Recording and processing of fetal movements and sounds obtained with the Inpho inductive transducer

Acquisition Devices for Fetal Phonocardiography: A Scoping Review

Timely and reliable fetal monitoring is crucial to prevent adverse events during pregnancy and delivery. Fetal phonocardiography, i.e., the recording of fetal heart sounds, is emerging as a novel possibility to monitor fetal health status. Indeed, due to its passive nature and its noninvasiveness, the technique is suitable for long-term monitoring and for telemonitoring applications. Despite the high share of literature focusing on signal processing, no previous work has reviewed the technological hardware solutions devoted to the recording of fetal heart sounds. Thus, the aim of this scoping review is to collect information regarding the acquisition devices for fetal phonocardiography (FPCG), focusing on technical specifications and clinical use. Overall, PRISMA-guidelines-based analysis selected 57 studies that described 26 research prototypes and eight commercial devices for FPCG acquisition. Results of our review study reveal that no commercial devices were designed for fetal-specific purposes, that the latest advances involve the use of multiple microphones and sensors, and that no quantitative validation was usually performed. By highlighting the past and future trends and the most relevant innovations from both a technical and clinical perspective, this review will represent a useful reference for the evaluation of different acquisition devices and for the development of new FPCG-based systems for fetal monitoring.

A wideband high common mode rejection ratio amplifier and phase-locked loop demodulator for multifrequency impedance measurement

Design considerations and implementation of a multifrequency measuring channel for application in the field of bio-impedance measurement are discussed in this paper. The input amplifier has a differential configuration which is electrically isolated from the remaining circuits. Transformer coupling provides improved common mode rejection when compared to non-isolated input stages. The frequency characteristic of the section between input and demodulator is flat within +/- 0.1 dB between 4 kHz and 1024 kHz. The synchronous demodulator is based on a wideband switched video amplifier. In contrast to commonly used lock--in techniques, the carrier for demodulation is recovered from the input signal by means of a phase-locked loop. This method ensures zero phase shift with respect to the input signal and improves the accuracy of measurement. The system has been developed primarily for thoracic impedance cardiography (TIC) but has also successfully been applied in the field of total body bio-impedance analysis (BIA). At present an electrical impedance tomograph is under development based on the instrumentation described. Results regarding the measurement range and accuracy are given and some recordings of patient data are shown.

European multicentre studies in the field of obstetrics

Within Europe a number of multinational, multicentre studies are performed in the field of Obstetrics and Gynaecology. Many of these are funded by the European Community. Unfortunately, concise information on currently ongoing European multicentre studies is not easily obtainable. There is no particular central information point. The current overview aims to provide insight in obstetrical EC/European multicentre studies which recently have been finished, are ongoing or have been planned for the near future. The various projects are described, and information on the number of participants, the research period, the responsible project leader and framework of each project is summarized in tables. A list with the addresses of the project leaders and/or contact persons in the EC member states is added. The paper hopes to facilitate researchers and institutes involved in Obstetrics within Europe to make easier contacts and to promote collaboration on the international level.