Antepartum vibroacoustic stimulation in patients with low fetal heart rate variability

Fetal vibroacoustic stimulation in computerized cardiotocographic analysis: the role of short-term variability and approximate entropy

The aim of this study was to evaluate the impact of vibroacoustic stimulation (VAS) on computerized cardiotocography short-term variability (STV) and approximate entropy (ApEn) in both low- and high-risk pregnancies. VAS was performed on 121 high- and 95 low-risk pregnancies after 10 minutes of continuous quiet, while their FHR parameters were monitored and recorded by cCTG analysis. Fetal heart rate was recorded using a computer-assisted equipment. Baseline FHR, accelerations, decelerations, STV, long-term irregularity (LTI), ApEn, and fetal movements (FMs) were calculated for defined observational periods before VAS and after 10 minutes. Data were also investigated in relationship with the perinatal outcome. In each group of patients, FHR after VAS remained almost unmodified. Fetal movements significantly increased after VAS in both groups. Results show that only in the high-risk pregnancies, the increase of STV and the decrease of ApEn after VAS were significantly associated with favorable perinatal outcomes.

Foetal response to music and voice

OBJECTIVE

To examine whether prenatal exposure to music and voice alters foetal behaviour and whether foetal response to music differs from human voice.

SUBJECTS AND METHODS

A prospective observational study was conducted in 20 normal term pregnant mothers. Ten foetuses were exposed to music and voice for 15 s at different sound pressure levels to find out the optimal setting for the auditory stimulation. Music, voice and sham were played to another 10 foetuses via a headphone on the maternal abdomen. The sound pressure level was 105 db and 94 db for music and voice, respectively. Computerised assessment of foetal heart rate and activity were recorded. 90 actocardiograms were obtained for the whole group. One way anova followed by posthoc (Student-Newman-Keuls method) analysis was used to find if there is significant difference in foetal response to music and voice versus sham.

RESULTS

Foetuses responded with heart rate acceleration and motor response to both music and voice. This was statistically significant compared to sham. There was no significant difference between the foetal heart rate acceleration to music and voice.

CONCLUSION

Prenatal exposure to music and voice alters the foetal behaviour. No difference was detected in foetal response to music and voice.

Vibroacoustic stimulation in normal term human pregnancy

OBJECTIVE

To examine the effects of vibroacoustic stimulation (VAS) on fetal heart rate (FHR) in term human fetuses by computerized carditocography system.

METHODS

FHR was analyzed 20 min before and 30 min after vibroacoustic stimulation using the Oxford Sonicaid System 8002 for computerized FHR measurement. Recordings were made in 31 uncomplicated pregnancies at 36-42 weeks' gestation.

RESULTS

Vibroacustic stimulation of the fetus evoked a significant increase in all the parameters evaluated (number of fetal movements, of accelerations above 10 and 15 bpm, in high- and low-variability episodes, and in short-term variations). Concerning the effect of behavioural states on the response to VAS, some changes (FHR, high-variability episodes) occurred independently of behavioural states, while other parameters (accelerations >10 and 15 bpm: short-term variation) underwent statistically significant changes only for behavioural states 1F and 2F.

CONCLUSIONS

Our study supports the hypothesis of a significant fetal response in normal term pregnancy, as clearly shown by computerized cardiotocography. The immediate response occurred independently of behavioural states, although some differences were present (mainly for F1 and F2 states) if the evaluation was extended in time.

Evaluation of non-reassuring fetal heart rate patterns with fetal pulse oximetry combined with vibratory acoustic stimulation

OBJECTIVE

To determine the value of fetal pulse oximetry and vibratory acoustic stimulation in the presence of non-reassuring fetal heart rate patterns during labor.

DESIGN

Prospective study in women monitored by cardiotocography and fetal pulse oximetry during labor.

MATERIALS AND METHODS

During a period of 18 months, 907 consecutive parturients in labor were monitored by cardiotocography. Out of these women, 63 were selected on the basis of a non-reassuring fetal heart rate tracing during the first stage of labor. In these cases, fetal pulse oximetry was applied. Vibratory acoustic stimulation was applied in fetuses without spontaneous reactivity in order to evaluate the fetal status.

RESULTS

Our cases were classified into three groups, according to the lower fetal oxygen saturation levels, from the time of oximetry application until delivery. Group A consisted of 29 cases where fetal oxygen saturation levels were > or = 41%, group B (20 cases) with fetal oxygen saturation of 31-40% and group C (14 cases) with levels of < 30%. Spontaneous reactivity was observed in 15 fetuses of group A and seven of group B, while no case of reactivity was noted in group C. Vibratory acoustic-induced reactivity was associated with low fetal oxygen saturation levels. The mean umbilical artery pH levels were 7.29 +/- 0.051 in group A, 7.21 +/- 0.057 in group B and 7.04 +/- 0.05 in group C.

CONCLUSION

Fetal pulse oximetry should be indicated not only in fetuses without any reactivity but also in those with induced reactivity, after the application of vibratory acoustic stimulation.