Circulating Cell-free Mitochondrial DNA Triggering Epidural Related Maternal Fever (ERMF) in Obstetric Anesthesia: a Pilot Study

Background: Giving birth is a critical moment for the mother and the fetus, potentially accompanied by stress, tissue damage, cell injury, placental hypoxia and sometimes multisystem vascular syndrome known as preeclampsia. Epidural analgesia with a local anesthetic is a common anesthetic approach during labor. Local anesthetics inhibit the oxidative phosphorylation and impair the synthesis of ATP, resulting in mitochondrial dysfunction and increased reactive oxygen species. Especially when the high demand of ATP during pregnancy cannot be reached, apoptosis will occur in an anaerobic environment. During apoptosis the cell membrane integrity is disturbed, releasing the cytoplasm into the blood circulation. Circulating cell-free mitochondrial DNA acts as a damage associated molecular pattern (DAMP) by activating the innate immune system leading to inflammation. These DAMPs are evolutionary conserved and have structural similarity to their bacterial ancestor. Therefore, cell-free mitochondria can act as a potent agent triggering the immune system in an autoimmune manner as well as a biomarker for cell damage and hypoxia.

Objective: The aim of this study is to investigate to role of epidural analgesia during birth, quantifying the copy number of circulating cell-free mitochondrial DNA in maternal serum and the placenta compared to controls. The investigators hypothesize that epidural analgesia with a local anesthetic has an effect on cell-free mitochondrial DNA levels, promoting the pathogenesis of ERMF and early inflammation. In addition, circulating mitochondrial DNA could be a potent biomarker for cell damage, early placenta hypoxia/insufficiency or preeclampsia.

Methods: For this study the investigators planned 3 groups each consisting of 15 patients. The intervention group (group 1) will be women with vaginal delivery having epidural analgesia and developing fever before delivery. The control group (group 2) will be women with vaginal delivery having an epidural analgesia without developing fever before delivery. Women with vaginal delivery without an epidural analgesia will serve as additional control (group 3). Blood will be taken at arrival at the delivery ward and immediately after delivery from a peripheral venous line. In addition, venous blood from the umbilical vein will be drawn postpartum. Axillary temperature will be measured routinely using a thermometer in a routine clinical fashion. Circulating cell-free mitochondrial DNA and other immunological markers will be quantified in maternal and umbilical cord (fetal) serum by real time quantitative PCR and statistical analysis will be performed by non-parametric tests.