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37 Cards in this Set
- Front
- Back
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Baseline Variability
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- Fluctuation in the baseline FHR of two cycles per minute or greater.
- Represents the interplay and balance between the sympathetic and parasympathetic divisions of the autonomic nervous system |
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What is the single most important characteristic of the FHR?
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Baseline variability!!
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Baseline variability continued...
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- HR has to go up 2 bpm or more during that minute that it's being taken.
- Tells of baby has an intact CNSthat is well oxygenated - Tells that fetus doesn't have acidosis. If variability, acidosis can be ruled out - Can be determined from an electronic fetal monitor, not a fetascope or a hand held doppler - baseline increases with SNS stimulation - baseline decreases with PaSN stimulation |
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Classifications of Variability
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* Absent: undetectable bpm
* Minimal: < 5 bpm * Moderate: 6-25 bpm * Marked: > 25 bpm |
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Amplitude range of absent variability
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undetectable
- not good b/c acidosis cannot be ruled out - non-reassuring |
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Amplitude range of minimal variability
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less than/equal to 5 bpm
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Amplitude range of moderate variability
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6-25 bpm
- this is what you want to see |
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Amplitude range of marked variability
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greater than 25 bpm
- not really anything wrong with marked variability b/c it's never been linked to fetal decompensation |
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What are the greatest causes of decreased variability?
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Hypoxia and acidosis
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Causes of decreased variability
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* Causes include but are not limited to:
- Hypoxemia & Acidosis - Drugs - Fetal Sleep cycles - Congenital Anomalies |
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Definition of sinusoidal Baseline
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- Characterized by a smooth, sine-wave-like pattern of regular frequency and amplitude
- This is not baseline variability - If this is seen, need to think fetal anemia and fetal acidosis (metabolic) |
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Causes of sinusoidal baseline
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fetal anemia and fetal metabolic acidosis
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Events associated with sinusoidal baseline
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- Rh isoimmunization
- severe fetal anemia - Abruption - Severe fetal acidosis - Fetal/maternal hemorhage - If seen, emergency c-section! |
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Definition of accelerations
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* Abrupt increase (defined as onset of acceleration to peak in < 30 seconds) in FHR above the baseline
- Peak (acme) is >/= to 15 bpm above the baseline and lasts >/= to 15 seconds and < 2 min from onset to return to baseline - If < 32 weeks: peak (acme) >/= to 10 beats/min above baseline with duration of ./= 10 seconds - very encouraging to see in a fetus! |
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Definition of Prolonged acceleration
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> 2 min and < 10 minutes
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Are accelerations reassuring to see in a fetus?
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Yes!
- Sign of fetal well being - May be associated with fetal movement |
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Definition of early decelerations
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- gradual decrease (onset of deceleration to nadir (trough) >/= 30 seconds) and return to baseline FHR associated with a uterine contraction.
- Nadir of the deceleration occurs at the same time as the contraction peak |
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Early Deceleration - physiology
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- Reflex vagal response to head compression
- No pathology - Not associated with oxygenation or acid/base balance - No concern about the fetus not receiving enough oxygenation |
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Is there a concern about the fetus receiving enough oxygenation during early deceleration?
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No.
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When are early decelerations usually seen?
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- Often seen during the active state of the first stage of labor.
- Around 4-8 cm |
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Definition of late decelerations
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- Gradual decrease (onset of deceleration to nadir >/= 30 seconds) and return to baseline associated with a uterine contraction
- Nadir of deceleration occurs after the peak of the contraction - nonreassuring |
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Late Deceleration - physiology
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- Diminished uterine blood flow with UC
- Critical reduction of pO2 following peack of UC - Hypoxic slowing of heart rate - Uteroplacental insufficiency (UPI) aka diminished uterine blood flow |
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What state is the fetus in during late decelerations?
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Hypoxic!
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Definition of variable decelerations
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- Abrupt decrease (onset of deceleration to beginning of nadir < 30 seconds) in FHR of >/= 15 bpm and lasting >/= 15 seconds and < 2 min from onset to return to baseline.
- abruppt and takes less than 30 seconds to get down to the nadir - Look V or W shaped |
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Variable deceleration - physiology
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* Umbilical cord compression
* Stimulation of baroreceptors - response originates in carotid bodies and aortic arch - Transmitted to the midbrain and then to parasympathetic NS - Decrease in FHR |
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Variable deceleration - etiology
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- Short umbilical cord
- Nuchal cord - Body entanglement - Prolapse cord - Second stage of labor - Decreased amniotic fluid - Knot in cord |
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Definition of Prolonged Deceleration
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- Decrease in FHR from baseline of >/= 15 bpm, lastine ./= 2 min, but < 10 min from onset to return to baseline.
- If FHR cannot be brought back up, there is need for an emergency C-section |
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Prolonged deceleration - etiology
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- maternal hypotension
- cord prolapse - rapid cervical change - sudden fetal descent - uterine hypertonus |
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Uterine hypertonus
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- uterus doesn't go down
- too much pitocin can cause this. - baby can't "catch" its breath - a big legal issue |
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What is a reassuring EFM?
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- Baseline rate of 110-160 bpm
- Accelerations - Minimal or greater baseline variability |
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If the EFM shows accelerations with abnormal rate or presence of variable or late decelerations, what information is reassuring
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- Minimal or greater baseline variability!
- must have this for there to be any kind of reassurance |
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Tx of Non-reassuring EFM: Late and variable decelerations with absent baseline variablity
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- lateral position
- O2 10L face mask (ALWAYS!) - 500 cc IVF bolus - DC oxytocin - Fetal scalp stimulation - notify MD/DNM |
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Tx of Non-reassuring EFM: Prolonged decelerations
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- ID the cause
- Notify MD/CNM |
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Tx of Non-reassuring EFM: Prolonged deceleration caused by maternal hypotension
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- Assess BP q 2-3 minutes
- IVF bolus - Lateral, recumbent position - Oxygen 10L face mask - Notify anesthesia - Notify MD/CNM (delivery) - Prep for delivery |
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Tx of Non-reassuring EFM: Prolonged deceleration - cord prolapse, sudden fetal descent, rapid cervical change
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- cervical exam
- Notify anesthesia - Notify MD/CNM (delivery) - Prep for delivery - Mask O2 |
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Tx of Non-reassuring EFM: Prolonged deceleration caused by uterine hypertonus
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- Assess uterine tone
- Decrease and/or DC oxytocin -Terbutaline .25 mg IV to bedside - Prepare for delivery - Oxygen 10L face mask |
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What are actions you should always take when there is a non-reassuring EFM?
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- Notify MD/CNM
- make a diagnosis - Evaluate uterine activity (does oxytocin need to be DCed?) - Reposition the mother - Will O2 help? |
