Fetal monitoring Flashcards
1
Q
What are the influences on the fetal heart rate?
A
Central nervous system - regulates autonomic NS
Autonomic nervous system
2
Q
When is the ANS expected to be fully developed by?
A
32 weeks
3
Q
What are the two parts of the ANS are?
A
- Parasympathetic NS
- Sympathetic NS
4
Q
What does the parasympathetic NS do? What stimulate it?
A
Vagus nerve stimulation –> slow HR
Stimulated by pressure on fetal head
Can also stimulate passage on meconium
5
Q
What does the sympathetic NS do? What is it stimulated by?
A
Increase HR and strength of heart contraction
Stimulated by loud noise, vibration, stimulation of scalp of pressure on maternal abdomen
6
Q
What changes is the ANS sensitive to?
A
Oxygen exchange
CO2 production
BP changes
7
Q
What are chemoreceptors? What do they respond to? What do they cause?
A
Receptors in the carotid arch and CNS
Respond to changes in fetal O2 CO2 and pH levels
Stimulation –> increase or decrease HR
8
Q
What are baroreceptors? What do they respond to? What do they cause?
A
Receptors in the carotid and aortic arch
Detect pressure changes
Stimulation –> vasodilation, decrease BP, and reflexive increase HR
9
Q
What are the influences on FHR?
A
Fetal reserves
Utero-placental unit
Factors that affect fetal perfusion
10
Q
What are fetal reserves? What occurs w/o fetal reserves?
A
Reserve O2 available to fetus to withstand change in BF during labor
W/O –> won’t withstand changes
11
Q
How does the Utero-placental unit affect FHR?
A
ability to transfer oxygen to fetus and remove waste products
12
Q
What are factors that affect fetal perfusion? (9)
A
Maternal HTN or HypoTN
Abruptio placenta
Diabetes
Smoking
Substance abuse
Maternal supine position
Post-term pregnancy
Uterine tachysystole
Cord compression
13
Q
How does maternal HTN/HypoTN affect FHR?
A
Decrease perfusion
14
Q
How does abruptio placenta affect FHR?
A
Placenta has separated before delivery –> decrease BF to fetus
15
Q
How does diabetes and smoking affect FHR?
A
Vasoconstriction –> decrease BF
16
Q
How does maternal substance abuse affect FHR?
A
Causes abruption
17
Q
How does maternal maternal supine position affect FHR?
A
Hypotension
18
Q
How does maternal uterine tachyststole affect FHR?
A
Too frequent contractions (more than 5/min) –> decrease perfusion because not enough time to recover/absorb in between contractions
19
Q
What occurs to the fetus when the uterus contracts?
A
Fetus holds their breath and using reserves
When uterus relaxes, reserves are restored
If healthy, fetus will have enough reserve to tolerate respective contractions
20
Q
Where do problems with O2 transfer occur? What do these all cause?
A
Placenta (cause decrease O2 transfer during relax)
Uterus
Maternal perfusion
All cause hypoxemia in fetus
21
Q
What are the results of decreased placental perfusion?
A
Normal oxygen (decrease PaO2/amount of O2 available)
Hypoxemia (blood shunted to vital organs)
Tissue hypoxia
Increased lactic acid
Metabolic acidosis d/t anaerobic metabolism in tissue
Injury or death
22
Q
What are 3 different methods for FHR assessment?
A
Intermittent auscultation with doppler or fetoscope
External ultrasound transducer
Fetal spiral electrode
23
Q
What are 3 methods for contraction assessment?
A
Palpation
External tacodynomometer “toco”
Intrauterine pressure catheter (IUPC)
24
Q
What are considered normal contractions?
A
5 contractions or less in 10 minutes averaged over 30 minutes
25
What are considered tachysystole contractions?
more than 5 contractions in 10 minutes averaged over 30 minutes
26
When do you use intermittent auscultation and palpation? What is the nurse ratio for this?
Assessment in low risk low - every 30 minutes and every 15 minutes
Requires 1:1
27
When is FHR assessed while using intermittent auscultation and palpation?
Before, during and after contraction
28
What are the benefits to using intermittent auscultation and palpation?
Non-invasive
Doesn't hook mom up to a bunch of machines
Increases hands on patient care
29
What are the disadvantages to using intermittent auscultation and palpation?
No permanent record
Maternal size and position can inhibit ability to auscultate FHR and palpation of contraction
Difficult to assess uterine pressure quantitatively
Time intensive
30
When palpating contractions what 3 things should be assessed?
Duration: length of one contraction from beginning to end
Frequency: onset of one contraction to the onset of the next contraction
Intensity
31
What are 3 different intensities used for assessing palpations?
Mild - push on nose
Moderate - push on chin
Strong - push on forehead
What focus feels like
32
What does the red line mean? pink lines?
Red : 1 minutes
Pink: 10 seconds
33
What is uterine activity measured in?
Intensity - mmhm
34
What does the ultrasound transducer measure? Placement? Compare to?
Measures FHR by reflecting high frequency sound waves off the movement of the fetal heart valves
Placed over the area of max intensity on moms abdomen (fetal back)
Compare rate to maternal pulse
35
What type of gel should be used in ultrasound transducer?
Water soluble gel
36
What does the tocodynomometer measure? Placement? How does it work?
Frequency and duration of uterine contraction
DO NOT measure intensity so need to palpate
Placed on fondus
As uterus contacts --> button is pressed
37
What does the fetal spiral electrode (FSE) measure? Placement? What are the requirements?
Measures FHR by reading fetal ECG
Fine wire placed under skin of presenting part
Require ruptured membranes and cervical dilation at least 1-2cm
38
What are the benefits of FSE? Disadvantages?
More accurate picot of FHR and not affected by movement
Invasive and risk of infection
39
What does the intrauterine pressure catheter measure (IUPC)? Placement?
Measures pressure in uterus (mmhg)
Frequency and duration
Resting tone of uterus bt/n contractions (tension in uterus bt/n contraction)
Intensity of contraction
Placed in uterus alongside fetus to the fondus
40
What is the IUPC used for?
Evaluate effectiveness of contractions
Amniofusion - putting fluid back into uterus
41
What would you do a amniofusion?
If there is too little fluid --> cord compression so you want to do IV fluid to help cushion the cord
42
What are Montevideo units (MVUs)? What do they assess?
The total of the intensity of each contraction in a 10 minute period
Assess if contractions are adequate: over 200 means labor will likely process. Under 200 means labor might still or not progress properly
43
How do you calculate MVUs?
Add up each pressure of contraction in a 10 minute period
Make sure to subtract the baseline pressure from each contraction pressure before adding
44
What is FHR baseline?
Mean FHR in a 10 minute period
Rounded to nearest 5 bmp
Exclude accelerations nad decelerations
Must be
45
FHR usually ____ with gestational age
Decreases
46
Bradycardia is... Causes?
Less than 110 for at least 10 minutes
Caused by vagal nerve stimulation (baby drops down into the pelvis)
Drugs
Maternal hypotension (epidural)
fetal hypoxemia
47
Tachycardia is... Causes?
Over 160 for at least 10 minutes
Maternal: fever, dehydration, drugs/meds, infection, anemia
Fetal: infection, activity, compensation after acute hypoxemia, chronic hypoxemia, cardiac abnormalities, tachyarrythmia, anemia
48
What are non-reassuring FHR patterns?
Absent or minimal activity
Late or severe variable decelerations
49
What is the most important predictor of adequate fetal oxygenation? What does it reflect?
Baseline variability
Interplay between fetal sympathetics and parasympathetic NS
Well functioning NS if able to make changes
50
What is baseline variability?
Visible irregular fluctuations in FHR above and below the baseline FHR
Two or more cycles per minute
Assessed between any FHR changes
51
What are categories of variability?
Absent
Minimal
Moderate
Marked
52
What is absent variability? Causes? Concerning?
Variation in amplitude is undetectable above or below the baseline
Fetal sleep
Medication side effect
Fetal hypoxia
Acidosis
Might be concerning
53
What is minimal variability? Causes? Concerning?
Variation in HR ranges detectable but < 5 bpm
Fetal sleep
Medication side effect
Fetal hypoxia
Acidosis
May be concerning
54
What is moderate variability? What does it predict? Concerning?
6-25 bpm above or below
Absence of metabolic acidemia
NO, happy baby
55
What is marked variability? Causes?
over 25 bpm
Unable to establish baseline
Early or mild hypoxemia
Fetal activity
Effects of medication/drugs
56
What is a sinusoidal rhythm?
Smooth, regular, wavelike pattern—looks like the letter S lying on it’s side and interconnected
Amplitude of 5-15 bpm and occur 3-5 times in 1 minute lasting for 20 minutes or more
57
What is the cause of sinusoidal rhythm?
Benign (pseudo sinusoidal)- not as smooth appearing. Caused by fetal sucking or medications
Pathologic
Non-reassuring finding
Causes: anemia, chronic fetal bleeding, CNS malformation, twin-to-twin transfusion syndrome, isoimmunization of fetus, cord occlusion
58
What is an acceleration? What should you measure? What does this identify?
Abrupt increase above baseline
Onset to peak of increase is less than 30 seconds
Identify a well oxygenated fetus and the absence of acidemia
59
What is an abrupt acceleration in pregnancy over 32 weeks?
ACMe of more than or equal to 15 bpm for more than or equal to 15 seconds from beginning to end
60
What is an abrupt acceleration in pregnancy less 32 weeks?
ACME of more than or equal to 10 bpm or more than or equal to 10 seconds
61
What is a prolonged acceleration?
more than 2 minutes and less than 10 minutes
62
What if an acceleration is over 10 minutes?
no longer an acceleration, now it is considered a change in baseline FHR
63
What is abrupt deceleration? What type is the deceleration? What is their relationship to the contraction?
Onset to nadir is less than 30 seconds
Variable
With or without contractions
64
What is gradual deceleration? What type is the deceleration? What is their relationship to the contraction?
More than or equal to 30 seconds
Early - during with the contraction
Late - after the contraction starts
65
Variable decelerations are.. When are they common? Criteria (depth, length, appear)?
ABRUPT decrease in FHR
Most common deceleration in labor
Depth: more than or equal to 15 bpm
Length is more than 15 seconds and less than 2 minutes
Appear: vary in shape, depth, duration
66
What are variable decelerations in r/t contractions? Causes?
With or without contraction
With every contraction or anytime in between contractions
Caused by cord compression
67
What occurs with cord compression?
Venous compression
→ ↓venous return
→ relative hypovolemia
→ reflexive ↑ FHR
Arterial compression
→ ↑ systemic
vascular resistance
→ ↑ BP & baroreceptor
stimulation
→ vagal response
→ ↓ FHR
68
After cord compression is released what could occur?
May see a reflexive increased HR also called a shoulder
69
What is the criteria for early decelerations? Relationship to contractions?
Onset begins at onset of UC
Nadir occurs at the peak of the UC
Recovery is at the end of the contraction
Onset to nadir is over 30 seconds
Mirror contractions
70
What is the cause of early decelerations?
Head compression
Vagal nerve stimulation
Benign - many babies have early decompensation
71
What are late decelerations? What is the criteria?
symmetric FHR decrease
Onset to nadir: more than 30 seconds
Onset begins after UC begins
Nadir always occurs after the peak of the UC
Recovery is after the end of the contraction
72
What is the cause of late deceleration? Is it a concern?
Uteroplacental insufficiency
Concerning:
1. When associated with absent or minimal variability
2. Reflects hypoxia and increased risk of significant fetal acidemia
73
What is the conpensatory response r/t late decelerations?
Late decelerations with moderate variability is not associated with significant fetal acidemia
74
What is the reasoning behind a late deceleration?
Decreased oxygen sensed by chemoreceptors --> vasomotor center --> peripheral vasoconstriction in the gut, kidneys and limbs and central redistribution to brain, heart and adrenals --> increased BP --> baroreceptor stimulation --> Parasymp response --> deceleration
75
Prolonged decelerations are a decrease of _____ for ______ minutes but not longer than _____ minutes
Prolonged decelerations are a decrease of 15 or more bpm for at least 2 minutes but not longer than 10 minutes
76
Prlonged decelerations are not concerning if ....
Not recurrent
Normal FHR baseline before and after deceleration
Moderate variability
77
What is the cause of prolonged decelerations? Categories?
Any mechanism that causes profound change in fetal O2
Uteroplacental insufficiency
Umbilical blood flow interruption
Vagal stimulation
78
What causes uteroplacental insufficiency?
tachysystole
Maternal hypotension
Abruption
79
What causes umbilical blood flow interruption?
Cord compression
Cord prolapse
80
What causes vagal stimulation?
Profound head compression
Rapid fetal descent
81
VEAL CHOP means?
V- variable condition C: Cord compression
E- early deceleration. H: Head compression
A- Acceleration O: Okay
L: Late acceleration. P: Problems with placenta
82
What is intrauterine resuscitation? (9)
Position change
IV fluid bolus to increase volume and perfusion
CALL FOR HELP
Notify provider and request immediate evaluation
Assess for tachysystole
Check blood pressure
Cervical exam
Prepare for possible amnioinfusion
Alter pushing efforts– stop, push every other contraction
83
If a a patient has tachysystole you should
Turn off Pitocin if running
Consider Terbutaline 0.25 mg SQ or IV (relaxes smooth muscles --> decreased contractions)
84
If a patient has hypotension you should
Correct if hypotensive– fluid bolus and meds (Ephedrine 5-10 mg IV or Phenylephrine 0.1 to 0.5 mg IV)
85
When during a cervical exam in intrauterine resuscitation you should be checking for?
Check for prolapsed cord, rapid cervical dilation, rapid descent
86
When would you prepare for an amnioinfusion?
If there is repetitive variable decelerations
Variable are caused by cord compression so increased fluid would relieve any pressure on the cord
ONLY VARIABLE
87
Why would you have your patient every other time?
To allow fetus to recover between alterations
88
What is a category 1?
Normal baseline rate between 110-160
Moderate variability
No late or variable decelerations
With or without early decelerations
With or without early accelerations
89
What are the goals in category 1? Actions?
Maximize perfusion and maintain appropriate uterine activity
Intermittent auscultation and palpation for low risk patients and appropriate patients
Intermitent EFM
90
Why would you have your patient every other time?
To allow fetus to recover between alterations
91
What is a category 2? Is this common?
All other patterns not included in 1 or 3
Majority of fetus will have this category during birth
92
What are the goals in category 2? Actions?
Prevent worsening and improve oxygen
Increase frequency of FHR assessments
Continue or initiate EFM
Initiate intrauterine resuscitation
93
What is category 3?
Absent variability WITH:
1. Recurrent lates
2. Recurrent variables
3. Bradycardia
4. Sinusoidal patern
94
What Is the goal of category 3? What are the actions?
Correct abnormal oxygenation
Continue EFM
Initiate intrauterine resuscitation
Prepare for c-section if not improvement
95
When it tests of fetal well being done? (6)
During antepartum period
Commonly done for high-risk conditions-DM, pre-eclampsia, IUGR, multiple gestation, postdates, decreased fetal movement
96
What is a non-stress test? How long are they monitored for? When is it done? Invasive?
With intact ANS and adequate oxygenation the FHR will accelerate in response to movement
Electronic monitoring is used for 20-40 minutes
In high risk pregnancies at least 2x/week
Noninvasive
97
What is a reactive NST over 32 weeks? 28-32 weeks?
Over 32: at least 2 FHR accelerations in 20 minutes. Accelerations should be 15 above baseline FHR and also at least 15 seconds
28-32: at least 2 FHR accelerations in 20 minutes of at least 10 bmp above baseline for at least 10 seconds
98
What does a positive NST mean?
Decreased risk for asphyxia in next 2-3 days
99
What is a negative NST?
Insuffuicent accelerations in 40 minutes
Need follow up testing
100
What could affect a NST? What should you do for this?
Fetuses have sleep cycles for about 20 minutes therefore if NST is non-reactive in 20 minutes wake the fetus and continue testing for additional 20 minutes
To wake fetus may use sound or vibration to stimulate movement such as vibroacoustic stimulation- “buzzer”
101
When using vibration to wake the fetus how is this done?
Placed over fetal head on moms abdomen
Vibration for less than 2-3 seconds
102
What does a biophysical profile (BPP) assess for?
Assessment of fetal reflex activities controlled by the CNS and sensitive to fetal hypoxia
103
How is a BPP scored? How long should you monitor for these on ultrasound?
Score of 2 (present) or 0 (absent) given for the following:
NST
Fetal breathing movements
Fetal movement
Fetal tone
Amniotic fluid volume
Monitor for 30 minutes
104
What classifies as present fetal breathing movements on a BPP?
at least 1 episode of fetal breathing lasting at least 30 seconds
105
What classifies as present fetal movement on a BPP?
3 or more discrete body or limb movements
106
What classifies as present fetal tone on a BPP?
One or more extension/flexion movements of extremities
107
What classifies as present amniotic fluid volume on a BPP?
at least 1 pocket of at least 2cm or AFI more than 5cm
108
A score of 8-10/10 on a BPP means? 6/10? 0-4/10?
8-10/10: normally oxygenated fetus and low risk of asphyxia in the next week and continue to monitor
6/10: possible asphyxia - repeat or possible induction
0-4/10: very worrisome, deliver baby
109
What is the Amniotic Fluid Volume Assessment? What is normal amount?
Measurement of the volume of amniotic fluid with ultrasound
Amount varies through pregnancy- average 8 to 24 cm
110
What is a amniotic fluid index?
Deepest pockets measured in 4 quadrants of maternal abdomen via U/S
Sum of these 4 pockets --> AFI
111
What is maximum vertical pocket?
Largest single pocket of amniotic fluid not persistently containing fetal extremities or umbilical cord
112
What is oligohydramnios? Causes?
Too little amniotic fluid: AFI less than 5 cm or MVP less that 2 cm
Prolonged fetal hypoxemia causes shunting of blood away from the kidneys
Decreases production of fetal urine and therefore the amniotic fluid volume is decreased
113
What is oligohydramnios associated with?
Increased risk of mortality d/t cord compression because there is not enough fluid to cushion the cord
114
What is hydramnios? Caused by? High risk for?
Too much fluid: AFI over 24 cm or MVP over 8 cm
Associated with fetal malformation such as obstruction of GI tract, neural tube defect, fetal hydrops, parental diabetes (high glucose --> polyuria in fetus)
High risk of cord prolapse
115
What is a modified biophysical profile? If both NST and AFI/MVP look good _____.
Less labor intensive and less expensive than BPP
Components
NST (Indicator of short-term fetal well-being)
Amniotic fluid volume assessment--AFI/MVP (Indicator of long-term placental function)
If both NST and AFI/MVP look good, low risk for asphyxia
116
What is a contraction stress test? What is adequate testing?
Evaluates response of fetus to the stress of contractions and how well fetus can tolerate decrease perfusion
Contractions causes decreased oxygen transport to fetus
Contractions can be spontaneous, induced with Pitocin or nipple stimulation
Three contractions in 10 minutes lasting 40 seconds
117
What is a negative CST?
GOOD
No significant variable or late decelerations noted
Associated with good fetal outcomes
118
What is a positive CST?
BAD
Late decelerations noted with at least 50% of contractions
Require further testing
119
What is Equivocal CST/Suspicious CST?
Questionable
Intermittent late or variable decelerations
Requires further testing
120
What are doppler flow studies? What does it measure? When is it used?
Ultrasound evaluation assessing placental function
Measures BF through umbilical artery
Systolic/diastolic ratio - absent, reversed or elevated is abnormal BF
Used for fetal growth restriction evaluation
121
When is fetal weight measured? Is it accurate? How often?
3rd trimester
Imprecise methods (off by 1-2 pounds)
High risk measured every few weeks to ensure baby is following growth curve
122
What does inadequate or excessive growth indicated?
Could indicate alterations in fetal well being
123
What are the causes of IUGR? (4)
Infections
Placental problems
Genetic abnormalities
Uteroplacental insufficiency
124
What are the causes of macrosomia?
4000-4500 grams
Diabetes d/t excess glucose because insulin doesn't get to baby so baby puts on weight
125
When is the evaluation of fetal lung maturity used? What do the results decide?
Used before elective childbirth of fetus before term
Immature lungs - delay deliver
Mature - risk of RDS is low
126
How is evaluation of fetal lung maturity done? Two types?
Amniotic fluid is obtain by an amniocentesis
Leithin/Sphingomyelin ratio
Phospatidylglycerol (PG)
127
What is a Leithin/Sphingomyelin ratio?
contains tow components of surfactant
When over 2:1 demonstrate low risk of RDS and mature lungs
128
What is a Phospatidylglycerol (PG)?
Component of surfactant
Appears at 36 weeks gestation and continues to increase until term
Presence demonstrates low risk of RDS
129
Is the eval of fetal lung maturity used on spontaneous labor?
No, only if elective
