electrocardiogramm derived respiratory signal (edr signal)

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EDST - UL Ecole Doctorale des Sciences

et de Technologie Université Libanaise

“Derivation of Respiratory Signal from

Electrocardiograms”

Submitted to Dr. Hassan Amoud & Dr. Ahmad Diab February 19th, 2016

Sarah Hussein Master TIS | TIS01 Course

O U T L I N E S

Context Problem Statement

Definition Signal Acquisition

Pre-Treatment

State of The Art Detailed Method

Brief Summary

INTRODUCTION EDR SIGNAL METHODOLOGIES CONCLUSIONS

1� 2� 3� 4�

2 Sarah Hussein Master TIS | TIS01 Course

INTRODUCTION

¨  Context ¨  Problem Statement 1�


I N T R O D U C T I O NContext

q  Respiration and heartbeat are physiological functions critical for life

q  Both are modulated by fluctuations of the autonomic nervous system (ANS)

q  Both carry information for the autonomic control of the cardio-respiratory system

q  Studies have shown a significant relationship between the ANS and

cardiovascular mortality, including sudden cardiac death

q  Heart rate variability (HRV) is a simple and non-invasive method to asses the

status of the autonomic modulation of the heart

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I N T R O D U C T I O NContext (Cont.)

q  HRV is the amount of variations of both RR intervals and instantaneous heart rate

q  A major component of HRV is respiratory sinus arrhythmia (RSA)

q  RSA is the naturally occurring beat-to-beat fluctuation in heart rate that occurs

during a respiratory cycle

q  Respiratory rate is crucial for the correct interpretation of RSA and thus HRV

q  Respiratory signal is recorded with spirometry, pneumography or

plethysmography


I N T R O D U C T I O NContext (Cont.)

q  These techniques require the use of cumbersome devices that may interfere with

natural breathing, and are unmanageable in certain applications

q  The joint study of the respiratory and cardiac systems is of great interest

q  The use of methods for indirect extraction of respiratory information is

particularly attractive to pursue

q  It is more convenient to use physiological signal that does not alter respiration,

easily accessible & carries unambiguous information of respiration

q  ECG is one such signal!


I N T R O D U C T I O NProblem Statement

“How can spontaneous respiration be derived from the Electrocardiograms?“


EDR SIGNAL

¨  Definition ¨  Signal Acquisition ¨  Pre-Treatment

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E D R S I G N A LDefinition | Respiratory Signal

q  Respiration is an involuntary act controlled the ANS via the medulla oblongata of

the brain

q  Medulla oblongata senses blood levels of CO2 and triggers respiration at

increased CO2 levels

q  Respiratory system’s function is to meet the respiratory demands of cells:

¨  To deliver a steady supply of oxygen to the cells of the body

¨  To remove the carbon dioxide released by the cells

q  During respiration, air is moved into & out of by changing the volume of lungs

q  Lungs volume changes due to contractions of intercostal muscles & diaphragm

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E D R S I G N A LDefinition | Respiratory Signal (Cont.)

10

F.H. Martini. Fundamentals of Anatomy and Physiology. Number ISBN: 0- 321-31198-1. Pearson, 7th edition edition, 2006



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q  Autoregressive power spectra of respiratory signal (RESP) during controlled respiration at 6 (CR 6), 10 (CR 10) and 16 (CR 16) breaths/min in one subject

Maria Vittoria Pitzalis et al. Effect of respiratory rate on the relationships between RR interval and systolic blood pressure

Fluctuations: a frequency-dependent phenomenon Oxford Journals


E D R S I G N A LDefinition | EDR Signal

q  EDR signals are the Electrocardiogram Derived Respiratory signals

q  EDR methods exploit the respiratory induced changes of the ECG to provide a

surrogate respiratory signal

q  These surrogate signals enable the estimation of the respiratory rate and the

temporal pattern of respiration

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Komorowski et al. BioMed Eng OnLine (2015) 14:60


E D R S I G N A LSignal Acquisition

q  A c q u i s i t i o n m e t h o d s o f E D R i s

consequently that of ECG

q  ECG is measured via electrodes on the

surface of the body

q  When the heart beats, a wave of

depolarization travels through the heart

q  A potential difference is measured

between 2 points

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F.H. Martini. Fundamentals of Anatomy and Physiology. Number ISBN: 0- 321-31198-1.

Pearson, 7th edition edition, 2006.


01 02 03

E D R S I G N A LSignal Acquisition (Cont.)

Limb Leads Augmented Limb Leads Precordial Leads

Three Lead Systems

Nobelprize.org. The electrocardiogram looking at the heart of electricity.

D. C. Randall and Y. M. El-Wazir. ECG Interpretation. Number ISBN 1593771800. Hayes Barton Press, 2004.


E D R S I G N A LPre –Treatment | System Requirements

q  The detected ECG signal is noisy

q  EDR extraction is done using ECG pure signal

q  A pre-treatment of the signal is required to remove artifacts

q  Pre-treatment should be performed on data that satisfies the following: ¨  The ECG should be recorded on equipment that satisfy voluntary standards ¨  The sample rate should be ≥ 500Hz

¨  The recordings of should be of 5 minute duration ¨  The environment of the recording should be controlled and physiologically stable


E D R S I G N A LPre –Treatment | Filtering & QRS Detection

q  Pre-treatment includes :

¨  Filtering the ECG

¨  Detection of the QRS complexes in 2 stages

Lasse Sohrt-Petersen Evaluation of Algorithms for ECG Derived Respiration

in the Context of Heart Rate Variability Studies Aalborg University, 2014


E D R S I G N A LPre- Treatment | Filtered ECG Signal

F.H. Martini. Fundamentals of Anatomy and Physiology. Number ISBN: 0- 321-31198-1.

Pearson, 7th edition edition, 2006.


E D R S I G N A LPre-Treatment | Filtered ECG Signal

ECG Statistics, Noise, Artifacts, and Missing Data Gari D. Clifford


METHODOLOGIES

¨  State of The Art ¨  Detailed Method 3�


M E T H O D O L O G I E SState of The Art | EDR Algorithms

q  Several EDR Algorithms were discussed in Literature:

¨  Multiple lead methods based on variations in angle of mean electrical axis (Moody

1985, Zhao 1994 & Caggiano 1996)

¨  Single lead methods based on R-wave amplitude or QRS area (Khaled 1992,

Felblinger 1997, Dobrev 1998, Mason 2001, de Chazal 2003, O’Brien 2007, Park

2008 & Arunachalam 2009)

¨  Methods based on heart rate (Womack 1971 & Correra 2008)

¨  Methods based on discrete Wavelet Transform and band pass filtering (Yi 2002 &

Boyle 2009)

¨  VCG methods based on variations in angle of mean electrical axis (Leanderson 2003

& Bailon 2003)

¨  Combinative methods (Varanini 1990, Orphanidou 2009 & Boyle 2009)


M E T H O D O L O G I E SState of The Art | EDR Algorithms (Cont.)

q  Several EDR Algorithms were discussed in Literature:

¨  Multiple lead methods based on variations in angle of mean electrical axis (Moody

1985, Zhao 1994 & Caggiano 1996)

¨  Single lead methods based on R-wave amplitude or QRS area (Khaled

1992, Felblinger 1997, Dobrev 1998, Mason 2001, de Chazal 2003, O’Brien 2007,

Park 2008 & Arunachalam 2009)

¨  Methods based on heart rate (Womack 1971 & Correra 2008)

¨  Methods based on discrete Wavelet Transform and band pass filtering (Yi 2002 &

Boyle 2009)

¨  VCG methods based on variations in angle of mean electrical axis (Leanderson 2003

& Bailon 2003)

¨  Combinative methods (Varanini 1990, Orphanidou 2009 & Boyle 2009)


M E T H O D O L O G I E SState of The Art | Detailed Method

Single Lead Method Based on QRS Area

q  EDR signal is obtained by calculating the area enclosed by the baseline and the

QRS complex in a certain interval

q  The leads most affected by the presence of air in the lungs are Lead II and Lead V4

Why?

¨  The amplitude of the QRS complex depends on the ECG lead

¨  The leads most affected by normally air filled lungs are lead II & lead V4

q  The QRS area approach is less affected by noise compared to pure amplitude EDR

methods


M E T H O D O L O G I E SState of The Art | Detailed Method (Cont.)

Power spectrum q Respiratory signal (solid

line) q EDR signals before

substitution of noisy beats (dotted line)

q EDR signals after

substitution of noisy beats (dashed line)

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Raquel Bailon, Leif Sornmo, and Pablo Laguna. Chapter 8 – ecg derived respiratory frequency estimation.



Single Lead Method Based on QRS Area (Cont.) q  Performance measures:

¨  Mean Square Error

¨  Correlation Coefficient : Pearson’s r



Single Lead Method Based on QRS Area (Cont.)

Lasse Sohrt-Petersen Evaluation of Algorithms for ECG Derived Respiration in the Context of Heart Rate Variability Studies Aalborg University, 2014

(RMSE=0.234 s & r=0.938)


CONCLUSIONS

¨  Brief Summary 4�


C O N C L U S I O N SBrief Summary

q  Respiratory rate is crucial for the correct interpretation of heart diseases

q  Respiratory signal is usually recorded with cumbersome devices

q  Physiological signals such as ECG are preferable à EDR signals

q  Signal Acquisition is done using 12 lead system

q  Detected noisy signal requires filtering and QRS detection in two stages

q  Single lead method based on QRS area detection exhibits good performance


THANK YOU

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R E F E R E N C E S

q  Sung-Bin park et al. An improved algorithm for respiration singal extraction from

electrocardiogram measured by conductive tectile electrodes using instantaneous frequency

estimation. Medical and Biological Engineering and Computing, 46:147–158, 2008

q  Raquel Bail on, Leif So rnmo, and Pablo Laguna. Chapter 8 - ecg-derived respiratory

frequency estimation. In Gari D. Clifford, Francisco Azuaje, and Patrick E. McSharry, editors,

Advanced Methods and Tools for ECG Data Ana- lysis. Artech House, Inc, 2006. ISBN -10:

1-58053-966-1

q  David Caggiano and Stanley Reisman. Respiration derived from the electrocardiogram: A

quantitative comparison of three different methods. Proceedings of IEEE 22nd Annual NE

Bioengineering Conference, pages 103–104, 1996


R E F E R E N C E S

q  Philip de Chazal et al. Automated processing of the single-lead electrocardiogram for

the detection of obstructive sleep apnoea. IEEE Transactions on Biomedical

Engineering, 50(6):686–696, June 2003

q  A. Despopulos and S. Silbernagl. Color Atlas of Physiology. Number ISBN

3-13-545005-8. Thieme, 5th edition edition, 1998

q  George B. Moody et al. Derivation of respiratory signals from multilead ecgs. Computers

in Cardiology, 12:113–116, 1985

q  I. Kestin. Control of heart rate. Update in Anaesthesia, (3):15–16, 1993


Back Up Slides

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q  The respiratory system is able to adapt to meet different levels of metabolic

need by increasing or decreasing the respiratory rate and volume

q  Respiratory rate is the number of breaths taken within a set amount of time,

usually one minute

q  Normal respiratory rate, called eupnea, ranges from 12 to 20 breaths per minute

in resting adults

q  The respiratory volumes and capacities are the amount of air inspired, expired

and stored within the lungs


E D R S I G N A LAcquisition Methods (Cont.)

q  Limb leads à Einthoven’s lead system à

Kirchoff’s voltage law (VI+VIII=VII)

q  Augmented Leads à Wilson’s Central

Terminal à WCT=1/3(RA +LA+LL)

q  Limb + Augmented leads = hexa-axial

reference system à calculate the electrical

axis of the heart in the frontal plane

Nobelprize.org. The electrocardiogram

looking at the heart of electricity.


E D R S I G N A LAcquisition Methods (Cont.)

q  6 Precordial leads à calculate the

electrical axis of the heart in the horizontal

plane

q  These 6 electrodes as positive references

and WCT as negative reference =

precordial leads (V1, V2, V3, V4, V5 and

V6)

q  Limb + Augmented leads + precordial

leads = 12 lead system à most commonly

used clinical ECG-system

D. C. Randall and Y. M. El-Wazir. ECG Interpretation. Number ISBN 1593771800. Hayes Barton Press, 2004.


E D R S I G N A LPre –Treatment | Pre – Filtering (1)

q  The composite amplitude, R(t), of a detected R-wave can be modeled as

¨  r is the true R-wave amplitude during the resting phase of a normal breath ¨  a is the amplitude modulation due to respiration ¨  Common sources of noise include power-line interference (np), zero mean

Gaussian noise (nG), EMG noise (nH) and baseline wander (b)

q  Due to the relation between baseline wander and respiration, the baseline wander

should not be much attenuated à HPF cut off frequency of 0.05Hz

q  Assuming lowest breath frequency of 3 breaths per minute à normal breathing in

resting adults is 12 to 20 breaths per minute (0.2Hz to 0.33Hz)



q  np is caused by improper grounding of the ECG recording equipment or interference

from surrounding electronic equipment à 50Hz 2nd order IIR notch filter

Lasse Sohrt-Petersen

Evaluation of Algorithms for ECG Derived Respiration in the Context of

Heart Rate Variability Studies

Aalborg University, 2014



q  np is caused by improper grounding of the ECG recording equipment or interference

from surrounding electronic equipment à 50Hz 2nd order IIR notch filter

Lasse Sohrt-Petersen Evaluation of

Algorithms for ECG Derived Respiration in the Context of





q  EMG noise, nH (t), and zero mean Gaussian white noise, nG(t) à 2nd order Butterworth low-pass filter with a cut-off frequency of 40 Hz

Lasse Sohrt-Petersen

Evaluation of Algorithms for ECG Derived Respiration in the Context of




E D R S I G N A LPre –Treatment | QRS Detection

q  Several QRS detection algorithms have been presented in the literature

q  The Hamilton-Tompkins QRS detector is one of the most robust and proven QRS detector algorithms

q  The original QRS Hamilton-Tompkins detector consist of a two stages:

¨  Stage 1: A preprocessing stage including filtering, differentiating, squaring, and time averaging

¨  Stage 2: A series of heuristic decisions rules which operates on the output of stage 1, in order to locate the QRS complexes in the original filtered ECG data


E D R S I G N A LPre –Treatment | QRS Detection | Phase 1

Lasse Sohrt-Petersen Evaluation of Algorithms for ECG Derived Respiration in the Context of Heart Rate Variability Studies Aalborg University, 2014


E D R S I G N A LPre –Treatment | QRS Detection | Phase 2




M E T H O D O L O G I E SState of The Art | Respiratory-Induced Modulations of ECG

q  To derive a surrogate respiratory signal from the information contained in ECG à Respiratory mechanisms that induce modulations of the ECG

q  Respiratory activity influences the measurements of ECG in various ways:

¨  Respiratory induced modulation of the heart rate (RSA) leading to a frequency modulation of the ECG

Lasse Sohrt-

Petersen Evaluation of

Algorithms for ECG Derived Respiration in the Context of




M E T H O D O L O G I E SState of The Art | Respiratory-Induced Modulations of ECG (Cont.)

¨  The filling and empting of air in the lungs leads to changes in the transthoracic impedance which lead to an amplitude modulation of the ECG

¨  The mean electrical axis of the cardiac vector changes its direction during respiration, leading to both an amplitude and a frequency modulation of the ECG


