fetal heart rate monitoring: terminology update sharon fickley, bsn, rnc-ob laura hall, adn, rnc-ob...
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Fetal Heart Rate Monitoring: Terminology
Update
Sharon Fickley, BSN, RNC-OBLaura Hall, ADN, RNC-OB
January 24th, 2011
Objectives
1. 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
(Macones, et al, 2008)
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
(Macones, et al, 2008)
Periodic/Episodic Changes - Decelerations
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
(Macones, et al, 2008)
Periodic/Episodic Changes - Decelerations
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
(Macones, et al, 2008)
Periodic/Episodic Changes - Decelerations
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
(Macones, et al, 2008)
Uterine Activity
Normal 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)
Terminology
Reactive 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 Overview
Category 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
References
American 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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