How do adult and fetal monitoring with pulse oximetry differ and what do these differences mean in terms of designing a fetal oximeter?
The underlying physics of the technology are actually quite similar. However, the uniqueness of the intrauterine environment presents a number of challenges for fetal oxygen saturation monitoring. The differences outlined below become significant factors in the design and use of the technology. Sensor application sites are limited on the fetus in utero, and direct observation of sensor placement is not possible. Because the crown of the head is not optimal for monitoring, and since relatively strong fetal pulses can be found beyond the hairline on the fetal face, the cheek/temple area was chosen as the preferred application site for the OxiFirst Fetal Oxygen Sensor. Arterial pulse amplitudes on the fetal face are typically two to ten times smaller than those seen on adult fingers (the most common site used in adult monitoring). Thus, the electronic design of the OxiFirst fetal pulse oximetry system was optimized to work with very small pulses. The fetal sensor has unique features desig
