exam two: fetal monitoring Flashcards
influences on fetal heart rate
- CNS: regulator of the autonomic nervous system which takes awhile to fully develop
- Autonomic nervous system:
- parasympathetic nervous system
- sympathetic nervous system
when is the autonomic nervous system fully developed
- 32 weeks
influences on the fetal heart rate: parasympathetic nervous system
- vagus nerve stimulation slows FHR
- pressure on fetal head (fontanelles) stimulates this parasympathetic response
- may also stimulate passage of meconium
influences on the fetal heart rate: sympathetic nervous system
- stimulation increases FHR and strength of heart contraction
- stimulated by loud noises, vibration, stimulation of scalp or pressure on maternal abdomen
Fetal autonomic nervous system is sensitive to changes in
- 02 exchange
- carbon dioxide production
- blood pressure changes
chemoreceptors
- located in carotid arch and CNS
- respond to changes in fetal 02, co2, ph levels
- stimulation results in either speeding up or slowing down HR
Baroreceptors
- located in carotid and aortic arch
- detect pressure changes
- stimulation results in vasodilation, decreased BP, and reflective increase in HR
fetal reserves
- reserves o2 available to fetus to withstand transient changes in blood flow during labor
- not much reserves = wont do well withstanding changes
utero placental unit
- ability to transfer oxygen to fetus and remove waste products (perfusion of placenta)
factors affecting fetal perfusion
- maternal HTN/hypotension
- ablution of placenta: part of the placenta separates before birth= decreased perfusion
- diabetes: vasoconstriction
- smoking: vasoconstriction and calcification to placenta= affects ability of placenta to perfuse fetus
- substance abuse: coccaine especially= abruption
- maternal supine position: hypotension
- post term pregnancy: placenta has shelf life and post this = decreased perfusion
- uterine tachysystole: too frequent contractions (more than 5 in 10 minutes)
- cord compression: compressed = blood cant flow from placenta to fetus
normal healthy fetus and repetitive contractions
- will have enough reserves to tolerate repetitive contractions (no perfusion)
too frequent or too long contractions
- decrease perfusion because there isnt enough time to recover (absorb o2) between contractions
poor maternal oxygenation
- impacts fetus by not providing enough 02 to the placenta
coord compression
- decreases ability to transfer 02 to fetus
problems from 02 transfer occur where
- placenta
- uterus
- maternal perfusion
contractions and their affect on flow
- before contraction: normal flow
- as contraction occurs: reduced flow
- peak of contraction: no blood flow into uterus
- as contraction resolves: reduced blood flow
- as contraction is finished: normal flow
- if too frequently these contractions occur: not enough time for baby to recover
results of decreased placental perfusion
- normal oxygenation in fetus»_space; something occurs that decreases 02 available»_space; hypoxemia (decreased o2 in blood)»_space; blood flow shunted to vital organs»_space; tissue hypoxia»_space; increase in lactic acid»_space; anaerobic metabolism in tissues»_space; metabolic acidosis = decreased tissue ph»_space; injury or death
guidelines for assessment
- know your hospitals guidelines
- may need to assess more frequently
- intermittent assessment is as appropriate in low risk pt as continuous EFM
high risk monitoring
- 1 st stage:q 15 minutes
- 2nd stage: Q 5 minutes
low risk monitoring
- 1st stage: Q 30 minutes
-2nd stage: Q 15 minutes
methods for FHR assessment
-Intermittent auscultation with doppler or fetoscope
-External ultrasound transducer
-Fetal spiral electrode (FSE)- internal
methods for contraction assessment
- Palpation
- External tocodynomometer “Toco”
- Intrauterine pressure catheter (IUPC)- internal
normal contraction
- 5 contractions or less in 10 minutes averaged over 30 minutes
tachysystole contractions
- more than 5 contractions in 10 minute period averaged over 30 minutes
- causes decreased perfusion to fetus
Intermittent Auscultation (IA) & Palpation of Contractions
-May be used for assessment especially in low risk women
- use doppler and fetoscope
-Requires 1:1 nurse-patient ratio and proper technique
-Follows low risk guidelines (q 30 min & q 15min)
-FHR assessed before, during and after contractions
benefits to Intermittent Auscultation (IA) & Palpation of Contractions
- non invasive
- doesnt tie the woman to a monitor
- increased hands on pt care
disadvantages to to Intermittent Auscultation (IA) & Palpation of Contractions
- no permenant record
- maternal size and position can inhibit ability to auscultate FHR and palpation of contractions
- difficult to assess uterine pressure quantitatively
- time intensive
contraction palpation
- Frequency (minutes) onset of one contraction to
onset of the next contraction - Duration(seconds) length of one contraction from beginning to end
- Intensity
-Mild: pressing on nose
-Moderate: compressing on chin
-Strong: compressing on forehead
interval between red lines
1 minute
interval between pink lines
10 seconds
FHR tracking (BPM)
5-10 BEAT increments
external monitors
- Ultrasound transducer: placed on lower abdomen
- Tocodynomometer or Tocotransducer or “Toco”
Ultrasound transducer
- external
- water soluble gel used to help conduct sound waves
-Measures FHR by reflecting high frequency sound waves off the movement of the fetal heart valves
-Placement: over the area of maximum intensity (fetal back)
-Compare rate to maternal pulse to make sure not picking up moms pulse
Tocodynomometer or Tocotransducer or “Toco”
- external
- upper abdomen
- measures; frequency and duration of uterine contractions
- doesn’t measure intensity: need to palpate for this
- placed on the fundus
contractions external measurements
- duration: beginning to end
- frequency: beginning to beginning
- intensity: by palpation- mild, moderate, strong
Internal Fetal Heart Monitor
-Fetal spiral electrode (FSE)
-Measures FHR by reading fetal ECG
-Fine wire placed under skin of
presenting part
-Require ruptured membranes and cervical dilation (1-2 cm)
benefits to fetal spiral electrode (internal monitor)
- more accurate picture of HR
- not affected by movement
disadvantages to fetal spiral electrode (internal monitor)
- invasive
- risk of infection
Internal Contraction Monitor
-Intrauterine pressure catheter (IUPC)
-Measures pressure in the uterus in mmHG
-Measures: frequency and duration, resting tone (tone of uterus between contractions= tension in uterus between contractions), intensity of contractions
-Placed in uterus alongside the fetus to the fundus
-Used for: to evaluate effectiveness of contractions and amnioinfusion = putting fluid back into the uterus because too little (cushions umbilical cord)
calculating intensity
- reported in Montevideo Units (MVUs)
- these represent the total of the intensity of each contraction in a 10 minute period
- MVUs > 200 = labor can progress (90% of labors)
- baseline pressure needs to be subtracted from each reading
FHR baseline
- this is the first component to be evaluated
- Mean FHR during 10 minute period rounded to the nearest 5 bpm
- exclude accelerations and decelerations
- must observe for 2 minutes of the 10 minute period (doesn’t have to be consecutive thought can be 1 minute at the begging and one minute at the end)
Normal FHR
110-160
- decreases with gestational age as the heart gets bigger
bradycardia
- < 110 bpm for at least 10 minutes
causes of bradycardia
- vagal nerve stimulation (baby suddenly drops down into the pelvis)
- Drugs
- maternal hypotension (epidural)
- fetal hypoxia
tachycardia
- > 160 bpm for at least 10 minutes
maternal causes of tachycardia
- fever
- dehydration
- meds/drugs
- infection
- anemia
fetal causes of tachycardia
- infection
- activity
- compensation after acute hypoxemia
- chronic hypoxemia
- cardiac abnormalaites
- tachyarrhythmias
- anemia
signs that tachycardia is non reassuring with other FHR patterns
- absent or minimal variability
- late or severe variable decelerations
baseline variability
- most important predictor of adequate fetal oxygenation
- reflects a well functioning nervous system
- visible regular fluctuations in FHR above and below the baseline FHR (two or more cycles per minute, assessed between any FHR changes)
- categories: absent, minimal, moderate, marked
absent variability
- variation in amplitude is undetectabale above or below the baseline
- flat line
- MAY BE CONCERNING
causes of absent variability
- fetal sleep
- medication effects
- fetal hypoxia and acidosis
minimal variability
- variation in HR changes detectable but </= 5 bpm
- caused by the same thing as absent
- may be concerning
moderate variability
- amplitude range of: 6-25 bpm above and below
- highly predictive of: absence of metabolic acidemia
- happy baby
marked variability
- range in FHR is > 25 bpm from top # and bottom #
- unable to establish a baseline (there is no time period of 2 minutes of one FHR)
- caused by: early or mild hypoxia, fetal activity, or medications/drug effects
sinusoidal
- not very common
- smooth, regular, wavelike pattern (looks like letter s on its side)
- amplitude of 5-15 bpm and occurs 3-5 times in 1 minute lasting for 20 minutes or more
- benign or pathologic
benign sinusoidal
- not as smooth appearing
- caused by fetal sucking or medications
pathologic sinusoidal
- non- reassuring finding
- causes: anemia, chronic fetal bleeding, CNS malformation, twin-twin transfusion syndrome, isoimmunization of fetus, cord occlusion
twin-twin transfusion syndrome
- connection between the placentas and one twin give the other a bunch of blood
- the donor twin will have this issue
FHR changes
- may occur with or without contractions
- with = periodic
- without = episodic
- can include accelerations or decelerations
- decelerations with all types for periodic
- decelerations with variables for episodic
accelerations
- abrupt increase above baseline
- onset to peak of increase < 30 seconds
- for pregnancies >/= 32 weeks: ACME of >/= 15 bpm for >/= 15 seconds from beginning to end of the increase
- for pregnancies < 32 weeks: ACME of >/= 10 bpm for >/= 10 seconds
- identify a well oxygenated fetus and the absence of acidemia
prolonged accelerations
- > /= 2 minutes and </= 10 minutes (2-10 minutes)
- if greater than 10 minutes its no longer an acceleration but baseline FHR change
decelerations
- transitory decrease in FHR below baseline
- abrupt: onset to nadir (bottom point) = < 30 seconds
- gradual: onset to nadir = >/= 30 seconds
abrupt deceleration
variable deceleration with or without contractions
gradual deceleration
- early deceleration during contractions
- late deceleration after contractions
variable decelerations
- ABRUPT decrease in FHR
- most common deceleration in labor
- > /= 15 bpm lasting >/= 15 seconds but < 2 minutes
- vary in shape, depth, duration, and position
variable decelerations relationship with contractions
- with or without contractions
- with every contraction or at anytime between contraction or after contraction
variable decelerations caused by
- cord compression
- cord could be around neck or between shoulders
variable decelerations: venous compression
- this is the first thing to compress
- decrease in venous return –> relative hypoxemia –> reflexive increase in FHR
variable decelerations: arterial compression
- increase in systemic vascular resistance –> increase in BP and baroreceptor stimulation –> vagal response –> decrease in FHR
early decelerations
- GRADUAL symmetric decrease in FHR
- ONSET BEGINS WITH ONSET OF CONTRACTIONS
- nadir occurs with the peak of the contractions
- recovery is at the end of the contraction
- onset to nadir: >/= 30 sec
- WITH CONTRACTIONS ONLY
- benign
- its okay to be early for dinner but dont be late: late decelerations indicate uteroplacental insufficiency
early deceleration causes
- head compression
-vagal nerve stimulation
late decelerations
- GRADUAL symmetric FHR decrease only with contractions
- onset to nadir: >/= 30 seconds
- onset begins after contraction
- nadir always occurs after the peak of the contraction
- recovery is after the end of the contraction
- compensatory response: late decelerations with moderate variability is not associated with significant fetal acidemia
cause of late decelerations
- uteroplacental insufficiency
- concerning when: its associated with absent or minimal variability because it reflects hypoxia and increased risk of significant fetal acidemia
why are lates late?
- decrease in 02 sensed by chemoreceptors
- causes vasomotor center to have peripheral vasoconstriction (gut, kidneys, limbs) and central redistribution- shunting to (brain heart and adrenals)
- these cause increase in BP, baroceptosr stimulation, parasympathetic response = deceleration
prolonged decelerations
- gradual or abrupt FHR decrease of >/= 15 bpm in >/= 2 min < 10 min
- not concerning if: not recurrent, normal FHR baseline before and after deceleration, moderate variability
prolonged decelerations
- gradual or abrupt FHR decrease of >/= 15 bpm in >/= 2 min < 10 min
- not concerning if: not recurrent, normal FHR baseline before and after deceleration, moderate variabilitycc
causes of prolonged decelerations
- anything that causes profound change in fetal o2
1. uteroplacental: tachysystole, maternal hypotension, abruption
2. umbilical blood flow interruption: cord compression, cord prolapse
3. vagal stimulation: profound head compression, rapid fetal descent
VEAL CHOP
- Variable deceleration caused by Cord compression
- Early deceleration caused by Head compression
- Acceleration Is A Okay
- Late deceleration is caused by Placental perfusion issue
intrauterine resuscitation
- Position change
- IV fluid bolus
- CALL FOR HELP
- Notify provider and request immediate evaluation
- Assess for tachysystole
-Turn off Pitocin if running
-have Consider Terbutaline 0.25 mg SQ or IV - Check blood pressure
-Correct if hypotensive– fluid bolus and meds (Ephedrine 5-10 mg IV or Phenylephrine 0.1 to 0.5 mg IV) - Cervical exam
-Check for prolapsed cord, rapid cervical dilation, rapid descent - Prepare for possible amnioinfusion
- Alter pushing efforts– stop, push every other contraction
category one: green
- normal oxygenation
- includes ALL of these:
1. normal baseline rate: 110-160
2. moderate variability
3. no late or variable decelerations
4. maybe early decelerations
5. maybe accelerations
goal for category one
- maximize perfusion
- maintain appropriate uterine activity
actions for category one
- intermittent auscultation / uterine palpation if low risk and appropriate
- intermittente EFM
category two: yellow
- all other patterns NOT included in category one or three
- goal is to prevent worsening and improve oxygenation
- actions: increase frequency of FHR assessment, continue or initiate EFM, initiate intrauterine resuscitation
category three: red
- abnormal oxygenation
- include EITHER: absent variability with any of these:
1. recurrent lates
2. recurrent variables
3. bradycardia
OR
sinusoidal pattern
category three goal
- correct abnormal oxygenation
category three actions
- continuous EFM
- initiate intrauterine resuscitation
- prepare for c section if no improvement
test of fetal well being
-Done during antepartum period
-Commonly done for high-risk conditions-DM, pre-eclampsia, IUGR, multiple gestation, postdates, decreased fetal movement
- Non stress test
- biophysical profile
- amniotic fluid volume assessment
- modified BPP
- contraction stress test
- doppler flow studies
- fetal growth and estimation of fetal weight
non stress test
-FHR will accelerate in response to movement
-Most widely accepted method of evaluation of well-being
-Electronic monitoring is used for 20-40 minutes
- reactive NST: at least 2 FHR accelerations in 20 minute period that meets requirements
- if it meets criteria = low risk for asphyxia in next 2-3 days
- in pregnancies > 32 weeks : >/= 15 bpm above baseline lasting >/= 15 seconds
- in pregnancies 28-32 weeks: >/= 10 bpm above baseline lasting >/= 10 seconds
non reactive NST
insuffieient accelerations in 40 minutes or increase in FHR didnt meet the criteria
- needs follow up
- reactive NST:
- at least 2 FHR accelerations in 20 minute period that meets requirements
- if it meets criteria = low risk for asphyxia in next 2-3 days
- in pregnancies > 32 weeks : >/= 15 bpm above baseline lasting >/= 15 seconds
- in pregnancies 28-32 weeks: >/= 10 bpm above baseline lasting >/= 10 secon
non stress test and fetus sleep cycle
-Fetuses have sleep cycles
-If NST is non-reactive in 20 minutes continue testing for additional 20 minutes
-To wake fetus may use sound or vibration to stimulate movement: Vibroacoustic stimulation- “buzzer” that is pushed for no more than 2-3 seconds
Biophysical Profile (BPP)
-Assessment of fetal reflex activities controlled by the CNS and sensitive to fetal hypoxia
-Score of 2 (present) or 0 (absent) given for the following:
1. NST (reactive = 2 and non reactive = 0) and:
2. Ultrasound of 30 minutes duration
-Fetal breathing movements: at least one episode of fetal breathing lasting at least 30 seconds
-Fetal movement: 3 or more discrete body or limb movements of extremities
-Fetal tone: 1 or more extension/flexion movements of extremities
-Amniotic fluid volume: at least 1 pocket of at least 2 cm or AFI > 5 cm
BPP total score of 8-10/10
normally oxygenated fetus and low risk of apshyxia
continue care and testing
BPP total score of 6/10
possible asphyzia
- repeat in 24 hours or possible induction
BPP total score of 0-4/10
very worrisome
deliver baby
Amniotic Fluid Volume Assessment
-Measurement of the volume of amniotic fluid with ultrasound
-Amount varies through pregnancy- average 8 to 24 cm
Amniotic Fluid Index (AFI)
Deepest pockets measured in 4 quadrants of maternal
abdomen via U/S
- sum = AFI
Maximum Vertical Pocket (MVP)
Largest single pocket of amniotic fluid not persistently
containing fetal extremities or umbilical cord
Oligohydramnios
- Complication associated with increased risk of mortality since the amniotic fluid cushions the cord
- Prolonged fetal hypoxemia causes shunting of blood away from the kidneys which Decreases production of fetal urine and therefore the amniotic fluid volume is decreased
- AFI of 5 or less or MVP less than 2 cm
Hydramnios- also knows as polyhydramnios
AFI of > 24 cm or MVP of >/= 8 cm
- may be associated with fetal malformation- obstruction of GI tract, neural tube defect, or fetal hydrops
- higher risk for cord prolapse when membranes rupture
Modified Biophysical Profile
-Less labor intensive and less expensive than BPP
-Components:
1. NST: Indicator of short-term fetal well-being
2. Amniotic fluid volume assessment–AFI/MVP: Indicator of long-term placental function
results:
reactive NST ans low amniotic fluid = low risk for hypoxia for the next week
Contraction Stress Test
-Evaluates response of fetus to the stress of contractions (AND HOW WELL HANDLE PERIOD OF LOW 02)
-Contractions causes decreased oxygen transport to fetus
-Adequate testing
-Three contractions in 10 minutes lasting 40 seconds
-Contractions can be spontaneous, induced with Pitocin or nipple stimulation
Negative CST
- good
- no signifigant variable or late decelerations noted
- associated with good fetal outcomes
positive CST
- bad
- late deceleration noted with at least 50% of contractions
- require further testing
Equivocal CST/Suspicious
- intermittent lates or variable decelerations
- further testing neede
Doppler Flow Studies
-Ultrasound evaluation assessing placental function
-Measures blood flow through umbilical artery
-Most common is systolic to diastolic ratio (S/D ratio)-absent, reversed or elevated demonstrates abnormal blood flow
-Commonly used for fetal growth restriction evaluation
Estimation of fetal weight in 3rd trimester
- Methods of evaluation are imprecise
- Inadequate or excessive growth may indicate alterations in fetal well-being
- Intrauterine growth restriction (IUGR)
-Any baby below 10th percentile
-Causes: infections, placental problems, genetic abnormalities, uteroplacental insufficiency - Macrosomia- excessive growth
0-Weight: 4000-4500 grams
-cause: diabetes especially poorly controlled because the baby receives the excess glucose from the mom but insulin wont pass the placenta so gain weight
Evaluation of Fetal Lung Maturity
-Used prior to elective childbirth of fetus before term (39 WEEKS)
-If lungs immature- delay delivery
-If lungs mature risk of Respiratory Distress Syndrome is low
-Amniotic fluid obtained by amniocentesis
1. Lecithin/Sphingomyelin Ratio
-Two components of surfactant
-When the L/S ratio is > 2:1 demonstrates low risk of RDS and mature lungs
2. Phospatidylglycerol (PG)
-Another component of surfactant
-Appears at about 36 weeks gestation and continues to increase until term
-Presence demonstrates low risk of RDS
- NOT USED WITH SPONTANEOUS LABOR
