Abstract
Cardiotocography (CTG) is widely used for antenatal monitoring and assessment of fetal well-being. CTG measurement methods based on the phonocardiographic principle and a home-monitoring system utilizing low-cost devices for data acquisition have been proposed and implemented by our research group. Assessment and storage of the recordings are carried out in medical centers, and their calculation capacity is no longer enough to evaluate the ever-increasing amount of incoming data on the constantly growing number of different assessment methods. The present work proposes a new method to create an easily scalable environment based on a P2P principle to share the workload and data between medical centers, while also representing a framework for discovering new correlations between evaluation method results and symptoms of fetal diseases.
TopBackground
The passive phonocardiographic (PCG) method for fetal monitoring has been developed in the 90’s (Kovács et al., 2000). The intention was the limited usage of ultrasound Doppler for long-time CTG measurements, because according to some studies, the ultrasound radiation is not fully harmless in such cases. The key factor of the PCG method, that made this examination possible, is the developed special acoustic sensor, which placed on the maternal abdomen delivers informative sound signals about the heart activity of the fetus. Using this passive method extremely long-term CTG measurements can be accomplished, yielding more reliable data about the fetus well-being.
In the course of the high-volume measurements which have been carried out during the last ten years it appeared, that the phonocardiographic method is capable to display some additional features of the fetal heart activity too, as the exact sound waveforms of the closing valves, and the murmur of the turbulent blood flow, which may be indications of some congenital diseases. These are detailed in the following.
The PCG method enables to indicate more precisely the heart rhythm irregularities, known as extrasystole, arrhythmia, bradycardia and tachycardia, as well as the bigeminal/trigeminal form of pulses (repeating duplicating or tripling), the origin of which is not cleared until now. The measurement of these requires not only the very exact determination of the periodicity, but the analysis of the waveforms, too. In addition, in some cases the detection of bradycardia and tachycardia is not possible at all with the usual short-time CTG. The PCG method, in contrary, is perfectly suitable for such examinations.
To indicate and evaluate the fetal split-effect the only way practically is the PCG method. The split signal is produced by the time-difference of the closing sound of the two heart valves, and contains two peaks. This symptom is well known by adults (Xu et al., 2001), but in the case of the fetuses its measurement with echocardiography is very difficult, accordingly there is poor knowledge about it.
The fetal PCG allows the continuous examination of the intrauterine growth retardation (IUGR), too. According to the recent research, from the ratio of low frequency (0.03-1Hz) components of the FHR spectrum, an information can be read out concerning the health of the fetus (Signorini et al., 2003), but this requires the very accurate determination of the TBB(t) time function of the repetition. The frequency distribution of the measure FHR spectrum is compared to the normal distribution and from the obtained difference the well-being of the fetus can be evaluated.
Key Terms in this Chapter
Application Level Network (ALN): The applications, which are running in the hosts, can create a virtual network from their logical connections. This is also called overlay network. The operations of such software entities are not able to understand without knowing their logical relations. Most cases this ALN software entities use the P2P model, not the client/server one for the communication.
Client/Server Model: A communicating way, where one hardware or software entity (server) has more functionalities than the other entity (the client), whereas the client is responsible to initiate and close the communication session towards the server. Usually the server provides services that the client can request from the server. Its alternative is the P2P model.
Overlay Network: The applications, which create an ALN work together and usually follow the P2P communication model.
Medical Application: Software developed for medical purposes, including home medical monitoring system, medical databases for healthcare professionals, etc.
Peer-to-Peer (P2P) Model: A communication way where each node has the same authority and communication capability. They create a virtual network, overlaid on the Internet. Its members organize themselves into a topology for data transmission. Each peer provides services the others can use, and each peer sends requests to other ones.
Passive Phonocardiographic (PCG) Method: It is used for fetal monitoring based on the special acoustic sensor, which placed on the maternal abdomen delivers informative sound signals about the heart activity of the fetus.
Home Medical Monitoring: Home medical monitoring system with computer-controlled base station provides medical supervision of an individual and controls medical monitoring, environmental, and safety devices.