July 6, 1998
OB page 1
Handout – fetal monitoring
Fetal Monitoring
- internal measuring of contractions
- 120- 150 bpm normal fetal heart rate, it is driven by autonomic nervous system,
sympathetic increases and parasympathetic decreases
- uterine activity – peak contraction between 50-70mmHg
- early uniform deceleration is indicative of head compression – does not usually
signify fetal distress
- late uniform deceleration – baby is not getting enough blood supply, can be from
epidural causing hypotension (treat with O2, oxygen, hydration and ephedrine)
- variable deceleration – don’t know exactly when it will come, drops to 50 over shoots
with correction to 190+ - corresponds to cord compression
- fetal heart rate accelerates with contractions = good thing, healthy fetus
- decreased fetal heart rate variability – see after sedation, baby may go into sleep
pattern, should recover after a short while, long term decreased fetal heart rate
variability is indicative of fetal distress = 20 minutes is cut off time
- fetal tachycardia from maternal fever or drug administration(ephedrine) or fetal
distress
- second stage head compression with pushing should recover heart rate
- sustained fetal bradycardia = rate below 90 – treat with O2, change of position,
increase fluids, ephedrine, stop oxytocin, stop contractions with Brethen – if doesn’t
stop immediate c-section – only give them a few minutes to recover heart rate
Contraction Stress test
See how baby responds to stress
Start contractions for ten minutes and see how baby responds
Negative test – recovers
Unstress test
Baby monitored with out contractions, looking for movement and heart rate changes
Nonreactive – no movement, no long term variability, may do c-section at that time
Test
Know what the different fetal monitoring problems are caused by which is from epidural
which is from head compression
Apgar score – calculate out score
Four patterns of fetal heart rate
- bradycardia – associated with late deceleration due to hypotension or uterine
hyperstimulation – treat with IV fluids, position change and ephedrine, if from
hyperstimulation stop oxytocin, may need turbutaline or brethen
- variable decelerations – associated with umbilical cord compression – treat with
position change, if persistent problem give amniotic infusion (rare), head compression
during second stage of labor also causes this – no treatment if heart rate comes back
up when there is no contraction
- late deceleration – decrease uterine blood flow – treat with O2, hydration, position
change sometimes ephedrine given, late deceleration is associated with decrease
variability – indicative of fetal distress – treat the same way but if does not respond =
immediate delivery of the child
Anesthesia’s knowledge base for fetal monitoring is to understand fetal heart rate, what
variability shows, understand what long term and short term variability shows,
understanding of responses and when OB nurse asks you to give ephedrine, you don’t
argue with them, just takes 5-10mg of ephedrine for above treatments
One or two questions on history –
No dates but maybe a couple of names, what is John Snow associated with = first used
Chloroform for OB anesthesia
Who was the first American women to have OB anesthesia – Fanny Wadsworth
Longfellow
Basically know anatomy and physiologic changes of pregnancy and what are its effects
on the maternal and fetal unit and what things does that mean as far as an anesthetic
standpoint either from a mechanical or pharmacological
Mechanical – means things that we may do to the patient, such as edema and swelling of
the airway – a mechanical problem would be difficult intubation and high risk for
esophageal intubation
Mechanical problems with regional anesthesia = decrease epidural space, landmarks,
difficulty placing the needle
Pharmacological problems = large volume of distribution, decreased MAC, drug
requirements are reduced due to decrease protein binding
Three factors that can cause decrease uterine blood flow
- vasoconstriction – endogenous and exogenous catecholaimines, hyperventilation
- uterine contraction – normally short term
- hypotention – from aortocaval compression, epidural anesthesia
Uterine blood flow is 700cc per minute
It is non-auto regulated
Nerve innervation for stage 1 labor – T10, 11 and 12
Second stage S 1 - 4
Will give a situation with labor stages and have to tell what anesthetic intervention would
be for it, think about which nerves are involved
Stage 1 intervention – pudendal block
During Stage 2of labor, COMPLETE pain relief can be obtained by which of the
following ?
spinal - correct
lumbar epidural - correct
paracervical block
pudendal block
Have an understanding of pharmacology as far as use of local anesthetics for regional and
effects of general anesthesia (decreasing MAC…) for vaginal and c-section deliveries,
tubals…
Questions about – surgery on the OB patient for non OB surgery
Differentiate characteristics of preeclampsia, eclampsia versus HELLP syndrome
Differentiate between bleeding disorders, placenta previa versus abruption
Match local anesthetic with a particular characteristic relative to OB
lidocaine
bupivicaine – characterized by cardiac arrest
prilocaine – hemoglobinemia
etidocaine- motor block outlasts sensory block
chloroprocaine – severe back pain, rapid metabolism in maternal and fetal blood (ester
metabolism)
Advantage of spinal over epidural anesthesia for c-section
- quicker onset of analgesia
- decrease dose of local
Disadvantages of spinal
- high incidence of PDPH
- less control = can’t give more, can’t predict spread
A decrease in uterine blood flow can occur with
aortocaval compression
contractions
drug induced hypotension
local anesthetics in high concentrations
Adverse effects associated with compression of the AORTA include
- nausea and vomiting
- changes in cerebral blood flow
- pallor
- decrease in uterine blood flow = answer
Venous compression causes – pallor, decrease blood flow to the brain, and nausea and
vomiting
Venous compression has maternal symptoms
Aortal compression associated with uterine and fetal blood flow problems
Factors which lead to an increased response to inhaled anesthetics (decrease MAC)
during pregnancy
- increased minute ventilation
- decreased FRC
- decreased MAC
Possible causes of late decelerations during fetal heart monitoring include
maternal hypotension
excessive uterine activity
Agents useful in decreasing the incidence of shivering during labor in which epidural
analgesia is employed
warming IV fluids
narcotics – demerol IV or via epidural, sufentenil will also work
Which of the following decreases fetal heart rate beat to bear variability
fetal asphxyia = answer
morphine
ephedrine
glycopyrolate
Emergency general anesthetic for a c-section, which of the following agents are useful for
raising the gastric pH
Sodium citrate = answer – raising gastric pH urgently
Reglan
Zantac
Signs and symptoms of PDPH
Nausea and vomiting, blurred vision, ringing in ears
Classic sign -Headache worse when standing better when lying down
Variable deceleration may occur in response to
Umbilical cord compression = answer
Fetal head compression
Utero-placental insufficiency
Maternal hypotension
During emergency c-section under spinal anesthesia, the parturient developed a cough,
wheezing, stridor, and becomes cyanotic, the trachea is intubated and food is noted in the
pharynx – appropriate treatment would include
Oxygen 100% with peep = answer
Tracheal suctioning = answer
Steriods
Saline lavage
Hemovate is administered directly into the myometrium to treat uterine atony in a 28 year
–old mother possible complications from this treatment would include?
Nasuea and vomiting
Bronchospasm
Fever
Hypoxemia (due to bronchospasm)
Answer – all of the above
Preeclapmtic patient with history of asthma that has uterine atony what is drug of choice
Oxytocin only hemovate and methergin contraindicated due to hemovate causing
bronchospasm and methergin causing hypertension
When preeclampsia is designated as serve, which of the following conditions exists?
Proteinruia > 5gm a day
Visual distrubances
Urine output less than 400cc/day
WBC > 15,000 (this one is not an answer others are)
Which of the following anti hypertensive drugs used to treat pregnancy induced
hypertension are smooth muscle relaxants could cause postpartum hemorrhage
Dantorlene
Nitroprusside
(both of these are correct)
Negative side effects of magnsium sulfate overdose
Heart block
Respiratory depression
Hypotension
Coagulopathy (all but this one)
Passive diffusion of substances across the placenta is enhanced by
low molecular weight of substance
decreased maternal protein binding
high lipid solubility
Which of the following is decreased during pregnancy
MAC
Pseudocholinesterase
Local anesthetic needs
Hematocrit
Answer – all of the above
Case scenerio
An epidural is placed into a 32 year-old parturient receiving Magnesium sulfate, for
preeclampsia, minutes after administration of the test dose, the bolus infusion is
interrupted due to a contraction, after the contraction subsides a slow epidural injection of
bupivicaine is resumed at the same time the patient complains of shortness of breath, she
is panic stricken, wrestles with the nurses, repeats that she can not breath and becomes
cyanotic and loses consciousness. During resusitation oozing is noted from the IV site
and a pink froth from the ETT. The most likely diagnosis is
Amniotic fluid embolism (answer)
High spinal
Intravascular bupivicaine injection
Magnesium overdose
Eclampsia
A 250 pound primigravida has B/P of 180/95 during an office visit at 18 weeks of
gestation and a pressure one week later of 170/95 some ankle but no facial edema and no
protein detected in the urine these findings would be classified as
preeclampsia
chronic hypertension = answer - 18 weeks, preeclampsia occurs after 20 with proteinuria
gestational chronic hypertension with superimposed preeclampsia
gestational hypertension
a normal finding
The most common side effect of intraspinal narcotics in the obstetrical population is
Puritis (answer)
respiratory depression
nausea and vomiting
urinary retention
23 year old in the first trimester is brought to the OR for emergency appy, general
anesthesia is planned, a increased risk of congenital malformations is associated with
which drugs has been suggested and should all most always be avoided
diazepam (answer – all BZD)
thiopental
nitrous oxide
isoflurane
Which of the following properties of epidurally administered local anesthetics determines
the extent to which epinephrine will prolong the duration of the block
Molecular weight
lipid solubility (answer)
pKa
Amide versus ester structure
concentration
Which of the following opioids is unique in that is has both local anesthetic and narcotic
properties?
morphine
meperidine –(answer- can give via spinal and get spinal block)
stadol
Under which of the following conditions will the smallest amount of stadol reach the
placenta?
At the onset of contraction
During peak of the contraction (answer)
At the end of a contraction
Between contractions
No relationship exists between the drug concentration and uterine contraction
A 45 year-old gravida 9, para 6 parturient presents to ER in labor, this patient has an
increased risk for all of the following except
uterine atony
placenta abruption
placenta previa
amnotic fluid emboli
preeclampsia (answer)
A 29 year-old gravida 1, para 0 parturient at 25 weeks gestation is going to undergo an
emergency appy with general anesthesia with isoflurane, nitrous oxide, and oxygen
which of the following is a proven untoward consequence of general anesthesia
nephroblastoma
cleft palate
mental retardation
behavioral problems
none of the above (answer)
A 24 year-old gravida 2, para 1 parturient is anesthetized for an emergency c-section, on
emergence from general anesthesia, the ETT is removed, and the patient becomes
cyanotic, oxygen is administered by positive pressure mask bag ventilation, high airway
pressures are necessary to ventilate the patient, wheezing is noted over both lungs, B/P
falls from 120/80 to 60/30, HR increases from 105 to 180, the most likely cause of these
manifestations
Venous air embolism
Amnotic fluid embolism
Aspiration (answer)
Mucous plug in trachea
pneumothorax
Cardiac output is the greatest immediately following the delivery of the newborn
True
A 1000gram cyanotic infant born with a heart rate of 85, completely limp, making no
respiratory effort and showing no response to stimulation, should receive a 1 minute
Apgar score of
1 minute Apgar score of = 1
Which of the following respiratory parameters is not increased in the parturient?
Minute ventilation
Tidal volume
Arterial PaO2
Serum bicarbonate (answer)
Oxygen consumption
A lumbar epidural place is placed in a healthy 25 year old for a c-section, 25 minutes
after a full dose of local anesthetic is administered, the patient complains she has
difficulty breathing through her nose, the most likely explanation for this is
Total spinal with inadvertant subarachnoid injection of local anesthetic
Total sympathetectomy and nasal congestion from high level of blockade (answer)
Volume over load
Amniotic fluid embolism
Classic side effects of magnesium sulfate when used to treat preeclampsia are all of the
following except
Potentiation of neuromusclar blockade with pancuronium
renal failure –(answer) improves renal blood flow
neonatal hypotonia
hypoventilation
Somatic pain associated with the second stage of labor can be controlled by any of the
following except
caudal
pudental
lumabr epidural
paracervical block - answer (first stage block only)
Which of the following signs and symptoms are not associated with amniotic fluid
embolism
hypertension – get hypotension
bleeding
hypoxemia
seizures
when is a fetus most susceptible to the effects of terotenogenic agents
1 –2 weeks gestation
3 – 8 weeks - answer
7 – 21 weeks
14 – 28 weeks
anytime during the third trimester
A 1000g infant is born to a 24 year-old mother addict to heroin, mother admits to taking
an extra hit of heroin before coming to the hospital because she was nervous, the infants
respiratory depression would be best managed by
Various doses of narcan
Don’t reverse as baby is all ready addicted
Leading cause of maternal death in the US is
Hemorrhage 30%
Followed by pulmonary embolism 24%
PIH 18%
Infection 8%
General anesthesia 3%
Leading cause of death from anesthesia = aspiration with failed intubation
What is P50 of fetal hemoglobin at birth = 19 (won’t be on test)
Cardiac output returns to the non-pregnant levels by how many weeks postpartum?
2 weeks
Normal fetal HR 120-160
Magnesium sulfate is used as a anticonvulsant and may produce all of the following
except
Sedation
Analgesia = answer
Hypotension
Respiratory depression
What percent of all pregnancies are affected by preeclampsia?
2%
7% - answer
12%
19%
An 18 year-old receiving subcutaneous heparin develops a Horner’s syndrome (very
small pupil on that side) on the left side after the placement of an epidural labor
analgesia, on physical exam a T-5 anesthetic level is noted, aside from the Horner’s
syndrome no other findings are revealed. The most appropriate course of action at this
time would be?
Remove the epidural
Consult a neurosurgeon
Obtain a cat scan
Secure the air way
None of the above – answer – it is from the sympathectomy it will go away
Which of the following vasopressors does not decrease uterine blood flow?
Epinephrine
phenylephrine
Ephedrine - answer
A general anesthesia is induced for 35 year-old for an elective c-section, no part of the
glottic apparatus is visible after 2 unsuccessful attempts at intubation but mask ventilation
is adequate, the most appropriate step at this time would be?
Continue mask ventilation with cricoid pressure
Attempt a blind nasal intubation
Wake the patient up – answer
Use an esophageal-combi tube
Which of the following lung volumes change the LEAST during pregnancy
Tidal volume
FRC
ERV
RV
Vital capacity - answer
A 38 year old primigravida with placenta previa and active vaginal bleeding, arrives in
the OR with a B/P of 75 systolic, a c-section is planned, the patient is light headed and
scared, which of the following anesthetic plans would be most appropriate
Spinal anesthetic with 8mg of tetracaine
Epidural anesthetic with 20cc of 2-chloroprocaine
General anesthetic induction with 3-4mg of thiopental, intubation with 100mg SUX
General anesthetic induction of .5 – 1mg/kg ketamine and 100mg SUX – answer
A 19 year-old mother is brought to the OR for emergency c-section under epidural, 25cc
of 3% 2-chloroprocaine are used to provide surgical anesthesia, well after the baby is
delivered, the mother complains of excruciating back pain, neurologic exam is normal,
the most appropriate treatment choice would be
Epidural blood patch
Cat scan
Emergency laminectomy
100 mcg of epidural fentanyl - answer
The statement which correctly describes the difference between maternal fetal blood
relationship, includes which of the following
Fetal blood has more hemoglobin concentration than maternal blood
Fetal hemoglobin has greater affinity for oxygen than maternal hemoglobin - answer
Fetal oxy-hemoglobin dissociation curve is shifted to the right of the maternal curve
Fetal blood has a lower pH than maternal blood - answer