OB Flashcards
Term pregnancy is a pregnancy greater than ___ how many weeks?
37
Pre term labor occurs when?
between week 20 and 37
What do tocolytics do?
stop labor if rupture of mem has not occurred, they are smooth muscle relaxers
3 ex of tocolytics?
mag, nifedipine, indomethacin
5 causes of uteroplacental insufficiency?
smoking, insulin dep diabetes, HTN, drug abuse, alcohol consumption
Blood volume increases by what % during pregnancy?
45%
CO increases by what % in pregnancy?
40%
HR increases up to what % in pregnancy?
20%
Do SV and HR increase?
yes
SVR decreases what % in pregnancy and is the result of what?
10-15% (says 21% too) due to decrease in overall vascular tone (decrease resistance in uteroplacental, pulmonary, renal, and cutaneous vascular beds)
What is another pregnancy induced CV change that is r/t muscle?
hypertrophy
Why does dilutional anemia occur in pregnancy?
increase in plasma volume in excess of rbc
Usual Hg during pregnancy?
11
What offsets the decrease in Hg (2)?
right shift of the oxyhg curve and increase in CO
What is responsible for decreasing DBP and SBP? When does this occur?
SVR, 2nd trimester
At term, blood volume is increased how much?
1000-1500 mL
Total BV at term is what/kg?
90mL/kg
When does BV return to normal after pregnancy?
1-2 weeks after delivery
HR and SV increase about how much?
HR 20-30% SV 20-50%
What happens to the cardiac chambers during pregnancy?
they enlarge
When do the cardiac effects during pregnancy start to be seen on echo?
1st and 2nd trimester
Greatest increase in CO in pregnant person is seen when?
in labor and right after delivery
When does CO return to normal after delivery?
2 weeks after delivery
CV changes begin as early as how many weeks pregnant?
4 weeks
Increase in HR begins when and peaks when?
begins 1st trimester and peaks 32 week
Beginning in what week does the CO increase by 40%?
5th week
Why does CO increase during uterine contractions?
autotransfusion from contracting uterus to central circulation
Immediately after delivery, CO increases by what % and why?
80%; d/t aortocaval decompression and increase in central volume from the uterus
Why does the heart appear enlarged on xray?
diaphgram displaces heart up and to the left
What heart sounds are normal during pregnancy?
grade 1 or 2 systolic murmur or 3rd heart sound
What heart sounds are not normal during pregnancy?
systolic murmur > grade 3 or accompanied by chest pain or syncope
Diastolic and cardiac enlargement are pathologic. T/F?
true
Plasma volume increases by what % whereas rbc increase by what %?
40-50%; 20%
Why does the plasma volume increase?
increased progesterone and estrogen resulting in RAAS
Vag birth EBL and c section EBL?
500 mL; 800-1000 mL
In labor, each contraction moves how many mL of blood from the contracting uterus to the central circulation?
300-500 mL
Why does maternal HR decrease during contractions?
adequate neuraxial anesthesa/little SNS stim + transient increase in preload
Why does the SBP not change much during pregnancy?
increased blood volume but decreased SVR
DBP decreases about how much so what happens to the MAP?
15 mm Hg; decreases
At term, the uterus gets how much (%) CO?
20%
In the supine position, what is compressed, which leads to?
IVC leading to decreased venous return/SV and hypotension
Normal maternal response to aortocaval decompression?
tachycardia and vasoconstriction in lower extremities
Respiratory maternal changes evident after how many weeks gestation?
12 weeks
What does cephalaud displacement of the diaphragm do to respiratory volumes?
decreased FRC, ER, and RV
Rapid desat in apneic pregnant pt d/t?
increased O2 consumption, decreased FRC
3 conditions which exaggerate the already rapid desaturation in pregnant women?
labor, morbid obesity, sepsis
What happen to TLC, VC, and IC and why?
they’re unchanged d/t subcostal widening and enlarging of thoracic AP diameter
O2 consumption at rest w term pregnancy?
increased 33%
O2 consumption increases by what % at labor and why??
100% or more; d/t increase in alveolar vent
When during the pregnancy does the diaphragm elevate?
3rd trimester
Elevation of diaphragm results in a what % decrease in FRC?
20% that mimics restrictive lung disease
During labor, pain can cause MV to increase how much and may cause CO2 to drop to what level?
300%; 15
What are some airway changes that occur during pregnancy?
edema from cap engorgement, friable tissues, narrowing of glottic opening from edema
Is a nasal intubation a good idea in pregnant pts?
no
Most common GA complication post op in pregnant pts?
aspiration
2 problems from gestational diabetes as far as the placenta is concerned?
decreased placental perfusion (35-40%), impaired oxygen transport
Why is the baby of a gestational diabetes mother at risk for hypoglycemia?
increased glu in mother= increased insulin in baby
Glucose challenge is done at how many weeks unless had gest diabetes previously and then it’s done at this many weeks?
24-28 weeks gestation; 13 weeks
Mom w gestational diabetes has an increased risk of?
c section d/t high birth wt
________, __________, and ____ metabolism is altered during pregnancy?
carb, fat, protein bc it favors fetal growth and development
Metabolic changes resemble a what state? Why?
starving; glu and AA are low while FFA, ketones, and TGL are high
T/F: pregnancy is a diabetogenic state?
true
What happens to insulin level during pregnancy?
they steadily rise
Insulin resistance during pregnancy is probably d/t?
secretion of human placental lactogen, human chorionic somatomammotropin
What occurs in response to an increased demand for insulin secretion?
pancreatic beta cell hyperplasia
What promotes hypertrophy of the thyroid gland?
HCG and estrogens
What happens to thyroid binding globulin, T3 and T4 levels? What about free T3 and free T4 and thyrotropin?
thyroid binding globulin is increased d/t hypertrophy of the thyroid gland, T3 and T4 elevated but free levels normal, thyrotropin normal
What happens to the kidneys size during pregnancy?
increase in size and weight
When do kidneys return back to normal?
6 months post partum
What happens to the renal pelvis and ureters? when does that begin and why?
dilate; 1st trimester, progesterone
Ureters hold how many times their normal volume during pregnancy?
25 times
2 consequences of kidney changes during pregnancy?
increased UTIs and decreased bladder tone
GFR increases how much during pregnancy?
50%
When does increase GFR peak?
9-16 weeks gestation
What happens to GFR as term approaches?
it falls
Are proteinuria and glycosuria pathologic in pregnant person?
no
GFR returns to normal after how many weeks postpartum?
3 weeks
Increased filtering and therefore excretion of?
AA, glucose, proteins, lytes, drugs, vitamins
Why does serum albumin level decrease?
expanded plasma vol
What happens to pseudocholinesterase activity at term? What drugs does that affect? When does it return to normal?
25-30% decrease in it; suxxs, ester anesthetics, 2-6 weeks post partum
Why is there poor emptying of the gall bladder?
high progesterone levels inhibit release of cholecystokinin
What 2 things does poor emptying of the gall bladder result in?
altered bile composition and gallstone formation
What clotting factors are increased during pregnancy?
fibrinogen/factor I, factor VII, platelets
What clotting factors are increased during pregnancy?
fibrinogen/factor I, factor VII-X, XII, platelets
Increased clotting levels coupled w what puts pt at increased risk for DVT?
venous pooling
One of leading causes of maternal mortality?
thromboembolic events
Which clotting factor may be decreased?
XI
Fibrinogen levels in pregnant state?
400-650
What happens to wbc count in pregnancy?
it rises, may be as high as 20-30K during labor
Upward displacement of stomach results in what 2 things?
poss decreased emptying and decreased sphincter tone
What causes increased acid levels in pregnancy?
increased levels of gastrin excreted by placenta
How long is woman at increased aspiration risk after delivery?
6 weeks in to postpartum period
All pregnant women are a full stomach from when to when?
8 weeks of pregnancy to 6 weeks after
What is Mendelson’s syndrome?
chemical pneumonitis caused by aspiration during GA
pH ___ can result in aspiration pneumonitis? What is this in most pregnant people?
2.5, 25; same values
This neutralizes stomach aciditiy
bicitra
When do you give H2 receptor agonists and what are ex?
night before surgery; cimetidine, ranitidine
When do you give PPIs?
night before surgery
What do PPIs do?
increase lower esophageal sphincter tone and increase gastric emptying
What muskuloskeletal hormone increases in pregnancy?
relaxin
Fetal gas exchange is completely dependent on?
maternal uterine perfusion pressure
Uterine blood flow in mL/min?
700 mL/min
Uterine blood flow in nonpregnant uterus?
50 mL/min
Can uterine vasculature further dilate?
no, it is maximally dilated. autoregulation is absent
Uterine blood flow is determined by this relationship?
uterine arterial pressure - uterine venous pressure / uterine vascular resistance
This ABG value can reduce uterine blood flow and cause fetal hypoxia and acidosis?
PaCO2
3 events that decrease uterine blood flow?
hypotension, uterine vasoconstriction, contractions
2 things that can cause uterine vasoconstriction?
stress induced release of catecholamines during labor and any drug w alpha adrenergic activity (phenyl)
How do you contractions decrease blood flow to the uterus?
elevating uterine venous pressure
A medication that can critically compromise uterine blood flow?
pitocin
Aortocaval compression occurs after what week in pregnancy when mom is supine?
28th week
Aortocaval compression corrected by what position?
left uterine displacement
The enlarged uterus inhibits what 2 things in supine position?
venous return which results in decreased uterine arterial flow
The enlarged uterus inhibits venous return which results in what in the supine position?
venous return which results in decreased uterine arterial flow
The fetus relies on the placenta for what 3 functions?
resp gas exchange, nutrition, waste elimination
What do the umbilical arteries do? How many are there?
sends oxygen poor blood to the placenta/mom to be oxygenated; 2
What does the umbilical vein do?
fetus receives oxygen rich blood from the mom/placenta
How do resp gasses and small ions move across the placenta? Is energy needed for this process?
diffusion; no
What is the typical size of anesthetic gasses and what does that mean for placental crossing?
small:
How does water move across the placenta?
bulk flow/osmotic/hydrostatic gradient
AA, vitamins, and some ions use what method to cross the placenta?
active transport
What is primary active transport?
goes against a gradient w a protein carrier
What is secondary active transport?
moving down a concen gradient by a protein carrier
Large molecules (immunoglobulins) move across the placenta by this method?
pinocytosis (binding of specific receptor on a cell surface and then it is enclosed on the plasma mem)
What is likely responsible for Rh sensitization?
breaks in the placental mem and mixing of maternal and fetal blood
First stage of labor consists of?
regular contractions until fully dilated (10 cm)
2 stages of the first stage of labor?
latent: progressive cervical effacement and minor dilation (2-3 cm); active: more frequent contractions (3-5 min) and progressive cervical dilation up to 10 cm
Second stage of labor consists of?
10 cm dilated until baby is complete (pushing stage)
What is the third stage of labor?
delivery of baby until placenta is delivered
First stage of labor, pain is at what level?
T10-L1
First stage of labor, nociceptor stimulation is mediated by?
C fibers (small, unmyelinated, nerves)
What nerves do pain travel along in the first stage of labor?
visceral afferents accompanying sympathetic nerves
Second stage of labor pain travels through what nerves?
pudendeal
Second stage pain nerves enter spinal cord where?
S2-S4
Anesthesia for second stage of labor must cover which levels?
T10-S4
What is the regional anesthetic preferred over other techniques?
continuous epidural
Is the incidence of inadvertent IV injection during epidural high in pregnant women?
yes
Look at indications for c sec?
previous classic c sec, previous vaginal reconstruction, transverse, oblique breech presentation, genital herpes w ruptured mem impending maternal death
What are the parameters for pregnancy induced hypertension?
SBP > 140; DBP > 90
What are the parameters for preexisting HTN in pregnant person?
SBP > 30 above baseline, DBP > 15 above baseline
PIH more accurately describes 1 of what 3 syndromes?
preeclampsia, eclampsia, HELLP
What is preeclampsia?
HTN, proteinuria, peripheral edema
What is eclampsia?
preeclampsia sx + seizures
What is HELLP?
hemolysis, elevated liver enzymes, low platelets
Preeclampsia usually occurs after how many weeks gestation?
24
Preeclampsia has a higher incidence in what 4 types of women?
african american, DM, extremes of age, multiple gestation
20% of preeclamptic women also have what symptom?
decrease in clotting factors
Mild preeclampsia is what SBP, DBP, protein in urine, and edema?
SBP 140-160, DBP 90-110, 1 + edema, trace proteinuria
Severe preeclampsia is what SBP, DBP, protein in urine, and edema?
SBP 160 +, DBP 110+, 2 + edema, > 5 g proteinuria in 24 hours
Definitive treatment of preeclampsia?
delivery of fetus
Leading cause of maternal mortality?
preeclampsia
Management for preeclampsia?
Mgsulfate, antiHTN (hydralazine, beta blockers ok too)
During GA with the preeclampic woman, be prepared for what?
extreme HTN response to intubation
Whats the priority for eclampsia?
secure airway and stop seizure
3 meds to stop seizure?
thiopental, benzos, magnesium
Only treatment for eclampsia?
delivery of fetus
HELLP usually occurs after what gestation?
36 weeks
Sx of HELLP?
malaise, HA, N/V, epigastric pain
HELLP can progress in to?
DIC
Rupture of what organ possible with HELLP?
hepatic
This occurs when the placenta obstructs fetal presentation?
placenta previa
Symptom of placenta previa?
painless vaginal bleeding
Be prepared for what w placenta previa?
lots of bleeding, must be c section
What is placenta accreta?
abnormally adheres to the surface of myometrium (muscle layer)
What is placenta increta?
invades myometrium
What is placenta percreta?
erodes myometrium, can invade bowel, bladder, etc…probable hysterectomy
Be prepared for what 2 things with placenta accreta, increta, and percreta?
massive blood loss and venous embolus
The outermost layer that covers the uterus?
perimetrium
The middle part of the uterus that contains the thick muscle layers
myometrium
The innermost layer of the uterus that responds to hormonal variations during the menstrual cycle?
endometrium
The chorionic villi that attach to the uterine wall penetrate this portion of the uterus?
endometrium
This is separation of the placenta after 20 weeks?
placenta abruptae
At what grade of placentae abruptae do you start seeing fetal distress?
2
Signs of amniotic fluid embolus?
sudden tachypnea, pul HTN, hypoxia, CV collapse, coagulopathy
What is the mortality rate of amniotic fluid embolus in the first hour?
50%
DIC occurs in what % of pts with amniotic fluid embolus in the first hour?
80%
Amniotic fluid embolus usually occurs when?
labor and delivery or 30 min of delivery
What lines do you want for amniotic fluid embolus treatment?
PAC, a line, 2 large bore IVs
Uterine rupture is most likely to occur when?
after VBAC and uterine manipulation (version)
What do you prepare for w uterine rupture?
emergent laparatomy with GA
2 possibles with uterine rupture?
blood loss and hysterectomy
Continued bleeding after delivery may be? Treatment?
retained placenta; D&C often w regional
2 anesthetic considerations for retained placenta?
follow hg closely, may be hypovolemic
This happens when the umbilical cord protrudes out of the cervix and ahead of the fetus and is an emergency!
prolapsed cord
Multiple gestation: what happens to FRC?
may be reduced further, decreased compliance
Why might someone w multiple gestations require higher ITC doses?
increased CSF
Is the blood volume increased with multiple gestation over the usual BV in a pregnant person?
yes
3 negative affects of multiple gestation on the mother?
higher incidence of thrombocytopenia, increased incidence of dilutional anemia, all rates of complications greatly increased
Good regional technique for multiple gestation?
epidural
In asthmatic or hypovolemic pts, what induction drug do you want to use?
ketamine 1 mg/kg
This sedative med is more likely to produce maternal hypotension and neonatal depression?
versed
C section under GA: surgery is only begun when?
ETT placement confirmed by ETCO2
Avoid what resp issue in C section under GA and why?
hypervent bc it may reduce uterine blood flow and has been associated w fetal acidosis
Good gas to use for c section under GA and why?
50% nitrous w 0.75 MAC bc low volatile agent will decrease likelihood of uterine relaxation
Do you want a muscle relaxant for c section under GA/
yes roc
If uterus does not contract readily, what should you do?
switch to balanced technique
Dose of methergine and side effect?
0.2 mg IM, increase arterial BP
Dose of hemabate?
0.25 mg IM
Good GI consideration for C sec under GA?
OGT to empty stomach contents
Sensory level for spinal for C section must reach what level?
T4: level of pt’s nipples
Common cause of maternal mortality during c section that can occur spontaneously?
hemmorrhage
2 negatives ab spinal?
less control than epidural and more drop in BP
in GA, whose life takes over precedence w failed intubation?
mother
