OB II

Question 1

General approach to providing anesthesia for OB patient?

Answer 1

• obtain H and P
• assess NPO status
  
  • ACOG guidelines say pt can eat up until they get epidural, but this varies from hospital to hospital
• ascertain analgesics given
• IV access
• aspiration prophylaxis
• fetal and maternal monitors in place
• supplement o2? may or may not be needed
• airway assessment
• emergency drugs and equipment available

Question 2

What is parturient?

Answer 2

female in labor, about to give birth

Question 3

what is gravida? multigravida? primigravida? multigravida?

Answer 3

gravida- # times pregnant

nulligravaida- never pregnant

primigravida- pregnant to first time

multigravida- pregnant for at least 2 times

Question 4

What is parity? Abertus?

Answer 4

Parity= # pregnancy reaching viable gestational age (live births and still births)

abertus= abortions/miscarriages before viability <20 weeks

Question 5

Questions ot ask when taking OB history?

Answer 5

• estimated date of delivery- by scan or dates (LMP + 9 months + 7 days)
• growth of fetus- wnl?
• placental location- placenta previa may alter delivery plans
• fetal movement- usually expereicned at around 18-20 weeks gestation
• labor pains- more relevant in third trimester
• planned method of delivery- vaginal/c-section
• medical illness during pregnancy- taking any meds?

Question 6

What to ask OB pt in regards to details of each pregnancy?

Answer 6

• date of delivery
• length of pregnancy
• singleton/twins or more?
• spontaneous labor or induced?
• mode of delivery
• weight of babies
• current health of babies

Question 7

What are some antenatal complications of pregnancies?

labor? postnatal?

Answer 7

• antenatal- IUGR (intrauterine growth restriction)/hyperemesis/pre-eclampsia
• labor- failure to progress/perineal tears/shoulder dystocia
• postnatal- postpartum hemorrhage/retained products of conecption

Question 8

Key symptoms to ask the pregnant patient?

Answer 8

• Nausea/vomiting- if severe may suggest hyperemesis gravidarum
• abdominal pain- may suggest the need for imaging
• vaginal bleeding- fresh red blood/clots/tissue
• dysuria/urinary frequency- urinary tract infection
• fatigue- may suggest anemia
• HA/visual changes/swelling- pre eclampsia
• systemic symptos- hever/malaise

Question 9

What are some theories for what causes labor?

Answer 9

1. progesterone withdrawal hypothesis
2. corticotropin releasing hyptothesis
3. prostaglandin hypothesis- prostaglandins increase

HOWEVER, we don’t know what causes labor

Question 10

What is stage 1 of labor?

Answer 10

• The cervix relaxes, causing it to dilate and thin out
• Cervical stage- aka latent (mom early in labor) and active (mom is 4-6 cm dilated)
• begins w/ mom’s perception of regular, painful uterine contractions and ends with complete cervical dilation (10 cm)
  
  • dull, aching, cramping and poorly localized
  • longest stage of labor (2-20 hours)
  • mostly visceral pain (T10-L1 innervation)
  • slow (unmyelinated) afferent, C fibers, enter spinal cord at T10-L1
    
    • ​Need to block level T10-L1!!

Question 11

What is 2nd stage of labor?

Answer 11

• Pelvic stage- uterine contractions increase in strenght and the infant is delivered
• begins with complete cervical dilation and ends with birth of the baby
• distention of the pelvic floor, vagina and perineum pain
  
  • sharp, severe, bloody show, vomiting, bear down–> pushing
  • most painful portion of labor (somatic parin) S2-S4
  • Rapidly conducting A-delta fibers, enter SC at S2-S4

Question 12

What is 3rd stage of labor?

Answer 12

• Placental stage
• begins with birth of baby and ends with delivery of the placenta

Question 13

What is the 4th stage of labor?

Answer 13

• 1st postpartum hour, during which hemorrhage is most likely to occur

Question 14

What can be done for stage 1 pain relief?

Answer 14

• should be focused on blocking pain impulses from cervix and lower uterine segment to the spinal cord
  
  • paracervical block–> obstetician administer–> needle to vaginal fornix–> can cause fetal bradycardia if injected into babies’ head
  • lumbar sympathetic block–> in last 3 decades has all but dissappeared in US
  • Epidural @ T10-L1 level! << most common

Question 15

Pain relief for stage 2 labor?

Answer 15

• Pudendal nerve block–> OB administered–> immediately before delivery (forceps deliver)
• extension of epidurla block from T10- S4
• Any neuraxial anesthesia that blocks pain at these dermatomes
  
  • saddleblock- single shot spinal (no epidural) with LA/opioid
    
    • will give numbness for few hours

Question 16

What are the componennts of labor and delivery?

Answer 16

1. powers
2. passageway
3. passenger

Question 17

What do the “powers” need to be like in order to progress labor?

Answer 17

• contraction
  
  • Increase in intensity
    
    • 40-60 mmHg intensity
  • increased frequency
    
    • 2-3 min apart
  • increased duration
    
    • 50-70 sec duration
• pushing (2nd stage)
  
  • need to be careful if pt given epidural and taking away motor
    
    • don’t want mom hurting and need good sensory blockade for that, but don’t want to take away motor/pushing
      
      • ropivicaine used often

Question 18

What type of uterus is most optimal for childbirth?

Answer 18

gynecoid pelvis

Question 19

What does the “passenger” need to be like in order to have optimal delivery?

Answer 19

• lie- the relationship of long axis of the fetus to the long axis of the mother (ie transverse, oblique, longitudinal)
• presentation- portion of fetus overlying the inlet–> cephalic, breech, or shoulder
  
  • 95% of labors at term, the presentation is cephalic and fetal head is well flexed (vertex presentation)
• position- refers to the relationship of the presenting fetal bony point to the anterior, post or side (right, left) of the maternal pelvis (ROA, LOA, ROP, LOP)
  *

Question 20

What position of the fetus facilitates delivery the most?

Answer 20

• LOA- left occiput anterior facilitates delivery the most

Question 21

What position of fetus makes delivery the most challenging?

Answer 21

• ROP, LOP
• Never want baby looking up during delivery. sometimes call this “sunny side up”

Question 22

What are the cardinal movements of labor?

Answer 22

• engagement- means head is at level of ischial spines= station 0
  
  • ​-1 station= 1 cm above ischial spine
  • +1 station= 1 cm below ischial spine
  • +5= delivery imminent
  • to remember, + is good, want to be positive with delivery becaues baby is coming!
• descent
• flexion
• internal rotation
• extension
• external rotation
• explusion

Question 23

What are methods for analgesia for labor and vaginal delivery?

Answer 23

• non pharmacological technique
• parenteral meds
  
  • opioids- meperidine, fentanyl remifentanil
  • agonists-antagonist- nubain, stadol
  • ketamine
  • anxiolytics- midazolam
• neuraxial blocks
  
  • epidural analgesia
  • CSE
  • SAB
• Inhaled analgesia

Question 24

Ideal anesthetic in OB?

Answer 24

• Effective and controllable analgesia
• maternal safety
• no weakening of maternal powers
• no alteration of maternal passages
• no depression of the passenger

Question 25

non pharmacological analgesic techniques?

Answer 25

• emotional support (doulas)
• touch and massage
• therapeutic use of heat and cold
• hydrotherapy
• biofeedback
• acupuncture
• hypnosis

Question 26

Risk factors for increased pain during childbirth?

Answer 26

• an occiput posterior presentation
• young maternal age
• history of severe dysmenorrhea
• increase maternal weight
• increased fetal weight
• type of labor
  
  • use of oxytocin- augments labor

Question 27

Why /when would IV meds be used? What are some disadvantages? what will it do to FHR variability

Answer 27

• good to admin during latent period
• s/e mom can vomit
• opioids do cross placenta
• might see FHR with fetal depression and decreased variability in FHR

Question 28

Meperidine in OB?

Answer 28

• 50-100 mg IM q 4 hours or 25-50 mg IV (max dose <100 mg )
• onset 5-10 min, duration 3-4 hours
• fetal exposure highest 2-3 hours after admin
• crossess the placenta/fetal acidosis/neonatal respiraotyr depression
• active metabolite normeperidine in neonate–> depressed behavioral assessment score

Question 29

Morphine in OB patient?

Answer 29

• linked to neonatal respiratory depression and somnolence
• leads to maternal sedation
• no longer widely accepted

Question 30

Fentanyl in laboring patient?

Answer 30

• high potency and short doa make it reasonable for labor
• usual dose 25-200 mcg in hourly increments
• onset 2-4 min; doa 30-60 min
• potent maternal respiratory depression
• may affect newborn feeding

Question 31

Sufentanil in labor?

Answer 31

rarely used to potency/maternal respiratory depression/neonatal bradycardia

Question 32

Remifentanil in labor?

Answer 32

• ultra-short acting
• metabolism by blood esterases therefore maternal and neonatal accumulation low
• usual dose
  
  • iv bolus 0.4mcg/kg q 1 min
  • PCA bolus 0.25 mcg/kg then 0.05 mcg/kg/min, lockout 2 min, 4 hours limit 3 mg, and background infusion 0.025-0.05 mcg/kg/min

Question 33

What are some agonist/antagonist agents used in laboring patient?

Answer 33

• Butorphenol (stadol)
  
  • 1-2 mg IV or IM, duration 4 hours
  • 5 times as potent as morphine
• Nalbuphine (nubain)
  
  • dose 5-10 mg IV, IM duraiton 6 hours
  • causes less dysophoria than butorphenol
• benefiical becaue they cause less N&V, dysphoria
• both agents cause significant sedation
• both agents rapidly transfer across placenta and produce alterations in FHR tracing

Question 34

Midazolam in laboring patients?

Answer 34

• low doses (0.5-1 mg IV) given to help alleviate anxiety without causing detriment to parturient and fetus
  
  • particularly useful in c section patients
    
    • causes amnesia

Question 35

Ketamine in laboring patients?

Answer 35

• occasionally intermittnet doses of 10-15 mg IV useful to produce intense analgesia for 10-15 min without causing detriment ot parturient and fetus
  
  • routinely co admin low dose midazolam
  • 25-50 mg (0.5 mg/kg) to supplement an incomplete neuraxial blockade during c section
  • in higher doses, dissociative anesthetic associated with emergence delirium/hallucinations
  • in higher doses, increases BP
  • induction agent of choic in pt with acute asthma undergoing urgent csection

Question 36

Inhalational anesthesia in laboring patients?

Answer 36

• varies by country
• nitrous oxide in most globally used inhalation agent for labor anes
  
  • 62% in UK
  • 43% Canada
  • <1% US
• Concentration- usually givne 50/50 mixture
• does it cross placenta- yes
• affect neonatal ventiatlion- no
• s/e - n/v, paresthesia
• who adminsiters? mom has to hold the mask, breaths when contraction comes
• book also mentions low dose sevo 0.6% but allan does not see in practice personally

Question 37

What is the best method of pain relief in labor?

Answer 37

neuraxial anesthesia

• only modality that can provide complete pain relief with minimum maternal or fetal depression
• common techniques
  
  • eipdural
  • combined spinal epidural
  • spinal techniques

Question 38

When can laboring mom recieve an epidural?

Answer 38

• ACOG guidelines state that in absence of medical contraindications, maternal request is a sufficient reason for labor analgesia
  
  • some clinicians may believe that labor needs to be adequatley progressed before epidural, believve that early epidurals slows down labor
    
    • ​patient needs to be contracting regularly and have cervicla change

Question 39

What are some advantages to labor epidural?

Answer 39

• More constant level fo analgesia
• more even level of block
• more stable vital signs
• can use to obtain surgical block in event of need for cesarean section

Question 40

What is a combined spinal-epdiraul?

Answer 40

• CSE combines advantages and mitigates the disadvantage of single-shot anesthesia and continuous epidural anesthesia
• anesthesia is inititaed with a spinal anesthetic injection of opioid and local anesthetic and maintained via the epidural catheter
  
  • allows you to admin spinla that will work immediately and then admin epidural dose which takes about 30 min to setup for pain relief
    *

Question 41

Common indication for spinal anesthesia?

Answer 41

• Imminent delivery (saddle block)
• cerclage- suture placed for incompetent cervix 16-18 weeks
• nonobstetric sx during pregnancy
• instrumental vaginal devliery (forceps)
• removal of retained placenta
• postaprtum tubal ligation
• postpartum tubla ligation
• cesarean section

Question 42

Advantages/disadvantages for spinal anesthesia for c/s

Answer 42

• Advantages
  
  • rapid onset
  • dense and reliable anesthesia
  • minimizes risk of aspiration
  • little risk of LA toxicity
  • minimal drug transfer to fetus
  • awake pateint
  • decreased risk of failed intubation
  • decreased blood loss
• disadvantages
  
  • hypotension
  • lmiited DOA- generally add opioid (morphine/fentanyl) to opioid. fent acts quick and morphine will last several hours because it’s hydrophilic
  • N &V
  • PDPHA- postdural pucture headache (decrease since advent of blunt tipped needles)

Question 43

Spinal anesthesia doc?

Answer 43

• Bupivicaine is most common cause of LA
• cSECTION
  
  • 7.5-15 MG FOR BUPI
• Most providers add an opioid to LA to improve quality of block and to privde postop analgesia. also opioids decrease n/v
  
  • fentanyl 20 mcg- intraop analgesia
  • morphine 0.2 mg- postop analgesia
  • epinephrine may be added to decrease systemic absorption–> prolong block

Question 44

What is a teratogen?

Answer 44

• any postnatal change in fucntion or form in an offspring after prenatal treatment
  
  • 1200 drugs are teratogenic in animals and 30 teratogenic in humans (all drugs in general)
• Gestational age at which exposure occurs determine the target organs or tissues, types of defect and severity of damage
  
  • structural abnormalities–> occurs during organogenesis (day 31-71 after 1 day of LMP)
  • Function (learning disabilities)–> a/w exposure during late pregnancy or postnatally because CNS continues to mature until 2nd year of life

Question 45

What is still developing in fetus as mom approaches term?

Answer 45

• CNS
• Eyes
• teeth
• external genitalia

Question 46

Investiagtion of anesthetic agents for teratogenicity?

Answer 46

• animal studies of reporductive effect of anesthetic agnets
• epidemiological surveys of OR personnel routinely exposed to subanesthetic concentration of inhalational agnets
• outcomes in females who have undergone sx while pregnany
• agents: mentioned in class
  
  • toxoplasmosis
  • alcohol
  • cocaine
  • warfarin
  • enalapril
  • caprtopril
  • accutane
  • VPA
  • ETOH
  • metabolic imbalances:
    
    • diabetes
    • hyperthermia

Question 47

What are non drug factors for teratogenicity?

Answer 47

• hypoglycemia
• hypoxia
• hyperglycemia
• hyperthermia (maternal fever)
  
  • congenital abnormalities, esp CNS, have repeatedly been a/w maternal fever durign the first half of pregnnacy
  • remember, fetal temp is 0.5-1 degree higher than maternal temp

Question 48

Are any anesthetic agents a/w tertogenicity?

Answer 48

• teratogenic have not been a/w use of any commonly used induction agents- barbs, ketamine and benzos, when they are admined in clinical doses during anesthesia
• diazepam/midazolam- controversial because noted increased risk for cleft lip/palate with valium
  
  • many providers don’t give it for that reason
• although anesthesia and sx are associated with a higher inciedence of abortion, fetal growth restriction and perinatal mortaility, these outcomes can be attributed to the procedure, site of sx (proximity to uterus) and/or underlying medical condition
  
  • ​evidence do not suggest that anesthesia during prengnacy results in overall increase in congenital abnormalities

Question 49

Nitrous teratogenicity?

Answer 49

• in contrast to VA, N2O has been shown to be a weak teratogen in rodent
  
  • neuronal apoptosis and learning impairments
  • reproductive effects occur only after lone exposure to high concentrations that are unlikely to be encountered in humans during clinical anesthesia
    
    • early weeks of pregnancy probably avoid

Question 50

Practical considerations for OB patient and anesthesia?

Answer 50

• elective sx should not be performed during pregnancy
• avoid sx in 1st trimester (organogensis)
• optimal time- 2nd trimester
  
  • preterm labor risk is lowest!

Question 51

Can we admin COX inhibitors?

Answer 51

• indomethacin/ketoralac
• used often in preterm labor
• MOA: inhibit COX and thus prevent the synthesis of prostaglandins
  
  • prostaglandins play an important role in stimulation of uterine contraction
• maternal admin may cause a closure of PDA
  
  • in 2nd half of pregnancy need to be avoided because of promotion of closure of PDA

Question 52

Anesthesia concern for c-section?

Answer 52

Preoperatively

• History /Physical
• Airway evaluation
• Informed Consent
• LUD (>20 weeks don’t lie on back!)
• IV access(free flowing 18-16 gauge)
• Hydration (minimal 500 mL)
• Aspiration prophylaxis (bicitra, metoclopramide, ranitidine)
• Supplemental O2
• Anesthetic plan/ postoperative analgesia plan

Choice of anesthetic depends on:

• Indications for surgery
• Degree of urgency
• Maternal status
• Condition of fetus
• Desires of the patient

Question 53

Spinal anesthesia for c/s?

Answer 53

Most popular technique:

• typically admin 10-15 mg hyperbaric bupi with 10-25 mcg fent and/or 0.1-0.25 mg preservative free morphine
  
  • studies indicate that 12 mg bupi optimal dose
• duration block 1.5-2 hours!
• level of block T4
• Hypotension may be prevented by LUD, crystalloid coloading, and treated with ephedrine (5-10 mg) or phenyl (50-100 mcg IV)

Question 54

What are some key levels of dermatomal blockade?

Answer 54

Way to remember

• C6= thumb= sex yes!
• C7= pointer
• C8= ate a burger (with pinky)

Question 55

Advantages/disadvantages to epidural anesthesia for C/S?

Answer 55

Advantages

• Less impact on maternal/fetal hemodynamics
• Can use if already in place
• Can place electively if patient high-risk of needing emergency c/s later
• Can re-bolus
• Can use for postoperative analgesia
• Less chance of PDPHA

Disadvantages

• Increased complexity of insertion and management
• Slower onset (up to 30 minutes)
• Can be less dense
• Large doses of LA–increased risk of toxicity

Question 56

What is usually given in epidural for c/s?

Answer 56

Typically bolus with

• 15-20 ml 2% lidocaine (with/without epinephrine)
• 10-20 ml 0.5% bupivacaine or ropivacaine
• 5-15 ml 2-3% chloroprocaine

Can add opioids

• 50-100 mcg fentanyl
• 10-20 mcg sufentanil
• 1.5-4 mg preservative free morphine (Duramorph)

DON’T NEED TO MEMORIZE FOR TEST!

Question 57

GA induction in emergency c-section?

Answer 57

• Preop assessment of airway
• Large bore IV
• Aspiration prophylaxis (Non-particulate antacid, H2-blocker, Reglan)
• Monitors/suction/ emergency airway cart
• Optimal airway positioning/ LUD
• Preoxygenate! (3 min or longer)
• Prep + drape –surgeon ready
• RSI w/cricoid (10 N while awake; inc to 30 N after LOC)
  
  • Agents available
    
    • Ketamine (used with maternal hypotensive crisis) 1 mg/kg
    • Etomidate 0.3 mg/kg
    • Propofol 2-2.5 mg/kg
    • Succinylcholine 1-1.5 mg/kg
    • Preferred muscle relaxant
• Intubate– let surgeon know you have tube placed because they will cut right away!
• Expect difficult intubation
• Proper positioning
• Short handled laryngoscope (Datta) recommended
• Use minimal amount of time; first attempt best attempt
• Smaller ETT 6.0 or 6.5
• Use caution…friable tissues and decreased airway size
• Verify placement of ETT, then
• Surgeon makes skin incision
• Ventilate with 50% O2/50% N2O & volatile agents (~1 MAC)
• Secure ETT, tape eyes, OGT
• ****Critical interval of 3 minutes between uterine incision and delivery of fetus
• Delivery of baby– iarea with tremendous recall in anesthesia, generally don’t give versed, fent, etc for emergeny csection- gas may not be at appropraite level yet
• Reduce volatile agents (.75 MAC), may increase N2O to 70%, and give opioids and benzodiazepine
  
  • ​reduce VA to reduce r/f vasodilation
• Possible NDMR
• Delivery of placenta
• Then can add oxytocin to IV <– so uterus can begin to clamp/contract
• At end:
  
  • Suction OGT
  • Reverse NDMR if necessary
  • Extubate AWAKE
  • Emergence and recovery is a critical period for anesthesia-related deaths from airway factors!
• •

Question 58

How much oxytocin is given?

Answer 58

• Small dose oxytocin sufficient to produce adequate uterine contraction after cesarean devliery

Rule of 3’s

• oxytocin 3 units, 3 min evaluation intervals, 3 total doses and oxytocin infusion 3 units/hr maintenance
  
  • 3 units given slow bolus
  • uterine tone reassessed 3-6 min
  • if inadequate, additional 3 doses are given after each reassessment
  • if uterine atony persists after 3 doses–> switch to another drug
  • after establishment of uterine tone, infuse 3 units/hr x 5 hours
• Oxytocin as a rapid IV bolus
  
  • direct smooth muscle relaxant–> decrease SVR, hypotension, tachycardia
  • hypotension may result in CV collapse
  • chest pain, MI may develop
  • structural similarities b/t oxytocin and vasopression–> water intoxication and hyponatremia

Question 59

2nd line meds if oxytocin doesn’t work to stop bleeding?

Answer 59

• Methylergonovine (methergine- ergot alkaloid)
  
  • dosage 0.2 IM
  • onset 10 min
  • duration 2-4 hours
• Cannot give IV! causes intense vasoconstriction, acute HTN, sz, retinal detachment, coronary artery spasm, CVA
• May be repeated x 1 after 30 min
• contraindications: HTN, preeclampsia, CAD

Question 60

3rd line to stop bleeding s/p csection?

Answer 60

• 15 methylprostaglandin F (carboprost- hemobate)
• dose 250 mg IM, may repeat q 15 min x 8 doses (2mg)
• S/E : fever chills, N/V, diarrhea and bronchoconstricitons
  
  • who should not receive this drug?
    
    • asthmatics