Fetal reactivity assessment during intrapartum stress by analysis of the fetal ECG signal

........................................................................................................................................................ 5 List of Original Papers .................................................................................................................................... 6 List of Abbreviations ...................................................................................................................................... 7 Introduction ................................................................................................................................................... 8 General Background ...................................................................................................................................... 9 Fetal physiology during delivery .................................................................................................................. 10 Fetal cardiovascular adaptations to stress .................................................................................... 10 Beta-adrenoreceptors and hypoxia ............................................................................................... 13 Fetal acid-base ............................................................................................................................... 15 Gestational age .............................................................................................................................. 16 Infections ....................................................................................................................................... 17 Fetal monitoring ................................................................................................................................ 17 Cardiotocography .......................................................................................................................... 17 Fetal monitoring techniques, adjuncts to CTG .............................................................................. 19 Computerized analysis of the FHRV .............................................................................................. 22 New approaches to assess FHRV during birth ............................................................................... 23 Aims of the thesis ........................................................................................................................................ 24 Material and Methods ................................................................................................................................. 25 Clinical database ................................................................................................................................ 25 RR Residual measurements ........................................................................................................... 27 Reducing the interference of unstable FHR baseline on FHRV ..................................................... 29 Residual and bandwidth ................................................................................................................ 30 Sequences Selected for Analysis Index cases .............................................................................. 31 Test for different polynomial settings and Reactivity Events (REvents) ....................................... 32 Case control study of cases with metabolic acidosis at delivery ................................................... 32 Surgical and experimental procedure ........................................................................................... 33 Statistical analysis .......................................................................................................................... 34 Results and Comments ................................................................................................................................ 35 Assessment of fetal reactivity biopatterns during labour by fetal ECG analysis (Paper I) ......... 35 Assessment of fetal heart rate variability and reactivity during labour a novel approach (Paper II) ....................................................................................................................................................... 37 Alteration in fetal reactivity in connection with fetal metabolic acidosis and spontaneous vaginal delivery (Paper III) ......................................................................................................................... 39 ECG and heart rate variability changes in preterm and near-term fetal lamb following LPS exposure (Paper IV) ....................................................................................................................................... 41 General Discussion ...................................................................................................................................... 42 Residuals and outcome ................................................................................................................. 44 ECG ST waveform response to LPS ................................................................................................ 46 Increased reactivity ....................................................................................................................... 47