Betamimetics in fetal distress: randomised controlled trial. A study on intrauterine fetal resuscitation with terbutaline.
The objective of the study was to investigate if a single dose of Hexoprenaline administered to patients diagnosed as having fetal distress improves neonatal outcome and whether there are any side effects and complications related to hexoprenaline injection. Patients with fetal distress diagnosed by electronic fetal heart rate monitoring with a gestational age of 35 weeks or more in active labor were eligible. Once the decision to deliver the patient by Cesarean section was made, patients were approached and randomised by sealed opaque envelopes to hexoprenaline or control groups. Ten micrograms of hexoprenaline were administered intravenously to study patients. Main outcomes were cord blood gas values, Apgar scores, the need for resuscitation and admission to intensive care. There were no statistically significant differences in the main outcome measures between the two groups. Fewer babies in the hexoprenaline group had a pH of < 7.2 and a base excess of < -10, but this was not statistically significant. The fetal heart rate pattern was improved in significantly more patients after hexoprenaline administration than controls. In conclusion, despite the statistically significant improvement in fetal heart rate tracings, Apgar scores and blood gas values showed only a trend towards improvement in the hexoprenaline group. A randomized study on the effect of terbutaline on fetal distress was carried out in 20 patients who showed evidence of ominous fetal heart rate patterns and fetal scalp blood pH values of less than 7.25. Of those, 11 received terbutaline (study group) and nine did not (control group). There was a significant improvement in the acid-base status of the fetus in the study group compared with those in the control group (p less than 0.01). No significant maternal or fetal morbidity occurred in the study group. Apgar scores at 1 minute were 7 or greater in 10 of the 11 study subjects whereas only four of the nine control subjects had a score of 7 or greater. These results suggest that terbutaline may become a useful agent in the treatment of intrauterine fetal distress.
Betamimetic therapy appears to be able to reduce the number of fetal heart rate abnormalities and perhaps reduce uterine activity. However, there is not enough evidence based on clinically important outcomes to evaluate the use of betamimetics for suspected fetal distress.