fetal heart rate monitoring: terminology update

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Fetal Heart Rate Monitoring: Terminology Update. Sharon Fickley, BSN, RNC-OB Laura Hall, ADN, RNC-OB January 24 th , 2011. Objectives. Provide brief review of National Institute of Child Health and Human Development (NICHD) 2008 Electronic Fetal Monitoring (EFM) Terminology Update - PowerPoint PPT Presentation


Fetal Heart Rate Monitoring: Terminology Update

Fetal Heart Rate Monitoring: Terminology UpdateSharon Fickley, BSN, RNC-OBLaura Hall, ADN, RNC-OBJanuary 24th, 2011ObjectivesProvide brief review of National Institute of Child Health and Human Development (NICHD) 2008 Electronic Fetal Monitoring (EFM) Terminology UpdateDiscuss physiologic basis for interpreting Fetal Heart Rate (FHR) tracingsIntroduce definitions of NICHD Categories for interpreting and discussing FHR tracingsBackground2008 WorkshopKey Players: National Institute of Child Health and Human DevelopmentAmerican College of Obstetricians and Gynecologists (ACOG)Society for Maternal-Fetal Medicine

Background (cont)Purposes:Review & Update FHR pattern definitionsAssess existing classification systems for interpreting FHR patternsMake recommendations about system for use in U.S.Make recommendations for research priorities regarding EFM (ACOG, 2009)

PurposeUsing a common language for discussion of fetal status is a key principle of effective clinical communication and has the potential to decrease communication errors(AWHONN, 2009, p. 72) And we all know how many mistakes involve communication. We also know how many times weve debated with physicians regarding a tracing. Although updates and clarifications in terminology will never end the debates completely, the panel attempted to objectify terms and place tracings into some fairly distinct categories while offering general guidance about how to manage tracings in different categories. MethodsSystematic Assessment is KeySystematic Assessment of FHR tracing includes:Baseline RateVariabilityPeriodic or Episodic ChangesUterine ActivityPattern of or changes in FHR over timeEvaluation of findings within total clinical picture(AWHONN, 2009)

Periodic associated with contractionsEpisodic not associated with contractionsInclude characterizing accelerations and decelerations our charting is a bit duplicate (boxes that say periodic and with contractions means the same thing dont need to chart both)

To start well very quickly review basic elements of NICHD terminology, just to make sure were all talking from the same vantage point. These 6 elements are included in each assessment of fetal heart rateNot always thought through individually, but represent the overall picture of FHR. However, each element should be considered when evaluating patterns, especially concerning onesBaseline RateApproximate mean FHR rounded to increments of 5 bpm during a 10 minute window, excluding accelerations and decelerations and periods of marked variabilityMust have at least 2 minutes identifiable, but not necessarily contiguous, baseline segmentsIf dont have at least 2 minutes of baseline in 10 minute period, baseline is indeterminateMay need to refer to previous 10 minute window to determine baseline(Macones et al, 2008)If baby very active, may be hard to get 2 contiguous minutes of baseline, but can either piece together or look back @ previous windowBaselineBradycardia: < 110 bpmTachycardia: >160 bpm

(Macones, et al, 2008)

Baseline VariabilityDetermined in 10 minute windowExcluding accelerations or decelerationsDefined as fluctuations in baseline FHR that are irregular in amplitude {height} and frequency {width} and are visually quantified as the amplitude of the peak-to-trough in beats per minute (bpm)Absent: amplitude range undetectableMinimal: amplitude range visually detectable but /= 15 bpm, lasting >/= 15 seconds from beginning to return to baseline

/= 10 bpm, lasting >/= 10 seconds

>/= 10 minute acceleration = baseline change(Macones, et al, 2008)

Periodic/Episodic Changes - DecelerationsEarly Deceleration:usually symmetricalgradual decrease and return of FHRassociated with contractiononset to nadir >/= 30 secondsnadir coincides with peak of contraction

(Macones, et al, 2008)Periodic/Episodic Changes - DecelerationsLate Deceleration:usually symmetricalgradual decrease and return to baselineassociated with contractiondelayed in timingnadir occurs after peak of contractiongenerally, onset, nadir, and recovery occur after the beginning, peak, and end of the contraction(Macones, et al, 2008)So no need to split hairs onset usually after beginning of contraction. No need to measure exactly how far after just after, and the lowest point in the decel is usually after the peak of the contraction. Decel gradually resolves after the end of the contraction. When auscultating, cant characterize type of decel, but this is often the one where youre listening through contraction and it sounds ok, but then after woman says contraction is over, you hear an audible drop in FHR. Our ears just arent able to immediately hear all that the eye sees on EFM, so thats why further eval is needed if this occurs more than once successively w/auscultation.Periodic/Episodic Changes - DecelerationsVariable Deceleration:Abrupt decreaseOnset to nadir /= 15 bpm, lasting >/= 15 seconds and < 2 minutesIf associated with contractions, onset, depth and duration commonly vary with successive contractions(Macones, et al, 2008)

So, quickish and fastish quick to drop to lowest point, and relatively quick to return to baseline. May have variables after contractions no more variables with a late component if theyre variables, theyre variables, and youll want to take action if theyre recurrent, no matter when theyre occurring in relationship to contractionPeriodic/Episodic Changes - DecelerationsProlonged Deceleration:Decrease from baseline >/= 15 bpmLasts >/= 2 minutes but < 10 minutesDeceleration lasting > 10 minutes = baseline change

Recurrent: occurring with >/= 50% contractions in any 20 minute windowIntermittent: occurring with < 50% contractions in any 20 minute window

(Macones, et al, 2008)Definitions for recurrent and intermittent become important when looking @ categoriesUterine ActivityNormal Uterine Activity: Five or fewer uterine contractions in 10 minutes, averaged over a 30 minute windowTachysystole: More than five contractions in 10 minutes, averaged over a 30 minute periodShould always be discussed in conjunction with FHR characteristicsTerms Hyperstimulation & Hypercontractility not defined, should not be used(ACOG, 2009; AWHONN 2009)TerminologyReactive and Nonreactive: apply to antepartum monitoring (non-stress test) vs. intrapartum Reassuring and Nonreassuring: Not used or addressed in new terminology. AWHONN FHM course states that one can feel reassured by a tracing, based upon the Category it is in.

(AWHONN, 2009 & 2010)Will certainly hear people say strips are reassuring, and they are. Its just that the terminology is really not defined in most recent document. Rather, encourage us to look @ elements of tracing and try to define according to categories. Its not that reassuring is wrong. Three Tiered SystemRepresents analysis of fetal acid-base status at the time assessment is madeCategory I: Normal acid-base status likely probability high that fetus is well oxygenatedCategory II: Indeterminate. Fetus likely exhibiting compensatory response has reservesCategory III: Abnormal fetal acid-base status likely

All definitions related to categories and their description are adapted from Macones, et al, 2008.Three tiered system is meant to categorize tracings according to probably acid-base status of fetus AT THE TIME tracing is being interpreted, recognizing that labor is a dynamic process, that fetuses come into the process with many different risk factors and amounts of reserve and that tracings often can and do evolve in and out of categories throughout labor Years of research now demonstrate that much of what we thought of in the past as a bad tracing may not have been associated with a bad baby weve all seen the 9/9 apgars in the OR after running around worrying. What this working group wanted to do was to help clinicians systematically evaluate and think through tracings, considering the entire clinical picture. They emphasize likely physiology behind tracings and evaluating and responding accordingly. Now well review each category in more detail.Points to EmphasizeFHR patterns change over timeClinical management individualized for each situationMust evaluate entire clinical picture, including risk factors for both mother and babyAll interpretation and management based upon understanding of physiologic mechanisms underlying FHR tracingFetal monitoring is a collaborative process of continual assessment, interpretation, diagnosis, intervention, and evaluationChanges over time you may have a strip that is category II and goes back to a I with intervention, or you may have a great baby that becomes category II or III happens all the time.Guidelines dont lock clinicians into any specific response in every situation need to consider the whole clinical picture risk factors, pre-existing status of fetus (ie. IUGR, known placental insufficiency, diabetic mother, congenital abnormalities, etc) and the mother in evaluating and making decisions re: managementThree Tiered System for Classifying FHR TracingsCategory ICategory IICategory IIIAll of the Following: Baseline 110-160 Variability: Moderate Late or Variable Decels: Absent Early Decelerations: Present or Absent Accelerations: Present or Absent

Examples: Moderate Variability with recurrent late or variable decelerations Minimal Variability with recurrent variable decelerations Absent Variability WITHOUT recurrent decelerations Bradycardia with Moderate Variability Prolonged DecelerationsEither: Absent Variability with: Recurrent late decels OR Recurrent variable decels OR BradycardiaOR: Sinusoidal PatternIf you recognize characteristics necessary for category I and Category III youll know whats not either one and by default is category