OB Flashcards
Who does the clear liquid = no limits NOT apply to?
on magnesium or insulin infusion, scheduled for surgery or admitted for observation….complicated patients = strict 8 hr NPO
NPO guidelines for elective or non schedules, non- urgent surgery
8 hrs - solids
6 hrs- soft
2 hrs- clear liquids
Lower limit for platelets for Epidural/ CSE
70,000
Lower limit for platelets for SAB
50,000
Platelets hsould be checked with preeclampsia or thrombocytopenia every ______
12 hrs
Epidural catheters should be removed immediately if EBL is_____
<1500 mls…..if creater order a CBC and plat count.
Epidural catheter should be removed if plat ____
equal or greater than 70,000
Aspiration prophylaxis at what gestation?
16 weeks or more = full stomachs
Aspiration prophylaxis medications and dose
10 mg IV metroclopramide (inject into IV bag (don’t give IV push -> EPS)
20 ml of bicitra PO.
famotidine 20 mg
ALL OB intubations are……
RSI
What preops are not routinely given because of the risk of fetal depression
midazolam and fent …..try bendryl instead
the decision to use as CSE is based on
prior C/S >=2
High BMI,
possible difficult airway
Other factors could prolong the case past 1.5-2 hrs.
What is the min or max cervical dilation for a patient to receive labor analgesia
there is none
What is in a test dose
3 ml of lidocaine 1.5 % w/ 1: 200,000 epi
what is a negative test dose
heart rate increase no greter than 20 BPM avove baseline , no signs of systemic effect within 2 min and no loss of ability to raise or lower extremities against gravity within 4 min after injection
Preloading / coloding dose
500-1000 ml of LR during neuraxial placement
what is the programmed intermittenet bolus concentration for epidural
0.1% ropic with 2 mcg/ml fent
first bump dose of 9 MLS is delivered 50 minutes after the initiation with programed 9 ml doses q 50 min there after.
PCEA bolus is 10 ml with q 10 min lockout and a max hourly allowed 55ml/hr
initial epidural bolus and how is it made?
0.1% rop 5-10 ml with 100 mcg of fent as the initial bolus mixed from 5 ml of 0.2 % and 5 ml of preservative free saline.
Do not inject more than ____ mls of LA solution at one time
5 mls ….use of higher concetrations (0..2%) may cause hypotension.
when to use a dural puncture epidural
anticipation/ proven difficult placment or during replacement of poorly functioning epidural catheter.
CSE initiation dose
manual injection of 1.6-2 mg ropivacaine (0.8-1 ml of rop 0.2%) intrathecally or epidural fent is unnecessary. maintenance is the same as the epidural analgesia after a negative test dose.
continuous spinal dose and when its does
inadvertent dural puncture in conditions when routine epdirual or CSE cannot provide reliable analgesia. no initiation dose, maintenance is provided with normal infusion in continuous mode at 2 ml / hr with PCEA bolus of 1 ml/20 min. max hourly is 7 ml. bupiv 0.5% and place in bedside box to be used in the event of an emergency cesarean delivery.
Patient positioning after epidural
lay on their back after epidural -> decrease venous return. w/ isobaric solution it is not necessary to place on the back to achieve a bilateral block.
treatment for inadequate block width
Administer a provider bolus with a syringe of ropivacaine 0.1% or deliver a provider bolus from the pump and increase pump delivery volume by 20%
treatment for inadequate block density
sufficient block level to ice but pain exists
administer a manual bolus of 5 ml of rop 0.2%. consider replacing the epidural father if no relief.
treatment for one sided block
withdraw the catheter by 1 cm and adminster 10 ml of rop 0.1% with 2 mcg /ml fent. consider replacing the epidrual catheter if no relief.
what are surgical concentrations of LA
bupiv 0.5%, lidocaine 2% for labor analgesia.
forceps vaginal delivery or perineal repair dose
chloroprocaine 3% as needed up to 10 ml consider with sodium bicarbonate, based on the patients pain level and ability to sense and push
for perineal repair “surgical” concentrations of LA agents and neuraxial narcotics can be used as needed.
SAB dosing
1.4-1.8 ml 0.75% bup w/ 20 mcg fent plus duramorph 0.1 mg.
place SAB then _____
place supine with LUD q 1 min NIBP and start phenylephrine infusion upon injection and return supine LUD.
Dermatome level for C/S
T2-T4. block shouldnt progress high enough to affect the C8 dermatome.
phonating = breathing. hard to swallow -> raise HOB.
antibiotic prior to skin incision
cefazolin 2 grams
Oxytocin mixture for C/S
500 ml/30 units of oxytocin ….all patients receive 60 units following delivery divided into 1 L total.
first bag infuses at 500 ml/hr
second bag at 125 ml/hr.
burp all IV bags since pressure bags are often used in OB to expedite uterine contractions
wait until after placental delivery before giving pitocine.
meds to give after deliver / mother - baby bonding
midazolam and fentanyl
What meds are given IM in OB anesthesia
Prostin (hemabate/carbaprost) and methergine given IM in the deltoid!!
who is at risk for uterine atony post - delivery
prolonged labor or a long induction with pitocin and mag sulfate for pregnancy-induced hypertension
frequency between giving uterotonic agents
frequency of admin for each drug is 15 minutes but in the case of severe atony it can be alternate drugs that shorted time of 7.5 min.
who do you not remove the epidural catheter at the end of the case on?
in coagulopathic patients,»_space;> EBL than normal, possible return to OR for bleeding, frequency flier wound debridement, difficult CSE placement. if left notify the high risk epidural manager.
what is considered an unreliable neuraxial analgesia
two or more provider boluses (top - ups) should be replaced before a cesarean delivery is called
procedure for C section with labor epidural
discontinue epidural infusion asap and waste whats left.
assess block level
redosing for antiemetics
bicitra q 30 min
regalan q 6 hrs
ASAP C/s with labor epidural dosing
2% lidocaine with epi and added sodium bicarb (10:1), plus 100 mcg of fent if none given epidrually over past hr. usually 10 ml to start with additional 5 ml doses as needed with level assessment.
STAT c/s with labor epidural dose
20 ml 3% 2-chloroprocaine to achieve operative analgesia quickly. consider adding 1 meq of sodium bicarb per 10 ml of 3% chloroprocaine. assess levels upon arrival to the or. also admin 100 mcg epidrual fent if none had been given over the past hour. subsequent dosing may be admin if necessary in 5 ml increments. 30 min duration of action requires subsequent dosing with lidocaine to maintain surgical analgesia.
to convert to intrathecal analgesia to cesarean anesthesia dose
1 ml of 0.5% bupiv with incremental dosing of 0.5 ml. 20 mcg of fent can be added aswell.
maintenance for c/s under General
volatile +/- nitrous, fent, midazolam , ketamine
high levels increase uterine atony and hemorrhage
what blocks can be performed for cesarean under GETA without neuraxial
TAP max 20 ml of liposomol bupiv (exxperel, 266 mg) and 20 ml of 0.25% bupiv (total 40 ml) 20 ml each side .
Bilateral tubal ligation post partum SAB doses
0.75% 1.2-1.8 ml with 20 mcg fent. tubal ligations are less than an hour.
SAB for D&C dose
0.75% 1.2-1.8 ml with 20 mcg fent, usually a smaller dose because the case is shorter
pitocin dose for D&C
20-30 units of pitocin are injected into IV bag for uterine contraction to assist with hemostasis.
anxiolytic if upset over loss of pregnancy
check hemaque if concerned.
steps to reduce PDPH
injection of csf from syringe back into subarachnoid space through needle, insertion of catheter subarachnoid, administration of continuous intrathecal labor analgesia, injection of preservative free NS through catheter before removal. or leaving the intrathecal catheter in-situ for 12-24 hrs.
PDPH diagnosis
HA is positional, occuring within 15 min of upright position and resolving within 15 min of supine position plus one of the following;
neck stiffness
tinnitus
hypercusia
photophobia
nausea
Gold standard for PDPH treatment
epidural blood patch
Epidural blood patch steps
pre-populated consult note, consent patient and arranged for transport to ECU/PACU
use a new aseptic venipuncture site for the blood draw and the space one level below the original entry side for EBP. inject 20 ml of fresh autologous blood,. lower volume is acceptable if the patient feels back discomfort or resolution of HA
place supine for 1-2 hrs or longer. instruct to avoid heavy lifting for 12 hrs. may return to the floor after 1-2 hrs.
REPEAT EBP CAN BE OFFERED IF SYPTOMS RECUR. CONSIDER IMAGING IF MORE THAN 2 ARE NEEDED. advise 100% O2 for 12 hr if imaging shows pneummocephalus.
what physiologic changes cause engorgement and hyperemia
increased progesterone, estrogen and relaxin
Rib changes in pregnancy
relaxin relaxes the ligaments of the ribcaage -> more horizontal positioning.
increase anterior - posterior diameter of the chest = more space for lungs.
lung volume changes in pregnancy
FRC is reduced
inc oxygen consumption -> hypoxemia w/ apnea.
frc is below closing capacity -> airway closure during tidal breathing
what hormone is a respiratory stimulant
progesterone -> inc mv by up to 50%.
moms PaCO2 falls and she develops resp alkalosis.
renal compensation eliminates bicarb and normalize blood pH.
Oxy hb dissocation curve changes with pregnancy
inc P50 (right shift) facilitates O2 transfer to fetus
how much co does the uterus receive and CO changes during labor
10%
uterine contraction causes autotransufion -> inc preload
1st stage if labor 20%
2nd stage of labor 50%
3rd stage of labor 80%
returns to preloabor 24-48 hrs
return to pre pregnancy - 2 weeks
progesterones effect on nitrous oxyide and angiotensin and ne
inc NO -> vasodilation -> inc SVR
increases RAAS / Dec response to angiotensin and NE
clotting changes with pregnancy
inc 1,7,8,9,10,12 -> hypercoagulable states
dec antithrombin (DVT risk)
inc fibrin breakdown. decrease factors 11 and 13 -> faster breakdown of clots —-> risk of consumption coagulopathy.
pregnancy changes to serum albumin and pseudocholinesterase
dec albumin -> inc free fraction of highly protein bound drugs
dec pseudocholinesterase -> no meaningful effect on succ metabolism
uterine blood flow and pheylephrine
not reduced. Using phenylephrine instead of ephedrine is associated with a higher fetal blood pH.
does uterine blood flow autoregulate
no. it is dependent on MAP, co and uterine vascular resistance.
uterine blood flow formula
uterine artery pressure - uterine venous pressure / uterine vascular resistance.
fick law of diffusion for drug transfer across the placenta
diffusion coefficine x surgace area x centraction gradient / membrane thickness
what drug characteristicks favor placental transfer
low molecular weight < 500 daltons
high lipid solubility
non ionized
non polar
what drugs have significant placental transfer
Local anesthetics (except chlorporcaine)
IV anesthetics
volatile anesthetics
opioids
benzos
atropine
beta blockers
magnesium
no placental transfer
nm blockers
glycopyrrolate
insulin
heparin
first stage of labor
begins with cervical dilation with regular uterine contractions and ends with full cervical dilation (10cm). divided into latent and active stage
pain begins in the lower uterine segments and the cervix. signals travel to the T10-L1 posterior roots
second stage of labor
full cervical dilation and ends with delivery of the newborn
adds in pain impulses from the vagina, perineum and pelvic floor
pain impulses travel from the perineum to the S2-S4 posterior nerve roots
neuaxial that provide T10 - L2 during the first stage must be extended to cover S2-S4 during the second stage for a total coverage of T10-S4
third stage of labor
egins with delivery of the newborn and ends with delivery of the placenta
NPO guidelines for laboring mothers
always a full stomach
healthy moms may drink a moderate amount of clear liquids throughout labor
eat solid food up to the point a neuraxial block is placed
pudendal nerve block covers what area
perineium S2-S4 pudendal nerve.
sharp and well localized
which local anesthetic reduces the efficacy of epidural morphine
2 chloroprocaine because it antagonizes mu and kappa receptors in the spinal cord.
side effects of neuraxial opioids
pruritis, n/v, sedation and resp depression
when administered alone include a lack of perineal relaxation and less analgesia compared to LA
normal fetal heart rate and variability
110-160
6-25 bpm = variability
what reduce variability
CNS depressants
hypoxemia
fetal sleep
acidosis
anencephaly
cardiac anomalies
Early decels mean….
head compression
Late decels mean….
uteroplacental insufficiency (maternal hypotension, hypovolemia, acidosis, preeclampsia
Variable decelerations means….
umbilical cord compression
How long does it take betamethasone to take effect and when does it peak
peaks in 48 hrs
takes effect in 18 hrs
Beta 2 agonists used as tocolytics
ritodrine
terbutaline
MOA of beta 2 agonsits as tocolytics
increase cAMP, in turn PKA turn off MLCK -> relaxes the uterus.
increase progesterone release, which contributes to additional myometrial relaxation
moa of magnesium sulfate as a tocolytic
calium antaonsits -> smm relaxation of the vasculature, airway and uterus. and hyperpoarizes membranes in excitable tissue -> sz prophylaxis and treats preeclampsia.
what is the first sign of mag toxicity
diminished of deep tendon reflexes
usually between 5-7 mg/dl with lethargy/ drowsiness, flushing, N/v
usually loose reflexes between 7-12 mg/dl
treatment for hypermagnesmia
supportive care
diuretics
IV calcium gluconate 1 g over 10 minutes (to antagonize mg)
CCB used as a tocolytic
nifedipine = first line
co - administer with mag can contribute to skm weakness
NO moa as a tocolytic
vasodilator and is essential in maintaining smm tone increases cgmp, turns off MLCK and relaxes uterine muscle.
rarely used due to hypotension
dose of methergine
0.2 mg IM
Where is oxytocin synthesized and stored/ released
paraventricular nuclei of the hypothalamus
stored and released in the posterior pit gland
side effects of oxytocin
water retention, hyponatremia, hypotension , reflex tachycardia, coronary vasoconstriction
metabolism of oxytocin
hepatic
half-life of oxytocin
4-17 min
routes of oxytocin administration
IV or intrauterine
Methergine type of medication
Ergot alkaloid
uterotonics
half life of methergine
2 hours
Hemabate/ carboprost type of medication
prostaglandin F2
Hemabate/ carboprost dose
250 mcg IM or intrauterine
Side effects of hemabate/carboprost
n/v, diarrhea, hypotension, htn, bronchospasm
normal amniotic fluid volume
700 mls
what medications are given as prophylactic aspiration
sodium citrate 15-30 ml within 15-30 min of induction
h2 receptor antagonists (ranitidine) 1 hr before induction
Gastrokinetic agent (metolopramide) 1 hr before induction
when is the best time for surgery in the pregnant patient
second trimester ; avoid teratogenicity and inc risk of preterm delivery that’s highest during the 3rd trimester
when is organogenesis
day 13-60
hyperventilation and the risk to the fetus
Maternal hypocapnia/metabolic alkalosis -> L shift in O2 curve -> dec O2 unloading to the fetus
redues placental blood flow -> risk of fetal asphyxia
maternal hypercapnia -> Co2 to fetus -> fetal acidosis/ myocardial depression
why do we avoid nsaids
potentially close the ductus arteriosus
what physiologic changes is preeclampsia associated with
increase proteinuria
increased thromboxane
increased vasoconstriction
decreased prostacyclin
enhanced protein aggregation
what is the batsons plexus
a network of epidural veins that drain the spinal cord and the meninges. typically passes through the lateral and anterior regions of the epidural space
What is the normal weight gain for a pregnant women and how is it divided up
12 kg ~ 1 lk / week
1 kg each to the uterus and amniotic fluid
4 kg to the fetal and placenta weight
4 kg to the new gat and protein stores
2 kg to blood volume increase
when does blood volume increase occur and by what percent and what factors. when does it return to prepregnancy levels
8-32 weeks majority inc at week 24
30-35% increase
inc plasma and RBCs (Plasma > RBC)
6 weeks postpartum = return to prepreg
EBV female pregnant vs non pregnant
nonpregnant female 65ml/kg
pregnant 85-90ml/kg
CO changes from pregnancy
inc by 40% at terms
inc maternal HR (6 weeks)
inc SV (8-10 weeks)- due to dec SVR
skin bf inc by 3-4 x; warm skin, flusing, itching
renin and estrogen changes with pregnanct
inc renin -> inc aldo -> inc na retention -> h20 reabsorb -> inc plasma volume -> inc SV/ CO
estrogens inc angiotensin -> inc aldo
Uterine blood flow pregnant vs not
non preg = 50 ml/min
preg = 700 ml/min (12% of CO)
what mediators cause a decrease in SVR
progesterone, prostacyclin, relaxin, estrogen -> vasodilation and VD of renal vasculature -> inc bf
20% lower than pre preg -> dec afterload …..High flow, low resistance.
LV hypertrophy with pregnancy
50% inc in LV mass by term. (eccentric hypertrophy) to accommodate for inc blood volume/ preload.
position change to left/ anterior. PMI @4th ICS mid clav.
EKG changes with preg
t wave inversion in lead 3
lead 1 and AVL +
Lead 2 and AVF -
shorter PR interval (inc sns @ 3rd trimester -> inc AV conduction velocity)
Inc QT interval
HR inc -> tachyarrhythmias / CT/PVCs/PACs (inc sns and usually benign)
causes of tachyarhthmias during pregnancy
inc ion channel conduction
inc heart size
change in autonomic tone
hormones
Valvular changes in pregnancy
tricuspid and pulmonic regurg in 90% of pts
mitral regur in 30% of pts
reversible
S/s of aortocaval compression and when does it start and how do you treat it
tachycardia-> bradycardia
N/V
Pallow/ sweating
LOC
fetal distress
starts at 13-16 weeks
treat w/ LUD
autotransfusion amount with contractions
Hr increases and autotransfusion of about 300-500 ml of blood from the uterus to the general circulation with each contraction
What are the pregnancy hormones
Estrogen and progesterone
Estrogen and progesterones role in pregnancy
estrogen inc the number and sensititivty of progesterone receptors in the respiratory centers in the brain
progesterone inc resp center sensitivity to CO2
bronchodilator
Hyperemia/edema of resp passages
activates spinal cord Kappa opioid r = anaglesia
Relaxins role in pregnancy
causes ligamentous attachment to lower ribs to relax -> barrel chest -> inc subcostal angle and widened Ap and transverse diameter of chest wall -> preserves TLC
inc joint mobility; sacroiliac pain/ knee pain
overstretching of joints = possible
lung volume changes during pregnancy
dec in FRC at term
dec ERV/RV -> dec reserve
when supine frc decreases even more
VT increases (due to inc Co2 production and resp drive from inc progesterone)
inspiratory capacity increases
TLC/ VC stay the same
pleural pressure in pregnancy
becomes more + -> earlier closure of small airway -> closing capacity may exceed FRC -> V/Q mismatch because of closure of small airway -> dec O2 saturation
Oxygen consumption changes with pregnancy
inc by 20% due to inc metabolism and inc metabolic needs of fetus/ uterus/ placenta
Reasons for inc WOB that begins in the first trimester
inc resp drive
inc O2 consumption
dec PaCO2
large pulmonary blood volume
Anemia
nasal congestion
Normal blood gas for pregnant women
Respiratory alkalosis
PaCo2 decreases ~ 8-10 mmhg
PaO2 increase ~ 5mmhg
Anemia in pregnancy
dilutional anemia from inc plasma volume more than the increased red cell mass. also iron needed to make RBCs and is treated with oral iron formulation (iron deficiency anemia)
HBG drops ~ 2.4 g/dl at 36 weeks
Hct dec ~6.5%
abnormal < 11g/dl
hemoconcentration/ preeclampsia > 13 g/dl
Platelet changes in pregnancy
normal 165-415,000mm3
< 150,000 = thrombocytopenia; may be idiopathic, htn disorder or gestational
transfuse if < 50,000
Coag changes with pregnancy
hypercoagulable
inc in factors (excep 2,5,11,13)
inc fibrinogen (factor 1 ) > 400 mg/dl at term
WBC changes with pregnacy
inc to 9-11,000 and inc up to 34,000 in labor
but due to polymorphonuclear leucocyte function being impaired -> inc risk and severity of infection.
and humora antibody titers decrease to certain viruses; measles, influenza A and herpes simplex
Gi changes with pregnancy
LES tone decreases. lowest at term
gastric emptying is only delayed during labor
Aspirator risk till how long after pregnancy
4-6 weeks postpartum. LES tone returns to normal at 4 weeks and uterus needs 6 weeks to get back to normal size
High aspirator risk/ mendelsons syndrome
gastric pH < 2.5, gastric volume > 25
mendlesons; perioperative aspirator of gastric contents. inflammatory response of lung parenchyma
Hepatic changes with pregnancy
inc splanchnic and portal and esophageal pressure
inc liver enzymes and cholesterol
dec total protein and dec albumin-globulin ration -> dec colloid oncotic pressure
Pseudocholinesterase activity in pregnacy
dec by 25% before delivery and by 33% on the 3rd postpartum day. returns to normal in 2-6 weeks. usually not enough to cause prolonged paralysis after single dose of succ.
cholestasis s/s
pruritis, high serum bilirubin, abnormal liver function tests
3rd trimeester 1/100 ppl
biliary stasis + inc bile secretions
inc risk of cholethiiasis, inc risk if subsequent pregnancy, cholecystectomy?
renal changes in pregnancy
75% inc in renal blood flow.
inc GFR
inc Creat clearance -> dec serum creae
dec BUN
Endocrine changes in pregnacy
thyroid enlarges (difficult airway?)
hypthyroidismm -> fetal cognitive issues, spont abortion, growth restriction and placental abruption if not treated
pancreas insulin resistance due to human placental lactogen, inc blood glucose
adrenal; inc cortisol (by 100% in 1st trimester and 200% at term)
plasma endorphins increase
pituitary ; ant pit inc prolactin secretion -> prep for breast feeding/ acne
post pit ; oxytocin section -> stimulation or uterine contractions, responsible for breast milk let down, bonding hormone.
Musculoskeletal changes with pregnacy
affect of Relaxin
nerve compression (sciatic pain common, meralgia parenthetic; comp of LFCN (tingling/ numbness/ burning pain)
lumbar lordosis change of center of gravity/ pelvic tilt. narrowing of intervertebral spaces.
CNS changes with pregnancy
inc cbf
inc BBB permeability
inc pain threshold
engorgement of epidrual veins
dec CSF volume -> greater spread of LA
dec total dose of LA requirement to produce same level of epidural/ spinal
NMBD; inc roc/ vec sensitivity
dec ACHe activity
What are the sources of uterine blood flow
primary; uterine arteries (branch off the internal iliac (hypogastric) arteries)
secondary; ovarian arteries (branch off the aorta @L4)
what are the characteristics that the rate / amount of transfer depends on in the intervillous space
concentration gradient
permeability
restriction of movement; bound to placental tissues/ proteins = minimize fetal exposure/ accumulation
how much blood pools in the intervillous space and how does blood enter the space
350 mls
enters via the spiral arteries
causes of dec uterine arterial pressure
aortocaval compression
hypovolemia (bleeding/ dehydration)
hypotension (neuaxia/ drug induced/ prop, mag, VA, opioids).
tx; give fluids/ vasoconstriction
causes of inc venous pressure
IVC compression
contractions/ pushing effect; inc contraction -> inc venous pressure/ hyperemia
tachysystole (oxytocin/ cocaine/ methamepheamines)
sz
causes of inc uterine vascular resistance
Stress response/ hypotension -> inc catecholamines
exogenous catecholamines
effects of ephedrine on the fetus
x placenta; inc fetal metabolic requirements -> dec fetal pH, base excess and umbilical O2 content.
Phenylephrine effect on fetus
vasopressor of choice if repeated doses are needed… results in inc uterine vascular resistance -> dec UBF
what are the effect of inc LA concentration
arterial constriction
inhibition of endothelium mediated vasodilation
stimulation of myometrial contraction
IV dexmedetomidtine/ clonidintes affects on UBF
IV admin = dec ubf -> inc UVR. VD at low dose. inc dose -> vasoconstrction -> uterine contractility / inc UVR/ intrauterine pressure
magnesium effect on uterine blood flow
increase UBF, relax smm, vasodilation
Volatiles effect on UBF
0.5-1.5 mac -> minimal efffect on ubf
inc mac -> dec CO/BP-> dec UBF
sides of the placenta
yellow side = chorionic plate = fetal size
purple side = basal plate = maternal side
what are the means of placental transfer
passive diffusion
facilitated diffusion
active transport
pinocytosis
what are the characteristics for drugs to transfer to the placenta
passive transfer (blood flow dependent)
lipid solubility (highly lipid soluble = bilayer penetration) -> trapping
protein concentration ; higher bound = less transfer
PKA; non ionized cross placenta
molecular size < 500 daltons
describe ion trapping
fetus w/ lower pH / higher H+ concentration the extra H+ will bind to the non ionized form of the drug and trap in fetal circulation
Drugs that cross the placenta
atropine
scopolamine
beta antagonists
nitroprusside
volatiles
benzodiazepines
lidocaine
opioids
ephedrine
propofol
ketamine
etomidate
dexmed
acetaminophen
neostigmine *
edrophonium
warfarin
How is drug teratogenicity graded
A = least dangerous
B= tylenol
C = benzos (clef palate formation)
D = most dangerous
Nitrous = not classified. harmful to dna synthesis in high doses
P50 changes of fetal vs adult
fetal hbg p50; 19 mmhg = partial pressure of oxygen when 50% of HCG is saturated.
the 2 alpha and 2 gamma subunits on the fetal hbg = inc affinity for O2. = higher p50
Maternal bohr effect
because the fetal blood has a higher Co2 and a lower ph -> decreased affinity of O2 for hbg -> right shift in O2 curve for the maternal.
Double bohr effect
fetus shifts oxyhbg curve to the left by; Co2 diffuses to maternal blood = dec co2 in fetal blood -> alkaline environment / inc pH -> left shift in O2 cuve -> inc afinity for O2 on hbg.
what does fetal monitoring reflect
nonspecific reflection of fetal acidosis
how are contractions quantified
quantified over 10 min
averaged over 30 min
beginning of one contraction to beginning of next
=/< 5 contraction in 10 min is normal
what is tachysytole
> 5 contractions in 10 min period
treatment of tachysystole
stop pitocin
nitroglycerine
beta - 2 adrenergic receptor agonist (terbutaline)
causes of fetal tachycardic
FHR > 160
chorioamniosis
sespsis
acute hypoxia
fetal heart failure
anemia
maternal hyperthyroidism
maternal fever
epi/ ephedrine
beta 2 adrenergic agonists (terbutaline/ritodrine)
Causes of fetal bradycardia
initial response to hypoxemia
umbilical cord compression
fetal head compression
hypothermia
maternal hypotension
maternal hypoglycemia
congenital heart block
accelerations
period of inc FHR at least 15 bpm, lasting at least 15 seconds
signs of variability
normal/ healthy
variability
fluctuations in baseline FHR
irregular in amplitude and frequency
quantified as amplitude of peak to trough of bpm
most important indicator of fetal oxygen status
absent - none detected
minimal - range less than 5 bpm variation
moderate - range 6-25bpm
marked- > 25bpm
causes of absent variability
fetal sleep cycles
prematurity
arrhythmias
fetal tachycardia
Pre-existing neurologic abnormality
congenital anomalies
severe hypoxemia
beta-adrenergic antagonists
antenatal corticosteroids (betamethasone)
ethanol
GA
dexamethasone
benzos
mag sulfate
systemic opioid analgesia
promethazine
causes of increased/ marked variability
fetal stimulation
mild and transient hypoxemia. umbilical cord compression in 2nd stage of labor
maternal illicit drugs/ stimulants
decelerations
Early; gradual. onset to nadir = > 30 sec. nadir is at peak contraction. FHR < 20bpm.
late; gradual. delayed onset. begins at peak contraction or after contraction is over. onset to nadin > 30 sec. smooth/ shallow.
variable; onset, depth, duration vary w/ contraction. irregular. abrupt dec and return. onset to nadir < 30 sec. fhr < 15 bpm dec. lasts 15 sec or longer. < 2 min duration.
Earlies indicate
uterine contraction = benign
head compression -> vagal nerve stimulation
usually limited to the active stage of labor
cephalopelvic disproportion if seen in early labor
Variable decel indications
transient hypoxemia
cord compression
if frequent in early labor -> cord occlusion
may also indicate oligohydraminos (low amniotic fluid)
severe decel
FHR < 70 bpm
decrease in FHR > 60 bpm from baseline
contraction duration > 60 seconds
decreased umbilical blood flow
impaired fetal CO
minimal/ absent variability -> concern for hypoxia
Late decels indication
can be benign as long as variability is present. dec / absent varilibty = ominous.
causes; hypoxemia, cont hypoxemia ->lactic acidosis
myocardial decompensation/ /failure
chorioamniosentsis
post term gestation
uterine hyperactivity
maternal hypotension/ htn disorder/ cardiac dz
maternal smoking
maternal anemia
placental abruption/ previa
prolonged decel and its cause
dec in FHR >/= 15 bpm lasting 2 min or more but < 10 min
causes; cord compression, maternal hypotension/ hypoemia. tetanic uterine contractions
prolonged head comp in 2nd stage of labor
Sinusoidal pattern
cycle frequency of 3-5 cycles/ min
amp range 5-15 bpm
persist > 20 min
required ob intervention
causes; fetal anemia, RH disease (incompatible blood), severe hypoxemia
Category 1 FHR tracing category
predictive of normal fetal acid-base status
Baseline FHR 110 - 160 bpm
Moderate baseline variability
No late or variable decelerations
Early decelerations present/absent
Accelerations present/absent
Category 2 fhr tracing category
Indeterminate
Fetal tachycardia
Absence of induced accelerations after fetal stimulation
Prolonged decelerations > 2 mins < 10 mins
Recurrent late decels w/ moderate variability
Not predictive of abnormal fetal acid-base status
Category 3 FHR tracing
Abnormal fetal acid-base status
Sinusoidal FHR pattern
Absent FHR variability w/recurrent late decels
Recurrent variable decels
Sustained bradycardia
Management of Category III Tracings
Maternal position change
Discontinue labor augmentation
Treatment of tachysystole
Surgical delivery
APGAR scoring
Five parameters assessed at 1 & 5 minutes, given a score of 0, 1 or 2:
Heart rate; absent < 100, >100
Respiratory effort, absent, irregular, crying
Muscle tone; limp, some flexion, movement
Reflex irritability; none, grimace, coughing/sneezing
Color; cyanotic, trunk pink extreme blue, pink
8-10 = normal
4-7 = moderate impairment
0-3 = immediate resuscitation required
Risk for mortality
inversely proportional to 1 minute score
second stage of labor is when its lasts greater than….
3-4 hrs
pain during first stage of labor
mechanoreceptor stimulation; stetching of lower uterine segments and cervic
visceral pain; transmitted bia unmylinated c fibers. enter SC at T10-L1. hard to localize. lower abd/ back. difficult to treat w/ opioids.
Latent phase; T10-12
Active phase T12-L1.
amenable to blockade of peripheral afferents
pain during the Second stage of labor
somatic pain; tranmitted via myelinated a delta fibers via the pudendal nerve. sharp, easy to localize. stretching and compression of pelvis and perineal structures.
T12-S4.
visceral pain is still significant as contractions continue
Where is the kyphotic apex of the thoracic curvature
T8 shift to T6….increased risk of cephalad spread
absolute and relative contraindications for neuraxial anesthesia
absolute;
Patient refusal
Uncooperative patient
Uncontrolled hemorrhage w/ hypovolemia
Epidural site skin/soft tissue infection
Moderate to severe bleeding issues/clotting disorder
Anticoagulation
relative;
Elevated ICP d/t mass lesion
Local anesthetic allergy
Language barrier w/o interpreter
Severe fetal depression
Severe maternal cardiac dz
Active coagulopathy
Untreated systemic infection
Pre-existing neurologic deficit
Skeletal anomalies
Hardware in spine
placement of CSE
L2-3 / L3-4 / L4-5
What should be monitored after an intervention (epidural/spinal)
Quality of analgesia
Progress of labor
Sensory level (Ice vs. “Pin Prick”)
Intensity of motor blockade
Maternal vital signs
FHR tracings
Treatment of pruritus from intrathecal opioids
Centrally acting mu-opioid antagonist;
Naloxone 40-80 mcg IV bolus or 1-2 mcg/kg/hr
Naltrexone 6 mg po
Partial agonist-antagonist;
Nalbuphine (Nubain) 2-5 mg IV bolus
Butorphanol (Stadol) 1-2 mg IV bolus
Types of skin incisions
Low transverse and low vertical/ midline
Types of uterine incision
Low transverse
vertical
classical
Describe the bezold jarish reflex
mechanoreceptors in the wall of the LV responding to “low stretch”
triad; vasodilation, hypotension, bradycardia
prevented with zofran
phenylephrine gtt rate
0.1-0.7mcg/kg/min or 25-100 mcg/min
Testing blockade quality
blunt needle; charp on your arm, can you feel it being here, can you feel me touching but you are not the sharp?
Average depth for LOR/ to reach the ligamentum flavum
4-6 cm you will want to leave 4-6 cm of catheter in the patient
Spinal needle gauges
24-25 gauge
Number of vertebra vs number of nerves
33 total vertebra, 31 total pairs of spinal nerves
high and low points of spinal colum
high = C3 and L3
low = T6 and S2
ligaments of the spine
suprspinous ligament
interspinous ligament
ligamentum flavum
epidural space
dura matter
subdural space
arachnoid mater
subarachnoid space
pia matter
Spinal cord ends at ….dural sac ends at….
L1 in adults
L3 in peds
dural sace ends at S2
dura mater start and end
start at foramen magnum and ends at S2. fuses with the film terminal
normal CSF volume and production rate
100-160 mls
produced at 20-25 ml/hr
entire volume replaced every 6 hrs
Tuffiers line
intercristal line
L3-L4 space is at or above the level of the superior iliac crest
Esters vs amides
different intermediate chains
same aromatic ring and tertiary amine groups
morphine vs fent hydrophilic vs lipophilic
morphine; hydrophilic
fent; lipophilic
factors that affect uptake of LA
factors affecting uptake of LA into neural space
concentration of LA in the CSF
surface area of the neural tissue
lipid content of the nerve
Blood flow of the nerve
Progression of differential blockade
B- fibers= sympathectomy
C and A delta = loss of pain/temperature
A gamma= loss of motor tone
A beta = loss of touch/ pressure
a alpha = loss of motor function/ proprioception
zone of differential block
sympathetic level is 2-6 levels higher than the sensory level
the sensory level is 2 higher than the motor level
how are LA eliminated
reuptake, usually reabsoprtion (vascular)
factors affecting intrathecal spread
dose, baracity, CSF volume, Advanced age/ pregnancy
patient position,
epidural injection post spinal
CSF specific gravity
1.00033 (pregnanct)
1.00067 (men)
how long are you able to determine dermatome spread with positioning
5 minutes
Where does sympathetic outflow oringinates
T6-L2
Names of cutting needles
quincke
pitkin
Names of non cutting needles
sprotte
whitacre
pencan
greene
gertie marks
Epidural needle gauge and curvature degree
tuohy needles is a 17 or 18 gauge
30 degree curvature
onset of local is based on what
pka
Uptake of local based on blood concetration
intravenous
tracheal
intercostal
caudal
paracervical
epidural
brachial
sciatic
subq
typees of epidural needles
husted - 15 degree
Tuohy- 30 degrees
crawford- preferred for thoracic epidrual
epidural catheter markins
two lines = 10 cm.
solid dark line = 12 cm
4 lines = 20 cm
painless vaginal bleeding indicates….
placental previa
EBL that can be tolerated w/o symptoms or changes in vital signs
~15%
FFP dosage
FFP x 1 per 20 kg body weight as initial dose (20 ml/kg)x
Normal and therapeutic mag levels
Normal = 1.7 – 2.4 mg/dL
Therapeutic range = 5-9 mg/dL
Leading cause of death in preeclampsia
CVA; intracerebral/ sah ….occur postpartum
