Prolonged fetal bradycardia as the presenting clinical sign in Streptococcus agalactiae chorioamnionitis

Optimizing the management of acute, prolonged decelerations and fetal bradycardia based on the understanding of fetal pathophysiology

Any acute and profound reduction in fetal oxygenation increases the risk of anaerobic metabolism in the fetal myocardium and, hence, the risk of lactic acidosis. On the contrary, in a gradually evolving hypoxic stress, there is sufficient time to mount a catecholamine-mediated increase in the fetal heart rate to increase the cardiac output and redistribute oxygenated blood to maintain an aerobic metabolism in the fetal central organs. When the hypoxic stress is sudden, profound, and sustained, it is not possible to continue to maintain central organ perfusion by peripheral vasoconstriction and centralization. In case of acute deprivation of oxygen, the immediate chemoreflex response via the vagus nerve helps reduce fetal myocardial workload by a sudden drop of the baseline fetal heart rate. If this drop in the fetal heart rate continues for >2 minutes (American College of Obstetricians and Gynecologists' guideline) or 3 minutes (National Institute for Health and Care Excellence or physiological guideline), it is termed a prolonged deceleration, which occurs because of myocardial hypoxia, after the initial chemoreflex. The revised International Federation of Gynecology and Obstetrics guideline (2015) considers the prolonged deceleration to be a "pathologic" feature after 5 minutes. Acute intrapartum accidents (placental abruption, umbilical cord prolapse, and uterine rupture) should be excluded immediately, and if they are present, an urgent birth should be accomplished. If a reversible cause is found (maternal hypotension, uterine hypertonus or hyperstimulation, and sustained umbilical cord compression), immediate conservative measures (also called intrauterine fetal resuscitation) should be undertaken to reverse the underlying cause. In reversible causes of acute hypoxia, if the fetal heart rate variability is normal before the onset of deceleration, and normal within the first 3 minutes of the prolonged deceleration, then there is an increased likelihood of recovery of the fetal heart rate to its antecedent baseline within 9 minutes with the reversal of the underlying cause of acute and profound reduction in fetal oxygenation. The continuation of the prolonged deceleration for >10 minutes is termed "terminal bradycardia," and this increases the risk of hypoxic-ischemic injury to the deep gray matter of the brain (the thalami and the basal ganglia), predisposing to dyskinetic cerebral palsy. Therefore, any acute fetal hypoxia, which manifests as a prolonged deceleration on the fetal heart rate tracing, should be considered an intrapartum emergency requiring an immediate intervention to optimize perinatal outcome. In uterine hypertonus or hyperstimulation, if the prolonged deceleration persists despite stopping the uterotonic agent, then acute tocolysis is recommended to rapidly restore fetal oxygenation. Regular clinical audit of the management of acute hypoxia, including the "the onset of bradycardia to delivery interval," may help identify organizational and system issues, which may contribute to poor perinatal outcomes.

Recurrent otitis media with effusion in preterm infants with histologic chorioamnionitis--a 3 years follow-up study

BACKGROUND

Recurrent otitis media with effusion (OME) is a leading cause of acquired hearing loss in childhood. Histological chorioamnionitis (HCA) is an important cause of preterm delivery and neonatal morbidity and mortality. Here, we tested the hypothesis of an association between recurrent OME during the first 3 years of life and HCA in very low birth weight (VLBW) infants.

METHODS

A total of 110 randomly selected VLBW preterm newborns with HCA and 135 gestational age and gender-matched, HCA-negative VLBW infants were evaluated prospectively during the first 3 years of life for the presence of OME, as diagnosed on the basis of otoscopy, type B or C tympanogram, ipsilateral absence of transient evoked otoacoustic emissions responses, and ipsilaterally increased threshold at diagnostic auditory brain responses evaluation. Potential risk factors for OME were also examined in the two groups.

RESULTS

The HCA-positive infants showed a approximately six times higher frequency of recurrent OME (P<0.0001), increased frequency (>5/yr) of clinical otitis media episodes (P=0.000020), approximately five times higher frequency of adenoid hypertrophy (P<0.00001), a significant seasonal pattern of birth with autumn predominance (P<0.00001), and the first OME occurred earlier (P<0.0001), as compared to the HCA-negative counterparts. Recurrent OME was significantly associated with HCA (O.R.=17.76, 95% CI: 8.98-35.13, P<0.00001), adenoid hypertrophy (O.R.=9.96, 95% CI: 5.17-19.18, P<0.00001), frequency of acute otitis episodes >5/yr (O.R.=8.91, 95% CI: 1.96-40.41, P=0.0005), and birth in autumn (O.R.=5.58, 95% CI: 2.79-11.12, P<0.00001).

CONCLUSIONS

These findings indicate that HCA is a previously unrecognized risk factor for the development of recurrent bilateral OME in VLBW preterm infants during the first 3 years of life.

FETAL BRADYCARDIA. A PRACTICAL APPROACH

Fetal bradycardia may herald fetal demise. This article highlights arrhythmic fetal bradycardia rather than bradycardia caused by perinatal distress. We briefly examine the embryonic conduction system's development and physiology and we review the classification, aetiology, evaluation, and approach to fetal bradycardia. Our aim is to provide the clinician with practical information about fetal bradycardia that enlightens causative conditions and aids management.

Early dynamic changes in pulse oximetry signals in preterm newborns with histologic chorioamnionitis

OBJECTIVE

No reliable clinical markers of histologic chorioamnionitis (HCA), a major and often subclinical cause of prematurity leading to high neonatal morbidity and mortality, are available to date. Increasing evidence indicates myocardial dysfunctions in affected fetuses and newborns. We sought to assess the value of nonlinear dynamics from pulse oximetry signals in identifying affected newborns.

DESIGN

Prospective case-control study.

SETTING

Tertiary level neonatal intensive care unit, Brindisi Hospital.

PATIENTS AND INTERVENTION

Pulse oximetry-derived signals (pulse rate, oxygen saturation, and perfusion index), recorded within the first 1.5 hrs of life, were analyzed for 110 very low-birth-weight infants, of whom 54 had histopathological evidence of HCA.

MEASUREMENTS AND MAIN RESULTS

Four different time series parameters were determined for nonlinear dynamical (NLD) analysis. Significantly decreased Lempel-Ziv, Lyapunov largest exponent, and correlation dimension, with significantly increased Hurst values for heart rate and perfusion index (p < .00001), were observed in newborns with HCA. Heart rate Lempel-Ziv </=0.218 showed 100% sensitivity (95% confidence interval, 98.8-100) and 100% specificity (95% confidence interval, 98.6-100) in distinguishing cases from controls, with positive and negative predictive values of 100% and 95.7%, respectively.

CONCLUSIONS

Our findings indicate that early autonomic tone balance abnormalities are present in newborns with HCA and suggest that early dynamic analysis of pulse oximetry signals could be useful in identifying affected infants.

Early postnatal changes in the perfusion index in term newborns with subclinical chorioamnionitis

BACKGROUND

Chorioamnionitis (HCA) in term newborns is often subclinical and associated with neonatal morbidity and mortality.

OBJECTIVE

To assess the value of the pulse oximetry perfusion index (PI) in the early prediction of subclinical HCA in term newborns.

METHODS

PI cut-off values were first identified in 51 term newborns with HCA and 115 matched controls, retrospectively categorised on the basis of placental histology (study phase 1). The PI thresholds obtained were subsequently tested on an unselected case series of 329 prospectively recruited, term newborns (study phase 2). PI was evaluated during the first five minutes after delivery. Initial illness severity and short term clinical outcomes were determined.

RESULTS

In study phase 1, newborns with HCA had lower PI one and five minutes (p<0.0001) after delivery, lower one minute Apgar score (p = 0.017), lower cord blood base excess (p = 0.0001), together with higher rates of admission to neonatal intensive care unit (p = 0.0001) and endotracheal intubation (p = 0.017), and higher SNAP-PE (p<0.0001) and NTISS (p<0.0001) scores than those without HCA. In the prospective validation phase of the study, the PI cut-off values generated (one minute < or =1.74, five minutes < or =2.18) showed 100% sensitivity, 99.4% specificity, 93.7% positive predictive value, and 100% negative predictive value in identifying subclinical HCA. Early identification of HCA was associated with a decreased rate of admission to intensive care (p = 0.012), as well as lower initial illness severity (p< or =0.0001) and therapeutic intensity (p = 0.0006) than the newborns with HCA in phase 1.

CONCLUSION

These findings suggest that early PI monitoring is helpful in identifying HCA in term newborns.