Fetal ischemia monitoring with in vivo implanted electrochemical multiparametric microsensors

Abstract

Under intrauterine growth restriction (IUGR), abnormal attainment of the nutrients and oxygen by the fetus restricts the normal evolution of the prenatal causing in many cases high morbidity being one of the top-ten causes of neonatal death. The current gold standards in hospitals to detect this relevant problem is the clinical observation by echography, cardiotocography and Doppler. These qualitative techniques are not conclusive and requires risky invasive fetal scalp blood testing and/or amniocentesis. We developed micro-implantable multiparametric electrochemical sensors for measuring ischemia in real time in fetal tissue and vascular. This implantable technology is designed to continuous monitoring for an early detection of ischemia to avoid potential fetal injury. Two miniaturized electrochemical sensors were developed based on oxygen and pH detection. The sensors were optimized in vitro under controlled concentration, to assess the selectivity and sensitivity required. The sensors were then validated in vivo in the ewe fetus model, by means of their insertion in the muscle leg and inside the iliac artery of the fetus. Ischemia was achieved by gradually obstructing the umbilical cord to regulate the amount of blood reaching the fetus. An important challenge in fetal monitoring is the detection of low levels of oxygen and pH changes under ischemic conditions, requiring high sensitivity sensors. Significant differences were observed in both; pH and pO2 sensors under changes from normoxia to hypoxia states in the fetus tissue and vascular with both sensors. Herein, we demonstrate the feasibility of the developed sensors for future fetal monitoring in medical applications.

Current Innovative Methods of Fetal pH Monitoring—A Brief Review

“…One such alternative is represented by the in vivo implanted electrochemical multiparametric microsensors. Dulay et al [ 49 ] developed a micro-implantable array of pH and pO 2 sensors for monitoring hypoxia in tissues. The experimental model was comprised of the sensor for pH (based on polypyrrole coated Pt working electrode) and the sensor for pO 2 (based on Pt-Nafion working electrode), which were implanted in vivo in the iliac artery, and in the femur muscle, and were connected to a portable multipotentiostate, which recorded the chronoamperometric response of the sensors in hypoxia conditions.…”

Towards Multiplexed and Multimodal Biosensor Platforms in Real-Time Monitoring of Metabolic Disorders

“…Although electrochemical sensors are relatively simple to use and easy to miniaturize, several instances, such as real-time monitoring of critically ill patients in an ICU (intensive care unit) setting, require the use of minimally invasive sensors that can be inserted inside the body with ease. Research demonstrates the development of implantable electrochemical sensors for in vivo monitoring [ 175 , 176 , 177 , 178 ]. However, such in vivo detection strategies require invasive surgery, which is often not feasible for neonates, seniors, or critically ill patients.…”