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Non-conventional abdominal signals: EEnG & EHG
PhD. Javier García Casado
Monitoring of Non-conventional abdominal myoelectrical recordings: intestinal (EEnG) and uterine activity (EHG)
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Index
o Presentation
o Intestinal activity studies
Internal EEnG. Caracterization
Surface EEnG. • Interference cancellation: Software
• Interference cancellation: Hardware
o Uterine activity studies
Preterm birth
Uterine dynamics monitoring
Enhancing and characterization of EHG in pregancy and labor
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Presentation
o Gbio-e tiene has more than 20 years of experience on Biomedical Engineering. Now is part of I3BH-UPV, Valencia
o Formed by 24 researchers (15 PhD)
o Principal Areas of R+D+I
Biomedical Systems and Devices for Diagnosis and Therapy
• Development of sensors and biosensors
• Development of Ad hoc monitoring systems
• Advanced signal processing and decisson support systems
Modelling and Simulation of Cells and Tissues
• Cardiac electrical activity models
• Signal simulation for diagnosis
o Collaborates with private companies, hospitals
and international research groups.
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Biolectrical signals on body surface
Electroencephalogram (EEG)
Electrooculogram (EOG)
Electrocardiogram (ECG)
Electrogastrogram (EGG)
Electrohysterogram (EHG)
Electromyogram (EMG)
Electroenterogram (EEnG)
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
o Intestinal Motility Segmentation and propelling the chyme
Mix food and enzymes
Gastrointestinal disorders are associated to intestinal motility dysfunctions
• Intestinal ischemia
• Intestinal obstruction
• Duodenal distention
• Myopathic disorders
• Paralytic ileum
• Thyroid abnormalities
• Etc.
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Pressure Recordings
o Myoelectrical Recordings
0 5 10 15 20 25 30time (s)
Slow Wave
IntestinalContractions
Spike Bursts Electroenterogram (EEnG)
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
0 5 10 15 20 25 30tiempo (s)
Intestinal Activity Studies
o Objetives Characterize internal EEnG
Relate it with Gold Standard (Pressure)
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
EE
nG (
mV
)
time(s)0 5 10 15 20 25 30
1.5
-1.5
Indi
ce M
otil
idad
(u.
a.)
200 6040 10080 140120 160 200180 220time (min)
240
Phase I: Inactivity 50min
Phase II: Irregular Activity 30min
Phase III: Maximum Activity 6min
I IIIII
Interdigestive Migratory Motor Complex (IMMC)
IMMC
Intestinal Activity Studies
o Activity Pattern in Fast State
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
EE
nG (
mV
)
time(s)0 5 10 15 20 25 30
1.5
-1.5
Indi
ce M
otil
idad
(u.
a.)
200 6040 10080 140120 160 200180 220time (min)
240
Phase I: Inactivity 50min
Phase II: Irregular Activity 30min
Phase III: Maximum Activity 6min
I IIIII
Interdigestive Migratory Motor Complex (IMMC)
IMMC
Intestinal Activity Studies
o Activity Pattern in Fast State
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
EE
nG (
mV
)
time(s)0 5 10 15 20 25 30
1.5
-1.5
Indi
ce M
otil
idad
(u.
a.)
200 6040 10080 140120 160 200180 220time (min)
240
Phase I: Inactivity 50min
Phase II: Irregular Activity 30min
Phase III: Maximum Activity 6min
I IIIII
Interdigestive Migratory Motor Complex (IMMC)
IMMC
Intestinal Activity Studies
o Activity Pattern in Fast State
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Indi
ce M
otil
idad
(u.
a.)
200 6040 10080 140120 160 200180 220tiempo (min)
240
After breath intake till the return of Phase III
Irregular contractile activity
Duration and intensity depend on the quantity and composition of ingested food
PostingestionPatternIngest
o Activity Pattern in Postingestion
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
EE
nG (
mV
)
10 2 3 4-1.5
1.5
time (s)
Amplitude
● Amplitude SB
● Nº of SB/min● Duration SB
Duration
● Nº of peaks/min
Nº peaks
Intestinal Activity Studies
o Intestinal Motility Parameters
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
● Amplitude SB● Duration SB
time (s)0 5 10 15 20 25 30
1.5
-1.5
EE
nG (
mV
)
time (s)0 5 10 15 20 25 30
1.5
-1.5
EE
nG (
mV
)
Threshold levels: subjective criteria
Intestinal Activity Studies
o Intestinal Motility Parameters
0 20 40 60 80 100 120 140 160 180 200 220 240
Time (min)
NºS
B/m
in
● Does not include information about the INTENSITY of the contractions
Non-conventional abdominal signals: EEnG & EHG
?
● Nº of SB/min
Non-conventional abdominal signals: EEnG & EHG
0 20 40 60 80 100 120 140 160 180 200 220 240
Tiempo (min)
RM
S
● Root Mean Square (RMS)
Energy SW
Intestinal Activity Studies
o Intestinal Motility Parameters
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
EE
nG (
mV
)
10 2 3 4-1.5
1.5
time (s)● Slow Wave (SW)
■ Slow oscillation of potential
● Spike Bursts (SB)■ Rapid changes of potential
Low Frequency
High Frequeny
Multicomponent Signal
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
frecuencia (Hz)5.000.15 1.00 2.00 3.00 4.00
PSW
1.0
-1.0
tiempo (s)1200 10 20 30 40 50 60 70 80 90 100 110
(mV)InternalEEnG
● Decreasing amplitude peaks
● At multiples of the SW repetition frequency (0.3Hz,18 cpm dog)
o Spectral Analysis of the SW
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
frecuencia (Hz)5.000.15 1.00 2.00 3.00 4.00
POL
Intestinal Activity Studies
■ The application of this technique to monitor EEnG dominant frequency (freq. SW) can detect pathologies such as intestinal ischemia
Intestinal
ischemia
DF
o Spectral Analysis of the SW
● At multiples of the SW repetition frequency (0.3Hz,18 cpm dog)
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
frecuencia (Hz)5.000.15 1.00 2.00 3.00 4.00
PSW
● Up to what frequency does it extend?
100100
1
0
0
10
010
f
f
w
f
f
w
dffPT
dffPT
f,fE
f,fEf,f,fE%
Residual energy tail =2.5%
● Where is concentrated the energy of the SW? %ESW(f)
● %Energy accumulated in frequency of the SW:
fhcSW● High limit in freq. of SW:
100
0
20
40
60
80
frecuencia (Hz)5.000.15 1.00 2.00 3.00 4.00
%ESW
fhcSW
% 97.5%SW OL SW
hc hcf E f
1.950.60 Hz
o Spectral Analysis of the SW
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Spectral Analysis of the SW
frecuencia (Hz)35.000.15 1.00 10.00
PN
SB, P
SB
No SB - SB
contractile inactivity (No SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
maximum contractile activity (SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
+Spike Bursts
SW ● Power spectral density in range SW >> amplitude than higher frequencies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Spectral Analysis of the SW
No SB - SB
● Power spectral density above 2 Hz increases significantly during periods of contractile activity
contractile inactivity (No SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
maximum contractile activity (SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
+Spike Bursts
frecuencia (Hz)35.002.00 10.00
PN
SB, P
SB
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
frecuencia (Hz)35.002.00 10.00
PN
SB, P
SB
o Spectral Analysis of the SW+Spike Bursts
● Energy Limits of SB?
contractile inactivity (No SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
maximum contractile activity (SB)1.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
Intestinal Activity Studies
o Increment in signal energy: contractile activity-inactivity
o Higher frequencies than SW range: f>2 Hz100
0
20
40
60
80
frecuencia (Hz)352 10
%E
SB
-NS
B
fhcSB
flcSB
27,251.30 Hz2,250.07 Hz
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
RM
S>
2Hz
RMS Orig.RMS FPA2Hz
0 20 40 60 80 100 120 140 160 180 200 220 240
Tiempo (min)
P2H
z^0.
5
1
RMS Orig.P2Hz0.5
o Intestinal Motility Parameters
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
removedSW energy
removedSW energy
High Pass Filter
f
G
2Hz
X(t) Y(t)
SpectralEstimator
X(t) P(f)
Non-conventional abdominal signals: EEnG & EHG
o Intestinal Motility Parameters
Intestinal Activity Studies
IM Pressure
IM EEnG
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
9.000.15 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00
PS
D (
mV
2 /H
z)
frecquency (Hz) 30
o Spectral Analysis Requires signals to be stationary
Lost of temporal information
Solution: Time-Frequency Analysis
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
o Time-Frequency Analysis: Permits independent resolution for T and F
The kernel function determines the properties of the distribution
Time-Frequency Analysis
Non-conventional abdominal signals: EEnG & EHG
T-F generalized (Cohen)
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinalparalisis
Intestinal Activity Studies
o Time-Frequency Analysis: Similarly to quantifying parameters from PSD,
marginals in T and F can be defined
Marginals
Detection of Gastrointestinal Pathologies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Internal Myoelectrical RecordingsRequire surgical intervention
No clinical application
Sensor
o Surface Myoelectrical RecordingsNon Invasive
Low Cost
Intestinal Activity Studies
o Objetives Characterize Surface EEnG
Relate it with Internal EEnG
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
o Internal Myoelectrical RecordingsRequire surgical intervention
No clinical application
o Surface Myoelectrical RecordingsNon Invasive
Low Cost
Intestinal Activity Studies
o Objetives Characterize Surface EEnG
Relate it with Internal EEnG
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Surface EEnG Very attenuated signal, specially in ↑freq. (SB)contractile inactivity (No SB)
0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
maximum contractile activity (SB)0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
o Surface EEnG Very attenuated signal, specially in ↑freq. (SB)
Intestinal Activity Studies
SurfaceRecording
AbdominalLayers
InternalRecording
1.0
-1.0
(mV)
0.1
-0.11 0
(mV)
● Estimation of the transfer function of abdominal layers for each freq.■ Energy ratio surface / internal in bands of 1 Hz
Gabd(f)su
int
( 1, )
( 1, )
SBrf
SB
E f f
E f f
for f=1,2,…35 Hz
Gabd(f)Eint(f) Esurf(f)
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
o Surface EEnG Very attenuated signal, specially in ↑freq. (SB)
Intestinal Activity Studies
-15
-35
-30
-25
-20
frecuencia (Hz)35.00.1 1.0 10.0
Gab
d(d
B)
● 1st segment: f → higher attenuation
Low pass filter of EEnG energy
● 2nd segment: f → lower attenuation
aditional energy in surface EEnG?
Most studies focus on the SW (low frequency)
in high frequencyINTERFERENCE
Non-conventional abdominal signals: EEnG & EHG
SurfaceRecording
AbdominalLayers
InternalRecording
Gabd(f)Eint(f) Esurf(f)
+Einterf
Non-conventional abdominal signals: EEnG & EHG
o Surface EEnG Very attenuated signal, specially in ↑freq. (SB)contractile inactivity (No SB)
0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
maximum contractile activity (SB)0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
Presents interferences:○ Contact potential
○ EGG
○ Respiration
Cancellation?
Intestinal Activity Studies
○ ECG
○ Movement artifacts
Low Freq. High Freq.‘Software’ ‘Hardware’
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Refer.Interf.
S+IECG
ÎECG
S
Intestinal Activity Studies
o Interference Cancellation: ‘Software’ Adaptive Filtering ECG
Cancellation?
‘Software’
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Refer.Interf.
S+IECG
ÎECG
S
Intestinal Activity Studies
o Interference Cancellation: ‘Software’ Adaptive Filtering ECG
Tp Ta
0.08
-0.08
Time (s)100 1 2 3 4 5 6 7 8 9
0.70
-0.70100 1 2 3 4 5 6 7 8 9
0.10
-0.10100 1 2 3 4 5 6 7 8 9
EC
G (
mV
)E
EnG
(m
V)
Inte
rf. (
mV
)
n=1
Tp Ta0
n=13
Tp Ta0
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
o Interference Cancellation: ‘Software’ Adaptive Filtering ECG
Original
Adapt. Filt.
Original
Adapt. Filt.
SW
SW+SB
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
o Interference Cancellation: ‘Software’ Adaptive Filtering ECG
Surface
Internal
Effect on intestinal motility parameters
Non-conventional abdominal signals: EEnG & EHG
removedECG energy
Non-conventional abdominal signals: EEnG & EHG
● It’s a subgroup (the +powerful and +employed) of the Blind Source Separation (BSS) techniques
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
x t A·s t n t Observed Signals
Unknwown Mixing
Process (A)
s1
sn-1
sn
x1
xm
Source Signals
● It’s a subgroup (the +powerful and +employed) of the Blind Source Separation (BSS) techniques
● Consists on extracting a set of statiscally independent components from a set of observed signals without prior knowlegde of the signal sources and the mixing matrix.
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
x t A·s t n t
ObservedEEnGUnknwown
Mixing Process
(A)
EEnG
Respiration
ECGMovem. Artif.
● It’s a subgroup (the +powerful and +employed) of the Blind Source Separation (BSS) techniques
● Consists on extracting a set of statiscally independent components from a set of observed signals without prior knowlegde of the signal sources and the mixing matrix.
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
Unknwown Mixing
Process (A)
ICA
(A-1)
x t A·s t n t
ObservedEEnG
EEnG
Respiration
ECGMovem. Artif.
x1
x2
● It’s a subgroup (the +powerful and +employed) of the Blind Source Separation (BSS) techniques
● Consists on extracting a set of statiscally independent components from a set of observed signals without prior knowlegde of the signal sources and the mixing matrix.
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
0.05
5
-0.05 0.015
-0.015
a)
b)
g)
h)
x 1[k
]
(mV
)
PS
D
(a.u
.)
PS
D
(a.u
.)
x 2[k
]
(mV
)
0.055
-0.05 0.015
-0.015
a)
b)
c)
d)
g)
h)
i) 5
-5 5
-5
x 1[k
]
(mV
)
j)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
x 2[k
]
(mV
) s 1
[k]
(a
.u.)
s 2
[k]
(a
.u.)
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
■ ICA concentrates the components from the signal of interest and from interferences in different outputs (sources)
Remaining Interf.
Remaining signal
Respiration
Resp.
SW
slow wave
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
x1
x2
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
SW+interf. ↓f
slow waveICA out
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
0.1
-0.1 0.02
-0.02
a)
b)
g)
h)
x 1[k
] (m
V)
PSD
(a
.u.)
PSD
(a
.u.)
x 2[k
] (m
V)
0.1
-0.1 0.02
-0.02
a)
b)
c)
d)
g)
h)
i) 0.05
-0.05 0.05
-0.05
x 1[k
] (m
V)
)
j)
PSD
(a
.u.)
PSD
(a
.u.)
PSD
(a
.u.)
PS
D
(a.u
.)
x 2[k
] (m
V)
0 01
s 1[k
] (a
.u.)
s 2[k
] (a
.u.)
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
Remaining signal
Interf.↓↓f (gastric)
Interf.
SW
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
■ ICA concentrates the components from the signal of interest and from interferences in different outputs (sources)
x1
x2
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
slow wave
slow wave
ICA out
Remaining Interf.
SW+interf. ↓f
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
20 40 60 80 1000
0.1
0.2
0.3
0.4
0.5
0
0.1
0.2
0.3
0.4
0.5 D
F (
Hz)
D
F (
Hz)
b)
Tiempo (min)
a)
120 140 0
Channel 1
Channel 2
x Original○ Processed
?
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
0.05
-0.05 0.01
-0.01
a)
b)
g)
h)
5
x 1[k
]
(mV
)
PS
D
(a.u
.)
PS
D
(a.u
.)
x 2[k
]
(mV
)
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
0.05
-0.05 0.01
-0.01
a)
b)
c)
d)
g)
h)
i) 5
-5 5
-5
x 1[k
]
(mV
)
j)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
x 2[k
]
(mV
) s 1
[k]
(a
.u.)
s 2
[k]
(a
.u.)
0 0.2 0.4 0.6 0.8 1 0 20 40 60Tiempo (s) Frecuencia (Hz)
Interf.↓↓f
Respiration
■ If there is more than 1 source of interference, ICA cannot separate the sources correctly.
Nº Chanels must be greater than Nº sources
o Interference Cancellation: ‘Software’ Independent Component Analysis (ICA)
x1
x2
Intestinal Activity Studies
slow wave
Remain.Interf.
SW+interf.
ICA out
SW+interf. ↓f
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
1
n
j nj
x t IMF t r t
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
● The Empirical Mode Decomposition (EMD) consists on decomposing a signal or temporal series in a finite number of Intrinsic Mode Functions (IMF)
● The IMF are non linear oscillatory functions that are directly extracted from the data. They must satisfy 2 conditions:■ the nº of extrema and the nº of zero crossing differ by one at most■ the average of the upper and lower envelope must be sufficiently close to
zero according to some criterion
● The decomposition process is adaptive and data driven. Empiric method, NO explicit equations.
● The technique is applicable to non-stationary and non-linear signals
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHG
-0.015
0.015
x[k]
(m
V)
g) a)
PS
D
(a.u
.)
SIR=0.3 dB
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)
-0.015
0.015 -0.015
0.015
-0.015
0.015 -0.015
0.015
x[k]
(m
V)
IMF
1[k]
(m
V)
r 3 [
k]
(mV
) y[
k] (
mV
)
g)
h)
i)
j)
k)
a)
b)
c)
d)
e)
f)
-0.015
0.015
-0.015
0.015
IMF
2[k]
(m
V)
IMF
3[k]
(m
V)
l)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
SIR=18.6 dB
SIR=0.3 dB
Resp.
Resp.
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
Intestinal Activity Studies
EMD out
Original
Processed
Resp.
SW+interf. ↓f
Non-conventional abdominal signals: EEnG & EHG
-0.1
0.1 g) a)
x[k]
(m
V)
PS
D
(a.u
.)
SIR=-4 dB
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)
-0.1
0.1
-0.1
0.1
-0.1
0.1
-0.1
0.1 -0.1
0.1 g)
h)
i)
j)
k)
l)
a)
b)
c)
d)
e)
f)
-0.1
0.1
x[k]
(m
V)
IMF
1[k]
(m
V)
r 3 [
k]
(mV
) y[
k] (
mV
) IM
F2[
k]
(mV
) IM
F3[
k]
(mV
)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
SIR=17.9 dB
SIR=-4 dB
Interf.↓↓f (gastric)
Interf. ↓↓f
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
Intestinal Activity Studies
Interf.↓↓f (gastric)
EMD out
Processed
SW+interf. ↓f
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)
-0.05
0.05
x[k]
(m
V)
g) a)
PS
D
(a.u
.)
SIR=2.8 dB
0 0.2 0.4 0.6 0.8 1 0 20 40 60 Tiempo (s) Frecuencia (Hz)-0.05
0.05 -0.05
0.05
-0.05
0.05 -0.05
0.05
x[k]
(m
V)
IMF
1[k]
(m
V)
r 3 [
k]
(mV
) y[
k] (
mV
)
g)
h)
i)
j)
k)
a)
b)
c)
d)
e)
f)
-0.05
0.05
-0.05
0.05
IMF
2[k]
(m
V)
IMF
3[k]
(m
V)
l)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
PS
D
(a.u
.)
SIR=2.8 dB
SIR=13.8 dB
Interf. ↓↓f
Interf.↓↓f
Resp.
Resp.
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
EMD out
Processed
SW+interf. ↓f
DF
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
0
0.5
0.4
0.3
0.2
0.1
0
DF
(H
z)
Tiempo (min)20 80 140 100 40 60 120
x Original○ Processed
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
SW+interf. ↓f
DF
Non-conventional abdominal signals: EEnG & EHG
0
0.5
0
0.50
0.50
0.50
0.50
0.5
DF2
(Hz)
DF2
(Hz)
DF2
(Hz)
DF2
(Hz)
DF2
(Hz)
DF2
(Hz)
Time (min)0 50 100 150 200 250
0.25±0.03 Hz
0.26±0.03 Hz
0.25±0.03 Hz
0.25±0.03 Hz
0.23±0.02 Hz
0.21±0.02 Hz
a)
b)
c)
d)
e)
f)
Intestinal Activity Studies
o Interference Cancellation: ‘Software’ Empirical Mode Decomposition (EMD)
DF Surface
DF Internal 1
DF Internal 2
DF Internal 3
DF Internal 4
DF Internal 5
SW+interf. ↓f
Non-conventional abdominal signals: EEnG & EHG
o Surface EEnG Very attenuated signal, specially in ↑freq. (SB)contractile inactivity (No SB)
0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
maximum contractile activity (SB)0.1
-0.11.0
-1.0
tiempo (s)300 5 10 15 20 25
(mV)
(mV)
SurfaceEEnG
InternalEEnG
Presents interferences:○ Contact potential
○ EGG
○ Respiration
Cancellation?
Intestinal Activity Studies
○ ECG
○ Movement artifacts
Low Freq. High Freq.‘Software’ ‘Hardware’
Non-conventional abdominal signals: EEnG & EHG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Interference Cancellation: ‘Hardware’ Electrodes in Laplacian configuration
Cancellation
‘Hardware’
Intestinal Activity Studies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
1
2
3
4 5
Rigid Electrodes
o Interference Cancellation: ‘Hardware’ Electrodes in Laplacian configuration
5 1 2 3 42
4 1
4VL V V V V Vb
Intestinal Activity Studies
Flexible Electrodes
Discrete approximation Continuous approximation
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
o Interference Cancellation: ‘Hardware’ Electrodes in Laplacian configuration
Rigid Electrodes
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
0
3
PS
D (
a.u) Resp
0
4e-3
PS
D (
a.u) Ch1
0 10 20 300
5e-4
PS
D (
a.u) TCB
Frequency (cpm)
-2
2
(V)
Resp
-0.1
0.1
(mV
)
Ch1
0 60-1
1
(mV
) ECG
Time (seconds)
(mV
)
-0.1
0.1
(mV
) TCB
(mV
)
Respiration
EEnG
Bipolar
EEnG
Laplacian
ECG
-2
2
(V)
Resp
-0.1
0.1Ch1
0 10-1
1
(mV
)
ECG
Time (seconds)
-0.1
0.1TCB
SW
Intestinal Activity Studies
Interf. ECG ↓
Int. LF↓ Int. Resp.↓
o Interference Cancellation: ‘Hardware’ Electrodes in Laplacian configuration
Non-conventional abdominal signals: EEnG & EHG
Intestinal Activity Studies
Int. Resp.↓
o Interference Cancellation: ‘Hardware’ Electrodes in Laplacian configuration
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm birth (<37 wog) 5-10% of total births
Main cause of perinatal deaths (85%); 1/5 mental retardation; 1/3 visual impairment; 1/2 cerebral palsy
73
54
41
32
9
63
85
82
85
23
24
25
26
27Ges
tati
on
alA
ge(
wee
ks)
0 20 40 60 80 100(%)Mortality %Survival without moderate or severe sequelae
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm birth (<37 wog) 5-10% of total births
Main cause of perinatal deaths (85%); 1/5 mental retardation; 1/3 visual impairment; 1/2 cerebral palsy
It involves prolonged hospital stays and a high economic cost
Semanas
36343230282624
Cos
te d
e cu
idad
os (
x 10
00 S
)
120
100
80
60
40
20
0
Car
eC
ost
(x10
00 $
)Weeks of gestation
Cost of surviving newborn
96
90
54
43
31
66
38
10
7
4
500 - 749
750 - 999
1000-1249
1250-1499
1500-1999
Newborn weight (gr)
0 20 40 60 80 100 120Average stay (days)
TotalIntens. Care
Excluding deaths and readmissions
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm birth (<37 wog) 5-10% of total births
Main cause of perinatal deaths (85%); 1/5 mental retardation; 1/3 visual impairment; 1/2 cerebral palsy
It involves prolonged hospital stays and a high economic cost
The effectiveness of tocolytic and lung madurationagents is subject to the early initiation of therapy
Reliable prediction of true labor
understanding the mechanisms that initiate labor
study of uterine contractions.
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Monitoring of Uterine Contractions Intrauterine Pressure (IUP)
• Direct and accurate measurement
• ‘Free’ of artifacts and interferences
• ‘Only’ mechanical information
• Requires membrane rupture
Gold Standard
Uterine Activity Studies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Monitoring of Uterine Contractions External Tocography (TOCO)
• Non invasive measurement
• Provides approximate duration and frequency of contractions
• Inaccurate measurement– Influence of probe location and pressure
– Subjectivity of the examiner
• Use of tight straps
• No information about efficiency of the contractions
Uterine Activity Studies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Monitoring of Uterine Contractions
• Non invasive measurement
• Provides approximate duration and frequency of contractions
• Inaccurate measurement
• Use of tight straps
• No information about efficiency of the contractions
?
Uterine Activity Studies
Electrohysterography (EHG)
•is NOT needed
– Amplitude depends on recording conditions
– Influence of body fat (less than TOCO)
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
-0.5
0
0.5
Can
al 3
(mV
)
-0.5
0
0.5
Can
al 4
(mV
)
-0.5
0
0.5
Can
al 3
(mV
)
-0.5
0
0.5
Can
al 4
(mV
)
-0.4
0
0.4
Bip
olar
(mV
)
0 20 40 60 80 100-0.4
0
0.4
Time (s)
Bip
olar
filt
rado
(mV
)
• Monopolar• Monopolar vs Bipolar
Uterine Activity Studies
o EHG Recordings
Presents interferences from:○ Contact potential
○ Respiration
Cancellation?
○ ECG
○ Movt. Artifacts
‘Software’
‘Hardware’
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
A
f (Hz)351
Preprocessing
o Interference Cancellation: ‘Software’ ECG cancellation by ICA
Uterine Activity Studies
1
16
x1[k]
x16[k]
.
.
.
ICA
G(s)=log(cosh(s))
IC1[k]
IC16[k]
.
.
.
(z)MxK
Identification & cancelling cardiac
ICs
Reconstruction Observed Signals
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Interference Cancellation: ‘Software’ ECG cancellation by ICA
Uterine Activity Studies
0 50 100 150 200-0.2
0
0.2
Tiempo (s)
EC
G
(mV
)
-0.2
0
0.2
ICA
(m
V)
-0.2
0
0.2
Filt
rado
(mV
)
-0.2
0
0.2
Ori
gina
l(m
V)
(a)
(b)
(c)
(d)
30 40 50 60 70 80 90 100 110 120-0.2
0
0.2
Tiempo (s)
-0.2
0
0.2-0.2
0
0.2-0.2
0
0.2(a)
(b)
(d)
(c)
0 5 10 15 20-0.2
0
0.2
Tiempo (s)
-0.2
0
0.2-0.2
0
0.2-0.2
0
0.2(a)
(b)
(d)
(c)
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Interference Cancellation: ‘Software’ ECG cancellation by Adaptive Filtering
Uterine Activity Studies
-0.05
0
0.05
Ch1
(m
V)
-0.05
0
0.05C
h2
(mV
)
-0.05
0
0.05
Ch3
(m
V)
-0.05
0
0.05
Ch4
(m
V)
0 1 2 3 4 5 6 7 8 9 10-0.2
0
0.2
EC
G m
ater
no(m
V)
Time (s)
Maternal ECG
Maternal+FetalECG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
-0.05
0
0.05
Ch1
(m
V)
-0.05
0
0.05
Ch2
(m
V)
-0.05
0
0.05
Ch3
(m
V)
-0.05
0
0.05
Ch4
(m
V)
0 1 2 3 4 5 6 7 8 9 10-0.2
0
0.2
EC
G m
ater
no(m
V)
Time (s)
-0.05
0
0.05
Ch1
(m
V)
-0.05
0
0.05
Ch2
(m
V)
-0.05
0
0.05
Ch3
(m
V)
-0.05
0
0.05
Ch4
(m
V)
0 1 2 3 4 5 6 7 8 9 10-0.2
0
0.2
EC
G m
ater
no(m
V)
Time (s)
o Interference Cancellation: ‘Software’ ECG cancellation by Adaptive Filtering
Uterine Activity Studies
Maternal ECG
FetalECG
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
0
50
100
IUP
(m
mH
g)
0 200 400 600 800 10000
50
100
Time (s)
TO
CO
(m
mH
g)
(d)
(c) -1
0
1
EH
G
(mV
)
(a)
o Interference Cancellation: ‘Software’ Artif. cancel. & contraction detection by expert system
Uterine Activity Studies
N=645 Sensitivity Specificity PPV NPV
LDA 69.4% 97.0% 93.7% 83.1%
QDA 84.3% 97.0% 94.8% 90.6%
SVM 87.1% 97.3% 95.5% 92.1%
Toco-Like signal generationUterine ContractionsArtifactsIdentify & Classify
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o SignalsEHG
• 5 Monopolar
• 4 Bipolar
• 1 Laplacian Discrete
• 2 Laplacian Continuous
M1
M2
M3
M4 M5
umbilicus
B1
B2
B4B4
L1 L2
LD
o Contraction detection: monitoring uterine dynamicscontraction detection
Cancellation?‘Software’
‘Hardware’
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o SignalsEHG
• 5 Monopolar
• 4 Bipolar
• 1 Laplacian Discrete
• 2 Laplacian Continuous
TOCO
IUP
TOCO
IUP
o Contraction detection: monitoring uterine dynamics
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Contraction detection: monitoring uterine dynamics
1
2
C
T E
NCCI
N N
• NC nº consitent contract.• NT nº contract. IUP• NE nº contract. EHG (o toco)
S/IECG (dB) S/N (dB)
Cancellation?‘Hardware’
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Contraction detection: monitoring uterine dynamics
1
2
C
T E
NCCI
N N
• NC nº consitent contract.• NT nº contract. IUP• NE nº contract. EHG (o toco)
S/IECG (dB) S/N (dB)
Cancellation?‘Hardware’
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
• MPTLS=multiple preterm labor symptons • Ctx=Nºcontractions (TOCO)
• BS= Bishop Score
• Cx=cervical length (ultrasound)
•CFFN+= Cervical fetal fibronectin test
• LIF: Cervical light-induced fluorescence
• EMG= No-Invasive Uterine Electromiogram (EHG)
[Garfield & Maner, 2007]
Uterine Activity Studies
o Preterm diagnosis
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
o Evolution throughout pregnancy
Physiological changes in EHG parameters:
• Amplitude
• Duration
• nº CT/h: 0.5‐6 CT/h pregancy vs. maximum 18 CT/h labor)
• Energy content shifts to higher frequencies
• relative energy of FWH
Uterine Activity Studies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
• Energy content shifts to higher frequencies
• relative energy of FWH
Mea
n pe
ak fr
eque
ncy
Uterine Activity Studies
o Preterm diagnosis
[Terrien, 2009]
FWH swifts to ↑ frequencies
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Preterm laborTerm labor
Uterine Activity Studies
o Preterm diagnosis Dominant Frequency between [0.34,1] Hz [Manner, 2003]
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm diagnosis Dominant Frequency between [0.34,1] Hz [Manner, 2003]
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm diagnosis Dominant Frequency [Lukovnik, 2011]+ Propagation velocity
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Preterm diagnosis Dominant Frequency + Propagation velocity
Depends on electrode orientation and direction of propagated wavefrontNOT
V1V2
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Predicting Horizon and Mode of Delivery
PREGNANT:EHG Recording
LABOR
NON LABOR
Classifier: QDA, SVM(Accuracy 94%)
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Predicting Horizon and Mode of Delivery
PREGNANT:EHG Recording
LABOR
NON LABOR
SPONTANEOUS
INDUCTION /RIPENING
CESAREA
Mode of future delivery
TIME TO DELIVERY
(days)Classifier: QDA, SVM
(Accuracy 94%) Classifier(Accuracy 95%)
Estimator(error <1 day)
+ Obstetric Parameters
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Uterine Activity Studies
o Future work Enlarge databases
Study the effect of different cervical ripening drugs
Individualized follow up of EHG during pregnancy
Analyze propagation patterns and velocities
Develop portable EHG, fECG monitoring device
Aid to predict preterm labor
Non-conventional abdominal signals: EEnG & EHGNon-conventional abdominal signals: EEnG & EHG
Dr. F. Javier García Casado
Thanks for your attention