of 3-5 mins, persist about 20 mins . Acels don't occur spontaneously There is minimal variability. • A FHR baseline pattern consisting of a series of cycles that are extremely smooth & regular in amplitude & duration • Resembles a perfect letter “S” on its side
• May be benign • Causes: o Fetal anemia o Chronic fetal bleeding o Fetal isoimmunization o Twin-to-twin transfusion o Umbilical cord occlusion o CNS malformations Base line variability- is a very good indicator how the baby is doing. " push and pull" from SNS & PNS affect FHR, defined as fluctuations in the baseline FHR, that are irregular in amplitude and frequency o Absent FHR- range can't be detected o Minimal FHR- ranges from detectable beats of 5 bpm or less o Moderate FHR- 6-25 bpm o Marked FHR- amplitude range greater than 25 bpm Epidsotic changes occur when there is no UC look more peaked and abrupt in acels. Periodic changes occur with UC's, if they happen with more than 50% or more of UC's in 20 mins it's characterized as recurrent change or pattern look more smooth, multiphasic and may precede variable decels Accelerations: associated with stimulation of the SNS, if it increases with CNS is a good sign beta blockers and CNS depressants, hypoxia is also associated with a lack of acels and may be the 1st sign of non reassuring FHR tracking abrupt increase in FBL • Visually apparent abrupt increase from FHR baseline • Term infants: o o For it to be an accel, it has to have a onset to peak of 30 or less seconds beginning from the most calculated BL o Duration ≥ 15 seconds > 15 bpm minutes • Preterm: 32 weeks o Onset to peak < 30 seconds; acme ≥ 10 bpm o Duration ≥ 10 seconds • Prolonged acceleration duration ≥ 2 minutes < 10 minutes • Longer than 10 mins is a change in baseline Decelerations: • Abrupt: onset to nadir < 30 seconds • Gradual: onset to nadir > 30 seconds • Basic Tx:
o Call for help! o Turn off Pitocin o Position change (lateral or knee-chest) o IV fluid initiation/increase o Oxygen o Notify MD/CNM o Vaginal Exam unless contraindicated (i. e. preterm, placenta previa ) with fetal scalp stimulation Early Decels: • Visually apparent gradual decrease & return to FHR baseline associated with UC • Onset to nadir ≥ 30 seconds with an increase of HR of 30 to 40 bpm • Nadir occurs at peak of contractions • assocaited with low apgar scores as well as fetal hypoxia or acidosis • Cause: HEAD COMPRESSION Late Decels: • Visually apparent gradual decrease & return to baseline FHR associated with contractions • Onset to nadir ≥ 30 seconds • Onset, nadir, and recovery occur after onset, peak and recovery of contraction • Caused by UTEROPLACENTAL INSUFFICIENCY; thus, they are always ominous. • To optimize uteroplacental blood flow and fetal oxygenation, the pt. should be place in the left lateral position Variable Decels : • Visually apparent abrupt decrease from FHR baseline; may occur with or without contractions • Onset to beginning of nadir < 30 seconds • Decrease ≥ 15 bpm •
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- Fall '12
- Obstetrics, Fetal heart rate, fetal well-being, fetal lung maturity