Fetal Heart Rate Monitoring during Intrauterine Open Surgery for Myelomeningocele Repair

Abstract

Objective: The aim of this study was to assess fetal hemodynamics during intrauterine open surgery for myelomeningocele (MMC) repair by describing fetal heart rate (FHR) monitoring in detail related to each part of the procedure. Methods: A study was performed with 57 fetuses submitted to intrauterine MMC repair between the 24th and 27th week of gestation. Evaluations of FHR were made in specific periods: before anesthesia, after anesthesia, at the beginning of laparotomy, during uterus abdominal withdrawal, hysterotomy, neurosurgery (before incision, during early skin manipulation, spinal cord releasing, and at the end of neurosurgery), abdominal cavity reintroduction, and abdominal closure, and at the end of surgery. Means ± standard deviations of FHR were established for each period, and analysis of variance with repeated measures was used to assess differences between these periods. The mean differences were assessed with 95% confidence intervals and were analyzed by Tukey's multiple comparison test. Results: The mean FHR during the specific periods mentioned above was 140.2, 140, 139.2, 138.8, 135.1, 133.9, 123.1, 134.0, 134.5, 137.9, and 139.9 bpm, respectively (p < 0.0001). Comparing the different periods, the highest frequencies were observed in the initial and final moments. The neurosurgery stage presents lower frequencies, especially during the release of the spinal cord. Conclusion: FHR monitoring revealed interesting findings in terms of physiological fetal changes during MMC repair, especially during neurosurgery, which was the most critical period.

Fetal modified left myocardial performance index monitoring during open surgery for myelomeningocele repair

“…With the reduced oxygen level, the vagal response mediated by carotid chemoreceptors results in fetal bradycardia after sensitization by a certain and established degree of hypoxia . We observed that this response is most frequently observed during neurosurgical myelomeningocele repair, especially during the exposure of nerve endings and the spinal cord, but no cases of fetal bradycardia were observed in this series …”

Fetal Heart Rate during in Utero Myelomeningocele Repair: Effect of Anesthesia and Analgesia

“…In our institution, we have also observed fetal bradycardia with high desflurane concentrations during in utero surgery. The findings by Santana et al [1] contrast that of Rychik et al [3], who found an increased fetal heart rate and decreased cardiac output during surgical incision despite a preincision administration of an intramuscular combination of fentanyl for fetal analgesia, vecuronium for muscle relaxation, and atropine for vagolysis to the fetus. …”

“…We read with interest the recent article by Santana et al [1] in which the authors prospectively assessed fetal heart rate at different stages during open fetal surgery for myelomeningocele repair. They reported that the fetal heart rate was significantly decreased during repair of the fetal neurosurgical defect, particularly during release of the spinal cord.…”

“…This could be a potential reason, as supplemental fetal analgesia with fentanyl was not reported in the series by Santana et al [1]. Sensory fibers and connections in the fetal thalamus are present by 20 weeks when mid-gestation in utero procedures are performed, but thalamocortical connections necessary for the appreciation of the emotional component of pain are not mature until 29-30 weeks [4].…”

“…This stress hormone elevation has been blunted with the administration of fentanyl as demonstrated by Fisk et al [6]. By withholding fentanyl, Santana et al [1] deviate from the standard protocol for fetal analgesia as delineated in the MOMS trial report [7]. Administration of maternal intravenous fentanyl only provides a very slow rate of transfer across the placenta with an average fetal:maternal ratio of 0.31 after a 1-μg/kg bolus [8] and, as such, is not likely to reliably provide fetal analgesia.…”