exam two: fetal monitoring Flashcards
(108 cards)
1
Q
influences on fetal heart rate
A
- CNS: regulator of the autonomic nervous system which takes awhile to fully develop
- Autonomic nervous system:
- parasympathetic nervous system
- sympathetic nervous system
2
Q
when is the autonomic nervous system fully developed
A
- 32 weeks
3
Q
influences on the fetal heart rate: parasympathetic nervous system
A
- vagus nerve stimulation slows FHR
- pressure on fetal head (fontanelles) stimulates this parasympathetic response
- may also stimulate passage of meconium
4
Q
influences on the fetal heart rate: sympathetic nervous system
A
- stimulation increases FHR and strength of heart contraction
- stimulated by loud noises, vibration, stimulation of scalp or pressure on maternal abdomen
5
Q
Fetal autonomic nervous system is sensitive to changes in
A
- 02 exchange
- carbon dioxide production
- blood pressure changes
6
Q
chemoreceptors
A
- 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
7
Q
Baroreceptors
A
- located in carotid and aortic arch
- detect pressure changes
- stimulation results in vasodilation, decreased BP, and reflective increase in HR
8
Q
fetal reserves
A
- reserves o2 available to fetus to withstand transient changes in blood flow during labor
- not much reserves = wont do well withstanding changes
9
Q
utero placental unit
A
- ability to transfer oxygen to fetus and remove waste products (perfusion of placenta)
10
Q
factors affecting fetal perfusion
A
- 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
11
Q
normal healthy fetus and repetitive contractions
A
- will have enough reserves to tolerate repetitive contractions (no perfusion)
12
Q
too frequent or too long contractions
A
- decrease perfusion because there isnt enough time to recover (absorb o2) between contractions
13
Q
poor maternal oxygenation
A
- impacts fetus by not providing enough 02 to the placenta
14
Q
coord compression
A
- decreases ability to transfer 02 to fetus
15
Q
problems from 02 transfer occur where
A
- placenta
- uterus
- maternal perfusion
16
Q
contractions and their affect on flow
A
- 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
17
Q
results of decreased placental perfusion
A
- 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
18
Q
guidelines for assessment
A
- know your hospitals guidelines
- may need to assess more frequently
- intermittent assessment is as appropriate in low risk pt as continuous EFM
19
Q
high risk monitoring
A
- 1 st stage:q 15 minutes
- 2nd stage: Q 5 minutes
20
Q
low risk monitoring
A
- 1st stage: Q 30 minutes
-2nd stage: Q 15 minutes
21
Q
methods for FHR assessment
A
-Intermittent auscultation with doppler or fetoscope
-External ultrasound transducer
-Fetal spiral electrode (FSE)- internal
22
Q
methods for contraction assessment
A
- Palpation
- External tocodynomometer “Toco”
- Intrauterine pressure catheter (IUPC)- internal
23
Q
normal contraction
A
- 5 contractions or less in 10 minutes averaged over 30 minutes
24
Q
tachysystole contractions
A
- more than 5 contractions in 10 minute period averaged over 30 minutes
- causes decreased perfusion to fetus
25
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
26
benefits to Intermittent Auscultation (IA) & Palpation of Contractions
- non invasive
- doesnt tie the woman to a monitor
- increased hands on pt care
27
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
28
contraction palpation
1. Frequency (minutes) onset of one contraction to
onset of the next contraction
2. Duration(seconds) length of one contraction from beginning to end
3. Intensity
-Mild: pressing on nose
-Moderate: compressing on chin
-Strong: compressing on forehead
29
interval between red lines
1 minute
30
interval between pink lines
10 seconds
31
FHR tracking (BPM)
5-10 BEAT increments
32
external monitors
1. Ultrasound transducer: placed on lower abdomen
2. Tocodynomometer or Tocotransducer or “Toco”
33
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
34
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
35
contractions external measurements
1. duration: beginning to end
2. frequency: beginning to beginning
3. intensity: by palpation- mild, moderate, strong
36
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)
37
benefits to fetal spiral electrode (internal monitor)
- more accurate picture of HR
- not affected by movement
38
disadvantages to fetal spiral electrode (internal monitor)
- invasive
- risk of infection
39
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)
40
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
41
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)
42
Normal FHR
110-160
- decreases with gestational age as the heart gets bigger
43
bradycardia
- < 110 bpm for at least 10 minutes
44
causes of bradycardia
- vagal nerve stimulation (baby suddenly drops down into the pelvis)
- Drugs
- maternal hypotension (epidural)
- fetal hypoxia
45
tachycardia
- > 160 bpm for at least 10 minutes
46
maternal causes of tachycardia
- fever
- dehydration
- meds/drugs
- infection
- anemia
47
fetal causes of tachycardia
- infection
- activity
- compensation after acute hypoxemia
- chronic hypoxemia
- cardiac abnormalaites
- tachyarrhythmias
- anemia
48
signs that tachycardia is non reassuring with other FHR patterns
- absent or minimal variability
- late or severe variable decelerations
49
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
50
absent variability
- variation in amplitude is undetectabale above or below the baseline
- flat line
- MAY BE CONCERNING
51
causes of absent variability
- fetal sleep
- medication effects
- fetal hypoxia and acidosis
52
minimal variability
- variation in HR changes detectable but
53
moderate variability
- amplitude range of: 6-25 bpm above and below
- highly predictive of: absence of metabolic acidemia
- happy baby
54
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
55
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
56
benign sinusoidal
- not as smooth appearing
- caused by fetal sucking or medications
57
pathologic sinusoidal
- non- reassuring finding
- causes: anemia, chronic fetal bleeding, CNS malformation, twin-twin transfusion syndrome, isoimmunization of fetus, cord occlusion
58
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
59
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
60
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
61
prolonged accelerations
- >/= 2 minutes and
62
decelerations
- transitory decrease in FHR below baseline
- abrupt: onset to nadir (bottom point) = < 30 seconds
- gradual: onset to nadir = >/= 30 seconds
63
abrupt deceleration
variable deceleration with or without contractions
64
gradual deceleration
1. early deceleration during contractions
2. late deceleration after contractions
65
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
66
variable decelerations relationship with contractions
- with or without contractions
- with every contraction or at anytime between contraction or after contraction
67
variable decelerations caused by
- cord compression
- cord could be around neck or between shoulders
68
variable decelerations: venous compression
- this is the first thing to compress
- decrease in venous return --> relative hypoxemia --> reflexive increase in FHR
69
variable decelerations: arterial compression
- increase in systemic vascular resistance --> increase in BP and baroreceptor stimulation --> vagal response --> decrease in FHR
70
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
71
early deceleration causes
- head compression
-vagal nerve stimulation
72
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
73
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
74
why are lates late?
1. decrease in 02 sensed by chemoreceptors
2. causes vasomotor center to have peripheral vasoconstriction (gut, kidneys, limbs) and central redistribution- shunting to (brain heart and adrenals)
3. these cause increase in BP, baroceptosr stimulation, parasympathetic response = deceleration
75
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
76
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
77
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
78
VEAL CHOP
1. Variable deceleration caused by Cord compression
2. Early deceleration caused by Head compression
3. Acceleration Is A Okay
4. Late deceleration is caused by Placental perfusion issue
79
intrauterine resuscitation
1. Position change
2. IV fluid bolus
3. CALL FOR HELP
4. Notify provider and request immediate evaluation
5. Assess for tachysystole
-Turn off Pitocin if running
-have Consider Terbutaline 0.25 mg SQ or IV
6. Check blood pressure
-Correct if hypotensive– fluid bolus and meds (Ephedrine 5-10 mg IV or Phenylephrine 0.1 to 0.5 mg IV)
7. Cervical exam
-Check for prolapsed cord, rapid cervical dilation, rapid descent
8. Prepare for possible amnioinfusion
9. Alter pushing efforts– stop, push every other contraction
80
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
81
goal for category one
- maximize perfusion
- maintain appropriate uterine activity
82
actions for category one
- intermittent auscultation / uterine palpation if low risk and appropriate
- intermittente EFM
83
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
84
category three: red
- abnormal oxygenation
- include EITHER: absent variability with any of these:
1. recurrent lates
2. recurrent variables
3. bradycardia
OR
sinusoidal pattern
85
category three goal
- correct abnormal oxygenation
86
category three actions
- continuous EFM
- initiate intrauterine resuscitation
- prepare for c section if no improvement
87
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
88
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
89
non reactive NST
insuffieient accelerations in 40 minutes or increase in FHR didnt meet the criteria
- needs follow up
90
- 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
91
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
92
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
93
BPP total score of 8-10/10
normally oxygenated fetus and low risk of apshyxia
continue care and testing
94
BPP total score of 6/10
possible asphyzia
- repeat in 24 hours or possible induction
95
BPP total score of 0-4/10
very worrisome
deliver baby
96
Amniotic Fluid Volume Assessment
-Measurement of the volume of amniotic fluid with ultrasound
-Amount varies through pregnancy- average 8 to 24 cm
97
Amniotic Fluid Index (AFI)
Deepest pockets measured in 4 quadrants of maternal
abdomen via U/S
- sum = AFI
98
Maximum Vertical Pocket (MVP)
Largest single pocket of amniotic fluid not persistently
containing fetal extremities or umbilical cord
99
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
100
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
101
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
102
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
103
Negative CST
- good
- no signifigant variable or late decelerations noted
- associated with good fetal outcomes
104
positive CST
- bad
- late deceleration noted with at least 50% of contractions
- require further testing
105
Equivocal CST/Suspicious
- intermittent lates or variable decelerations
- further testing neede
106
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
107
Estimation of fetal weight in 3rd trimester
1. Methods of evaluation are imprecise
2. Inadequate or excessive growth may indicate alterations in fetal well-being
3. Intrauterine growth restriction (IUGR)
-Any baby below 10th percentile
-Causes: infections, placental problems, genetic abnormalities, uteroplacental insufficiency
4. 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
108
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
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