Download - Fetal Heart Rate Monitoring: Terminology Update

Fetal Heart Rate Monitoring: Terminology

UpdateSharon Fickley, BSN, RNC-OB

Laura Hall, ADN, RNC-OBJanuary 24th, 2011

Objectives1. Provide brief review of National Institute

of Child Health and Human Development (NICHD) 2008 Electronic Fetal Monitoring (EFM) Terminology Update

2. Discuss physiologic basis for interpreting Fetal Heart Rate (FHR) tracings

3. Introduce definitions of NICHD Categories for interpreting and discussing FHR tracings

Background 2008 Workshop

Key Players: • National Institute of Child Health and Human

Development• American College of Obstetricians and

Gynecologists (ACOG)• Society for Maternal-Fetal Medicine

Background (con’t) Purposes:

Review & Update FHR pattern definitions Assess existing classification systems for

interpreting FHR patterns• Make recommendations about system for

use in U.S.• Make recommendations for research

priorities regarding EFM (ACOG, 2009)

Purpose“Using 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)

Methods Systematic Assessment is Key Systematic Assessment of FHR tracing

includes: Baseline Rate Variability Periodic or Episodic Changes Uterine Activity Pattern of or changes in FHR over time Evaluation of findings within total clinical

picture(AWHONN, 2009)

Baseline Rate

Approximate mean FHR rounded to increments of 5 bpm during a 10 minute window, excluding accelerations and decelerations and periods of marked variability

Must have at least 2 minutes identifiable, but not necessarily contiguous, baseline segments

If don’t have at least 2 minutes of baseline in 10 minute period, baseline is indeterminate

May need to refer to previous 10 minute window to determine baseline

(Macones et al, 2008)

Baseline

Bradycardia: < 110 bpmTachycardia: >160 bpm

(Macones, et al, 2008)

Baseline Variability Determined in 10 minute window Excluding accelerations or decelerations Defined 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 undetectable Minimal: amplitude range visually detectable but </= 5

bpm (greater than undetectable but </= 5 bpm) Moderate: amplitude range 6-25 bpm Marked: amplitude range > 25 bpm


Periodic/Episodic Changes - Accelerations

Acceleration: Visually apparent abrupt increase in FHR Onset to peak <30 seconds

>/= 32 weeks: Peak >/= 15 bpm, lasting >/= 15 seconds from beginning to return to baseline

<32 weeks: Peak >/= 10 bpm, lasting >/= 10 seconds –

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

2008)

Periodic/Episodic Changes - Decelerations

Early Deceleration: usually symmetrical gradual decrease and return of FHR associated with contraction onset to nadir >/= 30 seconds nadir coincides with peak of contraction



Late Deceleration: usually symmetrical gradual decrease and return to baseline associated with contraction delayed in timing nadir occurs after peak of contraction generally, onset, nadir, and recovery occur

after the beginning, peak, and end of the contraction



Variable Deceleration: Abrupt decrease Onset to nadir <30 seconds Decrease is >/= 15 bpm, lasting >/= 15

seconds and < 2 minutes If associated with contractions, onset,

depth and duration commonly vary with successive contractions



Prolonged Deceleration: Decrease from baseline >/= 15 bpm Lasts >/= 2 minutes but < 10 minutes Deceleration lasting > 10 minutes = baseline

change

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

Intermittent: occurring with < 50% contractions in any 20 minute window


Uterine ActivityNormal Uterine Activity: Five or fewer

uterine contractions in 10 minutes, averaged over a 30 minute window

Tachysystole: More than five contractions in 10 minutes,

averaged over a 30 minute period Should always be discussed in conjunction with

FHR characteristics Terms “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)

Three Tiered System Represents analysis of fetal acid-base status at

the time assessment is made Category I: Normal acid-base status likely –

probability high that fetus is well oxygenated

Category II: Indeterminate. Fetus likely exhibiting compensatory response – has “reserves”

Category III: Abnormal fetal acid-base status likely

All definitions related to categories and their description are adapted from Macones, et al, 2008.

Points to Emphasize FHR patterns change over time Clinical management individualized for each

situation Must evaluate entire clinical picture, including risk

factors for both mother and baby All interpretation and management based upon

understanding of physiologic mechanisms underlying FHR tracing

Fetal monitoring is a collaborative process of continual assessment, interpretation, diagnosis, intervention, and evaluation

Three Tiered System for Classifying FHR Tracings

Category I Category II Category III

All 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 Decelerations

Either: Absent Variability with:

Recurrent late decels OR Recurrent variable decels OR Bradycardia

OR: Sinusoidal Pattern

Category I OverviewCategory I tracings are normalStrongly predictive of normal fetal

acid-base status May be followed in routine manner

Category II Overview Includes all tracings not categorized as Category I or III Not predictive of either normal or abnormal fetal acid-base

status No evidence to categorize as either I or III Generally require “evaluation, and continued surveillance

and reevaluation, taking into account the entire associated clinical situation” (Macones 2008)

Additional tests (i.e. biophysical profile, amniotic fluid volume) may be needed to gather all information required to plan management

May require intrauterine resuscitative measures MOST IMPORTANT: try to identify &/or address underlying

physiologic mechanism which may be resulting in the characteristics of the tracing

Category II Overview Communicate with care provider Continue to evaluate and respond to

tracing Implement intrauterine resuscitative

measures as needed to attempt correction of underlying mechanism of FHR pattern characteristics

Consider tocolytics if intrauterine resuscitative measures do not bring resolution

Category III Overview Are abnormal Associated with abnormal fetal acid-base balance

at time of observation Must evaluate and intervene quickly Make efforts to resolve quickly:

Change maternal position Discontinue labor stimulation Administer IV fluids Treat maternal hypotension Provide oxygen to mother Request tocolytics if appropriate Mobilize team response

Category III Overview If Category III tracing does not

resolve relatively quickly with physiologically-based interventions, plan for expedited delivery

Medical provider should be notified immediately when tracing is a Category III

What does it mean for us? “Data concerning the FHR pattern should ideally

be conveyed using the definitions provided in the proceedings of the NICHD 2008 guidelines for EFM definitions, interpretation, and research” (AWHONN, 2009, p.178; Macones, et al, 2008)

Terminology should be defined in each institution’s policies (AWHONN, 2009)

“AWHONN and ACOG support use of 2008 NICHD guidelines for EFM definitions, interpretation, and research” (AHWONN, 2009, p. 182)

Questions

ReferencesAmerican College of Obstetricians and Gynecologists. (2009b).

Intrapartum fetal heart rate monitoring: Nomenclature, interpretation, and general management principles (Practice Bulletin 106). Washington, DC: Author.

Association of Women’s Health, Obstetrical and Neonatal Nursing. (2010). Intermediate Fetal Monitoring Course. (5th Edition). Washington, DC: Author.

Association of Women’s Health, Obstetrical and Neonatal Nursing. (2009). Fetal Heart Monitoring Principles and Practice. (4th Edition). Washington, DC: Author.

References (con’t)Macones, G.A., Hankins, G. D., Spong, C.Y., Hauth, J.D., &

Moore, T. (2008). The 2008 National Institute of Child Health and Development workshop report on electronic fetal monitoring: Update on definitions, interpretations, and research guidelines. Obstetrics and Gynecology, 112, 661-666; and Journal of Obstetric, Gynecologic and Neonatal Nursing, 37, 510-515.

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