P0965 - Fetoscopic Insufflation modeled in EXTEND: Warm Humidified Carbon Dioxide Insufflation is Safer for the Fetus

Purpose: Minimally invasive fetal surgery, or fetoscopy, is an alternative to open fetal surgery to repair common birth defects like myelomeningocele. Though fetoscopy may appear feasible and safer for the mother, the effects on the fetus are poorly understood. We sought to use the accessibility of the fetus in the EXTEND (EXTrauterine Environment for Neonatal Development) system to study the effects of insufflation on the fetus.

Methods: Fetal sheep at gestational age 104 to 107 days were cannulated onto the EXTEND system using dual umbilical artery/umbilical vein cannulation. The fetuses were allowed to recover for twenty-four hours, and their arterial blood gases normalized. Fetuses were exposed to two different insufflation conditions at a pressure of 7mmnHg for four hours each: warm, humidified carbon dioxide using an Insufflow Gas Conditioning Device (n=4) and untreated carbon dioxide (n=4). Animals were allowed to sufficiently recover between each exposure, as determined by normalization of hemodynamic status and laboratory values. Blood gases were assessed from the umbilical vein every twenty minutes. Statistical analysis was performed using Stata/IC 15.1.

Results: Fetal pCO2 levels increased more rapidly in the Untreated CO2 group than in the Warm Humidified CO2 group (p=0.01) (Figure 1). Umbilical blood flow decreased more slowly in the Warm Humidified CO2 group than in the Untreated Group (p=0.006). Oxygen delivery dropped acutely in the Untreated CO2 group (p=0.0266) (Figure 2).

Conclusions: Using the EXTEND system, we demonstrate that insufflation with Warm, Humidified CO2 is safer for the fetus than Untreated CO2 Insufflation. Fetoscopic interventions should therefore be performed with warm humidified CO2 Insufflation.