WO2012080909A1

WO2012080909A1 - Monitoring for postpartum hemorrhage

Info

Publication number: WO2012080909A1
Application number: PCT/IB2011/055524
Authority: WO
Inventors: Pallavi Vajinepalli; Rajendra Singh Sisodia; Celine Firtion; Ajay Anand; Hua Xie; Payal Keswarpu; Lalit Gupta; John Petruzzello
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2010-12-14
Filing date: 2011-12-07
Publication date: 2012-06-21
Also published as: RU2604704C2; CN103370012A; BR112013014560A2; CN103370012B; RU2013132468A

Abstract

A device for monitoring a subject for postpartum hemorrhage is disclosed. It comprises an ultrasound transducer for applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature. A second ultrasound transducer radiates ultrasound energy into the subject and receives the echoed ultrasound energy. By analyzing a signal representative of the received echoed ultrasound energy the speed of propagation of the shear wave in the uterine musculature is determined. The value of the tone of the uterine musculature is estimated based on the speed of propagation of the shear wave and conveyed to a user. Further, a device for detecting and locating a hemorrhage and estimating its severity are also disclosed.

Description

Monitoring for postpartum hemorrhage

FIELD OF THE INVENTION

This disclosure belongs to the field of monitoring a human subject in general. It belongs to the field of non-invasive monitoring of a human subject for hemorrhage, postpartum, using ultrasound, in particular.

BACKGROUND OF THE INVENTION

Worldwide, many deaths related to childbirth are caused by Postpartum

Hemorrhage (PPH). Normally, soon after childbirth the uterus contracts to a near normal size. When the uterus contracts the blood vessels in the uterine muscles become constricted and bleeding in the uterus stops. However, if there is residual placenta in the uterus or if the uterine muscles have lost their tone due to other reasons - a condition referred to as uterine atony - the bleeding does not stop. If it is unchecked the mother experiences severe loss of blood and that could be fatal. Often when a baby is born, the care givers' attention is focused on the new born and if the mother is left unattended even for short periods and she is hemorrhaging, the consequences could be fatal.

US-2008/0139967 Al discloses an electrode interface system for providing a connection between at least one electrode and a maternal- fetal monitor, wherein the interface system converts electrical muscle activity captured by the electrode(s) into uterine activity data signals for use by the maternal- fetal monitor. The electrode interface system of the invention preferably includes a conversion means for converting the signals from the electrode(s) into signals similar to those produced by a tocodynometer. this provides a means for monitoring the uterine tone, providing an early warning of atony and potential

hemorrhage.

SUMMARY OF THE INVENTION

It is preferable to have a device for non-invasively estimating the tone of uterine musculature and monitoring a subject during a period immediately after childbirth in a more direct way and provide early warning about a possibility of PPH to a user or a care giver. It is more preferable to have such device for also determining the location of the hemorrhage in the uterus and its severity. It is further preferable to have a device that also provides decision support to a care giver to manage PPH.

Such a device is disclosed herein. A device for estimating a tone of uterine musculature wherein the device comprises a first ultrasound transducer for applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature, a second ultrasound transducer for radiating ultrasound energy into the subject and receiving an echoed ultrasound energy, an analysis unit for analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature and a processor unit for determining a value of the tone of the uterine musculature, for further use, based on the speed of propagation of the shear wave.

The disclosed device may provide the advantage that using the value of the tone of the uterine musculature a subject may receive the required medical attention required to prevent sever blood loss. The device may further enable a subject being monitored for PPH without the need for a caregiver's presence in the immediate vicinity of the subject and providing constant attention to the subject.

Further, a system for monitoring a subject for postpartum hemorrhage is also disclosed. The system for monitoring a subject for postpartum hemorrhage comprises a first ultrasound transducer for applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature, a second ultrasound transducer for radiating ultrasound energy into the subject and receiving an echoed ultrasound energy, an analysis unit for analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature, a processor unit for determining a value of the tone of the uterine musculature based on the speed of propagation of the shear wave and a user interface for conveying an information based on the value of the tone of the uterine musculature, to a user.

Such a system may have the advantage that PPH can be managed comprehensively by a caregiver.

It is also preferable to have a method for detecting postpartum hemorrhage and warning a caregiver about it. Such a method for estimating a tone of uterine musculature comprises the steps of a stimulation step of applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature, a radiation step of radiating ultrasound energy into the subject, a receiving stepof receiving an echoed ultrasound energy, an analysis step of analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature and a processing step of determining a value of the tone of the uterine musculature, for further use, based on the speed of propagation of the shear wave.

Such a method may have the advantage of enabling the early detection of PPH so that a caregiver may manage the PPH to see that the life of the mother is not endangered.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will be described in detail, by way of example, on the basis of the following embodiments and implementations, with reference to the

accompanying drawings, wherein:

Fig. la is a schematic representation of the disclosed device for monitoring a subject for postpartum hemorrhage;

Fig. lb is a schematic representation of an embodiment of the disclosed device;

Fig. 2 is a schematic representation of an embodiment of the disclosed device;

Fig. 3 is a schematic representation of an embodiment of the disclosed system for monitoring a subject for postpartum hemorrhage;

Fig. 4 is a diagrammatic representation of the disclosed device for monitoring a subject for postpartum hemorrhage;

Fig. 5 is a schematic representation of the method of monitoring a subject for postpartum hemorrhage; and

Fig. 6 is a schematic representation of another implementation of the disclosed method,

in which, like reference numerals refer to like parts in the different figures.

DETAILED DESCRIPTION OF EMBODIMENTS

The disclosed device, system and method are described below in detail with reference to the figures.

Fig. 1 is a schematic diagram of an embodiment of the disclosed device. It comprises an ultrasound transducer 101 for applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature. The ultrasound transducer 101 is driven suitably by a driver 105. The shear wave so generated radiates through the uterine musculature. Another ultrasound transducer 103 radiates ultrasound into the abdomen of the subject. The reflected ultrasound is received by the transducer 103 and the analysis unit 107 analyses the electrical signal output by the transducer 103 and measures the speed of propagation of the shear wave in a known way and based on the speed of propagation, estimates a tone of the uterine musculature. The result of the analysis is conveyed to the user through a suitable user interface 111.

The ultrasound transducer 101 is an array of individual transducers so arranged and are so driven that the radiation emitted by the transducers of the array are focused at a small region inside the uterine musculature. Due to the acoustic radiation force created by the focused ultrasound a shear wave will originate at the focal region, which then radiates through the uterine musculature.

However, once the shear wave is generated, the ultrasound transducer 101 may be de-energized and ultrasound imaging pulses are radiated by the transducer 103 for tracking the propagation of the shear wave in the region surrounding the focal region. The signal representative of echoes received by the transducer 103 is then analyzed by the analysis unit 107 for estimating the speed of the shear wave. Since the shear wave travels faster in stiffer material than in softer material, the measured speed of travel of the shear wave results in an estimate of the shear modulus of the musculature and hence the tone of the uterine musculature. The shear modulus of the musculature may be calculated using well established models.

Based on the calculated shear modulus, the uterine tissue can be classified as either soft i.e., having atony, hard or stiff i.e., having adequate tone, based on suitable threshold values for the shear modulus. It is to be understood that the classification may have larger classes covering a whole range of the tone. Consequently, the classification may also result in different information being conveyed to the user.

Once the tone of the uterine musculature is assessed the result may be conveyed to the user in a suitable manner. If the tone is assessed as either soft or that there is atony means that there is a possibility of a hemorrhage. The device can then proceed to locate the hemorrhage.

It is possible to conceive that when the tone is classified at or near the middle of the range, i.e., neither hard nor soft, the device could allow a predetermined time to elapse and measure the tone again. If the tone either remains the same or worsens, that is to say reduces, it may proceed to detect and locate the hemorrhage, if present. The presence of a bleed in a vessel is characterized by changes in the spectral Doppler velocity profile and the quantitative indices such as Resistance Index (RI),

Pulsatility Index (PI) derived by analyzing the spectral waveform. A reduced vascular resistance at the bleed site and downstream of it results in an elevated forward end diastolic flow velocity in the feeding vessel, causing a reduction in the Doppler indices. Turbulence in the affected vessel can also be estimated from spectral Doppler signals as a measure of the severity of the bleed by evaluating the variance in the velocity estimates. These Doppler parameters can be evaluated from different locations of the uterus. Significant reduction in the Doppler indices (RI, PI) or increase in flow turbulence or both indicates the presence of bleeding in the uterus. By combining information on different characteristics of the flow profile from the Doppler measurements and applying thresholds on each parameter, a decision on the presence of the bleed is made. The severity of the bleeding can be quantified by correlating the quantitative Doppler indices in the affected vessels with independently measured bleed volume in a calibration step. If the subject's uterus is soft and a bleed is detected in the uterus then an alarm is triggered to warn the caregiver of the possible PPH.

Further, the analysis unit 109 may be configured to offer advice to a caregiver, through a user interface 111 for instance, regarding the appropriate management of PPH. This embodiment is described with reference to Fig. 2. This advice could be based on the severity of the atony of the uterine musculature, a location of the hemorrhage, a severity of the hemorrhage and available clinical guidelines. Various professional bodies periodically publish such clinical guidelines. For example, "Prevention and Management of Postpartum Haemorrhage" published by The Society of Obstetricians and Gynaecologists of Canada (SOGC), vide the document No. 88, dated April 2000 (available at

http://www.sogc.org/guideliries/public/88E-CPG-April2000.pdf as on 8 October, 2010). The contents of one or more such guidelines may be stored suitably in a memory 213. The analysis unit 109, using suitable software, accesses the various information stored in the memory and based on the results of the analysis, determines or selects one or more appropriate actions to mange PPH from the clinical guidelines and displays the selection to the user on the user interface 111.

In the foregoing description the radiation of focused pulses, generation of ultrasound radiation and reception of the echoes are described as though different transducers 101 and 103 perform the different functions for ease of description, it is possible to integrate all the functions mentioned, into the same transducer. This is shown diagrammatically in Fig. lb. Thus the disclosed device 200 could help detect uterine atony, presence and location of PPH and also assist in the management of PPH.

The disclosed system for monitoring a subject for PPH is described with reference to Fig. 3, which is a schematic representation of the system, shown generally as 300. The system 300 comprises the disclosed device 100 or 200 and a remote unit 315. The remote unit 315 comprises a user interface 311 ' which may be a replica of the user interface unit 111. It may also contain additional features. For instance, whereas the user interface 111 may be just an alphanumeric display, the user interface 311 ' may have additional features such as a flashing light and an audio device for emanating alarm sounds, for instance. The Remote unit 315 is in communication with the device 100 or 200, in particular with the processor unit 109, in a wired or wireless manner. The system may be so arranged that the remote unit is located away from the subject being monitored, in the nurses' station, for instance. When the unit 100 or 200 detects atony or hemorrhage or both, the information is displayed both on the user interface 111 and 311 '. If the system comprises the unit 200, i.e., it is capable of offering advice to the care giver on how to manage PPH, the advice is also displayed on the user interface 311 '. This enables the care giver to prepare for following the advice by collecting the necessary materials and additional personnel if need be, for instance.

Thus the system 300 enables the monitoring of postpartum uterine atony without a caregiver being in the immediate vicinity of the subject and also aid in the delivery of care early, in case of atony or hemorrhage or both.

Fig. 4 shows a possible implementation of the disclosed device or the system. The subject is shown wearing a belt like execution 402 that contains the necessary transducer or transducers. The transducer is electrically connected to the device. The electronics is housed in the unit shown as 400. The combination of the transducer in 402 and 400 is the device described hitherto. The unit 400 could be interconnected to the remote unit such as the remote unit 315 described with reference to Fig. 3. This is one of the possible implementation of the disclosed device or system and may be a matter of design.

The disclosed method of monitoring a subject for PPH is described with reference to Fig. 5 which is a schematic representation of the method in which the method is shown generally as 500.

In a stimulation step 517 the uterus is stimulated from an external surface of the abdomen of the subject. This stimulation is by way of applying an acoustic radiation force to the uterus of the subject through focused ultrasound to create a shear wave in the uterine musculature. Once the focused ultrasound has generated a shear wave, the focused ultrasound may be stopped and the ultrasound for measuring is radiated into the subject in a radiation step 519. In a receiving step 521 the echoed ultrasound energy is received and the received signals are analyzed in an analysis step 523 for determining the rate of propagation of the shear wave. In a processing step 525 a tone of the uterine musculature is determined. A decision about the presence or absence of atony is made based on the analysis and in a conveying step 525; an information based on the decision is conveyed to a user. This conveying could either be on the device itself or the information is conveyed by wired or wireless means at a remote location.

A variant of the method described above is disclosed, with reference to Fig. 6. This implementation comprises steps in addition to those described with reference to Fig. 5. After the analysis step 523, in a further second analysis step 624, a signal representative of the received echoed ultrasound signal is further analyzed to determine at least one of a hemorrhage in the uterus of the subject, a severity of the hemorrhage and a location of the hemorrhage in the uterus. In a second processing step 626, that follows the processing step 535, one or more messages from a set of messages based on clinical guidelines stored in a memory unit are selected for conveying to a user based on one or more of a presence of an atony, a severity of the atony, a presence of a hemorrhage, a severity of a hemorrhage and a location of the hemorrhage in the uterus. In the conveying step 527, in addition to the information regarding the presence or absence of atony, additional information such as a presence of a hemorrhage, a severity of a hemorrhage, a location of the hemorrhage in the uterus are conveyed to the user and advice or suggestions to the user with regard to the management of the PPH is also conveyed.

Thus, such a method may provide comprehensive information to the care giver to support the treatment or management of PPH if and when it occurs.

While the embodiments and implementations have been described in detail in the drawings and description, such drawings and description are to be considered exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Variations and combinations will occur to a practitioner and all such variations are deemed to be within the scope of the disclosed methods.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art, in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude elements or steps other than those mentioned, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or transducer or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

CLAIMS:

1. A device (100) for estimating a tone of uterine musculature, the device comprising:

a first ultrasound transducer (101) for applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature;

a second ultrasound transducer (103) for radiating ultrasound energy into the subject and receiving an echoed ultrasound energy;

an analysis unit (107) for analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature; and

a processor unit (109) for determining a value of the tone of the uterine musculature, for further use, based on the speed of propagation of the shear wave.

2. The device (100) of claim 1 wherein the analysis unit (107) is for further analyzing the signals representative of the received echoed ultrasound energy for detecting at least one of a presence of a hemorrhage in the uterus of the subject, a severity of the hemorrhage and a location of the hemorrhage in the uterus.

3. The device of claims 1 or 2 wherein the transducers are disposed in a belt like construction (402) for being worn by the subject around the midriff and such that the transducers are in contact with the midriff appropriate for radiating the ultrasound into the subject.

4. A system (300) for monitoring a subject for postpartum hemorrhage, the system comprising:

an analysis unit (107) for analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature;

a processor unit (109) for determining a value of the tone of the uterine musculature based on the speed of propagation of the shear wave; and

a user interface (111) for conveying an information based on the value of the tone of the uterine musculature, to a user;

5. The system of claim 4 wherein the user interface (111) comprises at least one of an audible alarm generating unit, an alphanumeric display, a video display unit and a visual alarm indication unit.

6. The system of claim 4 wherein the processor unit (109) is for selecting one or more messages from a set of messages based on clinical guidelines stored in a memory unit (213) for conveying to the user through the user interface (111) based on one or more of the value of the tone, a presence of a hemorrhage, the severity of the hemorrhage and a location of the hemorrhage.

7. The system of claim 4 operably connected to a remote unit (315) comprising a second user interface device (311 '), substantially similar to the user interface (311), for replicating the functions of the user interface (311) at a remote location.

8. A method (500) for estimating a tone of uterine musculature, the method comprising the steps of:

a stimulation step (517) of applying ultrasound energy focused at a region of uterine musculature of the subject for creating an acoustic radiation force for generating a shear wave in the uterine musculature;

a radiation step (519) of radiating ultrasound energy into the subject;

a receiving step (521) of receiving an echoed ultrasound energy; an analysis step (523) of analyzing a signal representative of the received echoed ultrasound energy for determining a speed of propagation of the shear wave in the uterine musculature; and a processing step (525) of determining a value of the tone of the uterine musculature, for further use, based on the speed of propagation of the shear wave

9. The method of claim 8 further comprising a conveying step (527) of conveying to a user at least one of an information based on the value of the tone of the uterine musculature and an alarm signal.

10. The method of claim 9, further comprising the steps of:

a second analysis step (624) of analyzing the signals of the received echoed ultrasound energy for detecting at least one of a presence of a hemorrhage in the uterus of the subject, a severity of the hemorrhage and a location of the hemorrhage in the uterus;

a second processing step (626) of selecting a message from a set of messages based on clinical guidelines stored in a memory unit for conveying to the user through the user interface based on one or more of the value of the tone, a presence of a hemorrhage, the severity of the hemorrhage and a location of the hemorrhage; and

wherein the conveying step (527) includes conveying the selected message to a user.