Preclinical development of a continuous fetal lactate biosensor to detect acidosis

Accurate detection of fetal acidosis in labor is an unmet clinical need. Objectives of this study are: To run a pilot validation of a subcutaneous biosensor for continuous lactate monitoring (CLM) to detect acidosis in a fetal lamb model of asphyxia.Assess the feasibility of the CLM biosensor for intrapartum fetal monitoring by correlating sensor-detected lactate levels with contemporaneously collected blood lactate values.

Ewes (n = 3) with singleton pregnancy were anesthetized and the lamb's head was exteriorized. Multiple biosensors were placed onto the lamb scalp, with electrical current outputs captured. Jugular venous blood samples were collected at regular intervals across the protocol, and lactate and other physiological parameters were recorded. After baseline, the umbilical cord was occluded for 10 min, with recordings continuing over at least 3 h during recovery.

Nine biosensors were tested across three animals. Six of the nine had a clear response to lactate rise from an acute hypoxic event, with five of these having strong correlation (R ² > 0.93). These five sensors responded to change in venous lactate from as low as 1.6 mmol/L up to 8.4 mmol/L over a range of pH (7.04-7.38) and p_vO₂ (1.6-23.5 mmHg) over 5.5 h, demonstrating the utility of the biosensor in monitoring in-vivo lactate levels.

This study demonstrates the capability of an innovative subcutaneous biosensor for CLM in detecting early signs of fetal lactic acidosis, highlighted by the strong correlation between sensor current and venous blood lactate levels. This technology has the potential to enable continuous fetal lactate measurement, with the ability to revolutionize intrapartum care and improve neonatal outcomes by enabling crucial early detection and management of fetal asphyxia during labor and delivery.