1. DETECTION TECHNIQUES FOR PULMONARY EDEMA
Pratibha Sharma, Kimberly Newman, Frank Barnes
Department of Electrical, Computer, and Energy Engineering, University of Colorado-Boulder, U.S.A.
Introduction
Methods
Congestive Heart Failure
Congestive heart failure is one of the leading causes of death with nearly 250,000 deaths every year worldwide [1]. Congestive heart failure (CHF) is a condition where the heart pumps insufficient oxygen rich blood to the body and is one of the leading causes of death in the U.S. [1]. Due to this inefficiency in the heart the excess fluid gets accumulated and shifts into interstitial spaces. The inefficiency of left ventricle causes fluids shifts into the lungs known as pulmonary edema.
 This paper reviews signals and detection techniques with potential application to remote monitoring for congestive heart failure management
Potential signals that may be useful to detect this condition are electrical signal, acoustic signal, mechanical signal and chemical signal. Our main objective is to develop a device which could measure all types of signals at a time and can alert the person at a sufficient time ahead to take effective measures. If any of the signals go beyond the minimum threshold value then the device can give alarm to the individual and could also send his data to the clinic via tele device.
Potential signals that may be useful to detect this condition are electrical signal, acoustic signal, mechanical signal and chemical signal. 
Electrical and mechanical signal can be detected by ECG measurement. The acoustic signal can be measured by stethoscope readings and chemical signal can be accomplished by exercise stress testing. All the three signals can be captured by non-invasive instruments. We will use skin electrodes for ECG and peak O2 and stethoscope or a multichannel lung sound analyzer for acoustic signals. Failure of peak O2(10 ml/min/kg) to decrease within 30 sec after peak exertion is associated with more severe reductions in left ventricular ejection fraction and moderate to severe impairment of pulmonary exchange. The signals will be analyzed first using Fourier analysis and by quantifying the distance a crackle spreads using a technique that cross-correlated the signal containing the highest amplitude crackle with the corresponding signal on all other ipsilateral channels The data was extracted and a Fourier Analysis was performed using MATLAB on both acoustic and thoracic data
𝐹 𝜔 = −∞ ∞ 𝑓(𝑡) 𝑒 −2𝜋𝑖𝜔𝑡 𝑑𝑡
There are two main forms of congestive heart failure, systolic heart failure and diastolic heart failure which maybe present in only one side of the heart, but is usually present on both sides.
Systolic heart failure is a result of the heart being unable to effectively pump blood out of the heart.
Diastolic heart failure is when the heart can’t contract effectively and is stiff; this affects the efficiency of the heart to fill with blood.
When the heart experiences systolic or diastolic heart failure fluid may build up in regions of the body. The fluid buildup caused by congestive heart failure can lead to pleural effusion.
Detection of congestive heart failure in early stages is hard to diagnose. The condition may lead to fatigue, shortness of breath, crackling sound produced in the lower lungs while inhaling, and swelling in parts of the body.
The crackle transmission coefficient (CTC) and crackle frequency when averaged give 25+8% and Hz respectively for CHF patients [3].Yongyudh Ploysongsang provided a frequency analysis on dogs with induced pulmonary edema as well as healthy specimens shown in fig.below [4].
Our data matches the frequency spectrum of tidal breath given by Youngyudh.We have taken the data on 6 healthy persons, five males and one female which resulted in frequency analysis of cardiac acoustic responses to be below 400Hz as expected.
Functionality of the Heart
Possible Future Research
Cells in the heart are arranged in a syncytium, therefore depolarization of one cell is spread to surrounding cells. It is this characteristic that allows the heart to keep a rhythm.
An action potential started by the Sinoatrial node in the right atrium will propagate through the right atrium to the Atrioventricular node and through the Bachmann’s bundle to the left atrium.
Once the action potential has reached the Atrioventricular node it will spread through the Purkinje fibers to the lower ventricles.
Model of the relationship of Pressure and Flow in open valves
𝛼 𝜕𝑄 𝜕𝑡 +𝛽 𝑄 2 =∆𝜌
The Action Potentials induced across the cardiac muscle causes coherent contractions to pump blood through the cardiovascular system. As the action potential travels through the atrium, both the right atrium and left atrium contract. As the right atrium contracts blood passes through the tricuspid valve to the right ventricle and as the left atrium contracts blood flows through the mitral valve to the left ventricle.
As the action potential travels through the ventricles, the right ventricle contracts passing blood through the pulmonary valve to the pulmonary artery and the left ventricle contracts passing blood through the aortic valve to the aorta.
The detection technique relies on multiple non invasive sensors to not only ascertain the incidents of CHF but also provide feedback to the patient and care provider to improving quality of service (QoS) of the healthcare system.
Results and Discussion
The acoustic data both from the cardiac muscles and the thoracic cavity were normalized, this is due to large variations in amplitude among subjects.
The results of all the individuals’ cardiac acoustic frequency analysis were below 400 Hz.
This in turn will help establish a method that maybe used to detect congestive heart failure in the early stages without the use of more expensive equipment and procedures used commonly today in clinical setting.
With respect to the thoracic acoustic response, there was significant variability between subjects. This is due to the uncontrollable nature of different breathing patterns among subjects.
The ECG data was meant as a method for filtering out data when the heart didn’t exhibit a normal response, to establish a baseline for healthy individuals. However based off of ECG data no acoustic data was discarded.
In a study performed on dogs with pulmonary edema, a frequency spectra of greater then 1 kHz was observed [2]. Based off of the frequency spectra of the dogs’ cardiac acoustics with pulmonary edema it is predicted that a significant difference in frequency spectra will be observed between healthy individuals and individuals with Congestive Heart Failure.
The authors will capture the synchronized combination of different signals and develop a wearable detection device in order to activate the triggers for effective provisioning of support services.
Subject C’s Cardiac Acoustic response
References
[1]
[2] Yong Yudh, P. M. (1989). Early detection of pulmonary congestion and edema in dogs using lung sounds. American Physiological Society ,
[3] Eugene Braunwald(1997), Braunwald Heart Disease : a Textbook of Cardiovascular Medicine , 5th Edition
[4] Andrey Vyshedskiy,Francisco Bezares, Rozanne Paciej,Margo Ebril; John Shane, and Raymond Murphy. Transmission of crackles in patients with interstitial pulmonary fibrosis ,congestsive heart failure and pneumonia
Detection techniques for pulmonary edema