Observations in perinatal heart rate monitoring. I. A quantitative method of describing baseline variability of the fetal heart rate.

Simultaneous magnetic tape recordings of fetal scalp ECG, maternal ECG and uterine contractions were obtained from 23 patients in active labor. Computer-derived distributions of beat-to-beat changes were used to develop a simple numerical and graphical description of the long and short-term variability patterns. The visually observed variability may be described by the R-R interval change (beat-to-beat change), which is greater than 90% of the total number of beat-to-beat changes. Thus, the 90th percentile of R-R interval changes quantitatively describes the baseline variability. The variability may be classified as fixed, minimal, moderate or marked, based on this simple calculation. Graphs of cumulative percentage of R-R interval changes provide additional visual information. The effects of meperidine HCl on the observed variability were easily detected and visualized by these methods.

Intrapartum maternal and fetal monitoring: the obstetric intensive care unit.

The Obstetric Intensive Care Unit (OBICU) at Bellevue Hospital in New York City has adapted intensive care and coronary care models to the care of patients in labor. During the past 3 years, 519 of the most serious of 2 250 high-risk obstetric patients treated at the hospital were monitored in the OBICU. There were two maternal and six perinatal deaths. The perinatal mortality rate of the very high risk population of the OBICU was 11.6/1 000, compared to 14.7/1 000 for all deliveries performed at the hospital. Our findings indicate that the OBICU system provides the ideal mechanism for the rapid and continuous control of symptoms in very high risk gravidas which is essential for stabilizing the patient, both for prompt delivery and for optimal maternal and fetal survival.