Vibroacoustic stimulation and fetal heart rate in nonstress tests. Fetal acoustic stimulation testing. II. A randomized clinical comparison with the nonstress test. A randomized controlled trial of a new fetal acoustic stimulation test for fetal well-being. Effect of vibratory acoustic stimulation on the duration of fetal heart rate monitoring tests. The predictive value of fetal acoustic stimulation. Non-stress antenatal cardiotocography--a prospective randomized clinical trial. Comparison of the acoustic stimulation test with nonstress test. A randomized, controlled clinical trial. Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial. FECG Study Group. A randomized, controlled trial of computerized physiologic trend monitoring in an intensive care unit.
Two methods of vibroacoustic stimulation were compared with traditional nonstress tests. Fetal heart rate tracings following stimulation had more accelerations and were of greater amplitude and duration than in the control group. The length of time required to obtain a reactive nonstress test was almost 15 minutes shorter when vibroacoustic stimulation was applied than when vibroacoustic stimulation was not used. Vibroacoustic stimulation elicited a heightened reactivity that persisted beyond the observation period in 30 of 45 (67%) of the experimental group subjects. Antepartum fetal heart rate testing, specifically the nonstress test, is of accepted value in the antenatal surveillance of high-risk pregnancies. Fetal rest-activity cycles coupled with arbitrary test intervals appear to lead to falsely nonreactive tests. Methods to alter fetal behavioral states have not been uniformly successful. A retrospective analysis of the adjunctive use of acoustic stimulation at our institution demonstrated a 50% reduction in the number of nonreactive tests. Consequently a prospective randomized clinical trial was undertaken to compare the standard nonstress test with the fetal acoustic stimulation test. Those patients randomized to the fetal acoustic stimulation test underwent transabdominal acoustic stimulation with a Model 5C electronic artificial larynx. The incidence of nonreactive tests was 14% in the control group and 9% in the study group (chi 2 = 11.09, p = 0.004). A significant reduction in testing time was also observed. The fetal acoustic stimulation test offers advantages over the traditional nonstress test by lowering the incidence of nonreactive tests and reducing testing time. Our purpose was to determine (1) whether a fetal acoustic stimulation test results in more palpable fetal movement compared with a mock test (control) and (2) whether palpated fetal movements after a fetal acoustic stimulation test are accompanied by a reactive nonstress test.
                In a randomized controlled trial we studied women seen in the labor and delivery suite for various indications. Women were excluded for multiple gestation, < 31 weeks' gestational age, treatment with magnesium sulfate or narcotics, or ruptured membranes. Informed consent was obtained from eligible women, who were then randomized to a test or control group. We placed an acoustic stimulator on the abdomen of each woman, but only the test group was stimulated. We assessed fetal movement by a grading system: 0 = no fetal movement felt by patient or tester, 1 = fetal movement felt by patient only, 2 = fetal movement felt by tester, 3 = visual movement seen by tester. A positive fetal acoustic stimulation test result was defined as one with any fetal movement felt or seen by the tester (grades 2 or 3). We then performed a nonstress test. We compared rates of a positive fetal acoustic stimulation test in the test and control groups with the chi 2 test. A p value < 0.05 was considered significant.
                We randomized 297 women to the test group and 280 women to the control (mock test) group. Of women tested with the fetal acoustic stimulation test. 81% had fetal movement by palpation or visualization (grades 2 or 3) compared with 19% of the control group (p < 0.0001, odds ratio 19.29, 95% confidence interval 12.42 to 30.07). Of the test group, 283 (95%) had a reactive nonstress test and 14 (5%) had nonreactive tests; the control group had 267 (95%) reactive and 13 (5%) nonreactive nonstress tests. Of 242 patients in the test group with a positive fetal acoustic stimulation test, 236 (98%) had a reactive nonstress test. Of those in the test group with fewer than three contractions per 10 minutes. 164 (89%) had a positive fetal acoustic stimulation test. Of these, 162 (99%) had a reactive nonstress test.
                The fetal acoustic stimulation test evokes significantly more palpated or visualized fetal movement than in controls. Palpated or visualized fetal movement after acoustic stimulation was almost always accompanied by a reactive nonstress test. The ability of vibratory acoustic stimulation to shorten the duration of antepartum fetal heart rate monitoring was investigated by a randomized controlled trial. Vibratory acoustic stimulation did not shorten the overall duration of testing. This failure to improve the performance of antepartum monitoring appeared to result from prolonged accelerations, which complicated one third of the tests in which vibratory acoustic stimulation was employed. Further investigation is warranted using less profound methods of fetal stimulation. To compare the predictive abilities, test duration times, and incidence of nonreactive results in the acoustic stimulation test (AST) and the nonstress test (NST).
                Four-hundred randomly selected patients, delivering within 7 days of a preceding test, were divided into two groups (group I: NST; group II: AST). In the AST group, fetal heart rate tracing were recorded for the first 5 minutes as a baseline recording. If the reactivity criterion was not met, transabdominal acoustic stimulation to the fetal head was performed. In the NST group, nonreactive tests were followed by a repeat NST. In both groups, nonreactive tests were followed by oxytocin challenge test (OCT) on the same day. Depressed 5-minute Apgar scores (< 7) and an umbilical arterial blood pH of < 7.2 were taken as indicators of fetal distress. Sensitivity, specificity, and predictive values of NST and AST were calculated and compared.
                The incidence of nonreactive tests was lower in the AST group. AST decreased the test duration time by 10.1 minutes. The sensitivity values were 87.5% in the NST group and 85.7 in the AST group; specificities of were found to be 94% for AST and 88% for NST. The negative predictive value was found to be 98% in each group, but the positive predictive value was 54.5% in the AST group and 38.8% in the NST group.
                AST offers benefits, by decreasing the incidence of nonreactive tests and reducing the test time. AST lowers the rate of false positives without changing the negative reliability of NST. It is a safe test and allows more efficient use of perinatal services. A randomized controlled trial examined the effects of non-stress antepartum cardiotocography on obstetric management and assessed its usefulness as a diagnostic test of fetal compromise. Daily cardiotocograph recordings were made in 396 antenatal patients at increased risk of fetal compromise but were withheld from the clinicians responsible for care in half the cases. The frequency of intrapartum fetal distress and low Apgar score was similar in the two groups. The three normally-formed perinatal deaths all occurred in the revealed group but in only one case could earlier obstetric intervention have altered the outcome. Availability of non-stress cardiotocography was not associated with an increased rate of induction of labour or caesarean section. The nonstress test (NST) is a helpful adjunct in the management of high-risk pregnancies. It has high predictability and a low false-negative rate but unfortunately has fairly high false-positive results. Attempts have been made to find a suitable stimulant to help decrease nonreactive results as well as to shorten the duration of testing: the recently introduced fetal acoustic stimulation test (AST) may have such attributes. This prospective, randomized clinical trial was carried out to assess the new test. A total of 1,300 individual tests were performed on high-risk pregnancies. Cases were randomized to receive either the AST or NST. All tracings were interpreted blindly by an independent perinatologist. The incidence of nonreactive tests was 6.8% in the AST group and 13.8% in the NST group (P < .001). There was a significant reduction in the time needed for a reactive test to occur. It can be concluded, therefore, that AST offers a greater advantage over NST by lowering both the incidence of nonreactive tests and testing time, thereby resulting in less of a need for the contraction stress test and biophysical profile. There is a need to improve the sensitivity and specificity of fetal monitoring during labour. We compared the gold standard, cardiotocography, with cardiotocography plus time-interval analysis of the fetal electrocardiogram in fetal surveillance. The aim was to find out whether time-interval analysis decreased the need for operative intervention due to fetal distress.
                We did a randomised, prospective trial in five hospitals in the UK, Hong Kong, the Netherlands, and Singapore. 1038 women undergoing high-risk labours were randomly assigned fetal monitoring by cardiotocography alone, or cardiotocography plus fetal electrocardiography (ECG). Outcomes measured were rates of operative intervention, and neonatal outcome. Analysis was by intention to treat.
                515 women were assigned management by cardiotocography, and 523 cardiotocography plus fetal ECG. There was a trend towards fewer operative interventions for presumed fetal distress in the time-interval analysis plus cardiotocography group (63 [13%] vs 78 [16%]), but this was not significant (relative risk 0.80 [95% CI 0.59-1.08], p=0.17). There was no significant difference between groups in the proportion of babies who had an umbilical arterial pH of 7.15 or less (51 [11%] vs 49 [11%]; 1.01 [0.7-1.47]), or in the frequency of unsuspected acidaemia (42 [9%] vs 35 [8%]; 1.17 [0.76-1.79]).
                The addition of time-interval analysis of the fetal electrocardiogram during labour did not show a significant benefit in decreasing operative intervention. There was no significant difference in neonatal outcome. To assess whether the provision of computerized physiologic trend data could improve outcome in newborn infants requiring intensive care.
                Randomized, controlled trial, with subsidiary questionnaire studies.
                Tertiary neonatal intensive care unit with 12 intensive care cots.
                All infants admitted between January 1991 and September 1993 who were < or =32 wks gestation or >32 wks gestation, and ventilated for >4 hrs or asphyxiated.
                Randomization to one of four groups for first 7 days of life: A) no display of trend data; B) continuous display of trend data; C1) alternating 24-hr display of trend data, starting with display in first 24 hrs; and C2) alternating 24-hr display of trend data, starting with no display in first 24 hrs.
                The short-term effects of monitoring on patient outcome was judged by volume of colloid given, number of blood gases taken, and by measurement taken from cranial Doppler ultrasound. Medium-term measures included time ventilated, time given supplemental oxygen, death, time to death or discharge, and cranial ultrasound at discharge. Long-term outcome was assessed by neurodevelopmental status at age 1 to 4 yrs of age. Staff and parent questionnaires assessed their respective attitudes to the introduction of this technology. None of the patient outcome measures, short-, medium-, or long-term, demonstrated any significant benefit from the provision of computerized physiologic trend monitoring. Staff questionnaires demonstrated an acceptance of the system and an improved understanding of neonatal physiology as a result of computerized physiologic trends. Parent questionnaires demonstrated increased anxiety caused by the system in 11% of parents, although only 1% of parents continued to have concerns if the system were able to help their child.
                A randomized, controlled trial was unable to demonstrate any benefit to patients resulting from the introduction of a computerized physiologic trend monitoring system. Benefits of the system have been recognized, however, in subsidiary studies, staff education, and research studies.
Vibroacoustic stimulation offers benefits by decreasing the incidence of non-reactive cardiotocography and reducing the testing time. Further randomized trials should be encouraged to determine not only the optimum intensity, frequency, duration and position of the vibroacoustic stimulation, but also to evaluate the efficacy, predictive reliability, safety and perinatal outcome of these stimuli with cardiotocography and other tests of fetal well-being.
[Note: The eight citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]