Fetal Surveillance During Labor + Powerpoint ECGs! Flashcards
what is fetal heart monitoring?
this is monitoring of the fetal heart that was developed to detect fetal heart rate patterns that may be associated with poor outcomes of an infant
in hopes that was an interves on such patterns and prevent irreversible damage
most studies reveal the incidence of neurologic damage and perinatal death with the use of electronic FHR monitoring is _ (IS/ IS NOT) significantly lower than that documented with older methods (like auscultation with a stethoscope or doppler)
is not
does FHR monitoring have a decrease incidence of cerebral palsy
no; however magnesium sulfate has show to decrease risk
why dont we just go back to more traditional ways of monitoring the fetus like doppler or auscultation?
FHR monitoring is good reasssures that there will be good fetal outcomes
expensive to have someone intermittently checking via ascultation
can provide potential problems and allows you to take action to improve fetal condition if necessary
what are the types of fetal monitoring available?
external fetal monitoring: continuous or intermittent
internal fetal monitoring (most acurate in tracings)
external intermittent monitoring if pregnancy is uncomplicated ?
monitor every 30 minutes in active phase of first stage of labor
monitor every 15 minutes in second stage of labor
external intermittent monitoring if pregnancy is complicated
monitor every 15 minutes in active phase
monitor every 5 mintues during the second stage of pregnancy
what are the options of external electronic fetal monitoring
doppler ultrasound transducer
pressure sesitive tocodynamometer
how does a doppler ultrasound transducer work
it is placed on the mothers abdomen above the fetuses heart and records sound waves from the fetal heart back to the transducer
measures fetal heart rate
how does a pressure sensitive tocodynamometer work?
detects and records contractions
detects frequency of contractions NOT strength
external fetal monitoring may not be recorded acurately if that mother is _ (skinny/obese)
obese
what are the options of internal electronic fetal monitoring?
Feta Scalp Electrode (FSE)
Intrauterine Pressure Catheter (IUPC)
how does a fetal scalp electrode work?
it is an internal feta heary monitor that determines the rate from the R waves on the fetal echocardiogram
the maternal or fetal movement will not alter the signal
FSE must be avoided in _ patients and rare cases have been associated with fetal pustules on scalp
HIV
how does IUPC work
a soft plastic catheter is placed inside the cervix and it gives strength of contractions (down to the milimiter)
internal fetal monitoring requires _ to be ruptured
membranes
fetal oxygen reserve is only enough to meet its metabolic needs for approximately _ minutes
1-2 minutes
blood flow from the maternal circulation that supplies the fetus with coxygen through placental exchage of respiratory gases is interrupted during a _
contraction
normal fetus can tolerate the termporary reduction in _ to the placenta during contractions without suffering hypoxia because adequeate _ exchange occurs during intervals between contractions
blood flow
oxygen
fetal heart rate is determied by the _ (atrial, ventricle) pacemaker
atrial
the vagus _ (decelerates/accelerates) the heart
decelerates (parasympathetic)
sympathetic nerves _ (decelterate/accelerate) the heart
accelerate
a fetus whose oxygen supply is marginal cannot tolerate the stress of contractions and will be _
hypoxic
under hypoxic conditions chemoreceptors and baroreceptors in the peripheral arterial circulation of the fetus influence the _ by giving risk to contraction related or periodic changes in the FHR
fetal heart rate
hypoxia when severe in an infact will result in _ (aerobic/anerobic) metabolism resulting in the accumulation of what 2 acids?
resulting in fetal _ (acidosis/alkalosis)
anerobic
lactic and pyruvic acid
fetal acidosis
pH of fetal scalp blood is normally?
7.25-7.30
pH less that _ is considered fetal acidosis
less than 7.20
with each contraction blood flow from the mother to the baby initally ceases as the unterine _ vessels are compressed
myometrial
during contraction the mom and baby are briefly physiologically seperated
how can uterine contractions affect fetal heart rate
contractions can increase or decrease fetal heart rate
as a contraction begins to subside the unterine myometrial arteries _ allowing oxygenated blood and nutrients to flow from mother to baby. Uterine veins reopen and allow blood carrying fetal waste products to flow from _ to _.
reopen
baby to the mother
on a fetal monitoring strip what is the upper and lower tracings?
upper tracing : monitors fetal heart rate
lower tracing: measures uterine contactions
normal uterine contractions are?
5 contractions or less in a 10 minute period averaged over a 30 minute period
tachysystole in uterine contractions is?
greater than 5 contraction in 10 minutes averaged over a 30 minute window
can have associated decelerations
contractions can be measured from _ to _
peak to peak
how do you meausure the strength of contractions
with montevideo units (MVU)
MVUs are taken with an ? (internal monitoring technique)
Intrauterine pressure catheter (IUPC)
montevideo units should be greater than _ for the sum of contractions in a 10 minute period for at least 2 hours
200
what is the baseline of fetal heart rate?
the mean fetal heart rate rounded to increments of 5 beats per minute during a 10 minute segment
normal fetal heart rate bpm?
110-160
tachycardia FHR bpm
greater than 160
bradycardia fetal heart rate bpm
less than 110
Causes of bradycardia fetal heart rate
**late sign of fetal hypoxia
anesthesia
pitocin (oxytocin)
maternal hypotension
compression of the umbilical cord
heart block
causes of tachycadia fetal heart rate
**early sign of fetal hypoxia
** fetal infections
arrythmias, prematurity, maternal fever, fetal infection
what fetal infection is the most common cause of tachycardia
chorioamnionitis
fetal heart rate is under constant _ from baseline
variation
chemorectpros produce _ in response to hypoxia
tachycardia
baroreceptors influence fetal heart rate via the _ in response to changes fetal _ _
vagus nerve
blood pressure
what is baseline variability in fetal heart rate
these are fluctuations in the baseline fetal heart rate that are irregular in amplitude and frequency
fetal heart rate variability is visually quantified as the?
amplitude of peak to trough in bpm of change in baseline rate
absent baseline variabilty means
amplitude from peak to trough is undetected
minimal basline variability means
amplitude from peack to trough is detectable byt less than 5 beat per minute
moderate baseline variability means
normal amplitude from peak to trough that ranges from 6-25 beats per minute
marked baseline variability means?
amplitude from peak to trough is greater than 25 beats per minute
decreased variability in baseline is an indicator of possible fetal _
stress
decreased variability is ominous if associated with perisitent _ (early/late) decelerations
late
decreased variability is associated with _ (hypoxia, adequate oxygen) and _ (alkalosis/acidemia)
hypoxia and acidemia
the lack of oxygen and buildup of acid in the fetus depresses the fetal heart rate and CNS
the fetal heart rate may vary with uterine contractions by slowing or accelarating: these responses are catagorized how?
- no change
- acceleration (prolonged)
- deceleration (early, variable, late, prolonged deceleration)
what is a fetal heart rate acceleration
an abrupt increase in FHR that is a normal reassuring response
what is an expected FHR acceleration at greater than 32 weeks
what about less than 32 weeks
> 32 weeks: heart rate of greater than 15 bpm above baseline for 15 or more seconds
<32 weeks: heart rate greater than 10 bpm above baseline for more than 10 seconds
both accelerations dont last longer than 2 minutes
a prolonged acceleration is if it lasts longer than _ minutes
2
an acceleration that is a CHANGE in baseline is?
if the acceleration lasts longer than 10 minutes
causes of accelerations in FHR of babies
spontenous fetal movements
fetal scalp stimulation
vaginal examination
decelerations are when the FHR _ in response to uterine contractions
decreases
early decels are secondary to ?
head compression
fetal autonomic response to increased intracranial pressure caused by transient comporession of the fetal head
are early decels associated with fetal distress?
no
what does an early decel look like?
the begining (nadir) of the deceleration occurs at the same time as the peak of the uterine contraction
it is a mirror image of a uterine contraction
describe the physiology of early decels
- compression of fetal skull raises intracranial pressure
- there is a reduction in cerebal bloow flow
- the vagus nerve is activated
- nerve stimulates decrease in heart rate
recovry happens as soon as pressure is relieved
variable decelerations are secondary to?
umbilical cord compression
what are variable decelerations
aburpt decreases in FHR that can occur before, during, or after contraction starts
v shaped
in variable decelerations decrease in FHR is greater than _ bpm lasting greater than _ seconds and less that 2 minutes in durations
15 bpm
15 seconds
variable deceleration physiology
- umbilical cord compresson
- collapse of umbilical vein
- occludes umbilical artery
- hemodynamic changes
- baroreceptors and chemoreceptors activate
- vagus nerve stimulated
- slow fetal heart rate
in variabel decelerations if the umbilical cord is only slightly compressed this will obstruct the umbilical _ which returns re-oxygenated blood to the fetal heart
vein
the inritial normal fetal response to this variable decelerations is a slight _ in fetal heart rate to compensate for the lack of blood return and the slowly diminishing oxygen supplies
increase
if a slight increase in FHR is followed by a major drop in FHR this phenomenon is called a ?
shoulder
late decelerations are caused by?
uterine placental insufficiency (UPI)
late decelerations are the most _ (harmless/ominous)
ominous
repetitive LATE decelerations usually indicate fetal metabolic _ and _ arterial pH
acidosis
low
in late decelerations nadir of the deceleration occurs _ (after/before) the peak of the contraction
after
potential causes of late decelerations
excessive uterine activity
materal supine hypotension
prolonged decelerations are caused by?
they are commonly seen during?
caused by: disruption of oxygen transfer
seen during maternal pushing
prolonged decelerations are when there is a decrease in FHR from baseline that is greater than _ bpm lasting more than _ minutes
15bpm
2 minutes
a change in baseline in a deceleration is if the deceleration lasts more than _ minutes
10
sinusoidal FHR pattern is seen with fetal _
anemia
category I fetal heart rate tracing ?
normal tracing
**- normal baseline 110-160
- no late or variable decelerations
- accelerations may be present**
category II fetal heart tracing
Iintermediate stge)
intermittent variable decelerations- usually associated with normal outcomes
**recurrent variable decelerations **- umbilical cord compression- want to alleviate cord compression
how can we treat cord compression?
amnioinfusion in the first stage of labor
(normal saline infused through a transcervical IUPC)
how do we increase fetal oxygenation ?
category II
lateral positioning
IV fluids
O2 administration
modifications in pushing efforts (push after a contraction)
decrease oxytocin rate
discontinue ocytocin
how can we treat tachysystole
category II
- reduce uterine contraction is the goal
- lateral positioning, IV bolus, decrease oxytocin
terbutaline ***if refractory (tocolytic beta 2 agonsist)
what does the fetal heart tracing show in category III
absent baseline variability
recurrent late decels
recurrent variable decels
bradycardia
sinusoidal pattern
how do we treat category III FHR
prepare for delivery!!!
reposition the mother, give IV bolus, O2 supplementation
Scalp test
in a catergory III FHR is scalp stimulation test does not result in acceleration _ is adviseable
delivery
what is fetal scalp stimuation
the scalp is stimulated
helpful to differentiate fetal sleep from fetal acidosis when the tracing shows reduced variability but not decelerations
acceleration of 15 pbm lasting 15 seconds occurs when the pH value is 7.22 of greater (not acidotic)
