Lecture 3 - Surgery in the Parturient Flashcards
Approximately how many births are C-sections?
30% and rising
What are the common indications for a C-section?
- Failure to progress
- Fetal distress
- Previous C-section
- Maternal condition making vaginal delivery unsafe
- Fetal condition making vaginal delivery unsafe
What are the different anesthetic techniques for birth?
- Local infiltration by surgeon
- General anesthesia
- Regional anesthesia: spinal, epidural, combined spinal-epidural
Local infiltration is:
- Rarely performed
- patient usually in extremis
- Surgery must be done via MIDLINE incision, gentle retraction, no exteriorization of the uterus
- Usually done to supplement a regional technique if local anesthetic toxicity not a consern
- Often combined with “OK Anesthesia
Regional anesthesia for a C-section is:
- Safer than general anesthesia
- Many patients already have a epidural in place when a C-section is called for
- Less neonatal depression with regional anesthesia
- Mother is awake and able to witness the birth of her child
Indications for general anesthesia with C-section:
-Acute severe fetal distress with no time for block
-Non functioning epidural catheter
-Parturient has contraindication to regional block
Regional block inadequate
-Patient refusal of block
What are the advantages of general anesthesia:
- Proven track record of safety (Regional is still safer)
- Produces rapid reproducible conditions for delivery
- ALWAYS WORKS
What are the disadvantages of general anesthesia:
-Still not as safe as regional
-Forces you to deal with a potentially difficult airway often under suboptimal rushed conditions
-Failed intubation
-Failed ventilation causing death or neurological injury
-Aspiration pneumonia
Awareness
What are the anesthesia effects on the fetus:
- Avoid hypotension, hypoxia, acidosis, hyperventilation
- Limit time between uterine incision and delivery to less than 3 minute
- Infants exposed to GA have lower Apgar at one minute but no difference at 5 minutes
- No significant alteration in neurobehavioral scores with regional techniques.
The importance of preoxygenation and denitrogenation in labor and delivery is:
- Critically important
- At term O2 consumption increased 20-30% (with decrease of FRC results in a faster desaturation during apnea)
Preoxygenate patient at _____% O2 with a tight mask fit for at least _ minutes.
100
3
What is the induction dose of propofol for the pregnant patient?
-2 to 2.8 mg/kg
T/F: Propofol easily crosses the placenta.
TRUE
What is the induction dose of Ketamine:
1 to 1.5 mg/kg
Ketamine is useful in the face of maternal __________ as it supports the BP, also decreases risk of _______.
- Hemorrhage
- bronchospasm
What are some side effects of ketamine?
- Hypertension
- dysphoria
Why is midazolam not commonly used in induction of a pregnant woman?
-Causes more neonatal depression the other agents
Why is etomidate not commonly used in indution of a pregnant woman?
-May cause transient adrenal supppression in the neonate
T/F: Rapid sequence induction is mandatory in all but the rarest of cases.
TRUE
T/F: A defasciculating does prior to succinycholine is mandatory in patients at term.
FALSE (No need for defasciculating dose…._
T/F: Any relaxant is safe as their hydrophilic charged nature significantly limits placental transfer.
TRUE
T/F: There have been cases of neonatal paralysis in infants with homozygous atypical pseudocholinesterase.
TRUE
What are the two different ways to give general anesthesia to the pregnant mother in the labor and deliverer:
- 50% nitrous oxide and 2/3 MAC of volatile agent
- NOT to use nitrous oxide until fetus is delivered and use 1.2 MAC with fentanyl 2-3 mcg/kg. After delivery 0.5 MAC with nitrous oxide and midazolam can be given.
In most prospective studies the _________ of neonatal depression is ________ between general and regional anesthesia.
- incidence
- similar
T/F: There is a correlation between neonatal depression and the interval between anesthetic induction and delivery.
FALSE (There is NO correlation….)
T/F: The uterine incision to delivery interval does make a difference, possibly due to uterine artery spasm.
TRUE
What are the advantages for epidural anesthesia for a C-section?
- Dose can be tailored to patient’s need
- Ability to prolong the block
- Ability to provide post op analgesia
- Ability to produce a gradual block with less rapid and severe hemodynamic changes
What are the disadvantages of an epidural for a C-section?
- Some patient have contraindication
- Often the block quality is not as good as a spinal
T/F: If an epidural is dosed for C-section and does not produce a surgical block, a general anesthetic may be required as the risks of a total spinal is ten-fold higher in this condition.
TRUE
Local anesthetic diffuses to epidural nerve _____ where ______ channels are blocked, reducing sensory and motor function.
roots
Sodium
T/F: Some of the epidural is absorbed by the vascular system and taken to other organs and metabolized.
TRUE
T/F: No portion of the epidural is diffused into the CSF to the cord itself.
FALSE (A samll amount diffuses into CSF to the cord itself)
Local Anesthetics: Mid-throracic block height results in ___________ of lower extremity and ________ beds, decreseases ________ return and decreased BP via this mechanism, and also direct ______ dilation.
- sympathectomy
- splanchnic
- venous
- arterial
If a local block extends to T1 a ________ in heart rate and __________ may be seen, cardiac accelerator fibers T1-4.
- reduction
- contractility
A sensory block above __ often gives patients a sense of dyspnea - reassurance is helpful.
T2
What is the epidural management for a C-section?
- Dose catheter slowly
- 15 cc of 2% LIDOCAINE OR 15 cc of 3% 2-CHLOROPROCAINE should be given over 5 minutes and continued monitoring for signs of local toxicity
- 100 to 150 mcg of FENTANYL via epidural
- NaHCO3 speed onset
Where is the ideal block for a C-section?
T4 - T8
What percentage of patients will have a break through of pain with epidurals?
10 - 50%
What treatment can be done with break through pain for a C-section with an epidural?
- Bolus of 5 cc of local
- Epidural or IV fentanyl
- Nitrous oxide
- Ketamine IV (Keep total dose blelow 1 mg/kg) ~10 mg at a time
- Ask surgeon to infiltrate with some local
- If epidural is clearly inadequate, convert to GA
What are the advantages of a spinal over an epidural for a C-Section?
- Extensive dense block with a single injection
- Defined end point - if you get CSF flow, you are in the correct place
- Intavascular injection is not a concern
- Technically simple, usually quick does not involve placing a catheter
What are the disadvantages of a spinal over an epidural for a C-section?
- Finite duration
- Risk of postdural puncture headache
- Risk of total spinal
- Maternal hypotension is more common
T/F: Laboring women have more hypotension with spinals then non-laboring women.
FALSE (Laboring women have LESS hypotension….)
T/F: Prehydration has limited ability to prevent hypotension.
TRUE
What is the drug of choice for the pregnant patient with hypotension?
Phenylephrine
Which local anesthetic is the best choice for a local anesthetic in a spinal?
Bupivicaine
What is the typical dose for a spinal?
-Bupivicaine 12-14 mg with 10-25 mcg of fentanyl and 0.1-0.3 mg of duramorph
During a C-section the baby is delivered what is the next step?
-Pitocin 20 units in a 1 liter IV bag
Currently ____% of pregnant patient require non-obstetric surgery during their pregnancy. The common procedure are ____________ and ____________..
1-2
- appendectomy
- cholecystectomy
What are other general anesthesia consideration to a pregnant mother:
- effect of the disease process/therapy
- Possible teratogenicity of anesthetic agents
- Intraoperative effects on uteroplacental blood flow
- Increased risk of preterm labor/risk of abortion
- ALREADY MENTIONED AS BEFORE PROBLEMS
What are the Maternal consideration of anesthesia?
- Decrease in MAC
- Increase sensitivity to neuraxial agents
- Decreased plasma cholinesterase
- Decreased protein binding
- Limited drug information in parturients
What are the fetal considerations of anesthesia:
TERATOGENICITY
-Limited ability to conduct trial
-Guidelines based on:
Effects on reproduction in animals
Epidemiological surverys of OR personnel
Studies on pregnant women who had to have
surgery
T/F: No anesthetic agent is a proven teratogen in humans.
TRUE
What anesthetic agents have been deemed safe from teratogenicity affect in the fetus:
- Thiopental
- morphine
- meperidine
- Fentanyl
- Succinylcholine
- NDMR
Anesthetic management in the parturient should be directed to:
AVOID
- hypoxemia
- hypotension
- acidosis
- Maintain normal PCO2 levels
- Minimize effects of aortocaval compression
What gestational age should fetal heart rate and uterine activity be monitored at:
20 weeks
What drugs should be avoided in the development of the fetus?
- benzodiazepines (especially during weeks 3 - 8)
- AVOID Nitrous oxide due to interference with B12 metabolism
T/F: Volatile agnent may suppress preterm labor.
TRUE
T/F: The physiological effects of pregnancy are usually well established by 30 week of gestational age.
FALSE (…established by 20 week of gestational….)
How long should elective procedure be postponed after delivery?
6 weeks
