OB Anesthesia

Denise Weiss DOAnesthesiologist

Goals of obstetricsGoals of obstetricsHealthy mom/baby = happy and healthy doctors and nurses, family

OB Anesthesia• NPO guidelines

– Solid food (fatty foods) = 8hrs– Light meal (toast, crackers, etc) = 6 hours– Clear liquids =2 hours– Breast milk = 4 hours

– On L/D clear liquids ok during labor, (often only ice chips allowed)

– Stricter adherence to ice chips if higher risk of operative delivery– Scheduled inductions should be instructed to be NPO– All pregnant pts are considered to have full stomachs but the

goal is to minimize risk if need for intubation occurs

OB Anesthesia

• Reasons for NPO guidelines:– Higher risk of aspiration in pregnant patients (1 in

661 vs 1 in 2131 gen pop)• Increased intragastric pressure due to large uterus• LES is pushed up and to the left (sim to hiatal hernia)• Decreased LES tone secondary to progesterone• High incidence of GERD• Gastric pH is more acidic• Active phase of labor slows gastric emptying

OB Anesthesia

• Higher risk of difficulty in airway management– Morbidity/mortality in pregnant pts have been

attributed often to failed or difficulty managing the airway

– Airway is more friable and edematous in pregnant pts

– Increased breast size can make laryngoscopy very difficult

– Decreased FRC so desaturate quickly

OB Anesthesia

• pH less than 2.5 and gastric volume greater than 25ml are identified risk factors for aspiration

• Pregnant pts going to CS either emergently or scheduled receive pharmacologic prophylaxis (we use reglan and alka selzer gold, bicitra increases pH without altering volume)

OB Anesthesia

• Difficult airway– Incidence of failed intubation in obstetric pts

@1:300– 1:2330 in general OR population– Airway complications are the leading cause of

anesthesia mortality– Single largest class of injury related claims from

the ASA Closed Claims database involves respiratory events

OB Anesthesia

• Basic Needs for the OR– Monitors• ECG,NIBP,SPO2, FHR monitor, suction• Equipment for difficult airway, and emergency drugs• Checked daily

OB Anesthesia for C-Section

• Spinal• Epidural• Combined Spinal/epidural• General• Local

Contraindications for Neuraxial Techniques

• Pt refusal or inability to cooperate• Increased ICP secondary to mass lesion• Skin or soft tissue infection at site of needle

placement• Coagulopathy• Uncorrected maternal hypovolemia• Low platelets (depends)

Complications with Neuraxial Techniques

• Infection• Postdural Puncture Headache• Incomplete or failed block• Neurologic injury(incidence is 20 in 1.2million for

subarachnoid blocks, 20 in 450,000 for epidurals)• Meningitis or arachnoiditis• Spinal hematoma(sharp back and leg pain-numbness

and motor dysfunction(loss of bowel/bladder fxn)• Emergent MRI or CT and referral (6-12 hr window for

decompression)

Spinal and Epidural Anesthesia

Combined Spinal/Epidural

General Anesthesia

• Maternal refusal or inability to cooperate with neuraxial tech

• Presence of contraindication to neuraxial tech• Insufficient time to induce neuraxial tech(cord

prolapse with persistent bradycardia)• Failure of neuraxial technique• Fetal issues (EXIT procedure)

Local Anesthesia

• Very rarely used• Dire emergencies when

anesthesiologist/CRNA not available• Success dep on avoiding use of retractors, and

not exteriorizing the uterus.• After delivery of baby, obtain hemostasis until

arrival of anesthesia personnel

Local Anesthesia

• 0.5% lidocaine with epi• 25g spinal needle to create skin wheal just

below umbilicus directed toward symphysis pubis. SQ injection along this full area.

• Ideally wait 3-4 min to take effect• Vertical incision to rectus then local into

rectus fascia and muscles. Takes 4-5min for anesthesia to be complete

Local Anesthesia

• Parietal peritoneum infiltration and incision• Visceral peritoneum infiltration and incision• Paracervical injection• Uterine incision and delivery• Obtain hemostasis• Await availability of general anesthesia

Local Anesthesia

• Disadvantages– Pt discomfort– Risk for local anesthetic toxicity (may use up to

100ml of local– Difficult operating conditions to say the least

Maximum Local Anesthetic Dosages

• Easy formula for bupivicaine (for 0.25% can give 1cc/kg, for 0.5% can give 1/2cc per kg. Lidocaine 4cc/kg plain, 7cc/kg with epi (for obese pts keep in mind max dose)

PCA Fentanyl• Great alternative for pts who cannot have an

epidural– All opioids cross placenta by diffusion secondary to

lipid solubility– All are associated with neonatal depression– Fentanyl readily crosses placenta but avg umbilical to

maternal conc ratio is low at 0.31– Studies show reduced FHR variability but difference in

APGAR scores, respiratory depression and Neurologic and Adaptive Capacity scores at 2-4 hrs or 24 hrs compared to infants whose mothers did not have fentanyl(Am Journal of Obst/Gyn; Anesth/Analgesia)

PCA Fentanyl

• Rapid onset• High potency• Short duration• No active metabolites• One of most commonly used for PCA

PCA Fentanyl

• Must have resuscitation equip available• Pulse oximetry, +/- etCO2 monitoring• One/one nursing• Education of family members• Loading dose (50-150mcg• Bolus 25-50mcg(start at 25, and assess) • Lockout 10min• No basal rate

PCA Fentanyl

• As labor progresses may need to decrease lockout time to 5min

OB in Rural Areas

• Likely will not have immediately available anesthesia provider

• OB nurses can assist with management of epidural infusions

• ASA has a consultation program that will help with setting up the anesthesia service to fit the needs of the facility

• Consensus of all involved that OB anesthesia is a priority and a worthwhile goal

OB in Rural Areas

• Anesthesia provider does NOT have to stay in house during course of epidural infusion

• ASA recommends it but recognizes difficulty

Questions???