FINAL Flashcards
When does aortocaval compression become significant in pregnancy?
18-20 weeks
-if uterus is larger than normal (multiple gestations/polyhydramnios) aortocaval compression may appear earlier
What are the signs and symptoms of supine hypotension syndrome?
-Hypotension
-Sweating
-Bradycardia
-Pallor
-Nausea
-Vomiting
What is the best vasoactive for treating hypotension in the parturient?
Phenylephrine
What is ion trapping, and how does fetal pH affect transfer of medications across the placenta?
Fetal pH is lower than maternal pH, so that weak bases become more ionized in the fetus, thus limiting their transfer back across the placenta. Normally, the difference in pH is only 0.1 and this “ion trapping” is irrelevant, but fetal acidosis can significantly increase the fetal concentration of drugs such as local anesthetics.
Significant maternal stress or lack of BF can cause fetal acidosis. Basic drugs are more likely to get trapped. Fetal acidosis can increase the concentration gradient which leads to ion trapping
Which medications do not cross the placenta?
NMBs
Heparin
Insulin
Glycopyrrolate*** answer to red book question
Which medications do cross the placenta?
Local anesthesthetics (except chloroprocaine d/t rapid metabolism)
IV anesthetics
Volatile anesthetics
Opioids
Benzodiazepines
Atropine
Beta-blockers
Magnesium
What are the symptoms of magnesium toxicity?
HYPOmagnesium 1mg/dL= seizures
HYPERmagnesium
-8-10mg/dl= decreased deep tendon reflexes
-10-15mg/dL= Widened QRS and PR interval (cardiac conduction defects), respiratory depression
-20+ = cardiac arrest
Treat with calcium gluconate or CaCl
Prostaglandin F2: Carboprost (Hemabate) indications, contraindications, and dosage:
3rd line uterotonic
Dose: 250mcg IM or injected into the uterus
(0.25mg IM) - can be given intrauterine
DO NOT GIVE TO ASTHMATIC PTS= BRONCHOSPASM
Side effects:
-N/V
-diarrhea
-hypotension
-hypertension
-bronchospasm
Methergine indications, contraindications and dosage:
Methergine: Second-line uterotonic
-Dose : 0.2mg IM
DO NOT GIVE IV= HTN/VASOCONSTRICTION
-IV administration can cause significant vasoconstriction, hypertension, and cerebral hemorrhage
-Hepatic metabolism half-life: 2 hrs.
Normal uterine blood flow:
700-900 mL /min at term
Uterine blood flow does NOT autoregulate – therefore, it’s dependent on MAP, CO, and uterine vascular resistance. It’s a low-resistance system, uterine blood flow is primarily dependent on MAP and CO
UBF = UAP-UVP/UVR
(uterine blood flow = Uterine arterial pressure- uterine vascular pressure/uterine vascular resistance)
What CV changes are increased in pregnancy?
Increased HR (15%)
Increased SV
Increased PaO2
Increased CO (highest just after delivery, returns to normal after 14 days)
Increased P50 (right shift, facilitated O2 delivery to fetus)
What CV parameters don’t change in pregnancy?
SBP-No change
MAP- No change
CVP- no change
PAOP- no change
What CV parameters decrease in pregnancy?
Decreased DBP
Decreased SVR
Decrease PVR (decreased response to angiotensin and NE)
Decreased PaCO2 (28-32)
Decreased HCO3
What axis deviation will you see in pregnancy?
Left axis deviation
What medications should not be used in reproductive technology?
Some lab studies suggest suggested that local anesthetic agents, nitrous oxide, and the volatile halogenated agents interfere with some aspects of reproductive physiology in vitro. However, avoid multimodal anesthesia, keep it clean, utilize sedation and perhaps avoid neuraxial analgesia.
Which of the following drugs should NOT be used during transvaginal oocyte retrieval (TVOR) for assisted reproductive technology (ART)?
A. Propofol
B. Ketamine
C. Midazolam
D. All are safe and can be used
D. All are safe and can be used
What are the symptoms of aspiration?
Bronchospasm, high airway pressures, hypoxemia, wheezing, HoTN and tachycardia
Other: sudden coughing, dyspnea/tachypnea, chest wall retraction, cyanosis not relieved by oxygen supplementation, in the development of pink frothy exudate
Tx: supplemental oxygen w/ positive pressure ventilation, peep, or continuous positive airway pressure and suctioning
Risk of aspiration greatly increases after 1st trimester
A 24-year-old gravida 2, para 1 parturient is anesthe- tized for emergency cesarean section. On emergence from general anesthesia, the endotracheal tube is removed and the patient becomes cyanotic. Oxygen is administered by positive-pressure bag and mask ven- tilation. High airway pressures are necessary to venti- late the patient, and wheezing is noted over both lung fields. The patient’s blood pressure falls from 120/80 to 60/30 mm Hg, and heart rate increases from 105 to 180 beats/min. The MOST likely cause of these manifestations is
A. Amniotic fluid embolism
B. Mucous plug in trachea
C. Pneumothorax
D. Aspiration
D. Aspiration
What are the consequences of general anesthesia on the fetus?
Neonatal respiratory & CNS depression
Non-obstetric surgery during pregnancy:
growth restriction
low birth weight
demise
↑incidence of preterm labor (highest during intraabdominal + pelvic surgery)
c. No anesthetic agent is a proven teratogen in humans.
d.Nitrous oxide has been shown to have teratogenic effect in rats during 1st trimester. Typically avoided during first 2 trimesters
When is the fetus most susceptible to the effects of teratogenic agents?
A. 1 to 2 weeks of gestation
B. 3 to 8 weeks of gestation
C. 9 to 14 weeks of gestation
D. 15 to 20 weeks of gestation
B. 3 to 8 weeks of gestation
What is placenta previa?
Typically presents as painless vaginal bleeding.
Considered complete previa when cervical os is entirely covered by placenta or can be some variation of partial cover
What places pts at risk for placenta accreta?
Pts with a previous history of c-section
Current placenta previa
What kind of previa is this?
COMPLETE
What kind of previa is this?
Partial
What kind of previa is this?
Marginal
What kind of previa is this?
Low-lying
What is placenta accreta?
Placenta Attached to the surface of the myometrium
What is placenta increta?
Placenta Invades the myometrium
What is placenta pancreta?
Completely through myometrium, into serosa, and potentially outside of uterus, with invasion into surrounding structures (e.g. bladder, colon).
Placenta extends beyond (penetrates) the uterus
Label the placenta accretas
A.) Normal
B.) Increta
C.) Accreta
D.) Percreta
Placenta accreta is suspected if the placenta has not been delivered within 30 minutes of the fetus delivery. Manual blunt dissection or placenta traction is attempted but can cause hemorrhage.
Increased risk with:
Placenta previa
Uterine scar (Asherman’s syndrome): D&C, myomectomy, c-section.
Thin placental decidua
Most common injury in ASA Closed Claim Project regarding OB anesthetic claims
Maternal nerve damage
Drugs which are the most appropriate in hemodynamically unstable parturient
Ketamine and etomidate, phenylephrine
What respiratory parameters increase in pregnancy?
Minute ventilation (MV)
respiratory rate (RR)
tidal volume (Vt)
Mallampati
What respiratory parameters do not change in prgnancy?
Vital capacity
Closing capacity (increased CV + decreased RV = no change CC)
What respiratory parameters are decreased in pregnancy?
total lung capacity (TLC)
functional residual capacity (FRC)
expiratory reserve volume (ERV)
residual volume (RV)
What are the side effects if intraspinal narcotics?
Most common: pruritis.
N/V
urinary retention
drowsiness.
How is diffusion across the placenta enhanced?
low molecular weight < 500 daltons (most anesthetic drugs),
high lipid solubility
non-ionized
nonpolar
What is the normal blood loss for a vaginal delivery
400-500mL
What is the normal blood loss for a c-section?
1000mL
What is a normal heart rate for a newborn?
110-160bpm
What are the 5 categories for the APGAR score?
-Heart rate
-Respiratory effort
-Muscle tone
-Reflex irritability
-Color
When is a 1 assigned for the APGAR categories?
HR: <100
Resp effort: irregular, slow, shallow, gasping
Muscle tone: some flexion of extremities
Reflex irritability: grimace
Color: Acrocyanotic (trunk pink, extremities blue)
What are some considerations with Mag therapy?
Neuromuscular blockade is enhanced
Increased muscle weakness with nifedipine
Best agents for increasing gastric pH
a. Sodium Citrate works within minutes to raise gastric pH- lasts ~30 min
b. H2 blockers (famotidine, ranitidine): Take at least 30 min to work
c. Metoclopramide (Reglan): dopamine antagonist which acts on intestinal tract via release of acetylcholine, this increases gut motility and facilitates gastric emptying, requires 40-60 min.
What can cause fetal bradycardia
a. < 110 –> HoTN, excessive uterine activity, hypoxemia, complete heart block
b. Fetal cause: asphyxia, acidosis
c. Maternal cause: Hypoxemia, Drugs that decrease uteroplacental perfusion
Symptoms of PDPH (post-dural puncture headache)
-Tinnitus
-diplopia
-photophobia
-Neck stiffness
-pain goes away while lying down
-can show up 12-48 hrs after dura puncture
Generalizations regarding diabetic parturient patients ie: large fetus, greater need for c-section, etc.
a. High blood glucose levels in mom brings extra glucose to baby, vitus makes more insulin to handle the extra glucose, extra glucose gets stored as fat & fetus becomes larger than normal
b. Progressive peripheral resistance to insulin in 2nd & 3rd trimesters, ↑ incidence of gestational HTN, polyhydramnios, and C-section
c. Considerations: stiff joint syndrome makes DL difficult d/t c-spine rigidity, w/ C-section keep tight control of serum BG(100< BG <180), gastroparesis with delayed emptying, HR variability, HTN, orthostatic HoTN, painless MI, response to meds (atropine and propranolol), resting tachycardia, infection prophylaxis, Possible toxicity if large volumes of lidocaine used in epidural
d. Initiation of early glycemic control is best way to prevent fetal structural abnormalities. Insulin requirements ↑ progressively & at the onset of labor + cont to after delivery
e. Protamine sulfate anaphylaxis in pts taking NPH or protamine zinc insulin epinephrine is your good friend
f. Placental insufficiency- reduced, superimposed preeclampsia, DKA where ketones cross placenta and fetal oxygenation have cont FHR monitoring
What is the cause of variable decelerations?
Cord compression
What is the cause of Early decelerations?
head compression
What is the cause of accelerations?
Don’t know- but OK- can give O2
What causes late decelerations?
Placental insufficiency
What is the concern with variable decelerations?
Risk for fetal hypoxemia
Abrupt decrease in FHR w no consistent pattern
Early fetal heart rate:
no risk of fetal hypoxemia, decrease in FHR that are usually < 20 beats/min, onset and offset parallel uterine contractions
Late fetal heart rate
fetal hypoxemia, FHR decrease 10-30 secs after the onset of a contraction and end 10-30 secs after contraction.
Sinusoidal fetal heart rate
regular smooth wave-like pattern with no short-term variability. Causes = severe fetal anemia, maternal administration of narcotics
Treatment for LAST?
STOP injecting LA, ventilate w/ 100% O2, avoid hyperventilation, control seizure (benzos), tx HoTN and bradycardia
INTRALIPID
Lipid emulsion therapy should be started: initial bolus of 20% intralipid is 1.5mL/kg over 2-3mins (~100mL in an adult) followed by a cont infusion of 0.25mL/kg (IBW)/hr. Repeat the bolus 1 or 2 mins for persistent CV collapse and double the concentration and infusion rate if the BP remains low. Upper limit of 20% intralipid is 10mL/kg over 30mins failure to respond pt should be placed on cardiopulmonary bypass
Which local anesthetic is best for emergent c-section?
3% 2-chloroprocaine w/ freshly added epinephrine (1:200,000) as well as 2% lidocaine w/ / freshly added epinephrine (1:200,000)
Faster onset of action!
What are the signs and symptoms of uterine rupture?
Sudden abdominal pain despite functioning epidural
vaginal bleeding
hypotension
cessation of labor
fetal distress- most reliable sign
TRUE or FALSE: The most common presentation of true uterine rupture is sudden profound fetal distress with continuous severe abdominal pain that CAN be masked by an epidural.
FALSE
How much blood do you inject for an epidural blood patch?
15-20 ccs
Stop injecting when pain goes away of pressure in ears
What is a historical fact that influences current OB practice?
In 1877, Gillette described 15 instances of neonatal depression that he attributed to morphine given during labor. Today, the effects on the fetus are considered before giving a drug to a mother.
What is the cost of IV iron?
$19
How do you calculate blood loss based on soaked raytects/laps?
1 g= 1mL
When should placenta accreta be suspected?
when placenta hasn’t been delivered within 30 mins of the fetus
What causes an increased risk for placenta accreta?
-placenta previa
-Uterine scar (Asherman’s syndrome d/t d&C, myomectomy or c-section)
- thin placental decidua
risk factors for abruptio placentae:
(most common cause of intrapartum fetal death)
-will have painful vaginal bleeding
- HTN
-Trauma
-cocaine use
-structural uterine abnormality
-multiparity
-alcohol use
At what amount of blood loss is it considered postpartum hemorrhage?
excess of 500mL
Common associations include prolonged labor, preeclampsia, multiple gestations
