Fetal transabdominal pulse oximeter studies using a hypoxic sheep model

Abstract

Objective. This study investigates the validity of transabdominal pulse oximetry using a sheep fetal hypoxia model with fetal arterial hemoglobin saturation.

Methods. Four pregnant ewes were anaesthetized and cannulated through the brachial artery to measure direct arterial blood saturation, SaO₂. Next, the transabdominal pulse oximeter was used to measure indirect measurement of the arterial saturation of the fetus, SpO₂, from the maternal abdomen. Hypoxia was induced by a balloon placed in the maternal aorta.

Results. There is a linear relationship between SaO₂, arterial blood saturation values of the fetus, and SpO₂, the values measured by the transabdominal pulse oximetry with a slope of 0.75 (r² = 0.76).

Conclusion. This information can be used to calibrate the transabdominal pulse oximeter as a measurement of fetal arterial saturation. With these results, we can advance the accurate, no-risk, noninvasive transabdominal fetal pulse oximeter for human use. This research may contribute to the more accurate diagnosis of the diseases of the fetus including Hypoxic Ischemic Encephalopathy.

• Transabdominal
• pulse oximeter
• sheep
• fetus
• hypoxia