Processing unit and method for fetal monitoring

Abstract

Apparatus and methods for deriving and displaying a time-averaged fetal heart rate signal in combination with microvariability information relating to beat-to-beat heart rate signal variability within different time-averaged epochs or windows. Supplementary information is displayed, for example, in temporal alignment or registration with the time-averaged heart rate signal, which indicates signal variability information during the averaging window of the time-averaged signal.

Description

TECHNICAL FIELD

[0001] The present invention relates to a processing unit and a method for deriving and presenting information related to a fetal heart from sensor data. BACKGROUND

[0002] Electronic fetal monitoring (EFM) comprises methods for recording life parameters of a fetus in utero, such as the heart rate, during pregnancy and delivery.

[0003] The most common EFM methods comprise cardiotocography, including the use of ultrasound to monitor the fetal heart rate (FHR), and fetal electrocardiography (fECG), which includes the use of ECG measurement technology. For fECG, this can be done by attaching electrodes to the fetal scalp in the later stages of delivery or by attaching electrodes to the maternal abdomen and electronically or digitally recovering the fetal ECG signal.

[0004] EFM measurements can be used, among others, to assess the health, metabolic condition and oxygen supply of the fetus. This information can be used to inform treatment decisions, for example, for determining whether a caesarean delivery is medically necessary to prevent hypoxic damage to the fetus.

[0005] Improving the quality of the information provided by EFM systems can therefore improve the medical outcome of patients and help to reduce the rate of unnecessary caesarean sections.

[0006] Current EFM systems typically output the measurement information in the form of a graph of the fetal heart rate over a time range of several minutes to several hours. Each recorded heart rate data point is typically an average of several beat-to-beat heart rate values over an averaging period of several seconds. This makes the graph more easily readable by smoothing very short-term fluctuations. However, it also has to discard some information contained in the true beat-to-beat heart rate recording. This type of information is often referred to as FHR microvariability or microfluctuation.

[0007] Microvariability information can be a useful clinical parameter, as for example high beat-to-beat heart rate variability or low variability can indicate different clinically significant states of the fetus. However, simply displaying the entire non-smoothed beat-to-beat heart rate would then impede the normal interpretation of the heart rate due to the high fluctuation level. Also, it is not desirable to change the standard representation of the fetal heart rate, as this would then appear unfamiliar to the clinician, making it difficult for them to quickly apply their previous experience in interpreting the graph for quick decision making.

[0008] An improved EFM system that is able to overcome one or more of the above problems would therefore be valuable.

[0009] Electronic fetal monitoring (EFM) typically uses Doppler ultrasound to acquire a pulse (heart rate) signal from a fetus in utero during pregnancy and delivery. The acquired pulse signal is used to compute a fetal heart rate (FHR). SUMMARY

[0010] The invention is defined by the claims.

[0011] According to examples in accordance with aspects of the invention, there is provided a processing unit for fetal heart rate monitoring, the processing unit being configured to:

[0012] receive physical sensor data containing information indicative of fetal heart activity, and process the sensor data to derive a fetal heart rate signal;

[0013] derive a moving time average signal from the fetal heart rate signal with a time average window of defined duration;

[0014] derive supplemental information for supplementing the time average signal with additional information on fetal heart rate microvariability based on local variations of the heart rate signal during each average window of the moving time average signal;

[0015] generate a display output for providing to a display device, the display output being for simultaneous display of a graphical representation of a signal trace of the moving time average heart rate signal and a graphical representation of the supplemental information.

[0016] Embodiments of the invention are based on deriving a beat-by-beat fetal heart rate signal containing microvariability information, then generating a display output comprising a smoothed (time average) heart rate signal (according to standard presentation modes for heart rates), and embodiments of the invention further comprise a simultaneous display of information (i.e. microvariability information) about variations of the signal during each average time window.

[0017] Thus, embodiments provide a system or method for supplementing a (e.g. long term) time average FHR graph with additional information on FHR microvariability while substantially preserving the appearance of a standard (time average) FHR graph that is familiar to people accustomed to EFM systems.

[0018] This is by means of presenting the information lost from the beat-by-beat FHR signal in the form of supplemental beat-to-beat variability information when deriving a time smoothed signal, in preferred embodiments the supplemental beat-to-beat variability information can thus be plotted in line with the fetal heart rate signal itself, e.g. parallel along the same time axis.

[0019] Fetal heart rate signal means a signal indicative of a fetal heart rate as a function of time, for example.

[0020] The derived fetal heart rate signal is preferably a beat-by-beat fetal heart rate signal.

[0021] The supplemental information preferably indicates the beat-by-beat variability of the heart rate.

[0022] The supplemental information is displayed graphically in a way that makes it more intuitive to interpret.

[0023] By displaying the supplemental information simultaneously with the time-averaged heart rate signal, but as a separate graphical representation, this ensures that the microvariability information is presented spatially in line or in conjunction with the corresponding heart rate signal (so that both can be read and interpreted together in the same context), while ensuring that the clinician’s natural interpretation of the standard time-averaged heart rate signal is not hindered.

[0024] In examples, the supplemental information can be provided as overlaid on or adjacent to the graphical representation of the fetal heart rate signal.

[0025] The supplemental information can be provided as displayed in time registration or alignment with the time-averaged heart rate signal, i.e. each supplemental data point or information point is aligned in time with the corresponding time-averaged window of the time-averaged signal it corresponds to.

[0026] In examples, the fetal heart rate signal can be displayed as a graph with an axis defining a graph area, and wherein the supplemental information is displayed within the same graph area. For example, the supplemental information can be represented in the form of one or more signal traces plotted on the same time axis as the time-averaged heart rate signal. In this way, the supplemental information can be provided in time registration or alignment with the time-averaged heart rate signal, meaning that both can be easily interpreted together in conjunction.

[0027] In some examples, the one or more signal traces can be spatially offset from the time-averaged heart rate signal, and optionally displayed in a different line style than the time-averaged heart rate signal. For example, they can be located above or below the time-averaged signal, for example.

[0028] By way of non-limiting example, different line style means different line thickness, line boldness, line color, line dash pattern (or continuous line).

[0029] According to one or more embodiments, the supplemental information can comprise a minimum fetal heart rate and / or a maximum fetal heart rate during each average window.

[0030] According to one or more embodiments, the supplemental information can comprise a first signal trace and a second signal trace representing a minimum fetal heart rate and a maximum fetal heart rate, respectively, during each averaging period, the signal traces being displayed below and above the time-averaged signal, respectively, plotted on the same time axis as the time-averaged signal.

[0031] According to one or more advantageous embodiments, the area between the time-averaged signal and each of the signal traces for maximum and minimum heart rate values can be provided at least partially shaded or colored. By thus providing the area between the maximum and minimum lines filled or shaded or highlighted, this provides a highly intuitive integrated representation of the supplemental heart rate information and the time-averaged heart rate information in a way that allows both to be read and understood in conjunction.

[0032] According to one or more further embodiments, the representation of the supplemental information can comprise a box plot of periodic intervals plotted at consecutive points along the time-averaged heart rate signal. For example, they can be plotted at points that are in time alignment with the particular time-averaging window they correspond to.

[0033] The supplemental information can further comprise a quartile range of the heart rate, a percentile range of the heart rate and / or a standard deviation of the heart rate (over an averaging period) for each of the averaging windows.

[0034] According to one or more sets of embodiments, the physical sensor data can be ultrasound data, and preferably Doppler ultrasound data.

[0035] Examples according to a further aspect of the application provide a system, comprising:

[0036] a processing unit according to any of the examples or embodiments outlined above or described below or according to any of the claims of the present application; and

[0037] a display device operatively coupled with the processing unit for receiving the display output.

[0038] The system can further comprise one or more physical sensors operatively coupled to the processor unit for supplying the physical sensor data, such as one or more ultrasound transducer units.

[0039] Examples according to a further aspect of the application provide a processing method for fetal heart rate monitoring, comprising:

[0040] receiving physical sensor data containing information indicative of fetal heart activity, and processing the sensor data to derive a fetal heart rate signal;

[0041] deriving a moving time average signal from the fetal heart rate signal with a time average window of defined duration;

[0042] deriving supplemental information for supplementing the moving time average signal with additional information on fetal heart rate microvariability based on local variations of the fetal heart rate signal during each average window of the moving time average signal; and

[0043] generating a display output for providing to a display device, the display output for simultaneous display of a graphical representation of the moving time average heart rate signal and a representation of the supplemental information.

[0044] Examples in accordance with a further aspect of the application provide a computer program product comprising code means which, when executed on a processor, are configured to cause the processor to carry out a method in accordance with any example or embodiment summarized above or described below or in accordance with any claim of this application.

[0045] These and other aspects of the application will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0046] For a better understanding of the application, and to show how it can be implemented in practice, reference will now be made, purely by way of example, to the accompanying drawings in which:

[0047] Figure 1 schematically illustrating example embodiments of the application;

[0048] Figure 2 illustrating an example display output in accordance with one or more embodiments;

[0049] Figure 3 illustrating a further example display output in accordance with one or more embodiments;

[0050] Figure 4 illustrating a further example display output in accordance with one or more embodiments;

[0051] Figure 5 summarizing an example system in block diagram form in accordance with one or more embodiments;

[0052] Figure 6 showing a further example system in accordance with one or more embodiments; and

[0053] Figure 7 An example method according to one or more embodiments is outlined in block diagram form. DETAILED DESCRIPTION

[0054] The application will be described with reference to the accompanying drawings.

[0055] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of apparatuses, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the application. These and other features, aspects, and advantages of the apparatuses, systems and methods of the present application will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the drawings are only schematic, and that they are not intended to be to scale. It should further be understood that the same reference numerals are used throughout the drawings for like or similar items.

[0056] The present application provides apparatuses and methods for deriving and displaying a time-averaged fetal heart rate (FHR) signal in conjunction with microvariability information relating to beat-to-beat signal variability within different time-averaged stages or windows. Thus, supplemental information is displayed, for example, in temporal alignment or registration with the time-averaged heart rate signal, which indicates the variability information of the signal during the averaging window of the time-averaged signal.

[0057] When using a FHR system or apparatus, a user interprets the fetal heart rate trace displayed on the display unit based on their prior knowledge and experience. This analysis is essentially a pattern matching process: the patterning of the signal trace is matched to the clinician's memory of previous signal traces and their clinical significance. Thus, to ensure timely and reliable interpretation by the clinician, it is preferred that the FHR system displays the fetal heart rate signal trace in a manner that does not deviate from the typical way of displaying and presenting the signal. For example, it is preferred that the aspect ratio, recording speed and appearance of the trace pattern remain substantially the same.

[0058] The typical way of presenting fetal heart rate information is via a time-averaged or smoothed fetal heart rate signal trace, in which the microvariability across a defined time period is smoothed by averaging over a moving time window of the length of the time period. Thus, in typical prior apparatuses, the microvariability is not displayed or presented. Abrupt changes in representation would lead to great difficulty in interpretation.

[0059] However, FHR microvariability is a clinically important parameter for assessing fetal wellbeing. Thus, it would be desirable to provide some representative presentation of this information to the user, so that they can use it in conjunction with the time-averaged fetal heart rate.

[0060] One way would be to simply display the entire non-averaged (beat-by-beat) fetal heart rate signal alongside the time-averaged heart rate signal, such that all information is presented to the viewer. However, this is not a particularly useful or intuitive way of presenting the information, as it is difficult for the clinician to relate the two to each other. Separating each in a separate graph, for example, spatially separates the data despite the fact that the data are part of the same background and should therefore be read and interpreted in conjunction.

[0061] Embodiments of the present application therefore propose a means for providing information to a user about the fetal heart rate, which can include both the time-averaged fetal heart rate signal for interpretation by the clinician as well as microvariability information, in a manner that allows the two to be easily read in conjunction with each other and interpreted together. For example, ideally, both would be displayed in a manner such that they are time-registered with each other, preferably on the same graph or graph area, for example within the same graph axis.

[0062] Figure 1 The input, processing steps and output of an example processing unit or method for fetal heart rate monitoring according to one or more embodiments of the present application are schematically outlined.

[0063] Figure 1 An example processing unit 22 is shown. Although the processing unit is illustrated as a single component, in further embodiments it can be implemented by a plurality of processing components, for example a plurality of processors or controllers. Its processing functionality can be distributed among a plurality of processors or components. However, it can be implemented by a single processor, such as a microprocessor unit.

[0064] The processing unit is adapted to receive physical sensor data 18 containing information indicative of fetal heart activity, and to process the sensor data to derive a fetal heart rate signal ("FHR signal"). By way of example, the processing unit can comprise one or more data input ports for receiving input sensor data. It can be arranged to receive input sensor data over a wired or wireless data communication link. The processing unit can have one or more pre-stored algorithms for processing the input data to derive a fetal heart rate signal.

[0065] Preferably, the input sensor data is sensor data having sufficient temporal resolution or data sampling rate for the processing unit to derive a beat-by-beat heart rate signal. Therefore, preferably, the derived heart rate signal is a beat-by-beat heart rate signal. This means a heart rate signal comprising a heart rate measurement value for each heart beat period.

[0066] The processing unit is further configured to derive a moving time average signal from the heart rate signal. The time average signal can be computed using a moving time average window of defined duration. The defined duration can be adjustable. It can be uniform across different average windows of a given signal, or can vary. Preferably, it is uniform. The time average signal provides a smoothed heart rate signal that is consistent with the standard presentation of the heart rate signal within standard FHR systems. Thus, the clinician is able to quickly and efficiently interpret the signal using their prior experience and knowledge.

[0067] The processing unit is further configured to derive supplemental information based on local variations of the derived heart rate signal during each average window of the time average signal. In this step, the processing unit derives information about the micro variability of the signal for each of the average windows applied in deriving the time average signal. Thus, micro variability information is derived for each data point of the time average signal, as each data point of the time average signal corresponds to a single average window of the overall heart rate signal. The supplemental information preferably indicates beat-to-beat variability of the heart rate.

[0068] The processing unit is further configured to generate a display output 26 for provision to a display device, the display output being for simultaneous display of: a graphical representation of the signal trace of the time average heart rate signal and a graphical representation of the supplemental information.

[0069] The display output can for example be a control signal or control output for controlling the display unit to display the two graphical representations. It can be a data output representing the desired display presentation of the two graphical representations on the display device in a data format recognised by the display device.

[0070] Graphical representation, as opposed to textual output, means pictorial or visual or diagrammatic. The representation can include text (e.g. labels or associated data values), but should include a graphical or pictorial aspect of the representation of the supplemental information. This makes the displayed information more intuitive to interpret, and means that the time average signal and the supplemental information can be graphically integrated, making it easier to interpret both consistently.

[0071] The graphical representation of the time average signal includes at least a representation of the signal trace or waveform of the time average signal.

[0072] The graphical representation of the supplemental information can take any of a number of different forms. In some examples, it can also include one or more waveforms representing the signal trace of one or more parameters derived from the variability information. It can take the form of different types or graphs or charts, such as a box plot, a bar or graph, a scatter plot or any other example graph or chart. Any other graphical representation can also be used.

[0073] The processing unit can be adapted to receive sensor data from any of a plurality of different sensor modalities. In one set of advantageous embodiments, the processing unit can be adapted to receive ultrasound data, and preferably Doppler ultrasound data. In one other example, the sensor data can comprise ECG sensor data.

[0074] It can receive the data directly from one or more sensor units, such as one or more ultrasound probes, or it can receive the data from a data store or a remote server.

[0075] There are different options for the supplementary information derived from the fetal heart rate signal. In each case, the supplementary information is information related to, or based on, or representing a feature or parameter of the variation of the (beat-by-beat) fetal heart rate signal across each average or smoothing window.

[0076] In some examples, it can comprise statistical parameters or values derived from the fetal heart rate signal across each average window. By way of non-limiting example, one option, the supplementary information can comprise any one or more of: an average heart rate value (e.g. mean and / or median), a minimum and / or maximum beat-by-beat fetal heart rate across each average window, a quartile range for each average window, a standard deviation of heart rate values across each average window, a percentile range of heart rate values across each average window, information about outliers in each average window, and any other statistics related to fetal heart rate variability over the average time interval.

[0077] The display output can be configured to display the supplementary information and the time-averaged signal in different ways. Preferably, the display output integrates the graphical representation of the supplementary information with the time-averaged heart rate signal in some way, so that both can be read in conjunction with each other. For example, the supplementary information can be superimposed on top of the graphical representation of the time-averaged heart rate signal, or the graphical of the time-averaged signal can be supplemented or enhanced with markers or annotations derived from the microvariability statistics.

[0078] For example, the fetal heart rate signal can be displayed as a graph with an axis defining a graph area, and wherein the supplementary information is displayed within the same graph area. Preferably, the supplementary information is displayed time-registered or aligned with the time-averaged heart rate signal. For example, each data point of the supplementary information is displayed time-registered or aligned with the average data point of the time-averaged signal it corresponds to, i.e. it is aligned with the time point of the particular average window it corresponds to (e.g. the center time point of the average window).

[0079] According to one or more embodiments, the supplemental information can be represented in the form of one or more signal traces plotted on the same time axis as the time-averaged heart rate signal.

[0080] The one or more signal traces can be, for example, spatially offset from the time-averaged heart rate signal. In some examples, these supplemental signal traces can be displayed in a different line style than the time-averaged heart rate signal. For example, they can be displayed above or below the time-averaged signal. For example, the supplemental signal traces can be plotted with a more faint line style or a dashed or dotted line, so that they are easily distinguishable from, for example, the time-averaged heart rate signal presented on the same time axis.

[0081] Figure 2 An example display output 32 is shown according to one or more embodiments. The display output includes a graphical representation of a signal trace 36 of a time-averaged fetal heart rate signal. The signal trace 36 of the time-averaged heart rate signal is displayed in the form of a graph having axes 34a, 34b. The x-axis 34b corresponds to time, and the y-axis corresponds to heart rate (beats per minute). The x- and y-axes define a graph area within which the time-averaged heart rate signal trace 36 is plotted.

[0082] A first supplemental signal trace 38a corresponding to the maximum heart rate value of each averaging window of the time-averaged heart rate signal 36 is displayed on the same graph within the same graph area. A second supplemental signal trace 38 corresponding to the minimum heart rate value of each averaging window of the time-averaged heart rate signal is also displayed on the same graph within the same graph area. The maximum signal trace 38a and the minimum signal trace 38b are displayed in temporal alignment (in time registration) with the time-averaged heart rate signal 36, so that each maximum of the maximum signal trace 38a and each minimum of the minimum signal trace 38b is aligned with the average heart rate point of the same averaging window of the average signal 36.

[0083] Figure 3 A further example display output 32 is shown according to one or more embodiments. This display output is the same as the display output of Figure 2 except that the area between the maximum signal trace 38a and the minimum signal trace 38b is provided as hatched or colored. Although in the display output of Figure 3The solid shading is shown in the middle, but this is by way of example only. It could be cross-hatched or highlighted or provided in a different colour or any other form of area fill or highlighting. By filling or shading the area between the maximum and minimum signal traces, this makes the supplementary information (i.e. the maximum and minimum values) easier and more intuitive to interpret in conjunction with the time-averaged heart rate signal 36. It effectively provides a "halo" area around the time-averaged heart rate signal 36 which enables the supplementary information to be read and interpreted in a highly visual manner. This form of visual presentation is quicker and easier to interpret than, for example, a textual output or simply the signal traces alone.

[0084] In Figure 4 A further example display output 32 according to one or more embodiments is shown in the middle. In this example, the supplementary information is displayed in the form of a series of periodic interval box plots 42. The box plots are each plotted superimposed on top of the time-averaged heart rate signal 36, with the time point of the time-averaged window to which the statistical information corresponds being aligned in time.

[0085] The box plot graph is a well-known and conventional graphical representation of statistical information. They can represent at least the maximum and minimum heart rate values for each of the time-averaged windows and / or the upper and lower quartiles and representation of the inter-quartile range for each average window. Although only a small selection of plotted box plot boxes are shown in the Figure 4 middle, this is by way of illustration only, and in further examples, a separate box can be plotted for each time-averaged window of the time-averaged heart rate signal 36.

[0086] According to one or more advantageous embodiments, the processing unit can be configured to derive an assessment of the status of the fetus from the time-averaged heart rate signal and / or the supplementary information. It can be configured to derive one or more parameters relating to or indicative of the status of the fetus, and also to display a representation or indication of this one or more parameters. It can be configured to generate one or more alerts or notifications in dependence on the value of the derived one or more parameters.

[0087] The derived information or parameters relating to the status of the fetus can include, for example, whether the fetal heart rate is within a predefined normal range or in a bradycardia / tachycardia range. It can include whether there is an arrhythmia.

[0088] The derived information or parameters relating to the status of the fetus can be derived from a combination of the average heart rate and the supplementary information. For example, tachycardia in combination with high microvariability can be indicative of an early stage of fetal hypoxia.

[0089] In one or more examples, the derived information may take into account changes in heart rate and / or supplemental information over time. For example, tachycardia with increased microvariability occurs in the early stages of fetal hypoxia, and if oxygen supply is not restored, this is followed by a decreased heart rate with decreased microvariability. On the other hand, if an episode of tachycardia with high microvariability is followed by a heart rate within the normal range with normal microvariability, this can be considered an indication that fetal oxygen supply is adequate again.

[0090] According to one or more embodiments, the derived information may include an Apgar score or a prediction of estimated fetal blood pH or estimated blood lactate levels. These estimates can be used as an indication of whether interventions such as performing a cesarean section are necessary.

[0091] Although in the embodiments discussed above, the processing unit is configured to generate display output for displaying supplementary information that causes the time-averaged heart rate signal, in other examples, the processing unit may generate graphical output for provision to different output devices (e.g., printers or projectors or a user's handheld mobile communication device). In all cases, the generated output is a graphical representation indicating or representing the time-averaged heart rate signal and supplementary information. Therefore, it can be more generally referred to as graphical output.

[0092] Embodiments of the present invention include means for processing input sensor data to derive a fetal heart rate signal. Processes and methods for performing this step are well known in the art, and those skilled in the art will know means for deriving a fetal heart rate signal from sensor data from different modalities.

[0093] By way of example, a typical method is to determine the short-term period of the ultrasound signal by its autocorrelation. The heart rate is the reciprocal of the short-term period. This method is discussed in US 3991365, "Instantaneous frequency measurement system".

[0094] In addition, other methods based on detecting short-term periodic components, such as short-term Fourier transform, can also be applied. Unlike ECG signals, Doppler ultrasound signals may not have a clear pattern because their detail depends on what anatomical structures (heart, arteries) are within the ultrasound beam field and on the relative orientation of the structures.

[0095] By way of example, from a fetal ECG, the heart rate can be determined by detecting the R-waves (or the entire QRS complex) and measuring the time between two R-waves or by other methods of detecting short-term periodicity such as autocorrelation or Fourier transform. There are a wide variety of methods for detecting R-waves ranging from simple methods such as peak detection to more complex methods such as using pattern matching or artificial neural networks.

[0096] By way of example, example methods for deriving a fetal heart rate from ECG measurement data are outlined in Chapter 5 of Rik Vullings’ “Non-invasive fetal electrocardiogram: analysis and interpretation” or Hasan et al. “Detection and Processing Techniques of FECG Signal for Fetal Monitoring” (https: / / www.ncbi.nlm.nih.gov / pmc / articles / PMC3055800 / ).

[0097] According to a further aspect of the application, there can be provided a system comprising a processing unit according to any of the examples or embodiments outlined above or described below or according to any claim of the present application and further comprising a display unit (or other output device) for displaying display / graphical output generated by the processing unit. In Figure 5 An example is shown in block diagram form in Figure 1. The display unit 28 is operatively coupled with the processing unit 22.

[0098] Figure 6 A further example system 70 according to one or more embodiments is schematically depicted. The system comprises a processing unit 22 (in this case, the system comprises a base station containing one or more processors for performing the functions of the processing unit). The system comprises a display unit 28 which is operatively coupled with the processing unit 72. In this example, the system further comprises a physical sensor unit 76 having a connector 78 for connecting with an input port 74 of the processing unit in use. The physical sensor unit is for acquiring physical sensor data for supply to the processing unit. The sensor unit may, for example, be an ultrasound transducer unit. In other examples, it can be an ECG sensor / electrode. In the case of ECG sensing, a plurality of ECG electrodes can be provided for supplying ECG data to the processing unit.

[0099] A further aspect of the application provides a method for fetal heart rate monitoring. In Figure 7 An example method 90 according to one or more embodiments is outlined in block diagram form in Figure 2.

[0100] The method comprises receiving 92 physical sensor data containing information indicative of fetal heart activity.

[0101] The method further comprises processing the sensor data to derive 94 a fetal heart rate signal.

[0102] The method further comprises deriving 96 a moving time average signal from the heart rate signal using a time average window of defined duration.

[0103] The method further comprises deriving 98 supplemental information based on local variations of the heart rate signal during each average window of the time average signal.

[0104] The method further comprises generating 100 a display output for provision to a display device, the display output being for simultaneous display of a graphical representation of the time average heart rate signal and a representation of the supplemental information.

[0105] Implementation options and details of each of the above steps can be understood and interpreted in accordance with the explanations and descriptions provided above for the device aspect of the invention, i.e. the processing unit aspect.

[0106] Any of the above-described examples, options or embodiment features or details in relation to the device aspect of the invention (in relation to the processing unit) can be applied or combined or incorporated into the method aspect of the invention mutatis mutandis.

[0107] Examples in accordance with a further aspect of the invention also provide a computer program product comprising computer program code means which, when executed on a computing device having a processing system, cause the processing system to perform all the steps of a method in accordance with any of the example methods outlined above or in any claim of the present application.

[0108] As described above, the system utilizes a processor unit to perform data processing. The processor unit can include one or more processors. The processor unit can be implemented in numerous ways, with software and / or hardware, to perform the required various functions. The processor unit typically employs one or more microprocessors that can be programmed using software (e.g., microcode) to perform the required functions. The processor can be implemented as a combination of dedicated hardware to perform some functions and one or more programmed microprocessors and associated circuitry to perform other functions.

[0109] Examples of circuitry that can be employed in various embodiments of the disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0110] In various implementations, a processor unit can be associated with one or more storage media such as volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM. The storage media can be encoded with one or more programs that, when executed on one or more processors and / or controllers, carry out at least some of the required functions. Various storage media can be fixed within a processor or controller or can be transportable, such that the one or more programs stored thereon can be loaded into a processor.

[0111] Modifications of the disclosed embodiments will occur to those skilled in the art upon reading the description of the application. The order of the steps of the methods can be varied, and other steps can be added or replaced. The drawings and the specification are, accordingly, to be regarded in an illustrative rather than a restrictive sense. In the claims, the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude a plurality.

[0112] Although specific measures are recited in mutually different dependent claims, this does not indicate that a combination of these measures cannot be used with advantage.

[0113] A computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state storage medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.

[0114] If the term "comprise" is used in the claims or the specification, it should be noted that the term "comprise" is intended to be equivalent to the term "configured to" or "is configured to".

[0115] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A processing unit (22) for fetal heart rate monitoring, said processing unit being configured to: Receive physical sensor data containing information indicating fetal cardiac activity, and process the sensor data to derive a fetal heart rate signal; The moving time-averaged signal is derived from the fetal heart rate signal using a time-averaged window with a defined duration. Supplementary information is derived based on the local variations of the fetal heart rate signal during each averaging window of the moving time-averaged signal to supplement the moving time-averaged signal with additional information about the microvariability of the fetal heart rate; A display output (26) is generated for providing to a display device (28), the display output being used to simultaneously display: a graphical representation of the signal trace of the moving time average signal and a graphical representation of the supplementary information.

2. The processing unit according to claim 1, wherein, The fetal heart rate signal is displayed as a graph with axes that define graph regions, and supplementary information is displayed within the same graph regions.

3. The processing unit according to claim 2, wherein, The supplementary information is represented in the form of one or more signal traces drawn on the same time axis as the moving-time average signal.

4. The processing unit according to claim 3, wherein, The one or more signal traces deviate spatially from the moving-time average signal.

5. The processing unit according to claim 4, wherein, The one or more signal traces are displayed with a line pattern different from that of the moving-time average signal.

6. The processing unit according to any one of claims 1-5, wherein, The supplemental information includes the minimum and / or maximum fetal heart rate during each mean window.

7. The processing unit according to claim 6, wherein, The supplementary information includes a first signal trace and a second signal trace representing the minimum and maximum fetal heart rates during each mean cycle, respectively, which are displayed below and above the moving-time average signal and plotted on the same time axis as the moving-time average signal.

8. The processing unit according to claim 7, wherein, The region between the moving time average signal and each of the signal traces for the maximum and minimum heart rate values ​​is provided as at least partially shaded or colored.

9. The processing unit according to claim 6, wherein, The representation of the supplementary information includes a box plot drawn at periodic intervals along consecutive points of the moving-time average signal.

10. The processing unit according to any one of claims 1-5, wherein, The supplemental information also includes the quartile range of the heart rate, the percentile range of the heart rate, and / or the standard deviation of the heart rate for each average window of the average window.

11. The processing unit according to any one of claims 1-5, wherein, The physical sensor data is ultrasonic data.

12. A processing system (70), comprising: The processing unit (22) according to any one of claims 1-11; as well as Display device (28), which is operatively coupled to the processing unit for receiving the display output.

13. The system of claim 12 further includes one or more physical sensors operatively coupled to the processing unit for supplying data from the physical sensors.

14. The system according to claim 13, wherein, The one or more physical sensors are one or more ultrasonic transducer units.

15. A processing method (90) for fetal heart rate monitoring, comprising: Receive (92) physical sensor data containing information indicating fetal cardiac activity, and process (94) the sensor data to derive a fetal heart rate signal; The (96) moving time average signal is derived from the fetal heart rate signal using a time-averaged window of defined duration; (98) Supplementary information (to add additional information about fetal heart rate microvariability to the moving time-averaged signal) is derived based on the local variations of the heart rate signal during each averaging window of the moving time-averaged signal; and Generate (100) a display output for providing to a display device, the display output being used to simultaneously display: a graphical representation of the moving time average signal and a representation of the supplementary information.

16. A computer program product including a code module, said code module being configured, when run on a processor, to cause the processor to perform the method of claim 15.

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