Evaluating of fetal heart tracing

Fetal heart tracing

Baseline heart rate is the mean FHR during a 10-minute segment of time,excluding periodic changes. Changes in fetal heart rate and normal periodic changes of FHR are related to the following:• Uterine hyperstimulation (commonly caused by

medications)• Fetal head compression• Umbilical cord compression• Placental insufficiency

Normal baseline FHR = 110–160 beats/minute.• Tachycardia (> 160 beats/minute) is most

commonly related to medications (β-agonist: terbutaline, ritodrine).• Bradycardia (< 110 beats/minute) is most

commonly related to medications β-blockers or local anesthetics).

Periodic change in heart rate include:

1. Accelerations: Abrupt increases in FHR lasting < 2 minutes that are unrelated to contractions. They always occur in response to fetal movements and are always reassuring.

2. Early decceleration

3. Late decceleration

4. Variability: Beat-to-beat fetal heart rate normally has variability. Normal variability is 6–25 beats/minute. Absence of variability is a nonreassuring pattern.

2. Early decelerations:Gradual decreases in FHR beginning and ending simultaneously with contractions. They occur in response to fetal head compression.

3. Late decceleration:are gradual decreases in FHR and delayed in relationto contractions. These are related to uteroplacental insufficiency. All late decelerations are nonreassuring and indicate fetal acidosis.

3. Variable decelerations: • Abrupt decreases in FHR that are unrelated to contractions.• These are related to umbilical cord compression. Severe

variables are nonreassuring and indicate fetal acidosis.

A 31-year-old primigravida at term is in the maternity unit in active labor. She is 6 cm dilated, 100 percent effaced 0 station, with the fetus in cephalad position. IV oxytocin is being administered because of arrest of cervical dilation at 6 cm. Fetal membranes are intact. The nurse informs you that the external fetal monitor tracing now shows the fetal heart rate baseline at 175/minute with minimal variability and repetitive late decelerations. There is no vaginal bleeding. What is the mostappropriate next step in management?

a. Change maternal positionb. Discontinue oxytocinc. Immediate cesarean sectiond. Perform obstetric ultrasounde. Obtain fetal scalp pH

• Answer: B. Medications are a common cause of baseline fetal tachycardia or bradycardia.• For management of nonreassuring fetal tracing, follow

the following stepwise approach.

Stepwise Approach to Nonreassuring Fetal Tracings

1. Examine the electronic fetal monitoring (EFM) strip: Look for nonreassuring patterns.

2. Identify nonhypoxic causes that can explain the abnormal findings. (Most common are medications, particularly β-agonists or β-blockers.)

3. Begin intrauterine resuscitation as follows:a. Discontinue medications (e.g., oxytocin)b. Give IV normal saline bolusc. Provide high-flow oxygen

d. Change patient’s position (left lateral)e. Vaginal exam to rule out prolapsed cordf. Perform scalp stimulation to observe for accelerations (reassuring)4. Prepare for delivery if the EFM tracing does not normalize.5. If the EFM is unequivocal, obtain fetal scalp pH (requires dilated cervix and ruptured membranes). Normal fetal pH > 7.20.

Answer : B -fetal head compression