Fetal heart rate responses in chronic hypoxaemia with superimposed repeated hypoxaemia consistent with early labour: a controlled study in fetal sheep

OBJECTIVE

Deceleration area (DA) and capacity (DC) of the fetal heart rate can help predict risk of intrapartum fetal compromise. However, their predictive value in higher risk pregnancies is unclear. We investigated whether they can predict the onset of hypotension during brief hypoxaemia repeated at a rate consistent with early labour in fetal sheep with pre-existing hypoxaemia.

DESIGN

Prospective, controlled study.

SETTING

Laboratory.

SAMPLE

Chronically instrumented, unanaesthetised near-term fetal sheep.

METHODS

One-minute complete umbilical cord occlusions (UCOs) were performed every 5 minutes in fetal sheep with baseline p_a O₂ <17 mmHg (hypoxaemic, n = 8) and >17 mmHg (normoxic, n = 11) for 4 hours or until arterial pressure fell <20 mmHg.

MAIN OUTCOME MEASURES

DA, DC and arterial pressure.

RESULTS

Normoxic fetuses showed effective cardiovascular adaptation without hypotension and mild acidaemia (lowest arterial pressure 40.7 ± 2.8 mmHg, pH 7.35 ± 0.03). Hypoxaemic fetuses developed hypotension (lowest arterial pressure 20.8 ± 1.9 mmHg, P < 0.001) and acidaemia (final pH 7.07 ± 0.05). In hypoxaemic fetuses, decelerations showed faster falls in FHR over the first 40 seconds of UCOs but the final deceleration depth was not different to normoxic fetuses. DC was modestly higher in hypoxaemic fetuses during the penultimate (P = 0.04) and final (P = 0.012) 20 minutes of UCOs. DA was not different between groups.

CONCLUSION

Chronically hypoxaemic fetuses had early onset of cardiovascular compromise during labour-like brief repeated UCOs. DA was unable to identify developing hypotension in this setting, while DC only showed modest differences between groups. These findings highlight that DA and DC thresholds need to be adjusted for antenatal risk factors, potentially limiting their clinical utility.

Comparison of phase rectified signal averaging and short term variation in predicting perinatal outcome in early onset fetal growth restriction

OBJECTIVES

To compare short term variation (STV) and phase rectified signal averaging (PRSA) and their association with fetal outcome in early onset fetal growth restriction (FGR).

METHODS

Data were used from a retrospective cohort study of women who were admitted for FGR and/or pre-eclampsia and who were delivered by pre-labor Cesarean section or had a fetal death before 32 weeks' gestation. Computerized cardiotocography (cCTG) registrations of the 5 days before delivery or fetal death were used for calculation of STV and PRSA. PRSA was expressed as the average acceleration capacity (AAC) and average deceleration capacity (ADC). FHR decelerations were classified visually as absent, 1-2 per hour or recurrent. Abnormality of STV and of PRSA was either analyzed as a single parameter or in combination with recurrent decelerations. Endpoints were defined as composite adverse condition at birth consisting of fetal death, low Apgar score, low umbilical pH, the need for resuscitation after birth and as major neonatal morbidity or neonatal death.

RESULTS

Included were 367 pregnancies of which 20 resulted in fetal death. An abnormal cCTG with either recurrent decelerations and/or low STV or recurrent decelerations and/or low PRSA were similarly associated with composite adverse condition at birth (n=99), but neither with major neonatal morbidity.

CONCLUSIONS

PRSA and STV have similar efficacy for measuring fetal heart rate variation in early onset FGR. An increased risk of a composite adverse condition at birth is indicated by a low value of either parameter and/or the presence of recurrent decelerations.

The Impact of Gestational Diabetes in Pregnancy on the Cardiovascular System of Children at One Year of Age

Gestational diabetes mellitus (GDM) is a common complication in pregnancy. The effect of GDM on the cardiovascular system after birth is still unclear. Between August 2015 and December 2018, 205 pregnant women were included in the prospective controlled observational study. Patients with GDM were assigned to the study group (n = 99), whereas (n = 107) healthy women served as controls. Postnatal follow up of their offspring was performed at 12 months of age. All included children (n = 125) underwent a specific standardized protocol including anthropometric data, such as weight, height, body mass index (BMI), blood pressure (BP) recordings and ultrasound measurements of the abdominal aortic intima-media-thickness (IMT). Furthermore, at least 10 min 3-channel electrocardiogram recording was done to evaluate the autonomic nervous system (ANS) by phase rectified signal averaging. There were no significant differences in anthropometric data between the groups, neither in the blood pressure nor in the intima-media-thickness of the aorta abdominals. However, in the study group, significantly lower average acceleration capacity (AAC) (study group −20.10 ± 3.04 ms, control group −18.87 ± 4.00 ms, p = 0.02) was found, indicating ANS activation at one year of age. Further studies are required to determine if these results are persistent and if these findings have long-term effects.

Study of atrial activities for abnormality detection by phase rectified signal averaging technique

Non-invasive detection of Atrial Fibrillation (AF) and Atrial Flutter (AFL) from ECG at the time of their onset can prevent forthcoming dangers for patients. In most of the previous detection algorithms, one of the steps includes filtering of the signal to remove noise and artefacts present in the signal. In this paper, a method of AF and AFL detection is proposed from ECG without the conventional filtering stage. Here Phase Rectified Signal Average (PRSA) technique is used with a novel optimized windowing method to achieve an averaged signal without quasi-periodicities. Both time domain and statistical features are extracted from a novel SQ concatenated section of the signal for non-linear Support Vector Machine (SVM) based classification. The performance of the proposed algorithm is tested with the MIT-BIH Arrhythmia database and good performance parameters are obtained, as indicated in the result section.