15. FHR Practicum # 2 Baseline rate: closest to 135 beats/min Baseline variability: Moderate (6-25 beats/min) Variable deceleration: Abrupt (<30 seconds) onset, meets 15 beats/min by 15 second minimum, lasts less than 2 minutes onset to offset
16. FHR Practicum # 3 Baseline: closest to 135 beats/min Baseline variability: Moderate (6-25 beats/min) Prolonged deceleration: Onset may be gradual or abrupt, key here is that the deceleration is 2 minutes or more onset to offset.
17. FHR Practicum # 4 Baseline: 180 beats/min Baseline variability: Absent (undetectable) Late decelerations: Gradual (30 seconds or more) onset, onset occurs after U/C begins, nadir occurs after peak of U/C, & return to baseline after U/C concludes
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Editor's Notes
Welcome class to part one of electronic fetal heart monitoring. My name is Debra Hastee. The purpose of this class is to discuss basic fetal heart tracing interpretation using the definitions determined by the National Institute for Child Health and Development (NICHD). ACOG and AWHONN have accepted this terminology as the standard of practice for healthcare professionals in Obstetrics and are to be used a common language.
The objectives for this class are : …..
The learners objectives by the end of this class you will be able to:….
What I will be covering in today’s class are the NICHD definitions for baseline FHR, variable, and late decelerations. We will also discuss a specific methodology for interpreting fetal heart tracings. We will exam four different fetal heart tracings using the appropriate methodology. You may work together in groups of three for the practicum. At the end of today’s presentation I have a 10 minute video on emergency response that shows the importance for using a common language for interpreting the fetal heart tracing when communicating with other healthcare professionals.
There is a specific methodology for interpreting the fetal heart tracing. You begin with determining the fetal heart baseline rate. Next determine if the variability is absent, minimal, moderate, or marked. You will then look at any variations or deviations in the baseline. You may have accelerations or decelerations that happen periodically or may be just episodic. When evaluating the fetal heart tracing, you want to look at any changes or trends that may be present over a period of time. We are also adding an evaluation of contraction to the overall evaluation of the tracing.
Let’s begin with the baseline fetal heart rate. When determining the baseline FHR, you are examining the average baseline rate and rounding the beats off by increments of 5. The average rate is determined over a period of 10 minutes and no less than 2 minutes. Any changes to the baseline such as accelerations and decelerations are excluded. The normal FHR baseline has a range of 110-160 beats per minute. A baseline of <110 is bradycardia and more than 160 beats per minute is tachycardia.
Next step in the evaluation of the fetal heart tracing is to look at the variability or fluctuations in the baseline that may be irregular in amplitude and frequency. Variability is the amplitude of the peak and trough of the beat to beat in the fetal heart. Variability is determined to be absent when there is no peak or trough noted. It is apparent as basically a flat line with no wavering. Minimal variability in determined as less than or equal to 5 beats per minute. Moderate variability is 6-25 beats per minute and marked is greater than 25 beats per minute. The variability is important in determining the well being of fetal oxygenation as we will discuss in future classes.
Accelerations or variable decelerations may have an abrupt of gradual onset. Abrupt is an onset that is less than 30 seconds to the nadir or peak of the acceleration or deceleration. Gradual is the opposite or an onset that takes more than 30 seconds to nadir or peak of the acceleration or deceleration.
Accelerations of the fetal heart in a fetus that is 32 weeks or greater gestation is an abrupt increase above the baseline that is equal to or greater than 15 beats per minute and with a duration of 15 seconds or more. These accelerations are less than 2 minutes in length. A fetus who is less than 32 weeks gestation and having accelerations, they will be abrupt as well but with a peak of 10 beats per minute lasting only 10 seconds and less than 2 minutes. Any acceleration that lasts longer than 2 minutes is a prolonged acceleration. The same hold true for decelerations, any decel lasting more than 2 minutes is described as prolonged.
Late decelerations have a more gradual decrease and return to the baseline and are most closely associated with contractions. The gradual onset of the late deceleration takes longer than 30 seconds to reach the nadir or peak of the deceleration and do not return to the baseline until after the end of the contraction. Timing of the deceleration is important in relation to the contraction so it is imperative that you have an adequate tracing of contractions. If not, some consideration may need to be given to placement of an intrauterine pressure catheter for more accurate account of the contractions on the tracing. Late decelerations are a more ominous sign of fetal hypoxia and so therefore accuracy in tracing both the fetal heart and the maternal contractions is important.
Variable decelerations are just as their name indicate. The vary in their onset, depth, and duration and may happen at any time. They are not evaluated in relation to the contractions due to their variability. They are abrupt in their onset and the depth of the deceleration is more than 15 beats per minute off the baseline lasting more that 15 seconds but less than 2 minutes. There may be other characteristics of the variables which require more attention but we will discuss those in a another class.
Prolonged decelerations may be gradual or abrupt in onset and are a decrease of 15 beats per minute or more from the baseline and have a duration of 2 minutes or more but no more than 10 minutes. Any deceleration or acceleration that lasts longer than 10 minutes is considered a change in the baseline.
We will now evaluate a few tracings using the standardized NICHD terminology that you will use in your documentation. You may take a few minutes to look at the tracing with your peers. We will then evaluate the tracings together with everyone’s input. Assume you have a ten minute window on each page of the strip.
Take a look at this tracing. I want you to determine your baseline first, variability, are there any deviations from the baseline for example accelerations, or decelerations and note timing of the contractions or how close are they. Who would like to evaluate this fetal heart tracing? Tell us the fetal heart baseline. The correct answer is 180. Next is the variability. Answer: minimal. Are there any accelerations or decelerations, No. Take a look at the contractions: they are every 1 ½ - 2 minutes apart. Now lets move on to the next tracing.
Next group please interpret this fetal heart tracing. Baseline is 135. Variability: moderate. Why? They are 6-25 beats per minute. Are there any variations in the fetal heart baseline? Yes, variable decelerations. Describe the variable decel: abrupt onset- less than 30 secs to the nadir, 15 beats and 15 secs off the baseline. Now tell me about the contractions. How close are they: 2 minutes apart, and mild.
Next group please evaluate this fetal heart tracing. Baseline fetal heart is 135. Variability is moderate and why? Because it is 6-25 beats per minute. Are there any periodic changes in the baseline? Prolonged deceleration. Why? Because has a gradual onset, more than 30 seconds to the nadir, and is 2 minutes in duration. Contractions- 2 minutes apart. Should we be worried about this tracing? Yes it does not appear that the deceleration is improving. You would need to communicate with physician using the common language and begin preparation for an emergency delivery by c-section.
Ok class, final group, will you please evaluate this tracing for the class. Baseline FH 180, variability- absent, are there any periodic changes? Yes- late decelerations and why? They are gradual onset more than 30 seconds to the nadir. The nadir occurs after the peak of the contraction and do not return to baseline until after the contraction has ended. Should we be concerned with this tracing? Yes. Why? Absent variability and late decelerations are indications of utero-placental insufficiency. You would want to place Oxygen on the mother at 8-10 liters per minute, change her position for optimal blood flow to the placenta, preferably place pt. on her left side assure IV access, turn pitocin off if any is running, be sure someone or yourself is notifying the physician and prepare for emergent delivery by c-section.
The video I would like to show you now is on Emergency response. The importance of the NICHD common language for healthcare professionals who are working in the labor and delivery setting is truly a matter of life and death for a fetus. Having personnel who are trained in fetal heart tracing interpretation can mean so much to preventing adverse outcomes for the newborn. Rapid response to abnormal fetal heart patterns that are indicative of fetal hypoxia is essential in preventing adverse outcomes. I had the pleasure of being trained in fetal heart rate monitoring and interpretation several years ago by Michael Fox, the presenter in this video. This video is the first of a four part series that you will see as we continue with our fetal monitoring classes.
Now what questions can I answer for you? Thank you for your attention in this our first class in a series of four. In the next classes we will be discussing the physiology behind the fetal heart patterns, fetal oxygenation, the nursing interventions to minimize any further insult to the fetus, and documentation in the medical record.
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