of -62 dB.

[0059] Using frequency shift keying (FSK) modulation, an RF chip with a bit error rate (BER) = IE-3 typically has a receiver sensitivity of -104 dBm @200 kb / s.

[0060] To limit communication to a distance of Im, the transmission power PI is therefore selected during the initiation phase

[0061] PI = -104 dBm - (-62 dB) = - 42 dBm Furthermore, with a low-lying implant e.g. iLP, the antenna gain would be approx. 10 dB lower, but there are no SAW filters and matching losses, so that the consideration is valid. This means that the power can be selected independently of the implant type.

[0062] Implants or implantable medical devices typically transmit with a power of 0 dBm. In free-space the RF-range is doubled with every 6dB increase of transmit power. The range would be 2(42 / 6)= 27= 128 times higher, i.e. 128m with pure free-space propagation (in free-space the RF-range is doubled with every 6dB increase of transmit power).

[0063] If an RF chip allows several data rates, it is advisable to select the highest one in order to minimize the transmission time and thus the energy consumption. Even in the case of the most favorable wave propagation in which two paths overlap in phase, i.e. constructive interference due to a reflection on a part of the body, e.g. an arm, the transmission radius would increase to a maximum of 2m. However, this extreme case is compensated for by the attenuation of a wall, so that it is guaranteed that a person who can be reached with the PI power is in the same room.

[0064] With the help of PI, the communication range has been limited to a distance of 1 m, i.e. from a distance of 1 m, the bit error rate quickly reaches BER=1E-1, see waterfall curve in Figure 3. At this bit error rate, the errors become too numerous to enable a packet to be transmitted. However, if the distance external device <-> implant is reduced significantly, e.g. to approx.

[0065] 10 cm, the free-space attenuation is limited to F = -4 dB. This reduces the bit error rate to BER<1E-1O, which ensures reliable transmission of a packet. RF telemetry can be used to ensure that the communication only reaches the desired patient, i.e. the distance dependency of coil telemetry has been simulated to a sufficient approximation.

[0066] The reliability of RF telemetry with the reduced power PI depends on the polarization mismatch and thus on the positioning and orientation of the external device in relation to the implant. If the orientation is unfavorable, communication may not be established on the first attempt. In this case, the external device should be repositioned, e.g. rotated to reduce the loss due to mismatch. The time interval between two attempts and therefore the typical latency time for establishing a connection is determined depending on the energy budget available for communication. Once communication has been successfully initiated, the transmission power is increased to the normal power level (PN level) permitted by the relevant standard in order to benefit from the greater range of RF telemetry.

[0067] The transmission power may be adjusted asymmetrically, i.e. different transmission power levels are selected for the external device (PN-ext) and implant (PN-Imp), as measurements are taken outside the body for radio approvals. The standard for the MICS band, for example, specifies a power limit of < -16 dBm. In order to be able to transmit long packets over a range of several metres without errors, taking into account fading and polarization mismatch, the RF chip in the implant works with a significantly higher transmission power.

[0068] Although specific embodiments have been illustrated and described herein, it will be understood by those skilled in the art that a variety of alternative and / or equivalent implementations exist. It should be noted that the exemplary embodiment or exemplary embodiments are examples only and are not intended to limit the scope, applicability or configuration in any way.

[0069] Rather, the foregoing detailed description provides the skilled person with a convenient guide to implementing at least one exemplary embodiment, it being understood that various changes in the scope of functionality and arrangement of the elements may be made without departing from the scope of the appended claims and their legal equivalents.

[0070] In general, this application intends to cover modifications or adaptations or variations of the embodiments disclosed herein. For example, a sequence of method steps may be modified. The method may further be carried out sequentially or in parallel, at least in part. Reference Signs

[0071] 1 Medical communication system

[0072] 10 RF -communi cati on request signal

[0073] 12 first medical device, e.g. patient communication device 14 second medical device, e.g. implantable medical device 16 first predetermined threshold value

[0074] 18 second predetermined threshold value

[0075] 20 response signal

[0076] 22 third predetermined threshold value

[0077] 24 fourth predetermined threshold value

[0078] Pl first signal transmission power level

[0079] P2 second signal transmission power level

[0080] P3 third signal transmission power level

[0081] R1 first signal range

[0082] R2 second signal range

[0083] R3 third signal range

[0084] S1-S2 method steps

Claims

Claims1. Communication method between medical devices, comprising the steps of:transmitting (SI) an RF-communication request signal (10) from a first medical device (12) to a second medical device (14), wherein the RF -communi cation request signal (10) has a first signal range (Rl); andafter establishing (S2) communication between the first medical device (12) and the second medical device (14), a communication signal (15) of the first medical device (12) has a second signal range (R2), wherein the first signal range (Rl) is less than the second signal range (R2).

2. Communication method of claim 1, wherein the first signal range (Rl) of the RF- communication request signal (10) of the first medical device (12) is determined by a first signal transmission power level (Pl) of the RF-communication request signal (10), and wherein the second signal range (R2) of the communication signal (15) of the first medical device (12) is determined by a second signal transmission power level (P2) of the communication signal (15).

3. Communication method of claim 1 or 2, wherein the signal range of the RF- communication request signal (10) of the first medical device (12) and the communication signal (15) of the first medical device (12) is further determined by a signal modulation method and / or a data transmission rate.

4. Communication method of any one of the preceding claims, wherein the first signal range (Rl) of the RF-communication request signal (10) is less than 3m, in particular less than 1.5m, wherein in the first signal range (Rl), the RF-communication request signal (10) has a signal to noise ratio that is above a first predetermined threshold value (16) and / or a packet loss that is below a second predetermined threshold value (18).

5. Communication method of any one of the preceding claims, wherein a response signal (20) of the second medical device (14) to the RF-communication request signal(10) of the first medical device (12) has a third signal range (R3), wherein the third signal range (R3) is less than the second signal range (R2) of the communication signal (15) of the first medical device (12).

6. Communication method of claim 5, wherein the third signal range (R3) of the response signal (20) of the second medical device (14) is determined by a third signal transmission power level (P3) of the response signal (20), and wherein the third signal range (R3) of the response signal (20) of the second medical device (14) is further determined by a signal modulation method and / or a data transmission rate.

7. Communication method of claim 5 or 6, wherein the third signal range (R3) of the response signal (20) of the second medical device (14) is less than 3m, in particular less than 1.5m, wherein in the third signal range (R3), the response signal (20) has a signal to noise ratio that is above a third predetermined threshold value (22) and / or a packet loss that is below a fourth predetermined threshold value (24).

8. Communication method of any one of the preceding claims, wherein the RF- communication request signal (10) from the first medical device (12) is a programming request for programming a function of the second medical device (14).

9. Communication method of any one of the preceding claims, wherein the first signal range (Rl) of the RF -communi cation request signal (10) of the first medical device (12) and the second signal range (R2) of the communication signal (15) of the first medical device (12) are adapted to an antenna characteristic of the first medical device (12), and wherein the third signal range (R3) of the response signal (20) of the second medical device (14) is adapted to an antenna characteristic of the second medical device (14).

10. Communication method of claim 5, wherein the transmission power level of the response signal (20) transmitted by the second medical device (14) is higher than a transmission power level of the RF -communi cation request signal (10) transmitted by the first medical device (12).

11. Communication method of any one of the preceding claims, wherein a signal attenuation used to determine the transmission power level of signals transmitted by the second medical device (14) and the first medical device (12) is solely a free space attenuation, in particular at a distance of Im.

12. First medical device (12), said first medical device (12) being configured to transmit an RF-communication request signal (10) to an second medical device (14), wherein the RF-communication request signal (10) has a first signal range (Rl), wherein the first medical device (12) is further configured, after establishing communication with the second medical device (14), to emit a communication signal (15) having a second signal range (R2), wherein the first signal range (Rl) is less than the second signal range (R2).

13. Medical communication system (1) comprising:the first medical device (12) of claim 12; anda second medical device (14) configured to generate a response signal (20) to the RF- communication request signal (10) of the first medical device (12), said response signal (20) having a third signal range (R3), wherein the third signal range (R3) is less than the second signal range (R2) of the communication signal (15) of the first medical device (12).

14. Computer program with program code to perform the method of any one of claims 1 to 11 when the computer program is executed on a computer.

15. Computer-readable data carrier containing program code of a computer program for performing the method of any one of claims 1 to 11 when the computer program is executed on a computer.

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