EP2496143A1

EP2496143A1 - Heart rate monitor

Info

Publication number: EP2496143A1
Application number: EP10829089A
Authority: EP
Inventors: Dwight Walker; Alan Frank Parr; James Scull
Original assignee: Glaxo Group Ltd
Current assignee: Glaxo Group Ltd
Priority date: 2009-11-04
Filing date: 2010-11-04
Publication date: 2012-09-12
Also published as: WO2011056974A1; EP2496143A4; JP2013509956A

Abstract

Systems and methods of monitoring the fetal heart rate in a human subject are described. The subject's umbilicus defines a point on an umbilicus axis length perpendicular to the subject's body. The axis is oriented on an umbilicus plane perpendicular to the subject's length. The system includes at least one sensor mountable in an ellipse defined by the subject's length and width. The width is the umbilicus plane's longest chord. The sensor senses acoustic energy and generates a signal. A processing unit receives the signal to determine average fetal heart rate frequency.

Description

Heart Rate Monitor

Field of the Invention The present invention relates to the field of monitoring fetal heart rate.

Background of the Invention

The monitoring and analysis of the heart rate has been a useful technique for diagnosis of cardiac disease for several decades. There are two significant measurements of this signal: the waveform profile and the rate. Both can be useful in clinical diagnoses. During pregnancy, the well-being and condition of a fetus can be assessed by monitoring both properties of the fetal heart rate. For example, the fetal heart rate can often reveal important information for an arrhythmia diagnosis.

Typically, during gestation, the only time a pregnant woman hears her baby's heart beat is during prenatal check-ups. However, women who have experienced miscarriages or complications in previous pregnancies are often more anxious in subsequent pregnancies. Thus, waiting between prenatal appointments for up-dates on their baby's health can be a source of stress to the parents. This need is often

compounded in instances where there are complications with a pregnancy. In such situations, parents may find themselves making frequent trips to the emergency room. Monitoring their baby's heart rate using a fetal heart rate monitor may also help reduce the number of hospital trips that parents have to make. Moreover, fetal heart rate monitors place no stress on the baby so it is safe to use during pregnancy.

Current technology used to follow fetal heart rate is based on Doppler ultrasound. The Doppler device is placed on the maternal abdomen with a coupling gel to find the fetal heart rate. This is typically done by a doctor or ultrasound technician and requires some degree of training and skill. These types of monitors can be purchased or rented for use as at-home fetal heart rate monitors. Both choices can be fairly expensive.

Summary of the Invention In one aspect, embodiments of the present invention are directed to a system for monitoring the heart rate of a fetus in a female human subject having an umbilicus, the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is

perpendicular to the length of the subject's body. The system includes at least one sensor mountable on the subject in an area defined by:

Area = π * (0.05 */_subject) * (0. 1 *w_subject) where /subject is the length of the subject and w_subject is the width of the subject. The width of the subject is equal to the longest chord swept out by the umbilicus plane. The area defines an ellipse such that the major axis is perpendicular to the umbilicus axis and the lower focus of the area is oriented along the umbilicus axis. The sensor is adapted to sense acoustic energy and generate at least one acoustic energy signal representing the acoustic energy. A processing unit is adapted to receive the acoustic energy signal, with the processing unit being further adapted to process the acoustic energy signal and determine average fetal heart rate frequency as determined by:

/ average 1 <· / _{^ ^ ^} matemalamplitudethreshold \

¹ 0 where Ri is a frequency between 50 and 250 Hz and R₂, R3 and R₄ are independently frequency ranges within which Ri falls, T is T_p and is a time between 10

/ average

FHR ^ ) ^{S avera}§^e f^etal ^{neart rate} frequency, m is 0 or

1 , n is 0 or 1 , where m+n is at least 1 , f is the current fetal heart rate within R₂,

J J f Ri / maternalamplitu det hreshold

is the maternal amplitude threshold within R4.

In a further aspect, embodiments the present invention is directed to a system for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is

Area = π * (0.05 */_subject) * (0. 1 *w_subject) where /subject is the length of the subject and w_subject is the width of the subject. The width of the subject is equal to the longest chord swept out by the umbilicus plane. The area defines an ellipse such that the major axis is perpendicular to the umbilicus axis and the lower focus of said area is oriented along said umbilicus axis. The sensor is adapted to sense acoustic energy and generate at least one acoustic energy signal representing the acoustic energy. A processing unit is adapted to receive the acoustic energy signal, with the processing unit being further adapted to process the acoustic energy signal and determine an aspect average fetal heart rate waveform profile, the profile comprising a leading edge, a trailing edge and a translational edge as determined by: 1

s^l°P^e _FHR ^iT^ ⁼ _j\ [^m*sl pe_R + n*{slope_R -slope_Rio τ where Ri is a frequency between 50 and 250 Hz and Rg, R9 and Rio are independently frequency ranges within which Ri falls, T is T_p and T_p is a time between

j average

10 milliseconds and 28 days, slODC (T ) is the slope of the leading edge of the

1 FHR P

average fetal heart rate waveform profile, m is 0 or 1 , n is 0 or 1 , where m+n is at least 1 , slope is the current average fetal heart rate waveform profile Rg, slope is the maternalamplitu det hres current average fetal heart rate waveform profile within R₉ and SlOpC is the maternal amplitude threshold average heart rate waveform profile within Rio.

In yet a further aspect, embodiments the present invention is directed to a system for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body. The system would includes at least one sensor mountable on said subject in an area defined by:

Area = π * (0.05 */_subject) * (0. 1 *w_subject) where /subject is the length of the subject and w_subject is the width of the subject. The width of the subject is equal to the longest chord swept out by the umbilicus plane. The area defines an ellipse oriented such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of the area is oriented along said umbilicus axis. The sensor is adapted to sense acoustic energy and generate at least one acoustic energy signal representing the acoustic energy. A processing unit adapted to receive said acoustic energy signal, and the processing unit is further adapted to process the acoustic energy signal and determine the average fetal heart rate frequency as determined by:

/ average \ r i ¾ -f ^ matemalamplitudethreshold \

FHR ^~ T J \^m*J Ru ^{+ n} Rii J R_a

1 0 where Ri is a frequency between 50 and 250 Hz and Rn, R12 and R13 are

independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a time

/average

is the average fetal heart rate frequency, m is FHR

0 or 1 , n is 0 or 1 , wherein m+n is at least 1 , f is the current fetal heart rate within

J R_n maternalamplitu det hreshold is the current fetal heart rate within Ri₂ and / is the

Rn J Ru

maternal amplitude threshold within R13. The processing unit is also adapted to receive the acoustic energy signal, and is further adapted to process the acoustic energy signal and determine the average fetal heart rate waveform profile as determined by: 1

s^l°P^eFHR ⁼j\ ^sloP^e _Ru ⁺ⁿ^^sloP^e _Rl ^sloP^e _Rl6 ψ where Ri is a frequency between 50 and 250 Hz and R14, R15 and Ri₆ are

independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a time between 0.01 minutes and 28 days, slope is the current average fetal heart rate waveform within R14, slope is ^me current average fetal heart rate waveform profile

j maternalamplitu det hreshold

within Ri5 and slope is the maternal amplitude threshold average heart rate waveform profile within Ri₆.

Brief Description of the Figures

Figure 1 shows an embodiment according to the present invention for the placement of a sensor in relationship to the fetus and the umbilicus; Figure 2 shows an embodiment according to the present invention of a plan view of the subject's umbilicus plane;

Figure 3 shows a signal flow for the fetal heart rate determination according to an embodiment of the invention;

Figure 4 shows another signal flow for the fetal heart rate determination according to an embodiment of the invention; Figure 5 shows another signal flow for the fetal heart rate determination according to an embodiment of the invention; and

Figure 6 shows a fetal heart rate waveform profile according to an embodiment of the present invention.

Detailed Description of the Invention

As discussed in detail below, the fetal heart rate monitoring system of the invention generally includes at least one sensor mounted on a subject, the sensor being adapted to sense acoustic energy and generates at least one acoustic energy signal. This acoustic energy signal is subsequently received by a processing unit adapted to process the acoustic energy signal and determine at least the average fetal heart rate frequency. As will be appreciated by one having ordinary skill in the art, the processing unit of the invention can be readily employed in conjunction with a multitude of sensors and would be capable of determining a number of parameters. Potential applications thus include, for example, the following: fetal tachycardia; fetal bradycardia; saltatory variability; variable decelerations associated with a nonreassuring pattern; and late decelerations with preserved beat-to-beat variability.

Repeat use of reference characters herein and in the figures is intended to represent same or analogous features or elements of the invention.

It is to be understood that this invention is not limited to particularly exemplified materials, methods or structures as such may, of course, vary. Thus, a number of materials and methods similar or equivalent to those described herein can be used in the practice of the present invention. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to be limiting.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the invention pertains. Further, all publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety.

As used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise.

Implementation of the methods and systems of embodiments of the present invention, as described herein, can involve performing or completing selected tasks or steps manually, automatically, or a combination thereof. In some embodiments of the present invention, several selected steps could be implemented by hardware or by software on any operating system or any firmware or a combination thereof. For example, as hardware, selected steps of embodiments of the invention could be implemented as a chip or a circuit. As software, selected steps of embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions.

Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying figures.

Figure 1 shows and illustrates a sensor (100) for monitoring the fetal heart rate of a fetus (101). The sensor (100) is located proximate to the umbilicus (102) on a subject's body (103). Figure 2 illustrates a human subject (203). The umbilicus (202) defines a point on an umbilicus axis oriented perpendicular to the length direction of the subject's body (205). The umbilicus axis is oriented on an umbilicus plane (204) that is perpendicular to the length of the subject's body. The fetal heart rate system comprises at least one sensor mountable on the subject in an area defined by:

Area = π * (0.05 */_subject) * (0. 1*w_subject) where /subject is the length (i.e., height) of the subject and w_subject is the width of the subject. The width of the subject is equal to the longest chord (206) swept out by the umbilicus plane. The resulting area defines an ellipse (207) such that the major axis is perpendicular to the umbilicus axis. The lower focus (209) of the area is oriented along the umbilicus axis and the upper focus (208) lies along the direction of the subject's body (205).

The sensor (100) is adapted to sense acoustic energy and generate at least one acoustic energy signal representing the acoustic energy as depicted in Figure 3. A processing unit (309) is adapted to receive the acoustic energy signal (308) with the processing unit (309) being further adapted to process the acoustic energy signal (308). The processing unit (309) is capable of determining a number of fetal heart rate parameters (301 -305 , 309). In one embodiment, the processing unit (309) would determine average fetal heart rate frequency as determined by:

/ average 1 <· / ^ ^ ^ matemalamplitudethreshold \

/ average

(T ) is the average fetal heart rate frequency, m is 0 or 1 , n is 0 or 1 , vv n^ ^FHR

m+n is at least 1 , ^ is the current fetal heart rate within R₂, _r is the current fetal / maternalamplitu det hreshold

is the maternal amplitude threshold within

R4

In some embodiments, Ri is a frequency between 50 and 250 Hz and R₂, R₃ and R4 are independently frequency ranges within which Ri falls. In other embodiments, Ri is a frequency between 80 and 230 Hz and R₂, R₃ and R₄ are independently frequency ranges within which Ri falls. In further embodiments, Ri is a frequency between 90 and 200 Hz and R₂, R₃ and R₄ are independently frequency ranges within which Ri falls.

In some embodiments, T is T_p and is a time between 10 milliseconds and 28 days. In other embodiments, T is T_p and is a time between 12 hours and 14 days. In further embodiments, T is T_p and is a time between 5 minutes and 24 hours.

One of skill in the art will appreciate that various sensors can be employed within the scope of the present invention, such as the one disclosed in U.S. Patent No.

6,512,830.

In one embodiment, the fetal heart rate system uses at least one sensor mountable laterally in the same transverse plane as the umbilicus. In one embodiment, at least one sensor is mountable laterally the transverse plane opposite the umbilicus.

In one embodiment, the sensor generates a plurality of acoustic energy signals representing the acoustic energy. The plurality can be 2, 3, 4, 5, 6 or more acoustic energy signals representing multiple fetal heart rates.

In one embodiment, the processing unit is further adapted to determine a number of additional fetal heart rate parameters such as an average fetal heart rate (303) determined by: average

= f ( V 60

B BPPMM J J F PHHRP

In some embodiments of average fetal heart rate, T is a time between 10 milliseconds and 28 days. In other embodiments of average fetal heart rate, T is a time between 12 hours and 14 days. In a further embodiment of average fetal heart rate, T is a time between 5 minutes and 24 hours.

In one embodiment, the processing unit is further adapted to determine a number of additional fetal heart rate parameters such as a prolonged rapid heart rate (305) by:

where ^averas^e ( / \ [_s calculated using:

FHR V

In some embodiments, Ti is a time between 10 milliseconds and 28 days. In other embodiments, Ti is a time between 12 hours and 14 days. In a further embodiment, Ti is a time between 5 minutes and 24 hours.

In one embodiment, the processing unit is further adapted to determine a number of additional fetal heart rate parameters such as a prolonged slow heart rate (304) by:

where ^averas^e( l [_s calculated using:

FHR 2^y

/ average 1 <· / ^ ^ ^ matemalamp litudethreshold \ In some embodiments, T₂ is a time between 10 milliseconds and 28 days. In other embodiments, T₂ is a time between 12 hours and 14 days. In a further embodiment, T₂ is a time between 5 minutes and 24 hours.

In one embodiment, the processing unit is further adapted to determine a number of additional fetal heart rate parameters such as a long-term variability (302) by:

T₃

Long tenn variability = ( ^ (Ϊ;) - /, average

FHR

o where f^average(T_~) is calculated using:

FHR 3^y

In some embodiments, T₃ is a time between 10 milliseconds and 48 days. In other embodiments, T₃ is a time between 1 second and 60 minutes. In a further embodiment, T₃ is a time between 1 second and 10 minutes. In a further embodiment, T₃ is a time between 1 second and 3 minutes.

In one embodiment, the processing unit is further adapted to determine a number of additional fetal heart rate parameters such as an accelerated heart rate (301) is determined b :

In some embodiments, T₄ is a time between 10 milliseconds and 60 minutes. In other embodiments, T₄ is a time between 1 second and 30 minutes. In a further embodiment, T₄ is a time between 1 second and 3 minutes.

In other embodiments, the processing unit is further adapted to display a variable and sound an alarm. As will be appreciated by one having ordinary skill in the art, the display and alarm can also be an integral component or feature of the processing unit.

Figure 3 illustrates a processing unit (309) that is configured to activate an alarm (306) or display (307) a message if a condition requires an alert, for example. As illustrated in Figure 3, these alert conditions include accelerated heart rate (301), long term variability of heart rate (302), fetal heart rate average (303), prolonged slow heart rate (304) and prolonged rapid heart rate (305); however, one of ordinary skill in the art will appreciate that the alert conditions can include one or more of the foregoing.

In one embodiment, the processing unit is adapted to receive and process a plurality of acoustic energy signals and determine at least one average fetal heart rate frequency therefrom. In another embodiment, the processing unit is adapted to receive and process the plurality of acoustic energy signals and determine two average fetal heart rate frequencies as determined by: average I f _{^ ^ ^} matemalamplitudethreshold

pi 0

and

/ average! 1 s* rmtemalamplitudethreshold

λ ρ2 0 ^X

/ average ,» average 2

(T . ) is the first average fetal heart rate frequency, (Γ , ) is FHR ^{p l} J FHR ^{p i} the second average fetal heart rate frequency, m is 0 or 1 , n is 0 or 1 , m+n is at least 1 , f is the first current fetal heart rate and is within R₂, f is the second current fetal

J R₂ J R₅ heart rate and is within R5, f is the first current fetal heart rate and is within R₃, f is the maternal the maternal

amplitude threshold frequency within R₇. In some embodiments, Ri is a frequency between 50 and 250 Hz and R₂, R₃, R₄,

R₅, R6 and R₇ are independently frequency ranges within which Ri falls. In some embodiments, T_pl and T_p2 are independently times between 10 milliseconds and 28 days. In other embodiments, T_pl and T_p2 and are independently times between 12 hours and 14 days. In a further embodiment, T_pl and T_p2 and are independently times between 5 minutes and 24 hours.

It is to be understood by one having ordinary skill in the art that the processing unit could be adapted to receive and process the plurality of acoustic energy signals and determine 3, 4, 5, 6 or more average fetal heart rate frequencies.

In one embodiment, a system for monitoring the fetal heart rate of a human subject can be adapted to receive the acoustic energy signal, the processing unit being further adapted to process the acoustic energy signal and determine an aspect average fetal heart rate waveform profile. The profile includes a leading edge (601), a trailing edge (603) and a translational edge (602) as determined by:

_j maternalamplitu det hreshold

rate waveform profile within Rg and slope is ^me maternal amplitude threshold average heart rate waveform profile within Rio.

In some embodiments, Ri is a frequency between 50 and 250 Hz and R₈, R9 and Rio are independently frequency ranges within which Ri falls. In some embodiments, T is T_p and T_p is a time between 10 milliseconds and 28 days.

Figure 4 illustrates a processing unit (41 1) adapted to receive the acoustic energy signal (410) with the processing unit (41 1) being further adapted to process the acoustic energy signal (410). The processing unit (41 1) is capable of determining a number of fetal heart rate parameters (401 and 402). One skilled in the art would also recognize that processing unit (41 1) could be configured to activate an alarm (408) or display (409) a message if a condition required an alert.

In one embodiment, the processing unit (41 1) can further be adapted to determine a fetal heart rate waveform deviation (401) by:

In one embodiment, slope^average (T₅) is calculated by

FHR

In a further embodiment, T₅ is a time between 10 milliseconds and 60 minutes. In other embodiments, T5 is a time between 1 second and 10 minutes. . In yet other embodiments, T5 is a time between 1 second and 3 minutes. In yet other embodiments, T5 is a time between 1 second and 1 minute. In one embodiment, the processing unit (41 1) can be adapted to receive and process a plurality of acoustic energy signals and determine two fetal heart rate shape profiles (402) as determined from equations by:

and

1 O 9 7 matemalamplitudethreshold slope ^ (T_P, ) =—\ [_m*slope _R + n*{_slope _R -slope_Rm }

0

where SLOVe (T Λ is the first average fetal heart rate waveform profile,

J FHR P

j average 2

Slope _FHR (T_p2) is the second average fetal heart rate waveform profile, m is 0 or 1 , n is 0 or 1 , m+n is at least 1 , slope _R is the first current fetal heart rate waveform profile and is within R₂, slope _R is t e second current fetal heart rate waveform profile and is within R5, slope _R is t e first current fetal heart rate waveform profile and is within R3, slope is the second current fetal heart rate waveform profile and is within R^,

j matemalamplitudethreshold

Slope is the maternal amplitude threshold frequency and is within R₄ matemalamplitudethreshold

and slope is the maternal amplitude threshold frequency within R₇.

In one embodiment, Ri is a frequency between 50 and 250 Hz and R₂, R₃, R₄, R₅, and R₇ are independently frequency ranges within which Ri falls.

In some embodiments, T_pl and T_p2 are independently times between 10

milliseconds and 28 days. In other embodiments, T_pl and T_p2 and are independently times between 12 hours and 14 days. In further embodiments, T_pl and T_p2 are

independently times between 5 minutes and 24 hours. Figure 5 illustrates a processing unit (5 1 1 ) adapted to receive the acoustic energy signal (5 10) with the processing unit (5 1 1 ) being further adapted to process the acoustic energy signal (5 10). The processing unit (5 1 1 ) is capable of determining a number of fetal heart rate parameters (501 -507). One skilled in the art would also recognize that processing unit (5 1 1 ) could be configured to activate an alarm (508) or display (509) a message if a condition required an alert.

A person or ordinary skill in the art would understand that these conditions could include accelerated heart rate profile (501 ), long term variability of heart rate profile (502), fetal heart rate average profile (503), fetal heart rate shape profile (504), fetal heart rate profile deviation (505), prolonged slow heart rate profile (506) and prolonged rapid heart rate profile (507), each of which can be determined using methodology similar to that described above with respect to Figures 3 and 4. Such conditions have been discussed in "Fetal heart rate patterns: monitoring, interpretation, and management", American College of Obstetricians and Gynecologists technical bulletin no. 207.

Washington, D.C.: ACOG, 1995. One of ordinary skill in the art will appreciate that the alert conditions can include one or more of the foregoing.

As will be appreciated by one having ordinary skill in the art, the displays and alarms of the aforementioned embodiments can also be an integral component or feature of the processing units, separate or remotely located components of the processing units, or any combination thereof.

In one embodiment, a system for monitoring the fetal heart rate of a human subject includes at least one sensor (100) mountable on the subject ( 103) in an area defined by:

Area = π * (0.05 */_subject) * (0. 1 *w_subject); and In another embodiment, a system for monitoring the heart rate of a fetus in a female human subject includes a processing unit (309) adapted to receive the acoustic energy signal (308). In a further embodiment, the processing unit (309) is further adapted to process the acoustic energy signal (308) and determine the average fetal heart rate frequency as determined by:

1 ^T /

^ average l C I matemalamplitudethreshold f_FHR = Ti (™*f_Rn ^{+ n} * (f_R - f_Rl3

is the average fetal heart rate frequency, m is 0 or 1 , n is 0 or 1 ,

FHR

m+n is at least 1, J f is the current fetal heart rate within Rn, J f is the current fetal

R Rn

/ maternalamplitu det hreshold

is the maternal amplitude threshold within

In one embodiment, Ri is a frequency between 50 and 250 Hz and Rn, R₁₂ are independently frequency ranges within which Ri falls.

In a further embodiment, T is T_p and T_p is a time between 0.01 minutes and 28 days.

In one embodiment, a system for monitoring the heart rate of a fetus in a female human subject also includes a processing unit (309) adapted to receive the acoustic energy signal (308), the processing unit (309) being further adapted to process the acoustic energy signal (308) and determine the average fetal heart rate waveform profile as determined by:

-_j average 1 f 7 7 7 matemalamplitudethreshold \ s^l°P^e _PHR ⁼T) (^m*stope_Ri + n*{slope_Ri5-slope_Ri6 τ

Ru

average fetal heart rate waveform wit current average fetal heart rate waveform profile within R 5 and is the maternal amplitude

threshold average heart rate waveform profile within Ri₆.

In one embodiment, Ri is a frequency between 50 and 250 Hz and Ri₄, R15 and Ri₆ are independently frequency ranges within which Ri falls. In one embodiment, the frequency of interest is where Ru is equal to Ri₄. In another embodiment, the frequency of interest is where R12 is equal to R15. In another embodiment, the frequency of interest is where R13 is equal to Ri₆. In a further embodiment, the frequency of interest is where Ru is equal to R_M, Ri₂ is equal to R15, R13 is equal to Ri₆.

In yet a further embodiment, T is T_p and T_p is a time between 0.01 minutes and 28 days.

Method and system embodiments of the present invention can thus be effectively employed in numerous applications. The applications include, without limitation, the ability to monitor fetal heart rate during pregnancy, labor and/or birth; to monitor fetal heart rate waveform profile during pregnancy, labor and/or birth; to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth; to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth and to detect fetal distress; to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth and to detect fetal distress and provide an electrical output; to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth and to detect fetal distress and provide an electrical output consisting of an acoustic, visual, mechanical, electrical indicator and combinations thereof; transporting the system to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth a distance of at least 5 miles from location A to location B; transporting the system to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth a distance of at least 5 miles from location A to location B by driving across land, sailing across water and/or flying through air; transporting the system to monitor fetal heart rate and fetal heart rate waveform profile during pregnancy, labor and/or birth a distance of at least 5 miles from location A to location B where A and B are in different countries.

Although specific embodiments of the present invention are herein illustrated and described in detail, the invention is not limited thereto. The above detailed descriptions are provided as exemplary of the present invention and should not be construed as constituting any limitation of the invention. Modifications will be obvious to those skilled in the art, and all modifications that do not depart from the spirit of the invention are intended to be included with the scope of the appended claims.

Claims

What is claimed is:

1. A system for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising:

at least one sensor mountable on said subject in an area defined by equation (1); Area = π * (0.05*/_subject) * (0.1 *w_subject) (1) wherein /_subject is the length of the subject and w_SUbject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis; and

said sensor being adapted to sense acoustic energy and generate at least one acoustic energy signal representing said acoustic energy; and

a processing unit adapted to receive said acoustic energy signal, said processing unit being further adapted to process said acoustic energy signal and determine average fetal heart rate frequency as determined by equation (2);

/

wherein Ri is a frequency between 50 and 250 Hz and R₂, R₃ and R₄ are independently frequency ranges within which Ri falls, wherein T is T_p and is a time

/ average

(T ) is the average fetal heart rate FHR

frequency, m is 0 or 1 , n is 0 or 1 , wherein m+n is at least \ ,† ^ is the current fetal heart rate within R₂, is

J f the current fetal heart rate within R₃ and

R3

matemalamplitu det hreshold

j is the maternal amplitude threshold within R₄.

2. The system of Claim 1 , wherein said processing unit is further adapted to determine an average fetal heart rate by equation (3);

average

average (Γ ) * 60 (3).

BBPPMM J FHR

3. The system of Claim 1, wherein said processing unit is further adapted to determine a prolonged rapid heart rate by equation (4); f (fZr<J_P)-fZrV ) dT_x (4)

0 wherein f^^age( ^) is calculated using equation (2) wherein T is T_ls and Ti is a time between 10 milliseconds and 28 days.

4. The system of Claim 1 , wherein said processing unit is further adapted to

determine a prolonged slow heart rate by equation (5);

wherein f^^age(T^) is calculated using equation (2) wherein T is T₂, and T₂ is a time between 10 milliseconds and 28 days.

5. The system of Claim 1 , wherein said processing unit is further adapted to

determine a long term variability by equation (6); Long term variability f;-^ge( (6)

wherein f ^averag^e [_s calculated using equation (2) wherein T is T₃ and T₃ is a

FHR 3 '

time between 10 milliseconds and 48 days.

6. The system of Claim 1 , wherein acceleration is determined by equation (7);

wherein f_p^™^ge(J"^) is calculated using equation (2) wherein T is T₄ and T₄ is a time between 10 milliseconds and 60 minutes.

7. The system of Claim 3, wherein Ti is between 12 hours and 14 days.

8. The system of Claims 3, wherein Ti is between 5 minutes and 24 hours.

9. The system of Claims 4, wherein T₂ 12 hours and 28 days.

10. The system of Claims 4, wherein T₂ is between 5 minutes and 24 hours.

1 1. The system of Claim 5, wherein T₃ is between 1 second and 60 minutes.

12. The system of Claim 5, wherein T₃ is between 1 second and 10 minutes.

13. The system of Claim 5, wherein T₃ is between 1 second and 3 minutes.

14. The system of Claim 6, wherein T₄ is between 1 second and 30 minutes.

15. The system of Claim 5, wherein T₄ is between 1 second and 3 minutes.

16. The system of Claim 1, wherein said at least one sensor is mountable laterally in the same transverse plane as the umbilicus.

17. The system of Claim 1, wherein said at least one sensor is mountable laterally in the same transverse plane opposite the umbilicus.

18. The system of Claim 1, wherein said sensor generates a plurality of acoustic energy signals representing said acoustic energy.

19. The system of Claim 18, wherein said processing unit is adapted to receive and process said plurality of acoustic energy signals and determine at least one average fetal heart rate frequency rate therefrom.

20. The system of Claim 18, wherein said processing unit is adapted to receive and process said plurality of acoustic energy signals and determine two average fetal heart rate frequencies as determined from equations (2) and (8); 1 Γ²

/ average^*! (· / s*n maternalamplitudethreshold

_™ <^T \ -^*ίί ^{+ »}·υϊ-Λ, > wherein Ri is a frequency between 50 and 250 Hz and R₂, R₃, R₄, R₅, R₆ and R₇ are inde endently frequency ranges within which Ri falls, wherein T is T_p and T² is T_p2,

rt is aternal

maternal amplitude threshold frequency within R₇.

21. A system for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising: at least one sensor mountable on said subject in an area defined by equation (9);

Area = π * (0.05 */_subject) * (0. 1 *w_subject) (9) wherein /_subject is the length of the subject and w_SUbject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis; and

a processing unit adapted to receive said acoustic energy signal, said processing unit being further adapted to process said acoustic energy signal and determine an aspect average fetal heart rate waveform profile, said profile comprising a leading edge, a trailing edge and a translational edge as determined by equation ( 10);

11 ^T f / , _{7 7 7} matemalamplitudethreshold \ \ / -ι slope _^ (T ) = - \ [m*slope_R + n * {slope _R - slope _Rm } k/r (i0)

wherein Ri is a frequency between 50 and 250 Hz and Rg, R9 and Rio are independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a _j average

time between 10 milliseconds and 28 days, slope _FHR (T_p ) is the slope of the leading edge of the average fetal heart rate waveform profile, m is 0 or 1 , n is 0 or 1 , wherein m+n is at least 1 , slope is ^me current average fetal heart rate waveform profile Rs, slope is ^me current average fetal heart rate waveform profile within

maternalamplitu det hreshold

Rg and SlOpC is ^me maternal amplitude threshold average heart rate waveform profile within Rio.

22. The system of Claim 21 , wherein said processing unit is further adapted to determine a fetal heart rate wave form deviation is determined by equation (1 1);

wherein slope^average(T₅ ) is calculated by equation (10) wherein T is T₅, and T₅ is a time between 10 milliseconds and 60 minutes.

23. The system of Claim 21 , wherein T_p is between 1 second and 10 minutes.

24. The system of Claim 21 , wherein T_p is between 1 second and 3 minutes.

25. The system of Claim 21 , wherein T_p is between 1 second and 1 minute.

26. The system of Claim 21 , wherein said sensor generates a plurality of acoustic energy signals representing said acoustic energy.

27. The system of Claim 26, wherein said processing unit is adapted to receive and process said plurality of acoustic energy signals and determine at least one fetal heart rate shape profile therefrom.

28. The system of Claim 26, wherein said processing unit is adapted to receive and process said plurality of acoustic energy signals and determine two fetal heart rate shape profiles as determined from equations (10) and (12);

T ²

₇ average! , \ _/· o τ matemalamplitudethreshold \ , ,_Λ slope _FHR (T ² ) = _Tj j (aslope² _R + * {slope² _R9 - slope _{R o} π )

0 wherein Ri is a frequency between 50 and 250 Hz and R₂, R₃, R₄, R₅, R₆ and R₇ are independently frequency ranges within which Ri falls, wherein T is T_p and T² is T_p2, T_p and T_p2 are independent times between 10 milliseconds and 28 days,

j average

SlOPe (Τ_{Ό 2} ) is the first average fetal heart rate waveform profile,

J FHR P

j average 2

SlOPC (T ₂) is the second average fetal heart rate waveform profile, m is 0 or

1 FHR

1 , n is 0 or 1 , wherein m+n is at least 1 , slope _R is ^me first current fetal heart rate waveform profile and is within R₂, slop _R is the second current fetal heart rate waveform profile and is within R5, slope _R is the first current fetal heart rate waveform profile and is within R₃, slop _R is the second current fetal heart rate

j matemalamplitudethreshold

waveform profile and is within R^, slopC_R is the maternal amplitude

j matemalamplitudethreshold

threshold frequency and is within R4 and slopC_R is the maternal amplitude threshold frequency within R₇.

29. A system for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising: at least one sensor mountable on said subject in an area defined by equation (13); Area = π * (0.05*/_subject) * (0.1 *w_subject) (13) wherein /_subject is the length of the subject and w_subject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse oriented such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis; and

a processing unit adapted to receive said acoustic energy signal, said processing unit being further adapted to process said acoustic energy signal and determine the average fetal heart rate frequency as determined by equation 14;

/

wherein Ri is a frequency between 50 and 250 Hz and Ru, Ri₂ and Ri₃ are independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a

/average

is the average fetal heart rate FHR

frequency, m is 0 or 1 , n is 0 or 1 , wherein m+n is at least 1 , f is the current

J R fetal heart rate within Ru, f is the current fetal heart rate within Ri₂ and

J Ru

/ matemalamp litu det hreshold

is the maternal amplitude threshold within Ri₃; and

Ru

a processing unit adapted to receive said acoustic energy signal, said processing unit being further adapted to process said acoustic energy signal and determine the average fetal heart rate waveform profile as determined by equation (15); j average

s^l°P^eF_HR =

wherein Ri is a frequency between 50 and 250 Hz and Ri₄, Ri₅ and Ri₆ are independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a time between 0.01 minutes and urrent average fetal heart rate waveform within Ri₄, verage fetal heart rate waveform profile within R15 and is the maternal

amplitude threshold average heart rate waveform profile within Ri₆.

30. The system of Claim 29, wherein Ru is equal to Ri₄.

3 1 . The system of Claim 29, wherein Ri₂ is equal to R15.

32. The system of Claim 29, wherein R13 is equal to Ri₆.

33. The system of Claim 29, wherein Ru is equal to Ri₄, Ri₂ is equal to R15, R13 is equal to Ri₆.

34. A method for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising:

mounting at least one sensor on said subject in an area defined by equation (16);

Area = π * (0.05 */_subject) * (0. 1 *w_subject) ( 16) wherein /_subject is the length of the subject and w_subject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis;

sensing an acoustic energy;

generating at least one acoustic energy signal representing said acoustic energy; processing said acoustic energy signal; and

determining an average fetal heart rate frequency as determined by equation (17);

T

/ average \ f / maternalarnplitudetrrreshold \

_™ ^(T T ¹ S 0 V "·« _*- Λ Ψ ⁽¹⁷⁾ wherein Ri is a frequency between 50 and 250 Hz and R₂, R₃ and R₄ are independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a time

/ average

(T ) is the average fetal heart rate FHR ^p

frequency, m is 0 or 1, n is 0 or 1, wherein m+n is at least 1,† _^ is the current fetal heart rate within R₂, f is the current fetal heart rate within R₃ and

J Ri

/ maternalamplitu det hreshold

is the maternal amplitude threshold within R₄.

35. A method for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising: mounting at least one sensor on said subject in an area defined by equation (18);

Area = π * (0.05*/_subject) * (0.1 *w_subject) (18) wherein /_subject is the length of the subject and w_SUbject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis;

sensing an acoustic energy;

generating at least one acoustic energy signal representing said acoustic energy; and

processing said acoustic energy signal; and

determining an aspect average fetal heart rate waveform profile, said profile comprising a leading edge, a trailing edge and a translational edge as determined by equation 19; 1

slope ^ (T) = -j(_m*slope_R + n*{slope_R9-slope_Rio (19)

0 wherein Ri is a frequency between 50 and 250 Hz and Rg, R9 and Rio are independently frequency ranges within which Ri falls, wherein T is T_p and T_p is a time

j average

between 10 milliseconds and 28 days, SIOO6 (T ) is the slope of the leading edge

1 FHR

of the average fetal heart rate waveform profile, m is 0 or 1 , n is 0 or 1 , wherein m+n is at least 1 , slope is the current average fetal heart rate waveform within R₈, slope is the current average fetal heart rate waveform profile within R9 and

j maternalamplitu det hreshold

Slope is the maternal amplitude threshold average heart rate waveform profile within R 10·

36. A method for monitoring the heart rate of a fetus in a female human subject having an umbilicus , the umbilicus defining a point on an umbilicus axis oriented perpendicular to the length of the subject's body, the umbilicus axis oriented on an umbilicus plane that is perpendicular to the length of the subject's body, comprising: mounting at least one sensor on said subject in an area defined by equation (20); Area = π * (0.05*/_subject) * (0.1 *w_subject) (20) wherein /_subject is the length of the subject and w_subject is the width of the subject, wherein the width of the subject is equal to the longest chord swept out by the umbilicus plane, said area defining an ellipse such that the major axis is perpendicular to the umbilicus axis and wherein the lower focus of said area is oriented along said umbilicus axis;

sensing an acoustic energy;

processing said acoustic energy signal;

determining an average fetal heart rate frequency as determined by equation (21);

wherein Ri is a frequency between 50 and 250 Hz and Ru, R12, R13, R14, Ris and Ri₆ are independently frequency ranges within which Ri falls, T is T_p and T_p is a

/ average

(T ) is the average fetal heart FHR P

rate frequency, m is 0 or 1 , n is 0 or 1 , wherein m+n is at least 1 , f is the current

J R fetal heart rate within Ru, f is the current fetal heart rate within R₁₂ and

J Rn

/ maternalamplitu det hreshold

is the maternal amplitude threshold within R13;

R\l

determining an aspect average fetal heart rate waveform profile, said profile comprising a leading edge, a trailing edge and a translational edge as determined by equation (22); matemalamplitudethreshold.

wherein T is T and T_p is a time between 0.01 minutes and 28 days,

maternal amplitude threshold average heart rate waveform profile within Rio.

37. The method of Claims 34, 35 or 36, wherein said fetal heart rate frequency comprises an event associated with a fetal heart rate, said fetal heart rate being selected from the group consisting of baseline beats per minute, prolonged rapid heart rate, prolonged slow heart rate, transients and constant variation from the baseline.

38. The method of Claim 37, wherein said processing unit is further adapted to detect fetal distress, and upon detection of said fetal distress provides an electrical output.

39. The method of Claim 38, wherein said electrical output is a human sensible output, said human sensible output consisting of an acoustic, visual, mechanical, electrical indicator and combinations thereof.

40. A method for transporting the processing system of any of Claims 1-29, said method comprising moving the system a distance of at least 5 miles from location A to location B.

41. The method of Claim 40, wherein said moving comprises at least one mode of transportation from the group consisting of driving across land, sailing across water and flying through air.

42. The method of Claim 40, wherein location A is in one country and location B is in another country.