Week 12 - Non-OB Surgery in the OB Patient Flashcards
What are common causes for non-OB surgery in an OB patient?
- Trauma (most common cause of maternal death, highest fetal risk due to placental disruption)
- Abdominal Surgery
- Neurosurgery
- Cardiac Surgery
- Fetal Surgery
What are the maternal and fetal risk factors undergoing anesthesia?
Maternal: physiologic changes, anatomical changes, psychological changes
Fetal: teratogenic potential, maintenance of adequate placental blood flow, premature delivery
What are the goals/objectives for non-OB anesthesia in an OB patient?
- First and foremost ensure maternal safety
- Avoid teratogenic drugs
- Avoid intrauterine asphyxia (deprivation of oxygen) – optimize/maintain utero-placental blood flow and delivery
- Prevent induction of pre-mature labor (avoid stimulation of the myometrium – tocolytics may be used)
- Optimize and maintain normal maternal physiological function
How is anesthesia pharmacology affected during pregnancy?
- MAC is reduced by 30% under influence of progesterone and endogenous endorphins
- Decrease in plasma cholinesterase levels by 25% from early pregnancy
- NDMRs have prolonged duration of action
- Increased sensitivity to local anesthetics
What is teratogenicity?
The observation of any significant change in the function or form of a child secondary to maternal treatment
- depends on dosage, route of administration, and the timing of fetal exposure
- genetic predisposition may also play a role
What trimester is preferred for surgical intervention? Why?
Second trimester
-it is the period after much organogenesis has taken place and it minimizes risk for preterm delivery or miscarriage
Why should NSAIDs be avoided during pregnancy?
First trimester may increase abortion rates
Third trimester can cause closure of the ductus arteriosus which is reliant upon PGE2 to remain patent
What is fetal asphyxia and how can it be avoided?
Fetus is deprived of oxygen causing unconsciousness or death
Maintaining maternal oxygenation and hemodynamic stability is of utmost importance (avoid: hypoxia, extreme hypercarbia or hypocarbia, hypotension, uterine hypertonia)
*most serious risk to fetus during maternal surgery
When is intraop electronic fetal monitoring appropriate?
- The fetus is viable
- It is physically possible to perform intraop monitoring
- A health care provider w/ OB surgery privileges is available and willing to intervene during surgery for fetal indications
- When possible, the woman has given informed consent to emergency c-section
- The nature of the planned surgery will allow the safe interruption or alteration of the procedure to provide access to perform emergency delivery
What is the anesthetic approach for non-OB surgery before 24 weeks?
- Postpone surgery until second trimester
- Request pre-op assessment by OB
- Use non particulate antacid preop
- Monitor and maintain oxygenation, CO2, normotension, and euglycemia
- Use regional anesthesia for postop pain when appropriate
- Document fetal heart tones before and after procedure
What is the anesthetic approach for non-OB surgery after 24 weeks?
- Postpone surgery until post partum if possible.
- Obtain OB consultation and discuss use of tocolysis
- Aspiration prophylaxis of choice (reglan, bicitra, RSI)
- Maintain uterine displacement
- Monitor and maintain oxygenation, CO2, normotension and euglycemia
- Consider use of FHR monitoring intraoperatively (know that most of the meds used for GA surgery will decrease baseline variability – utilize baseline HR)
- Monitor uterine contraction and FHR post op
- No outcome differences in GA vs RA (but.. RA can avoid potential effects of anesthetic drugs on fetus/sensitivity in mother)
What are general anesthetic considerations in non-OB surgery in an OB patient?
- Be prepared for possible difficult airway
- Full pre-oxygenation w/ de-nitrogenation
- Aspiration precautions
- Decreased MAC requirements
- Monitor NMB
- Treat hypotension quickly (fluids, phenylephrine or ephedrine)
- Extubate fully awake
What are regional anesthetic considerations in non-OB surgery in an OB patient?
- Biggest risk is hypotension if using neuraxial blockade (increased risk of higher block due to LA increased sensitivity and reduced capacity of the epidural space due to increased venous pressure)
- Pre load with IV fluids
- Treat promptly (or even prophylactically) w/ ephedrine or phenylephrine
- If peripheral RA, use lowest dosage of LA possible
What are laparoscopic considerations in non-OB surgery in an OB patient?
- May need higher peak pressures due to upward displacement of diaphragm
- Changes trendelenberg or reverse trendelenberg can have significant resp and CV effects
- Pneumoperitineum pressure should be limited to 15 mmHg
- Maintain CO2 of 32-35 to decrease risk of resp acidosis
In trauma, shock may not be clinically evident until how much maternal blood volume is lost?
25-30%
-maternal blood is shunted away from fetus to preserve vital organs
