maternity unit 3: ch 18 - fetal monitor

how can FHR be measured

• externally with doppler

• internally with fetal scalp electrode

tocodynamometer

• measures frequency of contractions externally on abdomen @ level of fundal height

• doesn't measure intensity

intrauterine pressure Catheter

• measures contractions internally

• measures intensity

baseline

average FHR over 10 minutes rounded to the nearest 5 bpm

variability

fluctuations in the FHR of 2 cycles per minute or greater

• absent

• minimal - normal

• moderate

• marked

• most important indicator of fetal Oxygen status

• should be traced for 10-20 minutes

this is what type of variability

absent variability - amplitude range is undetectable (straight line)

this is what type of variability

minimal variability - 5 or less change bpm

this is what type of variability

moderate (normal) - 6-25 change in bpm

this is what type of variability

marked - greater than 25 change in bpm

causes of decreased variability

• fetal sleep cycles

• hypoxemia / acidosis

• certain drugs (magnesium/ narcotics)

• prematurity

• arrhythmias

• fetal tachycardia

• nuero abnormalities

• congenital anomalies

how do we stimulate a sleeping fetus

• give mom ice, sugar (cookie or juice)

• fetal scalp stimulation

causes of increased variability

• fetal stimulation

• mild, transient hypoxemia

• sympathomimetic drugs

acceleration

• a visually abrupt increase in HR

• onset to peak is less than 30 seconds

• duration is measured from onset to when the HR returns to basleline

• we want 2 accels in a 20 minute period

accelerations in a 32 week baby

• acme (peak) of 15 bpm lasting 15 seconds or more, but no more than 2 minutes

accelerations in a baby less than 32 weeks

• acme (peak) of 10 bpm lasting 10 seconds or more, but no more than 2 minutes

prolonged acceleration

• lasts 2 minutes or more but no more than 10 minutes

• more than 10 minutes is a change in baseline

variable deceleration

• abrupt decrease in FHR

• onset to nadir is less than 30 seconds

• 15 bpm drop or less

• lasts at least 15 seconds or more but no more than 2 minutes

• not associated with contractions (can happen with or without contractions)

what are variable decelerations caused by

• cord compression

• fetal head compression - causes vagal nerve stimulation

• if it happens after ROM it is associated with cord prolapse (cord delivers before mom)

• when associated absent or minimal variability, it can indicate hypoxemia or acidosis

this is showing?

variable deceleration

early deceleration

• gradual decrease and return to baseline FHR

• onset to nadir is 30 seconds or more

• Nadir occurs at the same time as the peak of mom’s contractions

what are early decelerations caused by

• fetal head compression - causes vagal nerve stimulation

• not associated with hypoxemia or acidosis

• if early In labor , it may indicate cephallopelvic disproportion

this is showing

early decelerations - Nadir is aligned with peak of contractions

late deccelerations

• gradual decrease and return to baseline FHR

• onset to nadir is 30 seconds or more

• Nadir occurs after the peak of mom’s contractions

what are late decelerations caused by

• uteroplacental insufficiency (uterine perfusion, uterine tone or placenta function)

• always relative hypoxia, but not always hypoxemia or acidosis

• some causes are reversible some ore not

reversible causes of late decelerations

• maternal hypotension

• uterine hyperactivity - can stop with tocolytics (relaxes smooth muscle)

irreversible causes of late decelerations

• placental abruption or infarction (placenta detaches from uterine wall, must deliver baby immediately - both mom and baby are hemorrhaging)

• placenta previa - placenta implanted lower than normal

may or may not be reversible causes of late decelerations (5)

• chorioamnionitis - infection (high temp & tender uterus)

• IUGR

• maternal hypertension, diabetes, anemia or cardiac issue

• Rh isoimmunization

• maternal tabbacco use

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late deccels

prolonged decceleration

• decceleration drops 15 bpm or more, lasting at least 2 min but less Than 10 minutes

• after 10 minutes it is a change in baseline

causes of prolonged decelerations (7)

• cord compression/ cord prolapse

• profound maternal hypotension

• maternal hypoxia

• tetanic contractions - no break in between contractions

• amniotic fluid embolism (fatal) - goes into moms bloodstream, may go to her lungs/heart

• prolonged head compression

• paracervical anesthesia

this is showing?

prolonged decelerations

VEAL CHOP

causes of specific decelerations

causes of fetal tachycardia (greater than 160bpm)

• maternal fever, sepsis, chorio

• drugs

• fetal hypoxemia

• tachyarrythmias

• fetal heart failure

• hydrops - fluid overload in fetus

• severe fetal anemia

• maternal hyperthyroidism

interventions to fetal tachycardia

• assess moms temp - may have fever or chorioamnionitits

• asses for arrhythmias

• oxygen

• look for non-reassuring sings in FHR - may have to deliver

causes of fetal bradycardia (less than 110)

• drugs

• hypoxemia

• maternal hypotension

• hypothermia

• maternal hypoglycemia

• fetal bradyarrythmias

• congenital heart blcok

• cord compression

• amniotic fluid embolism

interventions to fetal bradycardia 9

• turn pt to left lateral Side - avoids supine hypotension

• fluid bolus (increases CO)

• lower head of bed

• vasopressor - ephedrine (raises maternal BP)

• give oxygen

• stop oxytocin / give tocolytic - gives rest time between contractions if tachysystole

• exam abdomen for rigidity - indicates bleeding/ placental abruption

• assess for congenital heart block

• may need to deliver if interventions fail

sinusoidal pattern

• medical emergency - must call MD ASAP

• severe fetal anemia

• caused by Rh isoimmunization, fetal blood loss, fetal hypoxemia or acidosis, or maternal drug use

• persists for 20 minutes or greater

psuedosinusoidal pattern

• seen intermittently in 15% of births

• associated with drugs administered during labor

• less uniform and transient

• not associated with adverse outcomes

this is showing

sinusoidal pattern

contractions

• counted as the # of contractions in a 10 minute window

• averaged over 30 minutes

• measured from peak to peak

• normal contractions: 5 or less contractions in 10 minutes

tachysystole contractions:

• more than 5 contractions in 10 minutes

• always qualified to presence or absence of fetal deccels

• applies to both SROM or induced labor

interventions for late deccels 8

• turn pt to left lateral Side - avoids supine hypotension

• fluid bolus (increases CO)

• lower head of bed

• vasopressor - ephedrine (raises maternal BP)

• give oxygen

• stop oxytocin / give tocolytic - gives rest time between contractions if tachysystole

• exam abdomen for rigidity - indicates bleeding/ placental abruption

• may need to deliver if interventions fail

interventions for variable deccels 5

• change maternal positon to receive cord compression

• give oxygen

• stop oxytocin / give tocolytic - gives rest time between contractions if tachysystole

• vaginal exam - check for cord prolapse

• amnioinfusion - replacing amniotic fluid loss

interventions for decreased variability

• observation to see if they are transient (fetal may be sleeping)

• look over hx - may be from maternal drug use

• Position change, O_2, fluids - helps relieve hypoxia

• stop oxytocin / give tocolytic

• fetal scalp stimulation

interventions for prolonged deccels

• stop oxytocin / give tocolytic

• Position change, O_2, - helps relieve hypoxia

• asses for hypoxemia, hypotension, placental abruption, or cord prolapse

• may need to deliver if it doesn’t resolve within 6 minutes

Category 1

• normal

• strongly predict normal acid -base status

• no intervention required

category 2

• intermediate

• do not predict abnormal acid-base status

• require evaluation and continued surveillance

category 3

• abnormal

• predict abnormal acid-base status

• require immediate evaluation and intervention