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Up to now, fetal distress can only be detected by CTG and invasive fetal blood analysis. The Erlangen Microlightguide Photometer (EMPHO) allows the non-invasive measurement of local intracapillary haemoglobin concentration (Hb02). The Hb02-monitoring device was developed at the Institute of Physiology and Cardiology at the University ofErlangen by Professor Kessler4• With the EMPHO, we have measured the local oxygen supply at the fetal scalp during labor. The non-invasive measurements are based upon remission spectrophotometry with a visible wavelength of between 502 nm and 630 nm. A lightguide enlightens the tissue and the remitted light is collected by six fibers surrounding it. The lightguide is fixed with a holding device made of Polyacetale, which is casted in silicone rubber. The contact surface between the silicone rubber and the fetal scalp is additionally coated with a very soft silicone rubber gel (Sil-Gel 612®). Furthermore, a ring-shaped channel is integrated in the silicone rubber-cast to improve the adhesion by negative pressure. In a first clinical study, we measured on the scalp of 20 fetuses sub partu. The measuring time varied between 7 and 90 minutes. Measuring started after the rupture of the membrane as soon as the vertex was located one cm above the ischial spines. The measurement failed if maternal blood was contaminating the lightguides or if the sensor was disconnected. The coating appeared essential: only because of the use of soft gel the device was adhesive to the haired skin, and a dry local measuring area could be achieved. The HbOrvalues ranged from 10% to 70% in the second stage of labor. Fetal heart-rate decelerations of Type I caused no deterioration of the intracapillary haemoglobin oxygenation, but a continuous decrease during a prolonged deceleration could be observed. We were able to show that the EMPHO in connection with the sensor applicator guaranteed a continuous Hb02-monitoring during delivery in most of the cases. The course of the intracapillary haemoglobin oxygenation might be a useful additional parameter for fetal monitoring in the second stage of labor. Keywords: EMPHO, haemoglobin oxygenation, fetal monitoring, remission spectroscopy
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