Ex1 OB 2 Part 2 Flashcards
Most common type of C/S
Low transverse incision
Types of C/S incisions
- low transverse (lower uterine part, horizontally)
- low vertical
- Classical incision (middle, vertical)
Pfannenstiel incision
Low transverse incision
most common C/S
Why did they stop the classical incision?
increased risk of uterine rupture in subsequent pregnancies/labor.
Most common indications for C/S
- failure of labor to progress
- fetal distress
- cephalo-pelvic disproportion
- prior uterine surgery or C/S
Advantages of regional over GETA
- Lower maternal mortality rates
- Can be used in fetal distress w/o facing difficult intubation + further fetal compromise
- patient awake, less aspiration risk
- Less exposure of fetus to depressant drugs
Disadvantages of regional vs GETA
- Accidental intravascular injection (possibility of convulsions, CV collapse, aspiration)
- Total spinal (severe HOTN, unconsciousness, aspirations)
- Risk of dural puncture H/A
Advantages of spinal anesthesia
- Simplicity of technique
- Speed of induction (vs epidural)
- Reliability
- Minimal exposure of fetus to Rx
- Minimization of hazards of aspiration
Disadvantages of spinal anesthesia
- High incidence of HOTN
- Intrapartum N/V
- Possibility of H/A after dural puncture
- Limited DOA (unless a continuous technique is utilized)
spinal anesthesia C/I
- Severe maternal bleeding
- Severe maternal HOTN
- Coagulation disorders
- Some forms of neurological disorders (ex. MS)
- Patient refusal
- Sepsis (area of needle insertion or generalized)
C/S Preop considerations
- Use of aspiration precautions recommended d/t pregnancy-induced GI changes:
- Metoclopramide 10 mg + an H2 blocker (famotidine 20 mg) IV can be used
- Nonparticulate antacid (bicitra 30-60 mL) depends on practice - Volume Loading (LR)
- T&S (unless emergent)
Vaginal birth EBL
300-500mL
C/S EBL
800-1,000mL
Volume loading for C/S
~1L; doesn’t matter how fast
- reduces incidence of HOTN
- no difference in acid/base status, ephedrine use
Spinal for C/S - drug + dose?
Hyperbaric Bupivicaine 0.75% 6-15mg
depending on location: 1.4-1.6mL
Bupivacaine 0.75% administering 1.4mL … how many mg is this?
1 mL = 7.5 mg
.4mL = 3mg
1.4mL = 10.5mg
Hyperbaric bupivacaine administration is associated with
Higher doses = greater reduction in MAP
1.6mL Hyperbaric bupivacaine 0.75% attains what level?
T4 - Nipple line
1.6mL Hyperbaric bupivacaine 0.75% lasts how long?
1.5-2 hours
C/S Local anesthetic protocol
- Hyperbaric bupivicaine 0.75% 1.6 mL
- Fentanyl 10-20 mcg
- Morphine 0.1-0.25 mg
C/S Local anesthetic protocol - fentanyl
10-20mcg (in TB syringe)
- decrease visceral discomfort
- may lower incidence of N/V during uterine manipulation
- 15mcg=adequate analgesia, significantly less N/V than 20 mg (research)
C/S Local anesthetic protocol - morphine
- Duramorph = preservative free
0. 1-0.25 mg (in TB syringe) - for postop analgesia from 18-24 hours post op
Why must preservative free analgesics be used intrathecally?
To avoid neurotoxicity
If intrathecal morphine is used, what should be implemented?
- *duramorph
- postop monitoring protocol to monitor for respiratory depression (1:1000) + pruritis
Tx for pruritis
Benadryl (postop d/t morphine)
Other LAs used for C/S
- Tetracaine 0.5% in 5% dextrose (lasts 90-120min), in practice up to 8h
- Bupi 0.5% in 8% dextrose (90-120m), off label use, sensory density less than hyperbaric
C/S Intraop considerations: prior to placing spinal what should be done?
IV x 1 (18g), Monitors, O2 (possibly C/I d/t masking of high spinal), position: R lateral or sitting
After placement of a spinal, what must be done?
Lay mom down + place in L uterine displacement until delivery of infant
Tx: HOTN d/t spinal
Ephedrine 5-10mg
+/or
Phenylephrine 50-100mcg IV
Tx: HOTN + bradycardia d/t spinal
*sympathectomy
Tx: atropine 0.4mg PRN
–> or reverse trendelenberg
Definition: maternal HOTN
Decrease in SBP < 100 mmHg
or
Decrease > 30 mmHg from preanesthetic value
**depends on moms baseline
Incidence of maternal HOTN
80%
Higher the sympathetic block, the greater the risk of ______
HOTN + emesis (> T4)
Incidence of HOTN from spinal (prior to C/S) is less if ______ because _____
- mom has been in active labor
- Autotransfusion (500 mL+) d/t uterine contractions
- decrease in size of uterus d/t loss of amniotic fluid if membranes have ruptured
- Higher maternal catecholamines in labor
warning signs of maternal HOTN d/t spinal
lightheadedness, nausea, difficulty breathing, and diaphoresis
*SET BP to 1-2.5 minutes!
DOC maternal HOTN
Ephedrine (or phenylephrine)
MOA Ephedrine
stimulates both alpha + beta adrenergic receptors, cardiac stimulation + subsequent increase in peripheral/uterine blood flow
Ephedrine - disadvantages
crosses placenta + increases fetal heart rate + heart rate variability
Given 10mg/mL vial phenylephrine …. how to draw up/administer?
Draw up vial, inject into 100mL saline, draw 10 mL from bag
=100mcg/mL
Disadvantage of using Phenylephrine
Profound bradycardia
Tx of phenylephrine induced bradycardia
Atropine or glycopyrrolate (0.1 rather than 0.2)
Which one is better for maternal HOTN: phenyl or ephedrine?
Depends on moms HR:
give ephedrine if large dose of phenyl drops HR
When do we administer a test dose during neuraxial anesthesia?
During epidural placement - to confirm correct placement (NOT INTRAVASCULAR)
(Any ringing in ear? Funny taste in mouth?)
Complications specific to epidural anesthesia
- PDPH
- unintentional intravascular injection
- shivering
Peak onset of shivering after epidural
10 minutes
MOA + Tx: shivering after epidural
vasodilation to BLE –> upper body compensates
Tx: full lower bair hugger
Epidural anesthesia: Local anesthetics used
- Chloroprocaine 3%
- Lido 2% + Epi 1:200,000
- Bupi/Ropi 0.5%
When is Bupi/Ropi used in epidural?
Labor epidural d/t greater ratio of sensory:motor blockade
When is Lido/Chloropr. used for epidural?
C/S d/t greater motor blockade
Stat C/S: which LA in epidural?
Chloroprocaine
Duration of surgical anesthesia: Chloroprocaine
30-40 min
Duration of surgical anesthesia: Lidocaine 2% with Epi 1:200,000
75-90 min
Duration of surgical anesthesia: Bupivicaine 0.5%
75-90 min
DOC OB Epidural
Lido 2% + Epi 1:200,000
ideal local anesthetic in the presence of fetal distress d/t rapid onset, short maternal half-life and fetal plasma half-life
chloroprocaine 3%
Chloroprocaine average onset of action
6-12 minutes
- up to 10 minutes for 2-choloroprocaine to attain a T4 level in a newly placed epidural
- to go from a T10 level with sensory blockade appropriate for labor analgesia up to a T4 block for surgical anesthesia can be obtained in approximately 5 minutes
Why isn’t Chloroprocaine used more often?
- antagonizes mu-agonist narcotics (fentanyl, morphine) in epidural
- may interfere w/ subsequent epidural bupi
Epidural of choice in emergency C/S
Chloroprocaine 3%
Bupivicaine advantages + disadvantages in epidural
- slower onset
- lesser degree of HOTN
- only available in .5% and below
What can speed the onset of action + spread block of epidural?
- 1 mL Sodium Bicarb (7.5 or 8.4%) per 10mL LA
- with Lido
- NOT with Bupi
Administration of epidural
- Confirm negative test dose
- 15-20mL LA administered slowly in 5mL increments (wait 5 min, monitor BP, inject another 5mL)
- Verification of catheter placement by aspiration is done with each new injection
- Injection completed when T4 level achieved
Mom is on OR table, prior to C/S, LA injection is not working via epidural. What next?
Possible that
- epidural catheter migrated
- epidural not bathing all nerves (“hot spot”)
Best option when Epidural is not working + mom has “hot spot” in middle of C/S
Kiss of ketamine: 10-20 mg
or 30% N2O
After delivery via C/S, mom is in severe pain, what is another option?
IV narcotics PRN
or
Fentanyl 100 mcg diluted into 10mL saline via epidural
Anticipation of post-op C/S pain: Tx (dose, DOA)
Preservative free morphine via epidural, 3-5mg
*lasts 12-24h
In addition to epidural morphine, post operative pain can be managed by _________
- patient-controlled epidural anesthesia (PCEA) with LA of low concentration +/or epidural narcotics
- ketorolac (Toradol)
NSAIDs - pain management post-op
- *no NSAIDs before baby is out
- verify with surgical team this is okay
- 30mg IM (or IV)
Why no NSAIDs before baby is out?
- suppresses uterine contractions
- promotes closure of fetal PDA
Failed epidural rate
12% (“high”)
s/s failed epidural
High # of top offs
Management of failed epidural
Management with RACE: Recognize the problem Assess the fetal heart rate Consider the options Evaluate the airway
Failure of epidural during labor: Tx
Replace epidural.
Sit mom up, go to different space, place epidural.
Failure of epidural during C/S: Tx
*Reason for C/S: baby stable or unstable?
Unstable: no time to replace epidural/spinal – GETA
Stable: time to evaluate next plan (replace epidural, spinal, etc.)
Failed epidural: General Options
- replace catheter if not urgent procedure
- remove + perform spinal
Failed epidural: Replace with Spinal
- if dose of epidural was < 10mL can use normal intrathecal dose
- hyperbaric
- Leave sitting 1 – 2 min (control level of block)
Failed epidural: do not give spinal if
- bolus given in last 30 min
- pt weighs > 120 kg
- height < 4’ 10”
CSEs are most commonly used for
-repeat C sections or for patients who have had previous abd surgery (prolonging surgical time)
what MUST occur prior to induction?
- surgical team + patient prepped + draped, ready to start w/ scalpel in hand
- regardless of emergency vs. planned
Non-emergent + emergent preoxygenation
emergent: 4 VC breaths
non-emergent: 100% O2 for 3 minutes
Induction agents
Thiopental Propofol Etomidate Ketamine Succinylcholine
Induction agents that cross placenta
thiopental, propofol
both lipid soluble
Induction agent: Thiopental
4mg/kg
Induction agent: Propofol
2-2.5mg/kg
Induction agent: Etomidate
.3mg/kg
Induction agent: Ketamine
1-2mg/kg
Induction agent: Succinylcholine
1-1.5mg/kg
Induction agent: mom bleeding or hypovolemic
Reduce doses or use etomidate/ketamine
Maintenance Drugs
Until delivery: mix of 50% N2O/O2 + Sevo/Iso @ 75% MAC
- judicious use of NDMR after Sux wears off
- avoid hyperventilation (AE on UBF)
What does hyperventilation cause?
Hypocarbia
What does hypocarbia do to the placenta?
Decreases UBF (uterine blood flow)
What inhalational agents cross the placenta?
Volatiles + Nitrous
-lipid soluble + have LMW
What NMBA cross the placenta?
Poorly lipid soluble + highly ionized - cross very slowly but pose no problems to fetus
Recall during C/S
Maternal awareness: 17-35%
high
Maintenance: Oxytocin
10 – 30 units/L
added to IV infusion + administered after delivery of placenta to stimulate uterine contraction
AE: vascular relaxation (rapid infusions after C/S can cause HOTN)
-needs to be diluted
-Can double dose if needed.
Maintenance: Methergine
0.2 mg IM
or Hemabate 0.25 mg IM
may be given for uterine atony and/or increased bleeding
Once baby is delivered, what should be done?
Decrease VA to 0.5 MAC
higher doses = decreased uterine tone = bleeding
Once cord is clamped, what may be done?
Balanced technique: N2O, narcotic + relaxant
Antibiotics for C/S
- Surgeon preference
- normally 2g Ancef
- given before incision
Timing of delivery
Neonatal status with C/S delivery under GA investigated using 2 time intervals:
- Induction to delivery time (I – D)
- Uterine incision to delivery time (U – D)
2 time intervals
- Induction to delivery time (I – D)
2. Uterine incision to delivery time (U – D)
I-D
Induction to delivery time
U-D
Uterine incision to delivery time
I-D outcomes
better outcomes when:
I-D time < 20 minutes
U-D outcomes
Uterine incision – delivery intervals > 180 seconds associated with low Apgar scores + acidotic babies
Increased U – D intervals also result in elevated fetal umbilical artery norepinephrine levels which may be a sign of fetal hypoxia
Adverse outcomes with prolonged U – D intervals may be the result of:
- The effect of uterine manipulation on uteroplacental + umbilical blood flow
- Pressure on uterus with accentuated aortocaval compression
- Compression of fetal head during difficult extraction
- Inhalation of amniotic fluid d/t gasping respirations by fetus in utero
Uterine Incision-Delivery Time Prolonged d/t tightened uterine muscle
Low dose nitroglycerin to relax muscle temporarily
1-2 mL of 100 mcg/mL Nitroglycerin
only if OB wants
C/S with GETA - no spinal/epidural/CSE
Anticipate postop pain
**administer analgesics during emergence
C/S GETA emergence
- NDMR reversal if used
- Anticipation of postop pain (admin analgesics)
- Ondansetron 4 mg IV for N/V prophylaxis
- Extubate when pt wide awake
What drugs cross the placenta?
Induction agents Inhalation agents Neuromuscular blocking agents Opioids (all) Local anesthetics Anticholinergics Neostigmine Benzodiazepines Vasoactive drugs
Drugs crossing placenta: Local Anesthetics
- LAs have to be absorbed in systemic circulation before can be transferred across placenta.
- BUPIV + ROPIV are highly lipid soluble + can transfer with simple diffusion
- LIDO is less lipid soluble but has a lower degree of protein binding, so it will also cross placenta
Drugs crossing placenta: anticholinergics
- Glycopyrrolate is fully ionized + therefore poorly transferred across placenta
- Atropine demonstrates complete placental transfer
Drugs crossing placenta: Neostigmine
- Neostigmine = a small molecule able to cross placenta more rapidly than glycopyrrolate
- In a few cases where neostigmine used with glyco to reverse NDMB in pregnancy, profound fetal bradycardia reported
- SO, for GA in pregnancy where baby is to remainin utero, advisable to use neostigmine with atropine rather than glycopyrrolate
Drugs crossing placenta: Benzos
Benzos = highly lipid soluble + un-ionized
= complete transfer
Non-OB surgery
1-2% of women undergo non-OB surgery during pregnancy
Most common procedure during 1st trimester = laparoscopy
Most common open abd procedure in pregnancy = appendectomy + cholecystectomy
Pregnancy + elective surgery
- avoid surgery during period of organogenesis during 1st trimester
- all elective procedures postponed until after delivery
Pregnancy + non-elective surgery
non-elective procedures should be performed in 2nd trimester if feasible
Fetal safety: teratogenic agents
- No agent proven to be teratogenic in humans
- nitrous oxide + diazepam in animal models = aroused concern, now questioned
Now we avoid N2O + all benzos
Non-OB cases: planning
-consult OB for all but the most minor surgical cases
**use regional techniques (esp spinal) when able!
- Continuous FHR monitoring may be indicated depending on operative site + fetal gestation
- A uterine tocodynamometer should be used to detect preterm labor (especially in posto)
If a pregnant pt is having a non-obstetric surgery and needed paralysis, how do you reverse?
Atropine rather than Glyco
adjunct to neuromuscular blockade reversal:
25–30 mcg/kg 30–60s before neostigmine
Atropine dosage when used in reversal with Neostigmine
25–30 mcg/kg 30–60s before neostigmine
dose is approx half of neostigmine (atropine 20µg/kg for neostigmine 40µg/kg)
FHR monitoring - non-OB surgery
- After 18 weeks gestation, FHR monitoring is practical
- After 25 weeks gestation, FHR variability is a reliable sign of fetal wellbeing
Cervical cerclage
Shirodkar + McDonald cerclages performed for cervical incompetence
- transvaginally during 1st/2nd trimester, prophylactically or emergently
- sutures removed @ 38 weeks
- no anesthesia req’d
Cervical cerclage: prophylaxis
12-14 weeks
Cervical cerclage: technique
- Spinal anesthesia is technique of choice, although an epidural may also be performed
- Avoid sedation or intrathecal adjuncts if possible d/t effect on fetus
- Avoid nitrous oxide + midazolam
cervical cerclage: spinal technique
Less medication, pt sits up for “dense saddle block”, do not need T4 coverage
1-1.2mL Hyperbaric 0.75% Bupi
Postpartum Tubal Ligation
- Usually done 8h after vaginal birth if no complications
- Surgeons make small sub-umbilical incision d/t fundus being at level of umbilicus
Postpartum tubal ligation: anesthetic considerations
- Delayed gastric emptying persists during early postpartum
- Bicitra, metoclopramide, famotidine given preop
- Easiest to use labor epidural (Keep in mind LA doses decreased with pregnancy)
- Otherwise, spinal most commonly done
- Ensure pt NPO between delivery + surgical procedure
VBAC
Vaginal birth after cesarean
-TOLAC: trial of labor after cesarean delivery (60-80% able to VBAC)
VBAC Risks
- Maternal hemorrhage
- Infection
- Operative injury
- Hysterectomy
- Uterine Rupture: Incidence of 0.7% - 0.9%, declines with each successful VBAC
Uterine Rupture: S/S
Vaginal bleeding Sharp pain between contractions Contractions slow or become less intense Bulging under pubic bone (baby’s head protruding outside of uterine scar) Uterine atony Maternal tachycardia
Uterine Rupture: Tx
Emergency C/S
Supportive Care
