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Uterine Tachsystole Rates and “Survival of the Fittest” Effect
Title: Uterine Tachsystole Rates and “Survival of the Fittest” Effect
- Describe the incidence of uterine tachysystole in a large population of healthy women.
- Determine the association of uterine tachysytole with fetal heart rate decelerations and cesarean section.
- Discuss nursing implications related to qualifying uterine tachsystole in relation to the presence or absence of decelerations.
Determine incidence of uterine tachysystole, its association with decelerations and with cesarean
Design: Restrospective
Setting: Suburban hospital in MidAtlantic city
Sample: 6234 women with singleton cephalic presenting babies at a gestational age of 37 weeks or more, who were monitoring electronically in the last 4 hours prior to delivery
Methods:
Clinical data was obtained from the institutional perinatal database that extracts data from the electronic medical record, PeriBirth® (Princeton, NJ). The digital tracings were analyzed using PeriCALM Patterns (Princeton, NJ),
We divided each tracing into 10-minute segments, which were numbered according to proximity to birth, 0 representing the last 10 minutes before birth and 24 occurring 240 minutes earlier. We counted the number of contractions and decelerations in each time segment
Results:
In this study 18.0 % of women experienced at least one episode of uterine tachysystole. The incidence of uterine tachysystole was around 2.7 % at 4 hours prior to delivery and rose to 8.0% times close to delivery. Continuous uterine tachysystole for more than 120 minutes was very uncommon.
Persistent uterine tachsystole was not associated with more decelerations( R=0.28 ) nor with higher cesarean rates ( R= 0.23) (Figures 1,2)
Only 55 or 0.88% of women in this study met the criteria for labor intolerance.
These women had fewer episodes of high contraction rates as is shown in Figure 3.
In contrast, they showed a much higher deceleration response to contractions especially at very low contraction rates as is shown in figure 4.
Over all the rate of cesarean was positively associated with rising rates of decelerations per contractions (R=0.92).
Conclusion/Implications for nursing practice:
We can conclude that some babies tolerate uterine tachsystole well and some do so for very prolonged periods.
These findings are consistent with the principle underlying the old CST- Contraction Stress Test where a controlled stress via induced contractions was used to determine fetal well being antepartum. Labor is the ultimate contraction stress test and this analysis showed that babies with the low tolerance to labor demonstrated strong deceleration responses to even small amounts of contraction stress, whereas others tolerated long periods of uterine tachsystole
Keywords: Uterine tachysytole association with decelerations and caserean delivery