Presented by:

Carol Burke MSN, APRN/CNS, RNC-OB, C-EFM

Loyola University Perinatal Center

April 9, 2018

Fourth Annual Northern Illinois Perinatal, Neonatal and Pediatric Conference

Uterine Activity as a

Critical Element of EFM

Disclosures / conflict of interest

Disclosures MOD Nursing Advisory Committee AWHONN Nominating Committee and the science team for the Care of the Perioperative Patient

No financial conflict of interest No FDA “off label” pharmaceutical antibiotic treatment will be discussed Best evidence to date presented

Discuss impact of uterine activity with fetal oxygenation.

Define significance of frequency, duration intensity and

resting interval when evaluating normal and abnormal

uterine activity.

Outline documentation recommendations for uterine

activity.

With either direct or indirect monitoring the suspicion of

fetal death,

apparent fetal bradycardia, or

apparent fetal arrhythmia

Fetal monitoring technology cannot detect a difference

between a fetal and maternal signal source

requires simultaneous maternal and

fetal heart rate and/or ECG recordings.

In the absence of the fetal ECG signal (IUFD), there will usually be

no tracing. However, depending the existing maternal R wave, the

maternal heart rate may be displayed vs. from the dead or dying

fetus

A woman with a cardiac pacemaker: The transmitted maternal

pacemaker pulse may be at a higher voltage than the fetal R wave

causing the scalp electrode to record the pacemaker signal

Should palpate maternal radial pulse or apply pulse oximetry for a

minimum of 1 minute while listening to the device sounds upon

initial placement and whenever artifact is suspected.

Maternal heart rate is usually significantly lower than the mean baseline FHR throughout all stages of labor and delivery and rarely exceeds 110 beats per minute between contractions.

Maternal heart rate may be increased with chorioamnionitis, pain, anxiety, result of medications

Most ‘maternal variability’ values fall within the moderate range for FHR variability (6–25 beats per minute), and thus this difference may not be large enough to be discriminatory.

The maternal heart rate usually accelerates with uterine contractions and bearing-down efforts in stage 2.

Very similar to FHR accelerations during the latent phase of the first stage but, as labor progresses, maternal ‘accelerations’ become more frequent, have higher amplitudes, and longer duration.

Maternal cardiac output increases progressively during labor due to:

Increased venous return to the heart leading to stroke volume

Increased heart rate

Increase in catecholamine

Valsalva with pushing.

Frequency is evaluated over a minimum of 10 min

Tachysystole: > 5 spontaneous and/or stimulated uterine contractions in 10 minutes, averaged over a 30 minute window.

• Applies to spontaneous and stimulated uterine contractions.

• Even if the FHR is normal, action must be done with tachysystole

Normal : < 5 contractions in 10 minutes, averaged over a

30 minute window.

Some experts do not consider excessive uterine activity problematic unless there are corresponding changes in the fetal heart rate (FHR) pattern.

When contractions are occurring every 2 minutes or more, recovery of FSpO2 to previous baseline levels is incomplete (Clark et. al,2013)

Pit to

distress...

UC 5/10 minutes: a negative 20% change in fetal oxygen saturation from 52-42% UC 6/10 minutes: a negative 29% change in fetal oxygenation from 52-37%

< 5 UC in 10 min

5 but <6 UC in 10 min

>6 UC in 10 min

Over 30 minutes

Simpson, AJOG, 2008

Oxygen saturation as measured by Fetal pulse oximetry in 56 healthy nulliparous women undergoing oxytocin induction

Tachysystole Management (with induction or augmentation)

Category of EFM

Cat 1

FHR remains

Cat 1 Decrease

oxytocin by ½

current rate

L or R lateral position and

give bolus 500mL LR

(unless restricted)

UA

normal

?

Cat 2 or 3

Discontinue

or Decrease

Pitocin

L or R lateral position and

give bolus 500mL LR

(unless restricted)

Continue

oxytocin

Y N

AWHONN, 2013 ACOG Practice Bulletin 116, 2010

O2 10L non-rebreather face mask

Have terbutaline

0.25mg readily available

Intrauterine resuscitation measures

tachysystole FHR changes Operative delivery or

interventions

dose-response correlation

Increases the chance of neonatal morbidity

Any oxytocin doubles likelihood of

Resolution of oxytocin-induced tachysystole

Intervention

Time to resolution

Oxytocin discontinuation

alone

14.2 minutes

Oxytocin discontinuation + IV fluid bolus of at

least 500mL LR

9.8 minutes

Oxytocin discontinuation + IV fluid bolus of at least 500mL LR + Change to lateral

position

6.1 minutes

Simpson & James, 2008

If oxytocin has been discontinued for < 30 minutes, and the FHR is normal and tachysystole resolved

• Resume oxytocin at no more than half the rate that caused the tachysystole

• Gradually increase as appropriate

based on unit protocol and maternal-fetal status

Resume oxytocin at the initial dose ordered.

If oxytocin has been discontinued for > 30 minutes, and the FHR is normal and tachysystole resolved

AWHONN, 2013

(Clark et al, 2013)

Due to an increase in the frequency and intensity, Uterine contractions are key to fetal acid-base outcome

Latent phase

• Minimal effect on base deficit

Active phase

• Mean base deficit increases by approximately 1mmol/L every 3 hours

Second stage

• Mean base deficit increases by 1mmol/L every hour

Tachysystole has a great effect on fetal-placental oxygenation

Metabolic acidemia usually does not appear suddenly, but can evolve gradually over a period of approximately 60 minutes.

Applies only to FHR tracings that are normal initially and subsequently develop minimal to absent variability with recurrent decelerations and no acute events.

(Clark et al, 2013)

The time in minutes and/or seconds, between contractions

Measured from the offset of 1 uterine contraction to the onset of the next uterine contraction

First stage: average normal interval = 60 seconds

Second stage: average normal interval = 45 seconds

Last hour of first stage of labor

Second stage

51 seconds pH < 7.11 63 seconds pH > 7.12

36 seconds pH < 7.11

47 seconds pH > 7.12

The more time between contractions, the more time there is to maximally perfuse the placenta and deliver oxygen to the fetus

1. True

2. False

Stopping pushing temporarily or pushing with every other or every third contraction based on the fetal response can be effective at allowing the fetus to recover and maintain adequate reserves

You do not necessarily have to wait for the full 30 minutes to declare tachysystole. If the pattern is trending towards tachysystole, initial actions such as a change in position may avert this issue.

Tachysystole refers to both spontaneous and induced labor

Tachysystole, inadequate relaxation time and/or hypertonus can result in a progressive adverse effect on fetal oxygenation (ACOG & AAP, 2014).

Shortened relaxation time leads to excess constriction of the spiral arterioles reducing placental blood flow.

Measured from the baseline resting tone (AKA) High Frequency Low

amplitude

Duration < 40 seconds

NORMAL

Duration ranges from 40-90 sec. generally not exceeding 90 seconds

Uterine irritability

Abruption, infection, dehydration, stress, preeclampsia, preterm labor

Relate to underlying physiology. Narcotic administration may cause a short duration (< 20 minutes) of undulatory heart rate pattern followed by &/or preceded by a normal FHR pattern.

Transient, short duration, resolve spontaneously (usually within 20-30 min) and usually preceded and followed by a normal FHR

Following maternal administration of some opioids (e.g. butorphanol and fentanyl)

Measured from the baseline resting tone

A contraction that plateaus and does not return to normal baseline for 2 normal contraction cycles or 5 minutes

Also defined as a uterine contraction lasting >180 seconds

NORMAL

Duration ranges from 40-90 sec. generally not exceeding 90 seconds

TETANY

Normal duration 40-90 seconds

Irritability (AKA: High Frequency/Low Intensity) Uterine activity with a duration of < 40 seconds

Consider abruption before giving terbutaline

May be a precursor to labor or preterm labor or an indication of infection

Irritability is usually not associated with decreased placental oxygenation unless abruption has / is occurring

Uterine tetany – may be caused by prostaglandins, oxytocin or be spontaneous

A normal fetoplacental unit may have its uteroplacental reserve exceeded with tetanic contractions.

Intensity

Palpation: strength of the UC (mild, moderate, strong) or

IUPC: in mmHg (peak minus resting tone)

Tone

The intrauterine pressure when the uterus is not contracting

Average resting tone during labor is 10mmHg

Document as “relaxed” (meaning easily indented using palpation) or “not relaxed” (remaining firm)

Hypertonus

A resting tone exceeding 20-25 mm Hg with IUPC, or

A uterus that palpates as “not relaxed” between UC.

Associated with oxytocin, prostaglandin, CPD, and polyhydramnios or any IV bolus drug administration

Relaxed uterus

Free exchange of O2 and CO2

Strong uterine contraction

Decreased to absent placental perfusion

Amniotic fluid

pressure 10mmHg

O2

CO2

Acidemia

Amniotic fluid

pressure 60mmHg

The spiral arterioles provide oxygen delivery to the placenta and fetus. Uterine contractions produce intermittent diminution of blood flow to the intervillous space where oxygen exchange occurs.

When fetal oxygenation is sufficiently impaired to produce fetal metabolic acidosis from anaerobic glycolysis, direct myocardial depression occurs and the FHR pattern becomes indeterminate or abnormal.

Is the fetus acidemic?

Underlying cause?

In-utero resuscitation helped?

Labor progress?

Well communicated plan?

Category 1 (~15-20%)

Category 2

(~80%)

3 Category 3 (1%)

Baseline 130

Moderate variability

No late, variable or prolonged decelerations

Does not require the presence of accelerations

Includes all FHR tracings not categorized as Category 1 or 3.

Represent about 80% of those encountered in clinical care

Multiple basic science investigations and clinical trials have been published but this body of work has primarily served to raise more questions than it has answered.

Am J Obstet Gynecol. 2013 Aug;209(2):89-97.

Category II patterns identify fetuses that may potentially be in some degree of jeopardy but are either not acidemic, or have not yet developed a degree of hypoxia/acidemia that would result in neonatal encephalopathy.

Must also avoid unnecessary intervention, and encourage vaginal delivery in women whose FHR patterns suggest minimal risk of significant deterioration prior to delivery.

Clark, et. al Am J Obstet Gynecol. 2013 Aug;209(2):89-97.

Clark, et. al Am J Obstet Gynecol. 2013 Aug;209(2):89-97.

Absent baseline FHR variability AND any of the following:

Recurrent late decelerations

Recurrent variable decelerations

Bradycardia

Sinusoidal Pattern

Highly FALSE POSITIVE

But you cannot be certain; therefore

intrauterine resuscitation measure are warranted.

25% are acidemic

Reasonable management decisions simply cannot be based on the results of a test that is virtually always wrong.

The negative predictive value of intrapartum FHR monitoring is nearly 100%.

Trying to use intrapartum FHR monitoring to diagnose neurologic injury is a recipe for failure.

In contrast, relying on the presence of moderate variability or accelerations, or both, to confirm adequate fetal oxygenation allows the clinician to formulate and articulate a rational, evidence-based plan of management that reflects consensus in the literature.

(Clark et al, 2013)