Feasibility of using a mobile cardiotocograph device in an ambulance during maternal transport

Maternal transfer generally refers to the emergency transportation of a pregnant woman to a medical facility with more advanced capabilities when her condition, or that of the fetus, deteriorates or is expected to deteriorate, thereby ensuring the safety of both mother and fetus. This procedure is frequently performed in Japan, where childbirth at primary obstetric facilities is common. However, no reports have described attempts to remotely monitor maternal and fetal vital signs inside an ambulance during transport and use these data to support clinical care at a remote location. The current study aimed to assess the feasibility of a system that enables real-time remote monitoring (RM) using a small mobile cardiotocograph (CTG) in an ambulance during maternal transport from primary obstetric facilities to a higher-level perinatal medical center. This study included women with singleton pregnancies beyond 22 weeks of gestation who were transferred from nine private clinics to a university hospital because of medical complications. Using a small mobile CTG device, the CTG data were transmitted during maternal transfer to a university hospital. The obstetrician of the university hospital checked the data in real-time using tablets to select the appropriate treatment. A questionnaire survey was conducted on the medical staff of the primary facilities who accompanied the patients during maternal transport. An online survey was also administered to paramedics only after the recruitment period. The study period was from August 2021 to August 2023. In total, 68 pregnant women were enrolled in this study and analyzed. The median time from getting into the ambulance to arrival at the university hospital was 34.5 (range: 15.0-67.0) min. No monitoring sessions were discontinued because of connectivity issues. All 68 fetal heart rate records were legible, and the median proportion of the total legible period in each recording was 91.1% (range: 53.9%-99.8%). Twenty-three (33.8%) women delivered by the next day after the transportation. The questionnaire survey revealed high levels of medical staff satisfaction and paramedical acceptance of real-time CTG RM during maternal transfer. Real-time CTG RM during emergency maternal transport is feasible and useful for making a medical decision more precisely in tertiary perinatal medical centers. Further, the use of the system in an ambulance is also acceptable for paramedics.