C.-C. Lin, B. Vassallo, R. Mittendorf
Is intrapartum vibroacoustic stimulation an effective predictor of fetal acidosis?
Objective: The hypothesis of this prospective study is
that intrapartum vibroacoustic stimulation (VAS) is an
effective predictor of fetal acidosis during labor. Various
clinical conditions, such as term versus preterm gestation,
first stage versus second stage of labor, and fetal
heart rate (FHR) variable decelerations versus late decelerations
will be tested.
Methods: During the study period, 113 patients were
studied prospectively in either active phase of first stage
(n = 53) or during the second stage of labor (n = 60).
They were selected from cases exhibiting moderate to
severe FHR variable decelerations or late decelerations.
The fetuses of study subjects received a VAS for three
seconds and FHR changes were recorded. Fetal scalp
blood pH or umbilical arterial blood pH was obtained
within 15 minutes of VAS. The relationship between
FHR responses to VAS and fetal blood pH in term and
preterm gestations, the relationship of two tests (VAS
and fetal blood pH) to type of FHR decelerations, and
the predictability of neonatal morbidity by two tests
were analyzed. Where appropriate, Fisher's exact test
(p < 0.05 was considered statistically different) and the
odd ratio with 95% confidence intervals were used for
statistical analyses.
Results: Excellent association between acceleration response
to VAS and pH ? 7.20, and between a negative
response to VAS (no acceleration or decelerations) and
pH < 7.20 were found in the first stage of labor, the
second stage of labor, and the combination of both
stages together (p = 0.0001, OR = 10.6 [3.3–34.0]). It
was observed that negative VAS responses for predicting
fetal acidosis (pH < 7.20) were comparable between
term (? 37 weeks) and preterm (< 37 weeks,
? 34 weeks) fetuses. Since the preterm fetuses enrolled
in the study were limited in number, it is difficult to
draw adequate conclusions. The positive predictive
value (PPV) of fetal acidosis was 67% in both groups
of FHR variable decelerations and late decelerations,
but the false negative rate of acceleration VAS response
for predicting no acidosis was significantly higher in the
group of late decelerations (29% vs 8 %, p = 0.034).
Finally, both a negative VAS response and fetal acidosis
(pH < 7.20) have equal predictability for neonatal morbidity.
The PPV of NICU admission by a negative VAS
response was two times higher than that of fetal acidosis
(PPV = 61% vs 29%, p = 0.038).
Conclusion: We found that intrapartum VAS was an
effective predictor of fetal acidosis in cases of FHR
variable decelerations, but its predictability for fetal acidosis
in cases of FHR late decelerations was limited.
Both VAS and fetal blood pH are good predictors of
neonatal morbidity.
Journal of Perinatal Medicine, Walter de Gruyter
Print ISSN: 1619-3997
Volume: 29, 11/2001
Pages: 506 - 512
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