Document Type
Thesis
Date of Award
1-31-1989
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical Engineering
First Advisor
Peter Engler
Second Advisor
Stanley S. Reisman
Abstract
With a microwave interferometer the vibrational velocity of the anterior (front), as well as posterior (back) chest wall can be monitored and recorded. The recorded signals are a reflection of the mechanical cardiac activity within the chest cavity, as opposed to Electrocardiogram (ECG) which is a reflection of the electrical cardiac activity. The interferometer recordings are obtained with no physical contact between the instrument and the subject. Moreover, the subject can be fully clothed since microwave energy readily passes through normal dry clothing.
A microwave interferometer that is capable of detecting the vibrational velocity of the surfaces of the chest cavity (anterior and posterior) has been described in detail in the thesis. The objective of this research work is to monitor, record and analyze these vibrational characteristics of the chest wall using the microwave interferometer from co-operative healthy, normal subjects, both males as well as females, and thus to evaluate the possibility of using this instrument as a non-invasive and non-contacting cardiopulmonary monitor. The recordings from an ECG are very well understood by doctors and engineers today. By studying the signals obtained from the microwave interferometer with the ECG as a timing reference, and bearing in mind that certain mechanical cardiac events, such as valves opening and closing occur at certain points in the RR interval of the ECG, an attempt has been made to identify a common 'signature' or repetitive vibration pattern of the chest wall in normal, healthy male and female subjects. The interferometer data from one subject is autocorrelated to accentuate those features that are repetitive and also to attenuate the non-repetitive features. High amplitude velocity peaks are noticed at similar times within each cardiac cycle . In order to relate the timing of the peaks in the raw interferometer signal to the timing of certain known events in the cardiac cycle, such as the R wave of the ECG (recorded simultaneously), the interferometer signal is cross-correlated with a pulse train obtained by filtering out the R peaks from the ECG of the same subject. With the existing knowledge of the timing of mechanical events within an RR interval an attempt is made to relate the high-velocity peaks to these mechanical events.
The interesting question is raised whether this technique can be used to detect those cardiac abnormalities that significantly alter the mechanical coupling of the cardiac musculature to the chest wall. This instrument may also prove useful as a monitor for both the cardiac and the respiratory rhythms of the premature infant who is susceptible to the sudden infant death syndrome (SIDS or "crib death").
Recommended Citation
Basu, Tanmoy K., "A microcomputer based non-invasive cardiopulmonary monitor using a microwave interferometer" (1989). Theses. 2722.
https://digitalcommons.njit.edu/theses/2722
