title: Transabdominal fetal heart rate detection using NIR photopleythysmography: instrumentation and clinical results.
abstract: In obstetrics, fetal heart rate (FHR) detection remains the standard for intrapartum assessment of fetal well-being. In this paper, a low-power (< 55 mW) optical technique is proposed for transabdominal FHR detection using near-infrared photoplesthysmography (PPG). A beam of IR-LED (890 nm) propagates through to the maternal abdomen and fetal tissues, resulting in a mixed signal detected by a low-noise detector situated at a distance of 4 cm. Low-noise amplification and 24-bit analog-to-digital converter resolution ensure minimum effect of quantization noise. After synchronous detection, the mixed signal is processed by an adaptive filter to extract the fetal signal, whereas the PPG from the mother's index finger is the reference input. A total of 24 datasets were acquired from six subjects at 37 +/- 2 gestational weeks. Results show a correlation coefficient of 0.96 (p-value < 0.001) between the proposed optical and ultrasound FHR, with a maximum error of 4%. Assessment of the effect of probe position on detection accuracy indicates that the probe should be close to fetal tissues, but not necessarily restricted to head or buttocks.
authors.affiliation: Department of Electrical, Electronic, and Systems Engineering, Faculty of Engineering and Built Environment, Universiti KebangsaanMalaysia, Bangi, Malaysia. kok_beng_gan@yahoo.com
authors.forename: Kok Beng
authors.initials: KB
authors.lastname: Gan
authors.forename: Edmond
authors.initials: E
authors.lastname: Zahedi
authors.forename: Mohd Alauddin
authors.initials: MA
authors.lastname: Mohd Ali
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D005260:Female; D005323:Fetal Monitoring / Q000295:instrumentation* / Q000379:methods; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D007259:Infrared Rays; D007746:Labor Presentation; D009010:Monte Carlo Method; D017156:Photoplethysmography / Q000295:instrumentation* / Q000379:methods; D011247:Pregnancy; D012815:Signal Processing, Computer-Assisted