1 research outputs found
Fetal respiratory movements improve reliability of heart rate variability and suggest a coupling between fetal respiratory arrhythmia and vagal activity
Fetal heart rate variability (FHRV) reflects autonomic cardiac regulation. The autonomic nervous system constantly adjusts the heart rate to maintain homeostasis. By providing insight into the fetal autonomic state, FHRV has the potential to become an investigational and clinical instrument. However, the method needs standardization and the influence of fetal movements, including fetal respiratory movements, is not well explored. Therefore, in a highly standardized setting, the aim was to evaluate the association between fetal movements and fetal heart rate variability (FHRV) including their impact on reliability. Fetal heart rate was obtained by noninvasive fetal electrocardiography (NIâFECG) and fetal movements by simultaneous ultrasound scanning in 30 healthy singleton pregnant women on two occasions with a maximum interval of 7 days. The standard deviation of normalâtoânormal RRâintervals (SDNN), root mean square of successive RRâinterval differences (RMDDS), highâfrequency power (HFâpower), lowâfrequency power (LFâpower), and LF/HF were measured. A multivariate mixed model was used and reliability was defined as acceptable by a coefficient of variance (CV) â¤15% and an intraclass correlation coefficient (ICC) âĽ0.80. During time periods with fetal respiratory movements, the highest reliability was achieved. Intraâ and interâobserver reliability measurements were very high (CV: 0â9%; ICC â§Â 0.86). Within the same recording, SDNN and RMSSD achieved acceptable reliability (CV: 14â15%; ICC â§Â 0.80). However, dayâtoâday reliability displayed high CVâs. In time periods with fetal respiratory movements, as compared to periods with quiescence RMSSD and HFâpower were higher (Ratio: 1.33â2.03) and LF/HF power lower (Ratio: 0.54). In periods with fetal body movements SDNN, RMSSD and HFâpower were higher (Ratio: 1.27â1.65). In conclusion, time periods with fetal respiratory movements were associated with high reliability of FHRV analyses and the highest values of parameters supposed to represent vagal activity