Disclosure: The authors report no conflict of interest or relevant financial relationships.
On Electronic Fetal Heart Rate Monitoring
Version of Record online: 3 NOV 2011
© 2011 AWHONN, the Association of Women's Health, Obsteric and Neonatal Nurses
Journal of Obstetric, Gynecologic, & Neonatal Nursing
Volume 40, Issue 6, pages 669–671, November/December 2011
How to Cite
King, T. L. and Parer, J. T. (2011), On Electronic Fetal Heart Rate Monitoring. Journal of Obstetric, Gynecologic, & Neonatal Nursing, 40: 669–671. doi: 10.1111/j.1552-6909.2011.01291.x
- Issue online: 18 NOV 2011
- Version of Record online: 3 NOV 2011
To the editor:
Management of fetal heart rate (FHR) patterns is rapidly changing following the 2008 consensus guideline from the National Institutes of Health and Child Development (NICHD) and a 2010 Practice Bulletin from the American College of Obstetricians and Gynecologists (ACOG). The FHR category II identified in the NICHD document does not assist clinical decision making. Although ongoing research is addressing this gap, multidisciplinary development of FHR interpretation and management systems will aid clinical practice. In a recent editorial on FHR monitoring, Dr. Nancy Lowe (2011) highlighted a key point in the commentary by Grimes and Peipert that almost every “positive” electronic fetal monitoring (EFM) test is wrong in that it does not benefit the newborn and harms women due to unnecessary operative procedures (Grimes & Peipert, 2010). If this is so, there is something enormously wrong with what we call a “positive” result. Let's not throw the baby out with the bath water before taking a more nuanced look at the effectiveness of FHR monitoring in obstetrics today.
In a fetus without risk for acidemia at the outset of labor and in the absence of a sudden sentinel event, the development of clinically significant acidemia evolves over a period of time (Parer, King, Flanders, Fox, & Kilpatrick, 2006). Given this known progression, it is appropriate to intervene before the fetus decompensates. For example, based on assessment of the category III FHR tracing (Macones et al., 2008) shown in Figure 1, a cesarean was performed to avoid irreversible metabolic acidosis in the fetus. The newborn was vigorous and had umbilical arterial cord gases that revealed a pH of 7.04, PCO2 of 77 mm Hg, PO2 of 10 mm Hg, and a base excess of −8.mEq/l. The Apgar scores were 6 at one minute and 8 at five minutes. In the screening test paradigm, this case is classified as a “false positive test” because the newborn did not have evidence of significant acidemia. However, based on the FHR tracing, which worsened despite efforts to ameliorate it by conservative means such as position change or maternal hyperoxia, it is likely that this newborn would have had adverse consequences of metabolic acidosis if labor had continued without intervention.
It is not our goal to identify fetal acidemia once it is present. Our goal is to identify the fetus with a FHR pattern that is associated with a significant risk for acidemia. If the FHR pattern cannot be ameliorated in utero, the goal is to intervene at the appropriate time to prevent substantial metabolic acidemia in the newborn. In the screening paradigm used by Grimes and Peipert (2011), the cesarean was unnecessary because the infant was healthy at birth. However, a vigorous infant is, in fact, the optimal result desired. Screening tests are designed to identify a potential problem for which there is a treatment. We use FHR monitoring to avoid such a problem.
The dozen or so frequently quoted randomized controlled trials (RCTs) on FHR monitoring and subsequent meta-analysis (Alfrevic, Devane & Gyte, 2006) found that FHR monitoring does not improve perinatal mortality and does increase cesarean rates. However, those trials are now several decades old, and there are significant problems with how they were conducted. Each RCT identified different FHR patterns that necessitated intervention. In addition, they used management protocols that failed to factor in the importance of FHR variability as a reflection of central nervous system integrity. Thus the cesarean rates were predictably higher in the cohort who had EFM. These RCTs did not have sufficient numbers to determine a real change in neonatal mortality. Finally and most important, the published RCTs on FHR monitoring are not applicable to intrapartum management today (ACOG, 2010). Key changes in practice today are multidisciplinary use of standard terms for communicating FHR characteristics, evaluation of FHR variability as the key indicator of determining the risk for acidemia, selective use of “intrauterine resuscitation” techniques, and close attention to the effect of tachysystole (ACOG; Macones et al., 2008). Yet some continue to be influenced by the conclusions of these earlier RCTs, which are cited as current evidence for why FHR monitoring should be abandoned.
The real problem today is the extensive individual variation in making the diagnosis of “fetal distress,” or more precisely, “risk of serious fetal acidemia” that occurs in clinical practice. In our view, rather than follow Lowe's (2011) suggestion that nurses, midwives, and physicians study Grimes and Peipert's (2011) commentary, we believe this problem needs to be fixed. It can be done by achieving a broad consensus on a system of FHR pattern interpretation and management based on the best available evidence for the link between specific FHR patterns and fetal acidemia (Elliot, Warrick, Graham, & Hamilton, 2010; Okai et al., 2010; Parer, King, Flanders, Fox, & Kilpatrick, 2006). The current focus of research on FHR monitoring is evaluation of the reliability and effectiveness of standardized interpretation and management paradigms. (ACOG, 2010; Bannerman et al., 2011; Macones et al., 2008; Parer & Ikeda, 2007). We suggest that all obstetric care givers, including nurses and providers, become involved in delineating a system of FHR management which is based on a multitier system of FHR pattern interpretation that includes pattern evolution and is based on institutional resources. Only then can these collaboratively devised systems of FHR interpretation and management be subjected to appropriate epidemiologic testing for effectiveness.
FHR monitoring during labor has incontrovertibly largely reduced the incidence of intrapartum fetal death, and a recent epidemiologic analysis suggests FHR monitoring is a factor in the reduction of early neonatal mortality (Chen et al., 2011). There is consensus today on which specific FHR patterns signify a significant risk for fetal acidemia (ACOG, 2010; Macones et al., 2008; Parer et al., 2006). In addition, management strategies that include this knowledge are currently being tested (Elliot et al., 2010; Katsuragi et al., 2011; Kikuchi et al., 2011; Okai et al., 2010). Continuous EFM may not be advised for women who are low risk for fetal acidemia at the time they go into labor (Holmgren et al., 2011). Yet intermittent auscultation protocols require appropriate workforce presence and also need to be tested for effectiveness.
FHR monitoring was not appropriately tested prior to being implemented into clinical practice. With the clarity of hindsight, we can identify many reasons why FHR monitoring increased the cesarean rate without improving perinatal mortality in the first few decades of use. But focusing on why FHR monitoring has not worked in the past and calling for discontinuation of this technique is not the solution. As research on the effectiveness of these management schemes continues, FHR monitoring needs to be utilized in a systematic evidence-based manner, which includes identification of women who will benefit from this tool, standardized interpretation, and collaboratively planned management based on individual institutional resources.
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