OB COPY Flashcards
explain dilutional anemia w pregnancy 3rd semester normal hgb 11-12g/dL
blood volume increases ~40%
plasma volume increases ~50%
RBC volume only increases ~20%
progesterone and estrogen activate RAAS, which causes water retention.
pregnancy increases which clotting factors?
VII, VIII, IX, and fibrinogen (I).
fibrinolysis activity decreases.
platelets stay the same.
end result is a hypercoagulable pt.
WBC in 3rd trimester
can get up to 30,000mm during labor
airway changes
glottic lumen narrows due to swelling
edema makes tissues more prone to bleeding
use smaller tube 6.0 ETT
use shorter handle (Datta handle) to not hit breast tissue
O2 consumption with labor
33% higher just before labor.
100% higher w labor
GI: progesterone causes..
- GI smooth muscle relaxation
- delayed gastric emptying
- increased risk of gallbladder disease/cholelithiasis (progesterone inhibits SM, so can’t clear from the gallbladder leading to biliary stasis)
renal changes during pregnancy
- increased CO leads to increase in GFR and CC
- BUN lowers to 8mg/dL
- creat lowers to 0.5mg/dL
- glucose in urine bc absorption can’t keep up w flow
- trace protein in urine for same reason
- uterus can compress the ureter and cause urinary obstruction (hydronephrosis common)
uterine blood flow at term
800mL/min (10% CO)
most ends up in intervillous space
molecular weight to cross
> 1000 daltons cross poorly.
most anesthetic drugs are <500Da and cross readily.
stages of laborstage 1
- cervical dilation in response to REGULAR uterine contractions
- effacement occurs (softening, shortening, and thinning of cervix)
stages of laborstage 2
full cervical dilation to delivery of fetus
stages of laborstage 3
includes delivery of the the placenta
3 Ps of successful vaginal delivery
powers-uterine contractions
passenger-fetal positioning to get into position
passage-bony pelvis shape, relaxation and soft tissue relaxation
parenteral opioid effects
spinal and supraspinal effects
neuraxial opioid effects
bind in substantia geltinosa (Rexed lamina II) in dorsal horn of spinal cord
normal magnesium level
1.7-2.4
Therapeutic Magnesium level
5-9
Mag level when patellar reflexes are lost
12
mag level when respiratory arrest
15-20
mag level when cardiac arrest
> 25
Mag MOA
*competitive antagonist of calcium.
Also decreases release of Ach at NMJ and sensitivity of motor endplate to Ach
unwanted fetal effects from indomethacin(3)
premature closure of ductus arteriosus, pulm htn, low amniotic fluid levels
MAC level when uterine atony becomes a concern
MAC >0.5
GTPAL
G-Gravidity T-term births P-preterm births A-abortion (spontaneous/elective) L-living children
distance from skin to epidural space in athin pt
3cm if thin
distance from skin to epidural space in an adult
4-6cm in adult
distance from skin to epidural space in an obese pt
up to 8 cm
duration of a spinal
<2hours (why they are rarely used for labor)
levels that epidurals are inserted
L2-3 or L3-4
epidural analgesia dosing
8-12mL/hourup to 15mL/hour
volume for epidural boluses
6-10mL
spinal dose (volume)
1.6mL+/- opioid
neuraxial opioids act where
on the substantia geltinosa in the dorsal horn of the spinal cord (Mu receptors)
uncomplicated C-section blood loss
500-1000mL EBLamniotic fluid is usually 700 counted in the EBL
Why can’t chronic HTN be managed w ACE inhibitors?
they cause renal damage in pregnancy and congenital abnormalities in the fetus.
what is a molar pregnancy
absence of a fetus w placental formation (can still cause preeclampsia)
HELLP syndrome
Hemolysis, Elevated LFTs, Low Platelets
other S/S:epigastric pain, jaundice, N/V.
Hepatic rupture is rare and indicates immediate delivery needed
eclampsia
when seizures are present
platelet cut off for neuraxial for preeclamptic pts
80,000
what is the defn. of antepartum hemorrhage?
vaginal bleeding after 24 weeks gestation and into immediate postpartum period
how much bleeding occurs in postpartum hemorrhage?
> 500mL vaginal delivery or >1000mL cesarian
what is 80% of post-partum hemorrhage from?
uterine atony
what are atony risks?
multiparity, prolonged oxytocin infusions, polyhydramnios
placenta previa s/s
PAINLESS vaginal bleeding significant blood loss
What is Vasa Previa?
fetal vessels implanted on cervical OS.
fetal mortality 70%
rupture of vessels is emergency, rare
placenta accreta
abnormal growth of the placenta ONTO the myometrium
most common
placenta increta
abnormal growth of the placenta INTO the myometrium
placenta percreta
abnormal growth of the placenta into other non-uterine structures
LBW
<2500g (5lb, 8 oz)
VLBW
<1500g (3lb, 4oz)
ELBWextremely LBW
<1000g (2lb, 3 oz)
What is a normal fetal heart rate?
110-160 BPM
FHR variability
- best indicator of fetal wellbeing
- nervous system responses to adjust the HR up or down
- represents a functional of autonomic nervous system
fetal heart rate monitoring: moderate variability
6-25bpm=normal
*is the goal
increase/decrease HR CO SV SVR MAP (SBP, DBP)
HR = increase CO = increase SV = increase SVR = decrease MAP = decrease SBP = decrease a little DBP = decrease more
Postpartum CO
-increases because great vessels in abdomen are no longer compressed allowing for increased venous return
Why does CO change?
-increase in HR + SV (larger effect)
increase of decrease of RASS activation?
increase
EKG changes
- left axis deviation (3rd trimester)
- right axis deviation (1st trimester)
- shortened PR and QTc
aortocaval compression
- supine position starting at 20 weeks
- treatment is left uterine displacement
increase/decrease: Minute Ventilation, FRC, ERV, RV, CC dead space
Minute Ventilation = increase due to tidal volume FRC = decrease ERV = decrease RV = decrease CC = same dead space = increase
respiratory blood gas
compensated metabolic alkalosis
nervous system changes
- increased SNS
- increased sensitivity to LA and GA
liver
- enzymes increase (AST, ALT, LDH)
- albumin level decrease from dilutional anemia = higher free drug levels that are protein bound
- cholinesterase activity decreases
spiral arteries
-terminal arteries that spill into the intervillous space
do maternal and fetal blood interact (touch)?
-no
differences in fetal circulation
- foramen ovale
- ductus arteriosus
- ductus venosus (shunt in liver)
- umbilical artery(2)/vein
factors affecting placental drug transfer to fetus
- concentration gradient
- molecular weight (<1000 Daltons)
- lipid solubility
- ionization
fetal circulation factors affecting placental drug transfer to fetus
- diluted in intervillous blood
- redistributed
- fetal first-pass effect-fetal shunt
drugs that don’t cross the placenta
- glycopyrrolate
- anticoagulants
- muscle relaxants
- sugammadex
- insulin
progesterone
promotes smooth muscle relaxation
oxytocin
- promotes smooth muscle contraction
- prostaglandin production
labor stage 1 - pain
- due to cervical distention, stretching lower uterine segment, myometrial ischemia
- T10-L1
- UNMYELINATED C-fibers travel through hypogastric plexus
- poorly localized visceral pain
labor stage 2 - pain
- due to stretching/distension of pelvic floor, vagina, perineum
- somatic pain from pudendal nerves, S2-S4-MYELINATED
pregnancy pharmacology risk categories
A: controlled studies demonstrate no risk
B: controlled animal studies demonstrate no risk
C: studies have revealed adverse effects on fetus
D: fetal risk but benefit outweighs risk
X: known fetal abnormalities
MAC for pregnant women
- reduced up to 40% (d/t progesterone, CNS depressive effect)
- induction rate increased
first line treatment for hypotension
phenylephrine
most common sign of hypotension in spinal anesthesia
maternal nausea/vomiting
Uterotonics
- methergine: avoid in HTN, pulm HTN, preeclampsia, PVD, ischemic heart disease
- prostaglandin E2: avoid in asthma, glaucoma, renal/pulmonary/hepatic disease
- prostaglandin E1: given for uterine atony, side effects - malaise
- prostaglandin F2a: (hemabate) side effects bronchospasm, increase PVR, PHTN
- oxytocin: increases strength + frequency of contractions, side effects - hypotension from preservative, water intoxication
Tocolytics (given to halt contractions)
- calcium channel blockers (1st line)-niphedipine
- magnesium sulfate - competitive antagonist of calcium, increases sensitivity to NMB
- nitroglycerin
When MAC >0.5, uterine atony becomes a concern, not a concern w N20.
local anesthetics: amines vs ester
amines: two i’s in name, metabolized by liver
ester: one i in name, metabolized by cholinesterase
local anesthetics: bupivacaine
- long duration, sensory>motor
- 0.0625%-0.125%
- black box = 0.75% for epidurals
- preferentially bind to cardiac receptors leading to refractory cardiac arrest
local anesthetics: ropivacaine
- long, sensory>motor
- less cardiotoxic than bupivacaine
- epidural 0.1%-0.2%
local anesthetics: lidocaine
- intermediate duration
- rapid onset
- transient neurological symptoms
- subarachnoid space administration potentially neurotoxic
- metabolites that can cause seizures
local anesthetics: 2-chloroprocaine
- rapid onset, short duration (epidural use)
- reduces effectiveness of opioids bc of competition w the receptors
neural axial opioids: respiratory monitoring
- lipophilic = 2 hours
- hydrophilic = 12 hours
neural axial opioids: side effects
- less complete analgesia
- perineal tone maintained
- pruritus
- nausea/vomiting
- sedation
- respiratory depression
neural axial opioids: morphine
- less lipophilic
- may cause HSV reactivation
neural axial opioids: dosing
- epidural bolus = similar to IV dose
- intrathecal = 1/10 of epidural dose
local anesthetic test doses
- use to confirm non-vascular, non-sub arachnoid placement
- aspiration
- 3 mL test dose between contractions (1.5% lidocaine, 1:200,000 epinephrine)
neuroaxial complications: most common drugs used
bupivacaine > ropivacaine > levobupivacaine > lidocaine > 2-chloroprocaine
neuroaxial complications: treatment
-stop drug, administer O2, support ventilation-20% lipid therapy 1.5 mL/kg over 1 minute than 0.25-0.5 mL/kg/min infusion-anticonvulsants (not cardiac depressing)-avoid vasopressin, BB, CCB, LA
post dural puncture headache: risks
- large bore needle
- younger age
- bevel orientation
- beveled cutting needles
- inexperienced operator
- air for loss of resistance syringe
post dural puncture headache: treatment
- bed rest
- caffeine
- oral analgesia
- epidural saline
- epidural blood patch
- sphenopalatine ganglion block
optimal timeframe between induction and delivery of fetus
- 3 minutes
- patient draped and surgeon ready before induction
MAC level necessary to avoid anesthesia awareness
0.8
c-section: necessary epidural level
T4
c-section: epidural volume
1-2 mL per dermatome level
c-section: blood loss
- 500-1000 mL
- amniotic fluid is counted in blood loss (300-1500 mL)
pre-eclampsia criteria
- HTN
- proteinuria
- non-dependent edema (+/-)
*must be greater than 20 weeks pregnant
pre-eclampsia treatment
- definitive=delivery
- corticosteroids (infant lungs)
- magnesium sulfate
- labetalol, esmolol
pre-eclampsia anesthesia considerations
- prefer neuraxial
- laryngoscopy risk(HTN & hemorrhagic stroke)
- avoid opioids before delivery
- usually remain hypertensive throughout
what is polyhydramnios?
too much amniotic fluid
fetal hgbmaternal hbg
fetal 15
maternal 12
pretreat if GA/RSI
nonparticulate antacids
H2 receptor antagonists
metoclopramide
placental arterial supply (uterine side)
- arcuate arteries
- radial arteries
- spiral arteries-spill into intervillous space (KNOW THIS) responsive to alpha agonists
fetal-placental supply
2 umbilical arteries (finger shaped projections) where gas and waste diffuse across
no mixing of maternal and fetal blood
perfusion limited gas exchange
p17, 18 pwpt
if you are a RBC, explain your route from mother’s heart, through the uterine circulation and back to the maternal heart…
p20 pwpt?
uterine arterial supply
2 uterine arteries
first pass effect
the umbilical vein picks up blood from the placenta and goes the fetal liver 1st.
fentanyl
onset and how long it lasts
onset: 2-3 min
lasts: 30-60 min
nalbuphine
onset and how long it lasts
onset: 2-3 min
lasts: 3-6 hours
butorphanol
onset and how long it lasts
onset: 5-10 min
lasts: 4-6 hours
tramadol
onset and how long it lasts
onset: 10 min IM
lasts: 2-4 hours
meperidine
onset and how long it lasts
onset: 5-10 min
lasts: 2-3 hours
morphine
onset and how long it lasts
onset: 10min IV, 20-40min IM
lasts: 3-4 hours
what is the most common sign of hypotension in spinal anesthesia
maternal nausea and vomiting
when passing a needle for an epidural, what structures in order do you pass through?
skin, subQ, supraspinous ligament, interspinous ligament, ligamentum flavum.
neuraxial complications: LAST
bupivacaine>ropivacaine>levobupivacaine>lidocaine>2-chloroprocaine
LAST treatment
stop drug intralipid 1.5mL/kg over 1 min then infusion (0.25-0.5mL/kg/min) anticonvulsants reduce epi to <1mcg/kg avoid vaso, CCB, BB, and other LA CPB/ECM
RSI induction doses
prop 2-2.5mg/kg ketamine1mg/kg etomidate 0.3mg/kg succinylcholine 1-1.5mg/kg roc 0.5-1mg/kg MAC >0.8
VBAC contraindication
if high vertical incision was made, fetal distress, or previa. uterine rupture a life-threatening complication. epidural can mask signs (abd pain mostly)
rhogam
give if mother rh negative and hemorhage occurring. maternal and fetal blood may mix.
placental abruption
risk factors
placenta separates from uterus before delivery=decreased fetal blood supply
risk factors: HTN, prior placental abruption, trauma, cocaine, premature ROM, coagulopathy, excessive amniontic fluid.
HIGH risk maternal heart disease=high mortality rates
coarctation of aorta (with valvular involvement)
marfan syndrome w aortic involvement
cardiac arrest in pregnancy
compressions 2-3 cm higher in 3rd trimester
push uterus to the side during compressions
fetal scalp blood gases. what pH is acidotic
pH<7.2 is abnormal and deliver is expectant
early FHR decelerations
uniform, occur w uterine contractions, gradually decrease rate then return to baseline
thought to be caused by vagal stimulation from head compression of the fetus
late FHR decelerations
lowest point in FHR occurs after the peak of uterine contraction. reflects fetal chemoreceptor response to hypoxemia.
*worrisome
variable FHR decelerations
most frequent type of FHR changes, irrespective of uterine contraction. comes from baroreflex to fetal cord compression
ACOG
category 1
normal
ACOG
category 2
observation needed
possibly abnormal acid/base
ACOG
category 3
prompt intervention
abnormal acid/base
S/S of ectopic pregnancy
abd pain
menses absent
irregular vag bleeding
shoulder pain comes from rupture of ectopic pregnancy causing hemoperitoneum and diaphragm irritation.
what is adenomyosis?
when endometrial glands are within the myometrium
treatment-hysterectomy
what is endometriosis?
when there are functional endometrial glands outside the uterine cavity
placental abruption signs and symptoms
- massive hemorrhage
- early contractions
- fetal distress
- abdominal pain
- DIC
- amniotic fluid embolism
uterine rupture S/S
- pain is common
- hypotension
- cessation of labor
- fetal compromise
uterine rupture anesthesia plan
-general anesthesia unless epidural already in place
amniotic fluid embolism response
-biphasic: pulmonary vasospasm + LV failure/pulmonary edema
amniotic fluid embolism S/S
- anxiety
- dyspnea
- hypoxia
- hypotension
- coagulopathy
- CV collapse
amniotic fluid embolism treatment
- supportive
- airway management
- coagulopathy
- corticosteroids
thyroid levels in pregnancy
-increased, contributes to increased sympathetic response
umbilical cord prolapse - S/S + treatment
- sudden fetal bradycardia
- manual displacement of compression, emergency C-section
Gestational Age: LPT
34 weeks - 36 weeks 6 days
Gestational Age: VPT
<32 weeks
Gestational Age: EPT
<28 weeks
normal fetal pulse oximetry
35-65%
fetal heart rate monitoring: minimal variability
<5 BPM
*worrisome, non-intact autonomic nervous system
fetal heart rate monitoring: marked variability
> 25 BPM
APGAR scale: signs
- heart rate
- respiratory effort
- muscle tone
- reflex irritability
- color
APGAR scale: what total scores mean
WNL = 8-10
moderate impairment = 4-7
HELP NOW = 0-3
cervical cerclage: procedure and anesthesia
- suture around incompetent cervix
- spinal (T10), epidural, general
