Obstetrics 3 Flashcards
Fifteen minutes after a patient’s epidural as dosed, the patient becomes hypotensive and experiences respiratory arrest. What is the MOST likely etiology?
a. epidural catheter migration
b. loss of accessory respiratory muscle strength
c. subdural injection
d. eclampsia
C. subdural injection
this patient has experienced a total spinal
Describe the ways that a patient can develop a total spinal.
an epidural dose injected into the subarachnoid space
an epidural dose injected into the subdural space (s/sx may be delayed)
a single-shot spinal after a failed epidural block
Describe the treatment for a total spinal.
treatment is supportive and includes airway management, IVF, vasopressors, left uterine displacement, and leg elevation
___________________ will rule out subdural placement.
Neither catheter aspiration nor a test dose
Symptoms of a total spinal will include
dyspnea, difficulty phonating, and hypotension; loss of consciousness occurs as a result of cerebral hypoperfusion secondary to severe hypotension
Differential diagnosis for high spinal includes
anaphylactic shock, eclampsia, and amniotic fluid embolism
________ are causes of late decelerations.
maternal acidosis and preeclampsia
______ is consistent with early decelerations.
Fetal head compression
______ is a surrogate measure of fetal wellbeing.
Fetal heart rate
Fetal heart rate provides an indirect method to asess
fetal hypoxia and acidosis
_________ is a function of uterine and placental blood flow
Fetal oxygenation
The fetus responds to stress with
peripheral vasoconstriction, hypertension, and a baroreceptor-mediated reduction in heart rate
Normal fetal heart rate is
110-160
Bradycardic fetal heart rate is
<110
Tachycardic fetal heart rate is
> 160
What are the three types of fetal decelerations
early
late
variable
Which fetal decelerations put the fetus at risk?
late and variable
An absence of variability may indicate
fetal distress
Causes of lack of variability include
CNS depressants, hypoxemia, and acidosis
Variability is an indicator of
oxygenation, normal acid-base status
intact central nervous system
& SNS & PNS are functioning in a healthy way
Fetal causes of bradycardia include
asphyxia and acidosis
Maternal causes that lead to fetal bradycardia include
hypoxemia
drugs that decrease uteroplacental perfusion
Fetal causes of tachycardia include
hypoxemia
arrhythmias
Maternal causes that can lead to fetal tachycardia include
fever
choriomnionitis
atropine
ephedrine
terbutaline
What is normal variability?
6-25 bpm
What is the mnemonic VEAL CHOP?
Variable decels: Cord compression
Early decels: Head compression
Accelerations: Ok or give oxygen
Late decels: Placental insufficiency
According to the American College of Obstetrics and Gynecologists, which findings are predictive of poor fetal status?
a. sinusoidal pattern
b. no late or variable decelerations
c. bradycardia without absence of baseline variability
d. absent baseline variability
A & D.
Someone trained in fetal monitoring must monitor and document fetal status
before and after any anesthetic procedure
Describe Category 1 for evaluation of fetal heart rate.
suggest normal acid-base status with no threat to fetal oxygenation
Describe Category 2 for evaluation of fetal heart rate.
Is not 1 or 3 and cannot predict a normal or abnormal acid-base status
Describe Category 3 for evaluation of fetal heart rate.
suggest abnormal acid-base status with a significant threat to fetal oxygenation
Describe Category 1 findings.
Baseline heart rate between 110-160
moderate variability
accelerations absent or present
early decelerations absent or present
No late or variable decelerations
Describe category 2 findings.
Bradycardia without the absence of baseline FHR variability
tachycardia
variable variability
absent or minimal acceleration with fetal stimulation
recurrent variable decelerations
Describe category 3 findings.
bradycardia
absent baseline variability
recurrent late deceleration
recurrent variable deceleration
sinusoidal pattern
The first sign of magnesium toxicity is
diminished deep tendon reflexes
Premature delivery is defined as delivery before
37 weeks gestation
The leading cause of perinatal morbidity and mortality is
premature delivery
The incidence of prematurity rises with
multiple gestations and premature rupture of membranes
Select fetal complications of prematurity include
respiratory distress syndrome, intraventricular hemorrhage, and NEC
_______ may be used to delay labor by suppressing uterine contractions (up to 24-48 hours).
Tocolytic agents
Examples of tocolytic agents include
beta-agonists
magnesium sulfate
calcium channel blockers
nitric oxide donors
In the setting of preterm labor, ________ are given to hasten fetal lung maturity.
corticosteroids (betamethasone)
Tocolytic agents or corticosteroids are seldom given after
33 weeks of gestation
Side effects of beta agonists include
hyperglycemia resulting from glycogenolysis in the liver
hypokalemia from intracellular potassium shift
cross the placenta and may increase FHR
newborn of a hyperglycemic mother is at risk of post-delivery hypoglycemia
What are examples of beta agonist tocolytics?
ritodrine and terbutaline
How do beta agonists prevent uterine contraction?
beta-2 stimulation increases intracellular cAMP–> turns on protein kinase, turns of MLCK–> relaxes the uterus
also increases progesterone release which contributes to additional myometrial relaxation
How to calcium channel blockers work to prevent uterine contraction?
Blocks the influx of Ca+2 into the uterine muscle–> reduces Ca2+ release from the SR–> turns off myosin light-chain kinases–> relaxes uterine muscle
_______ is the first-line calcium channel blocker agent.
PO Nifedipine
Co-administration of calcium channel blockers with ______ can contribute to skeletal muscle weakness.
Magnesium
How do nitric oxide donors work?
nitric oxide is a vasodilator that is essential in maintaining smooth muscle tone
increases cGMP–> turns off myosin light-chain kinases–> relaxes uterine muscle
_______ are rarely used due to hypotension.
Nitric oxide donors
How does magnesium sulfate work?
calcium antagonist–> relaxes smooth muscle by turning off MLCK in the vasuclature, airway, and uterus
also hyperpolarizes excitable tissues
The ______ eliminate Mg2+, so mothers with ______ should be closely monitored
kidneys; renal insufficiency
What is the normal range of magnesium?
1.8-2.5 mg/dL
Hypomagnesemia can lead to
tetany, seizures, and dysrhythmias
We start to see diminished deep tendon reflexes at a magnesium level of
5-7 mg/dL
We see a loss of deep tendon reflexes, hypotension, EKG changes, and somnolence, at a magnesium of
7-12 mg/dL
We see respiratory depression, complete heart block, cardiac arrest, coma, and paralysis at a magnesium level of
> 12 mg/dL
Additional side effects of hypermagnesemia include
skeletal muscle weakness (potentiates NMBD)
pulmonary edema
reduced responsiveness to ephedrine and phenylephrine
Treatment for hypermagnesemia includes
supportive measures
diuretics (to facilitate excretion of Mg2+)
IV calcium gluconate 1 g over 10 minutes (to antagonize Mg2+)
List 6 complications of premature delivery
NEC
intraventricular hemorrhage
respiratory insufficiency
hypocalcemia
hypoglycemia
hyperbilirubinemia
Anesthetic considerations for the use of methergine include:
a. IV administration is safe
b. tocolysis
c. administration of 0.2 mg
d. risk of water intoxication
c. - should always be given IM
