Intrapartum fetal heart rate variability and subsequent neonatal cerebral edema

Abstract

Objective: To determine whether fetal heart rate variability (FHRV) in the neurologically impaired neonate is associated with cerebral edema.Study design: Through retrospective chart review, singleton term infants with neonatal encephalopathy and permanent neurologic impairment were identified in a national registry of brain-injured infants. Cerebral edema was defined as follows: (1) ultrasound-generalized increases in echodensity throughout the brain with loss of normal landmarks or slitlike ventricles, (2) computed tomography scan-low attenuation throughout the brain, or mass effect as evidenced by sulcal effacement, displacement of the midline structures, ventricular distortion, or compression of subarachnoid spaces, and (3) low magnetic resonance imaging signal on T1-weighted images and high signal on T2-weighted images or morphologic change on T1-weighted image detected by gross enlargement of structures or by distortion of normal adjacent structures. Cases with a Hon intrapartum fetal heart rate (FHR) pattern (reactive pattern on admission followed by tachycardia and repetitive FHR decelerations) were selected. These cases were then categorized according to the FHR variability at the end of the monitor strip as follows: average ≥6 bpm or diminished (D) <6 bpm. Exclusion criteria were as follows: (1) nonqualifying FHR pattern—183; (2) no neuroimaging studies within 7 days of birth—48; (3) insufficient data—19; and (4) other—7.Results: Of 300 singleton term brain-injured neonates, 43 (14%) neonates met entry criteria. Prior to birth, the FHRV average was 10 (23%) or diminished (33 [77%]). Of these infants, cerebral edema was found in 18 (42%) patients. But, average FHRV was associated with significantly less cerebral edema (average 1/10 [10%] versus diminished 17/33 [52%] [P = 0.02]).Conclusions: In brain-injured neonates, cerebral edema appears to be associated with the Hon FHR pattern. Cerebral edema also appears to be associated with diminished FHRV. These findings suggest that the presence of average FHRV in the fetus with the Hon FHR pattern is associated with fetal brain injury, but not necessarily neonatal cerebral edema.