1

A Proposal for Standardized Management of FHR Patterns

J T Parer, MD, PhDMaternal Fetal Medicine

Department of Obstetrics, Gynecology & Reprod Sci University of California San Francisco

Obstetrics & Gynecology Update: What does the Evidence Tell us?

San Francisco, California

October 18, 2007

Prior Approaches to Consensus

• FIGO Workshop on FHR Guidelines. Int J Gyn & Ob, 1987

• NICHD FHR Guidelines AJOG & JOGNN, 1997• RCOG Clin Effectiveness Support Unit. Use of

EFM. RCOG Press, 2001• SOGC Policy Statement on Fetal Health

Surveillance in Labour. JSOGC 1995• ACOG Practice Bull no 70. Intrapartum FHR

Monitoring, 2005

2

Quantitation of variable decelerationsChao, 1990

3

Three aspects of FHRM are inadequately studied

Paneth et al, 1993

• Reliability of pattern interpretation: Is there adequate intra- & inter-observer agreement?

• Validity: Are certain patterns reliably related to adverse outcomes, eg, newborn metabolic acidemia?

• Utility: Can timely obstetric intervention avoid adverse outcomes in cases with evolving patterns suggestive of acidemia?

CLINICAL OPINIONCLINICAL OPINIONCLINICAL OPINIONCLINICAL OPINIONElectronic fetal heart rate monitoring: Research guidelines for interpretationNational Institute of Child Health and Human Development Research Planning National Institute of Child Health and Human Development Research Planning National Institute of Child Health and Human Development Research Planning National Institute of Child Health and Human Development Research Planning WorkshopWorkshopWorkshopWorkshop

The purpose of the National Institutes of Health research planning workshops is to assess the research status of clinically important areas. This article reports on a workshop whose meetings were held between May 1995 and November 1996 in Bethesda, Maryland, and Chicago, Illinois. Its specific purpose was to develop standardized and unambiguous definitions for fetal heart rate tracings. The recommendations for interpreting fetal heart rate patterns are being published here and simultaneously by the Journal of Obstetric, Gynecologic, and Neonatal Nursing. (Am J Obstet Gynecol 1997;177:1385-90.)

Are there associations between FHR patterns and newborn acidemia?

Parer et al, 2006

• The presence of moderate FHR variability, even with decelerations, is 98% associated with absence of pH <7.15 or Apgar <7 @ 5’

• Minimal or less FHRV with decelerations has a 23% association with pH <7.15 or Apgar <7 @ 5’

• The liklihood of acidemia increases with depth of decelerations, especially with late decelerations, and with reduced FHRV

• Potentially hazardous acidemia develops over a period of 1 hr or more in a fetus whose pattern evolves from normal to decelerative with reduced FHRV

4

Interrelations between fetal pH, FHR variability, & depth of late decelerations

Paul et al, 1975

Ruptured Uterus ObservationsLeung et al, 1993

• Intact survival if the fetus is delivered in 18 min or less after the fetal bradycardia signaling the rupture

• If the bradycardia is preceded by decelerations, the required bradycardia to delivery time is shorter; the specific time is not yet established

What FHR Factors Contribute to Urgency of Delivery?

• Risk of acidemia• Probability of evolution of pattern to higher

risk- type of deceleration- depth of deceleration- reduction of FHR variability

5

XVI. NICHD Statement on FHR Monitoring (1997)

• Standardized definitions of FHR characteristics.• Consensus that the normal pattern predicts

absence of acidemia with high degree of reliability.

• Consensus that absent variability in the presence of decelerations or substantial bradycardia is evidence of actual or impending potentially damaging acidemia.

• No consensus on virtually all other patterns (~50%) which are variants of the normal pattern, due to absence of sufficient data in the literature.

XVI. NICHD Statement on FHR Monitoring (1997)

• Standardized definitions of FHR characteristics.• Consensus that the normal pattern predicts

absence of acidemia with high degree of reliability.

• Consensus that absent variability in the presence of decelerations or substantial bradycardia is evidence of actual or impending potentially damaging acidemia.

• No consensus on virtually all other patterns (~50%) which are variants of the normal pattern, due to absence of sufficient data in the literature.

6

XVI. NICHD Statement on FHR Monitoring (1997)

• Standardized definitions of FHR characteristics.• Consensus that the normal pattern predicts

absence of acidemia with high degree of reliability.

• Consensus that absent variability in the presence of decelerations or substantial bradycardia is evidence of actual or impending potentially damaging acidemia.

• No consensus on virtually all other patterns (~50%) which are variants of the normal pattern, due to absence of sufficient data in the literature.

“There are deep, late decelerations with considerable loss of beat-to-beat

variability, mandating prompt intervention” . 2001

Implications of these observations for FHR pattern management

• They are mostly based on observational studies (Grade III evidence), and are preliminary findings until a prospectively gathered series in unselected patients is available

• Such a series will correlate FHR patterns up until the time of birth, to cord acid-base state

• The findings support a management approach which assumes a risk of fetal acidemia based on depth of decelerations, reduction of FHRV, and a period of evolution of a worsening FHR pattern of approximately 1 hr

Threshold of Acceptable Acidemia in Umbilical Arterial Blood at Birth

• pH > 7.1

• Base excess >-12 meq/lit

Helwig et al, AJOG

7

General hierarchy of interventions

• MD/CNMs: Inform< request presence at bedside< request MD able to do C/S or OVD

• Insert IV• Conservative interventions• Inform anesthetist, pediatrician• OR availability• Labour in OR• Ancillary testing; stimulation testing, fetal blood

sampling

Five Gradations of Acidemia

• No acidemia• No central fetal acidemia (adequate oxygen)• No central fetal acidemia, but FHR pattern

suggests intermittent reductions in O2 which may result in fetal O2 debt

• Fetus potentially on verge of decompensation• Evidence of actual or impending damaging fetal

asphyxia

8

Risk of Acidemia, Evolution of Patterns To More Serious, and Recommended

Action

Risk of Acidemia Risk of Evolution Action

Green

0 Very low None

Blue

0 Low CT & begin preparation

Yellow

0 Moderate CT & increased surveillance

Orange Borderline/

acceptably low High CT & prep for urgent

delivery

Red

Unacceptably high Not a consideration

Deliver

* CT = Conservative ameliorating techniques

Conservative Techniques to Ameliorate FHR Patterns

• Position change• Hyperoxia• Correct hypotension• Adequate intravascular volume• Correct excessive contractions (oxytocin?)• Avoid constant pushing• Tocolysis• Amnioinfusion to correct amniotic fluid deficit

9

Proposed Management of the Colour Coded Categories

Conservative Techniques Op Room Obstetrician Anesthetist

Newborn Resuscitator

Patient Location

Green

No - - - - -

Blue

Yes available informed - - -

Yellow

Yes available at bedside informed informed -

Orange

Yes immediately available

at bedside present immediately available

OR

Red

Yes open at bedside present present OR

10

A Proposal for Standardized Management of FHR Patterns

J T Parer, MD, PhDMaternal Fetal Medicine

Department of Obstetrics, Gynecology & Reprod Sci University of California San Francisco

Seventh Annual University of Illinois at Chicago Wilson Perinatal Conference

Chicago, Illinois

October 19, 2007