5.2c Fetal Heart Rate Patterns Flashcards
Baseline FHR
- Increases in sympathetic response also increases FHR
- Increases in parasympathetic response slows FHR
- Baseline is average FHR during a 10 minute segment
EXCLUDES - Periodic/episodic changes
- Periods of marked variability
- Segments of baseline that differ more than 25 bpm
- Normal FHR is 110-160 bpm
Variability
- Irregular/fluctuations from baseline
- Does not include accelerations or decelerations
Absent Variability
- Fluctuation not detectable by unaided eye
Minimal Variability
- Less than 5 bpm variation Caused by - Fetal hypoxia - Metabolic acidemia - Fetal sleep cycles - Fetal tachycardia - Extreme pre-maturity - Medications causing CNS depression - Congenital anomalies - Preexisting neurologic injury
Moderate Variability
- 6-25 bpm
- Predicts normal acid-base balance
FHR is not affected by - Fetal sleep cycles
- Tachycardia
- Prematurity
- Congenital anomalies
- Preexisting neurological issues
- CNS Depression medications
Marked Variability
- > 25 bpm
- Likely normal
Sinusoidal Pattern
- Regular, smooth, undulating wavelike pattern
- Uncommon and associated with severe fetal anemia
Variations are associated with
- Chorioamnionitis (bacteria infected amniotic fluid, chorion and amnion)
- Fetal sepsis
- Administration of opioid analgesics
Tachycardia
- FHR greater than 160 for 10+ minutes
- Early sign of fetal hypoxemia (especially with late decelerations or minimal variability)
Bradycardia
- FHR lower than 110 for 10+ minutes
- Rare and not specifically related to fetal oxygenation
CAUSES - Fetal cardiac problem
- Viral infection (cytomegalovirus)
- Maternal hypoglycemia
- Maternal hypothermia
Usually not caused by medication
Tachycardia
- Is abnormal when associated with late decelerations, severe variable decelerations, or absent variability.
Periodic/Episodic Changes in FHR
Periodic - Occur with contractions
Episodic - Not associated with contractions (accelerations/decelerations)
Accelerations
- Abrupt (less than 30 seconds) increase in FHR above baseline (at least 15bpm)
- Lasts 15+ seconds
- Returns to baseline within 2 minutes of beginning of acceleration
- Acceleration lasting 10+ minutes is considered baseline change
- Can be caused by fetal movement, transient compression of umbilical vein
- Indication of fetal well being
Early Deceleration
- Matches with Uterine Contraction
- Caused by transient fetal head compression (normal and benign)
- Usually occurs during 1st stage of labor (4-7cm dilation)
- Sometimes seen in 2nd stage during pushing
Late Decelerations
- Begins after contraction started.
- Caused by hypoxemia during uterine contractions
- Caused by maternal hypotension and uterine hypertonia
- Can cause metabolic acidemia and hypoxic myocardial depression
Variable Decelerations
- Abrupt decrease in FHR below baseline
- At least 15 bpm below and lasting at least 15 seconds
- Returns to baseline in less than 2 minutes of onset
- Caused by compression of vessels in umbilical cord
- U,V,W shape
- If recurrent, it can mean hypoxia, hypoxemia, metabolic acidosis, metabolic acidemia
Prolonged Deceleration
- Deceleration of at least 15 bpm longer than 2 minutes but less than 10 minutes
Causes - Maternal lung apnea during eclamptic seizure
- Umbilical cord compression, stretch, prolapse
Fetal scalp stimulation, vibroacoustic stimulation
Methods of assessment that use digital sound or light stimulation to determine the reaction of the FHR
Tocolysis
Relation of the uterus that can be achieved through administration of drugs that inhibit uterine contraction
Brethine
The most commonly used is tocolytic
Umbilical cord acid–base determination
Assessment method used immediately after birth as an adjunct to the Apgar score; it measures pH, pO2, pCO2, and base deficit or excess of the newborns’ blood
Intrauterine resuscitation: supplemental oxygen, maternal position change, and an increase in IV fluid rate
Group of interventions initiate when an abnormal (nonreassuring) FHT patters is noted to improve uteroplacental perfusion and increase maternal oxygenation and cardiac output
Prolonged Late Deceleration
1 - Discontinue oxytocin
2 - Assist into left lateral position
3 - Administer 10 L/min oxygen through non-rebreather face mask
4 - Elevate legs (correct hypotension)
5 - Increase maintenance IV fluid rate
6 - Palpate uterus for tachysystole
7 - Notify physician
8 - Consider internal monitoring for more accurate reading
9 - Assist with birth if pattern cannot be corected
Variable Deceleration
1 - Discontinue oxytocin
2 - Change position (side to side, knee to chest)
3 - Administer oxygen 10 L/min non-rebreather mask
4 - Notify physician
5 - Assist in examination for cord prolapse
6 - Assist amnioinfusion if ordered
7 - Assist with birth if pattern cannot be corrected
Nursing Management of EFM
- Evaluation of equipment and accuracy
- Evaluate FHR tracing every 30 min during active phase of 1st stage of labor
- Evaluate FHR tracing every 15 min during second stage of labor for low risk patients
- Every 15 minutes for high risk patients during active phase of 1st stage of labor
- Every 5 minutes in second stage of labor for high risk
Basic Interventions for Abnormal FHR
- Administer 10 L/min O2 for 15-30 min
- Assist woman into left lateral position
- Increase IV infusion rate (increasing maternal blood volume)
Maternal Hypotension Interventions
- Increase IV infusion rate
- Change to Lateral or Trendelenburg positioning
- Administer ephedrine or phenylephrine if other measures unsuccessful
Uterine Tachysystole Interventions (Excessive frequent Uterine Contractions)
- Abnormal FHR Pattern during Second Stage of Labor
- Reduce/discontinue stimulants such as oxytocin
- Tocolytic such as Terbutaline (Uterine relaxant)
- Use open-glottis pushing
- Fewer pushing efforts during each contraction
- Individual pushing efforts should be shorter
- Push only every other contraction
- Women with anesthesia should only push when they have the urge
Categories of FHR
Category 1 - Normal
Category 2 - In between 1 and 2
Category 3 - Abnormal (immediate evaluation needed)
Components of FHR Tracing
The below need to be evaluated regularly
- Baseline Rate
- Baseline Variability
- Accelerations
- Decelerations
- Changes or Trends over time
Any abnormalities in the above need to be corrected immediately for fetal oxygenation
Intrauterine Resuscitation
- Interventions when abnormal FHR pattern is noted These include - Providing Supplemental O2 - Maternal position change - Increasing IV fluid rate
Others can include
- Correcting hypotension
- Reducing uterine activity
- Altering pushing techniques
Variable Deceleration
- Visually abrupt FHR decrease any time during contraction in response to umbilical cord compression
Variability
- Expected irregular fluctuation in the baseline FHR of 2 cycles per minute or greater as a result of the interaction of sympathetic and parasympathetic nervous system.
Acceleration
- Abrupt increase in FHR at least 15 BPM lasting 15 seconds or more with return to baseline within 2 minutes
Late deceleration
- Gradual FHR decrease after start of uterine contraction in response to uteroplacental insufficiency. Lowest point occurs after peak contraction and baseline not regained until the uterine contraction is over
Episodic Change
- Changes in FHR from baseline not associated with contractions
Tachycardia
- FHR greater than 160 for over 10 minutes
Early Deceleration
- Gradual FHR decrease starting with onset of contraction in response to fetal head compression
Baseline FHR
- Range 110-160
- 10 minute segment that excludes periodic or episodic changes and periods of marked variability
Prolonged Deceleration
- Abrupt/Gradual decrease in FHR 15bpm+ that lasts 2-10 minutes
Bradycardia
- Baseline under 110bpm over 10 min
Periodic Changes
- Changes in FHR baseline that occur with uterine contractions
Fetal Scalp Stimulation/Vibroacoustic Stimulation
- FHR acceleration in response to digital/vibroacoustic stimulation
- Predictive of normal scalp blood pH (absence of acidemia)
- Desired result of accelerated FHR 15 bpm+ for 15+ seconds
- Further evaluation needed if acceleration not noted
- Do not use during decelerations or bradycardia
Umbilical Cord Acid-Base Determination
- Used with APGAR score
- Sample of cord blood
- Tested for pH, CO2, O2, base deficit/excess
Artery sample measures fetal condition
Vein sample measures placental function
Fetal Scalp Blood Sampling
- Blood sample of fetal scalp through dilated cervix
Amnioinfusion
- Infusion of isotonic fluid into uterine cavity due to low amniotic fluid volume
- Relieves intermittent umbilical cord compression
Tocolytic Therapy
- Tocolysis (relaxation of uterus)
- Medication to inhibit contractions
- Terbutaline (Brethine)
- Administered for patients who have excessive contractions
- Can also be administered for c-sections
