Chapman ch 9. FHR Assessment Flashcards
Three requirements for fetal heart rate interpretation
Baseline. Interpretation of episodic and periodic changes of fetal heart rate. Interpretation of uterine activity.
IUPC
Intrauterine pressure catheter.
Causes of decreased fetal oxygen supply
Reduction of blood flow through maternal vessels/hypertension, PIH
Reduction of oxygen via maternal blood such as the mom holding the breath, baby lying on vena cava.
Alterations in fetal circulation such as baby on cord, decreased blood flow to the placenta, hemorrhage, deterioration of the placenta
Reduction in blood flow to the placenta
Reassuring FHR Pattern
Baseline should be 120 - 160. Accelerations with fetal movement. Should have moderate variability.
Normal uterine activity in labor
Contractions every 2 to 5 minutes, lasting less than 90 seconds, intensity less than 80, relaxation 20 or less, the average pressure is 50 to 85
Fetal compromise
Associated with fetal hypoxemia. Can lead to fetal hypoxia.
Hypoxemia
Deficiency of oxygen
Hypoxia
In adequate oxygen
Causes a release of epinephrine and norepinephrine to increase fetal heart rate and blood pressure
Nonreassuring fetal heart rate patterns
Progressive increase or decrease in the baseline
Tachycardia/above 160
Decrease in variability
Severe variable deceleration’s equals less than 60, and lasting longer than 30 to 60 seconds
Late decelerations/not good with repetition or uncorrectable
Absence of variability/no movement
Prolonged deceleration/greater than 60 to 90 seconds
Severe bradycardia/less than 70
Intermittent auscultation
Done with an ultrasound fetoscope, stethoscope, it DeLee/Hills fetoscope
Leopold’s maneuvers
Know how to spell
Assesses fetal position to get the best PMI/point of maximum impulse
Procedure for auscultation
Leopold’s maneuver’s
Place listening device over PMI
Palpate abdomen between contractions
Count maternal pulse while listening to fetal heart rate
Count fetal heart rate for 30 to 60 seconds
Auscultate fetal heart rate during contraction and 30 seconds afterwards to see how baby is responding
Internal fetal monitoring
Membranes must be ruptured
Cervix sufficiently dilated about 2 cm
Presenting Part low enough to place electrodes
Fetal tachycardia
Baseline above 160 that lasts for at least 10 minutes
Moderate =161-180
Marked 180+
Early sign of fetal hypoxemia
If heart rate persists from 200 to 220 fetal death may occur
Causes on the fetal side could be infection, drugs, chronic hypoxemia, Stimulation, compensation for hypoxemia, cardiac abnormalities, anemia.
Causes from the maternal side could be a anemia, hyperthyroidism, dehydration, fever, ChorioAmnionitis (infection uterus), anxiety, medications, drugs
Bradycardia
Baseline below 110 that lasts at least 10 minutes
Less than 100 is a later sign of hypoxia
Occurs before fetal death
May be tolerated if it remains about 80 with variability
Moderate 110-119
Marked 100-
A decreased fetal heart rate leads to decreased cardiac output causes a decrease in umbilical bloodflow leads to decreased oxygen to the fetus causing hypoxia
Bradycardia with variability maybe benign. Bradycardia with a loss of variability or late decelerations is associated with impending hypoxia
Maternal supine hypotensive syndrome
Caused by uterine pressure on the vena cava, decreases bloodflow return to heart, reduces cardiac output and blood pressure, decreases fetal heart rate causing bradycardia.
Treat by turning the mom on the right side, and rise slowly.
Variability of fetal heart rate
One of the most reliable indicators of fetal health and oxygenation, confirms no metabolic acidosis. Shows irregular fluctuations in the baseline, short-term is Beat to beat. long-term is rhythmic waves or cycles from the baseline.
Four ranges of variability
Absent or undetected: the amplitude range is undetectable, looks like a flatline
Minimal: not more than five bpm
Moderate: 6-25 from peak to trough
Marked: greater than 25bpm
If absent, turn mom to right side, Adjust the straps, give ice chips, no longer than 30 minutes. Fetus could be asleep or premature.
Nervous system on fetal heart rate
Sympathetic increases it, responsible for long term variability, can be stimulated during hypoxemia.
Parasympathetic decreases it
Head compression stimulates the Vagus nerve causes a decrease.
Accelerations
An abrupt increase above baseline
It’s a good thing predictive of good O2.
15 bpm or greater, last 15 seconds or more
Returns to baseline within two minutes from start
Periodic or episodic
Periodic are caused by the sympathetic nervous system or usually a breech presentation
Episodic occur during fetal movement and indicate fetal well-being
Require no interventions.
Decelerations
Periodic changes that last from a few seconds to no longer than two minutes.
Caused by the parasympathetic and they are either benign or nonreassuring
Described by relation to onset and the end of contraction and shape
Early, late, or variable
Recurrent occur with at least 50% of the contractions over a 20 minute.
Intermittent are with less than 50% of the contractions over 20 minutes
Early decelerations
Gradual decrease and return to baseline during contraction. Caused by head compression. Normal and usually benign. Uniform shape that mirrors contraction. Usually during the first stage while 4 to 7 cm dilated and also during the second stage during pushing
NADIR is the lowest point of deceleration
No intervention is needed
Late decelerations
Sign on fetal intolerance to labor. Cause by uteroplacental insufficiency such as a smoker or cocaine user. Also caused if the placental cord is compressed. Gradual decrease and return to baseline usually after a contraction. Nadir is after peak of contraction. Returns after the contraction is over.
Indications of late decelerations
Presence of fetal hypoxemia/insufficient placental perfusion. Fetal hypoxemia progressing to hypoxia. Acidemia progressing to acidosis.
*** Ominous when uncorrectable, especially with variability and tachycardia. Turn the mom to the right, place 02 at 10 L, if no change probably go for a Csection
Causes of late deceleration
Oxytocin, pregnancy induced hypertension, postterm pregnancy, amnionitis/infection, small for gestational age from smoking, maternal diabetes, placenta previa, abruptio placenta, Anesthesia producing maternal hypotension in which she would need to get an IV bolus, maternal cardiac disease or anemia
Variable late deceleration
Visual abrupt decrease below baseline. Most common decelerations. More than 15 bpm. Lasts at least 15 seconds, but less than two minutes. Occurs any time during contraction. Usually caused by cord compression. U, V, W pattern. They have a sudden drop in a rapid return, sometimes returning over baseline (shoulder).
Change positions, oxygen, give IV fluids, amnioinfusion, decrease oxytocin
First stage of labor is a partial, brief compression of the cord.
Second stage of labor is cord compression during fetal descent
Prolonged decelerations
Decrease in the heart rate below baseline at least 15 bpm and lasting more than two minutes, but less than 10
Not associated with hypoxemia
Benign changes
Pelvic exam, spiral electrode, rapid fetal descent, sustained maternal Valsalva maneuver which is pushing.
Less benign causes we may need to worry about
Progressive severe variable deceleration. Sudden cord prolapse. Hypotension caused by spinal or epidural. Paracervical anesthesia. Tetanic contractions which are long. Maternal hypoxia during a seizure or from preeclampsia
Notify Dr. immediately of prolonged decelerations
Amnioinfusion
Put in with the IUPC. Saline or LR. Supplements the amount of amniotic fluid or dilutes meconium stained fluid. Reduces severity of variable Decels caused by cord compression. Reduces the risk for meconium aspiration syndrome.
Oligohydramnios -Low amniotic fluid
Risks include uterine over distention, increased uterine tone, uterine rupture. Not recommended for previous C-section mothers
Sinusoidal pattern
A deceleration. Having a visually apparent smooth sine-like wave like undulating pattern in fetal heart rate baseline with a cycle frequency of 3 to 5 minutes that last longer than 20 minutes.
Palpation of contractions
Measured at the fundus.
Mild 1+ easily dented
Moderate 2+ slightly indent
Strong 3+ no indent
Frequency of fetal heart rate assessment
INTERMITTENT
With no risk factors. Latent phase every one hour. Active phase every 5 to 15 minutes second stage every 5 to 15 minutes. Continuous monitoring if there are risk factors present
ELECTRONIC
No risk factors latent phase every hour, active phase every 30 minutes, second stage every 15 minutes. If there are risk factors latent phase every 30 minutes, active phase every 15 minutes, second stage every five minutes.
Transfer of oxygen and CO2 between fetal and maternal bloodstream depends on
Adequate uterine bloodflow. Sufficient placental area. Unconstructed umbilical cord
Adequate oxygenation to the fetus depends on
Adequate oxygenation of the mother. Adequate blood flow to the placenta. Adequate uteroplacental circulation. Adequate umbilical circulation. Fetuses ability to regulate the fetal heart rate.
Other factors that influence fetal oxygenation
Uteroplacental function. Uterine activity. Umbilical cord issues. Maternal physiological function.
Category one
Tracings are normal, looks well oxygenated, with normal acid-base balance.
Baseline normal, variability moderate, late or variable deceleration are absent, early decelerations absent or present. Accelerations absent or present
Category two
Indeterminate, not predictive, require evaluation and surveillance.
They can include bradycardia, tachycardia, minimal variability, absent variability, Marked variability, absence of induced accelerations after stimulation, prolonged decelerations, Recurrent decelerations, variable deceleration with a slow return to baseline.
Category three
Abnormal. Indicate an abnormal acid-base balance, requires prompt evaluation
Absent variability with recurrently decelerations, recurrent variable deceleration’s, or bradycardia
Or
Sinusoidal pattern
Interpretation of fetal heart rate baseline
Rate, variability, acceleration, tachycardia, bradycardia, short and long-term variability
Interpretation of periodic and episodic changes
Decelerations either early, variable, late, or prolonged
Interpretation of uterine activity
Frequency, duration, intensity, resting tone, relaxation time between contractions
Ominous patterns
Absent variability with tachycardia bradycardia under 80, recurrent late decelerations, recurrent variable deceleration’s increasing in depth and duration.
Minimal variability with tachycardia with late deceleration, bradycardia with late decelerations, recurrent late decelerations, recurrent variable deceleration’s increasing in depth and duration
Treatment for tachycardia
Give antibiotics or antipyretics. Ice packs with a fever, assess hydration, reduce anxiety, position change or oxygen, decrease or discontinue oxytocin.
Reasons for bradycardia
Maternal: supine position, dehydration, hypotension, rupture of uterus, placental abruption, anesthetic, maternal cardiopulmonary compromise
Fetal: response to hypoxia, umbilical cord occlusion, hypoxemia, hypothermia, fetal head compression, bradyarrhythmias
Treatment: confirm monitor is placed right, assess fetal movement, assess response to scalp stimulation, check for prolapsed cord, Change positions, discontinue oxytocin, oxygen, stop pushing,
Periodic and episodic changes
Periodic is in relation to contractions and persists over time. Includes accelerations and early, variable, late, and prolonged deceleration.
Episodic are accelerations and decelerations not associated with contractions.
Contractions
Frequency is The start of one contraction to the start of the next contraction
Duration is from the beginning to the end of a contraction is measured in seconds
Intensity is the strength of the contraction
Resting tone is the pressure between contractions.
Normal is five or fewer contractions a 10 minute.
Tachysystole is more than five in a 10 minute. It needs to be treated because it can result in decreased uteroplacental blood flow. Characteristics include contractions lasting two minutes or longer, contractions occurring within one minute of each other, increasing resting tone, increasing pressure greater than 80.
Hyperstimulation and tetanic
