Electronic Fetal Monitoring Flashcards
What 2 things will you look at on the fetal monitoring strip?
- fetal HEART RATE (baby)
2. UTERINE contractions (mom)
What are the 2 types of fetal monitors?
- EXTERNAL= little doppler transducers with stretchy straps.
- INTERNAL= fetal scalp electrode (FSE) placed on the baby’s scalp by going in through the mother’s cervix.
When do you use internal fetal heart monitors?
- if pt is very obese, or you can’t pick up the fetal heart beat using the external monitor.
What is a potential risk of placing an internal fetal monitor?
- infection
What is electronic fetal monitoring (EFM)?
- cardiotocography (aka cardiography + uterine contractions (tocodynamometer)
Is the top line or bottom line the fetal heart rate?
TOP LINE
What tells us the variability of the baby’s heart rate on the fetal heart strip?
- the “squiggliness” of the line, indicating sympathetic and parasympathetic nervous system activities working together.
- aka you want VARIABILITY
*** What is the normal range or fetal heart rate?
110-160 BPM
- less than 110= bradycardia.
- greater than 160=tachycardia.
Where is the contraction pattern on the fetal monitor strip?
- bottom line that looks like mountain peaks.
What are the units for contractions?
- MONTEVIDEO UNITS= calculated by subtracting the baseline uterine pressure from the peak contraction pressure for each contraction in a 10-min window and adding the pressures generated by each contraction.
Ex. 5 pressure changes of 52, 50, 47, 44, and 49 mm Hg are added together= 242 Montevideo units.
*greater than 200 indicates adequate contractions!
Why do we care if the contractions are high enough?
- to get her fully dilated so she can start to push.
Why do we use electronic fetal heart monitors?
- to determine if a fetus is well oxygenated. Hypoxia changes activity of the nervous system, which affects HR and will result in changes on EFM.
How is EFM described?
- baseline HR
- variability
- presence or absence of accelerations and decelerations.
- frequency of contractions.
What actually makes up the irregular horizontal line of the fetal heart rate monitor?
- it’s just a series of closely-spaced R to R waves in the fetal EKG.
How do you get the mean fetal HR?
- round to nearest 5 BPM during a 10 min segment.
** What are some causes of fetal BRADYcardia (less than 110 BPM)?
- maternal HYPOtension
- umbilical cord prolapse
- rapid fetal descent
- uterine tachysystole
- placental abruption
- uterine rupture
- myocardial conduction defect
** What are some causes of fetal TACHYcardia (greater than 160 BPM)?
- infection (chorioamnionitis)
- medications (terbutaline, cocaine)
- fetal anemia
- placental abruption
- maternal disorders (HYPERthyroidism)
- fetal tacharrhythmia
*** What is variability?
- the fluctuation in beat to beat rate (amplitude of peak-to-trough in BPM).
*** What is ABSENT variability?
- amplitude range undetectable
*** What is MINIMAL variability?
- amplitude range less than 5 BPM
** What is MODERATE variability? (TEST QUESTION)
- amplitude range 6-25 BPM
*** What is MARKED variability?
- amplitude rang greater than 25 BPM
Is variability sensitive to fetal acid-base status?
YES
What does MODERATE variability suggest?
adequate oxygenation :)
What could cause decreased variability?
- medications (opioids, magnesium sulfate)
- fetal sleep cycle (only 30-40 mins max).
- prematurity
- CNS or cardiac abnormalities
- fetal hypoxia
- fetal acidemia
*** What is an ACCELERATION?
- abrupt increase in fetal HR (FHR) with peak of greater than 15 beats above baseline. This is associated with fetal movement, a mature neurocardiac tract, and indicates that the fetus is not acidemic.
- duration of at least 15 sec, up to 2 min.
- aka this reassures fetal well-being
** What happens if an acceleration is greater than 2 min?
- this is a prolonged acceleration
* if over 10 min, it is a CHANGE IN BASELINE.
*** What is a DECELERATION?
- decrease in FHR from baseline:
- recurrent= occurs for more than 50% of contractions.
- intermittent= occurs with less than 50% of contractions.
** What are the 3 types of DECELERATIONS? (she said she wants us to know these)
- EARLY= associated with HEAD COMPRESSION.
- VARIABLE= associated with CORD COMPRESSION.
- LATE= associated with UTEROPLACENTAL INSUFFICIENCY; BAD.
* all about timing.
What type of deceleration is TIMED WITH THE CONTRACTIONS?
- EARLY (mirror image of the contraction; as the contraction goes up, the HR goes down).
What should you do in an EARLY deceleration?
- no treatment necessary, but check pt as head is probably descending.
*** What does a VARIABLE deceleration look like?
- ABRUPT decrease in FHR (goes down faster; less than 30 sec).
- decrease in FHR is greater than 15 BPM with a total duration greater than 15 sec.
- V configuration!
When do VARIABLE decelerations occur?
- can occur at ANY time; not necessarily associated with contraction.
What do we do for VARIABLE decelerations?
- ALLEVIATE CORD COMPRESSION by maternal repositioning, amnioinfusion, or check for prolapsed cord.
*** What are LATE decelerations?
- symmetrical gradual decrease in FHR.
- begins at or after peak of contraction and returns to baseline after contraction is over.
- associated with uteroplacental insufficiency from decreased uterine perfusion or decreased placental function.
** What do we do for LATE decelerations? (she wants us to know this)
- maternal repositioning (left or right lateral).
- maternal oxygen administration
- administer IV fluid bolus
- reduce contraction frequency (discontinue oxytocin (pitocin) or cervical ripening agents)
- administer TOCOLYTIC medication.
- goal is to IMPROVE UTEROPLACENTAL BLOOD FLOW
What is the ABCD approach?
- Assess oxygen pathway.
- Begin conservative corrective measures.
- Clear obstacles to rapid delivery.
- Determine decision-to-delivery time
** What are the 3 categories of strips and what do they mean?
- Category I= normal HR, moderate variability, no lates or variables, early decelerations don’t matter, accelerations may be present or absent, normal acid-base status (aka everything is GOOD).
- Category II= everything else.
- Category III= absent baseline FHR variability, late decelerations, recurrent variable decelerations, bradycardia, sinusoidal pattern, abnormal acid-base status (aka all the BAD stuff).
What do we do for category II management?
- continued monitoring and possibly intrauterine resuscitation (maternal repositioning, O2 administration, IVF, reduce contraction frequency, possible amnioinfusion).
What is normal uterine activity?
- less than 5 contractions in 10 min averaged over 30 min window.
What is tachysystole of uterine activity?
- greater than 5 contractions in 10 min averaged over a 30 min window.
