A simulation model to study maternal hyperoxygenation during labor.

OBJECTIVE To investigate the effect of maternal hyperoxygenation on fetal oxygenation and fetal heart rate decelerations during labor, using a simulation model. DESIGN Use of a mathematical model that simulates feto-maternal hemodynamics and oxygenation, designed in Matlab R2012a. SETTING Clinical and engineering departments in the Netherlands. METHODS We simulated variable and late fetal heart rate decelerations, caused by uterine contractions with a different contraction interval. We continuously recorded oxygen pressure in different feto-placental compartments and fetal heart rate, during maternal normoxia and during hyperoxygenation with 100% oxygen. MAIN OUTCOME MEASURES Changes in oxygen pressure in the intervillous space, umbilical vein and arteries, fetal cerebral and microcirculation as well as fetal heart rate deceleration depth and duration. RESULTS Maternal hyperoxygenation leads to an increase in fetal oxygenation: in the presence of variable decelerations, oxygen pressure in the intervillous space increased 9-10 mmHg and in the cerebral circulation 1-2 mmHg, depending on the contraction interval. In addition, fetal heart rate deceleration depth decreased from 45 to 20 beats per minute. In the presence of late decelerations, oxygen pressure in the intervillous space increased 7-10 mmHg and in the cerebral circulation 1-2 mmHg, depending on the contraction interval. The fetus benefited more from maternal hyperoxygenation when contraction intervals were longer. CONCLUSIONS According to the simulation model, maternal hyperoxygenation leads to an increase in fetal oxygenation, especially in the presence of variable decelerations. In addition, in the presence of variable decelerations, maternal hyperoxygenation leads to amelioration of the fetal heart rate pattern.