GENERAL ANESTHESIA for C/S DELIVERY

FIRST, PLEASE READ AND FAMILIARIZE YOURSELF WITH OB DIFFICULT AIRWAY MANAGEMENT** Decisions to proceed with, or abort surgery depend on ability to manage the airway, and emergency level of c/s, and have to be made rapidly under GA. Difficult OB Airway management has special considerations and needs to be understood before inducing an obstetric patient

LINK:

Difficult & Failed OB Airway.

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Whether it’s a STAT GA, GA for failed neuraxial, or elective GA for c/s when neuraxial is contraindicated, a GA case will always have the same timing and medication flow. This will be a coordinated, WELL COMMUNICATED induction with surgical team, incision as soon as ETT placed, and rapid delivery of fetus (usually <5min). [Assuming successful airway…see DIFFICULT & FAILED OB AIRWAY page]

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THE OB GA RULES

• Know BEFORE EVERY GA case – how emergent is this case? IF we fail intubation, are we proceeding no matter what? (Maternal or fetal emergency) or can we wake her up?
• Have all airway supplies ready and available:
  • ETTs 6 &7 with regular & glidescope stylets, LMAs 3, 4, 5, Boujie, oral airways.
  • Slim/pedi Fiberoptic scope & Aintree catheters for difficult intubation available at your institution.
• RSI: After ~12 weeks all pregnant pts need RSI. Use Succs/Roc & Prop ONLY (ideally no maternal IV fent/versed – we give IV narcs/benzos right after cord clamped/delivery.. and avoid succs in pts on prolonged bedrest (ex: previas in-hospital on prolonged bedrest or on prolonged MgSO₄ gtt – hyperK+ arrests have been reported w/ succs)
• PREOXYGENATE well.
  • = 100% FiO2 for either 3-5 min TIDAL breathing or 8 VITAL CAPACITY breaths
    • Although, if needed, *gentle* bvm, with oral airway & cricoid pressure maintained to minimize gastric insufflation is OK and worth doing. If she really needs O₂, she really needs O₂, end of story. But preoxygenate as much as possible to avoid needing this – bc obvi aspiration risk is huge.
• POSITIONING for airway management: ramp/sniffing if appropriate – and ensure ability to extend neck if EMERGENCY NECK ACCESS needed in failed airway.
• HISSING suction ready to go – higher aspiration risk: preggo = full stomach.
• Have pitocin ready, as delivery will occur within ~4mins of intubation.
• Pre-op prophylactic meds hopefully already given if time allowed
  • Bicitra & Reglan
• COMMUNICATE WITH SURGICAL TEAM when ready to induce.
  • Pt prepped, drapes up, and surgeon ready to go with a scalpel on the other side
  • CLOSED LOOP COMMUNICATION when READY TO INDUCE
  • CLOSED LOOP COMMUNICATION when ETT through CORDS. – obgyn will make incision immediately after intubation.
• ORAL AIRWAY/BITE BLOCK AFTER INTUBATION to prevent BITING ETT and NPPE as succs/paralytic wears off.
  • Because it’s usually unnecessary to maintain paralysis – can give prop boluses for stimulation – careful with narcotics until pt is back breathing and narcotics can be titrated to minimum effective dose
    • Since extubation can be more dangerous than intubation in these swollen OB airways, any increased risk of airway obstruction/narcosis can have serious respiratory consequences.
      • Long story long: I just place a bite block and give propofol boluses throughout the case (under 1/2 mac sevo with N₂O/O₂ 50/50) – When pt comes back breathing and on *minimal* PSV, I titrate fent 25mcg at a time to RR ~ 10-14ish ~ aka comfy pt.
      • If they’re bleeding or unstable and I have to get the sevo off for uterine tone, I’ll keep N₂O on and work in some ketamine if case runs long (glyco helps with ketamine secretions to avoid ++secretions and potential laryngospasm on extubation. The OB airway is unforgiving..)
      • ALSO, WAIT TO EXTUABATE until AFTER the OBGYN does the routine post-op vaginal exam to expresses uterine clots!! Done at very end of case, after drapes are off and legs come out of stirrups. This is VERY stimulating, especially if no neuraxial block is onboard, and can easily cause laryngospasm if no ETT in place.
        • When they’re awake and extubated and airway is so patent that they can tell me they are uncomfortable (if at all) – then I’d start giving them whatever fent I had left or start giving dilaudid (and place dilaudid or fent post-op orders.)
        • L&D pacu isn’t always as accustomed to post-op GA/ airway obstruction/ osa/ airway management as main OR pacu nurses/staff are (just bc most c/s pts are under neuraxial and instrumented airways aren’t normally a concern – so it’s unfair to expect them to be airway experts), so we have to bring our OB pacu teammates AWAKE, BREATHING patients. Esp OB pts who are are high risk of desat/ low FRC/high MRO₂, high risk airway swelling….. OB GA pts need to be OKIE DOKIE before going at L&D pacu! 👍💕
          • To that end, personally I don’t leave the OB OR (where I can BMV with a vent/APL valve, and airway-manage) until the pt is *talking*. It may be a few extra minutes, or as long as it takes – I don’t care – a few extra minutes in the OR can save distasters in PACU.
• Back to GA rules:
  • 1/2 MAC sevo to minimize uterine relaxation, mix with N₂O 50%, and give versed 2mg right after delivery to prevent mom’s recall at ¹/₂ mac sevo %.
  • * Keep narcotics minimal until mom back breathing – I give only 100 fent after delivery and then wait to see how her RR comes back, and titrate more from there, if needed.
    • [If GA used for hemorrhage – ketamine is a good choice to maintain/balance anesthetic with more CV stability and maintain uterine tone: ketamine has uterotonic properties* reduces narcotic requirements, and maintains respiratory drive. Great option if GA used in obese/OSA or substance abuse pts too..]
  • EXTUBATION IS JUST AS DANGEROUS AS INTUBATION, assc with maternal airway compromise and death 2/2 swelling and airway instrumentation, and decreased FRC and physiologic cardiopulmonary reserve for hypoxia tolerance. (CO doubled after delivery – heart and lungs both working hard)
  • A quick cuff leak test is a good idea prior to extubation
  • OG** tube to empty stomach after intubation or prior to cuff leak test and extubation (NO NGT or nasal instrumentation/airways in pregnancy)
    • Place OGT gently and carefully, avoiding additional glottic/pharyngeal trauma/bleeding and swelling*
  • AGAIN, WAIT TO EXTUABATE until AFTER the OBGYN does routine post-op vaginal exam to expresses uterine clots!! This is VERY stimulating, especially if no neuraxial block is onboard, and can easily cause laryngospasm if no ETT in place.
  • AWAKE extubation, patent airway confirmed prior to moving to L&D pacu.
    • Again, L&D PACU staff may not be as accustomed to airway obstruction management (since most pts are neuraxial, awake pts) as Main OR PACU who often have prior ICU experience, are used to GA recovery, and deal with much sicker/more complicated post-op pts. Just make sure pt will be ok/awake enough/good patent airway for L&D PACU, as the pts FRC is still decreased, and 0₂ demands are increased postpartum, leading to rapid desaturation with airway obstruction. And and obstruction can easily go unrecognized in OB PACUs – this just isn’t what they see every day.

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The Effects of Sevoflurane on Isolated Gravid Human Myometrium – R. J. Turner, M. Lambros, C. Holmes, S. G. Katz, C. S. Downs, D. W. Collins, S. P. Gatt, 2002

Tocolytics and Uterotonics

Sevoflurane Induction for Emergency Cesarean Section in a Parturient in Status Asthmaticus

General anesthesia for cesarean section: are we doing it well?

MEDS NEEDED

• Propofol (or etomidate/ketamine if unstable pt – eg: hemorrhage)
• Succs/Roc for RSI
  • (Succs unless contraindicated: paralysis, burns, neuro dx, bedrest* (think previas on bedrest for weeks that may also be on prolonged MgSO4- gtt – they may need emergent c/s – can have extrajunctional Ach receptor proliferation – better to use roc to avoid lethal hyperkalemia)
• Pitocin bag spiked
• Antibiotics
• Midazolam 2mg (after delivery)
• Fentanyl 100mcg (after delivery)
• Pressors: neo/ephedrine
• If using Roc: Sugammadex or neostigmine/glycopyrrolate for reversal

Suxamethonium-Induced Hyperkalemia: A Short Review of Causes and Recommendations for Clinical Applications

Unexpected Hyperkalemia following Succinylcholine Administration in Prolonged Immobilized Parturients Treated with Magnesium and Ritodrine

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Anesthesia Considerations

• Good airway position essential, ramp if necessary, think ahead for difficult airway management for EVERY patient.
• Plan to need pitocin within 2 minutes of intubating. 
• Fetus delivered RAPIDLY (<2-4min) under GA
  • It’s always a fast first few minutes where you’re doing 20 things at once. 
• Propofol passes to the fetus, which can* theoretically make neonate floppy/apneic on delivery, so the MINIMUM time fetus spends exposed to GA, the better. EVERY GA case, whether emergent or elective, is a FAST delivery (< 4 min). It still takes a few minutes for fetal transfer to occur though, evidenced by the fact that many of these babies still come out screaming with high APGAR scores. Low APGAR likely has more to do with the reason for emergent c/s, and not the anesthetics (prop/sevo), as no studies can prove a causal relationship between prop administration and lowered APGAR scores, and have even shown no relationship between APGARS and maternal prop levels. Less time from incision to delivery seems to have the highest correlation with improved APGAR scores. There’s also complex pharmacokinetics/dynamics of possible placental uptake, ionization, prolonged fetal metabolism, etc all influencing actual fetal clinical effect. (See prop/remi combo link below)
  • Sevo passes to fetus as well, but doesn’t cause the level of respiratory depression/apnea that propofol causes. Neonate can breathe sevo off, but could still affect apgar scores.
• Goal is minimum GA time between INDUCTION and DELIVERY
• After delivery, anesthetic goal is preventing awareness with versed, and minimizing bleeding 2/2 uterine relaxation (from sevo)
  • Sevo causes dose-dependent uterine smooth muscle relaxation. <1 MAC should be OK, especially considering MAC is decreased in pregnancy by ~20-30%. Usually managed with 1/2 MAC and 50/50 N₂O. Can give propofol pushes or hang gtt as well to deepen anesthetic. Ketamine also a great adjunct for pain control and deeper sedation without effect on uterine tone (ketamine actually has uterotonic properties* and obvious benefit of HD stability if mom is bleeding, plus mom already got versed after delivery so you’re good to go with the ketamine re: bad dreams. Consider glyco though to dry her secretions up before extubation – SHOULD BE AN AWAKE extubation! But if you don’t follow that advice and she laryngospasms on secretions.. you’re gonna have a bad day.)
    • Careful with narcotic titration – without neuraxial onboard, this is just a normal GA case and will need narcotics – but these are often quick cases (even quicker than a usual C/S bc there’s minimal <4 min dissection time getting to uterus) so I personally give max 100mcg fent after baby is out and manage further stimulation with propofol. I wait until succs wears off and she comes back breathing to titrate in more narcotic – fent or dilaudid to her own spontaneous RR. I don’t want to over-narcotize a high-risk swollen-airway with decreased pulmonary reserve prior to extubation… before going to an L&D PACU that has zero experience managing airways.. much less dangerous zero-reserve airways..
      • EXTRA REMINDER TO PLACE BITE BLOCK after intubation!! As soon as succs wears off and she’s stimulated she’ll want to bite that tube – placing her at risk for NPPE. Her risk of pulmonary edema is already so much higher than a non-preg patient 2/2 dilutionally lower serum albumin, and her tolerance for pulmonary edema and impaired O₂ exchange is so much less than a non-preg pt (MRO₂ up 20%, FRC down 20%)

• It ALWAYS involves clear, closed- loop communication about when everyone is ready for induction. Drapes will always be up, and pt will be prepped and ready.
• It is AWAYS communicated when ETT goes through the cords and the surgeons can cut.
• It is ALWAYS a rapid < 4 min uterine incision and delivery.
  • Pitocin needs to be ready. If not on the pump yet, just run it wide open until it can be programmed.

Propofol in combination with remifentanil for cesarean section: Placental transfer and effect on mothers and newborns at different induction to delivery intervals

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Step-by-Step

1. PREOXYGENATE: start ASAP as long as possible before induction. Goal ETO2>85%ish and reassure mom – this can be VERY scary for them.
2. Position airway – assess neck extension – ramp if needed.
3. Baseline Vitals *BP SpO2 EKG*
4. Communication w/ team about readiness to induce
   • Prop (or etomidate/ketamine if unstable) & Paralytic ONLY. (Succs common, but Roc is also great if you have enough sugammadex in the room) Succs/roc do not cross placenta, prop does. Skip the IV lido, narcotics, and benzos. Narcotics and benzos given immediately after fetal delivery.
5. RSI with Cricoid pressure and HISSING READY suction.
6. CLEAR COMMUNICATION ABOUT TEAM READINESS FOR RSI INDUCTION
7. VERBALIZE INDUCTION : RSI prop&succs ONLY
8. Verbalize ETT through Cords- LOUDLY to surgical team.
9. Sevo 1/2 MAC and N2O 50/50
   • [Prop & N₂O do not cause uterine smooth muscle relaxation, and won’t increase bleeding risk like sevo does. ¹/₂ mac Sevo, however, shouldn’t cause much uterine relaxation, as the smooth muscle relaxation is dose dependent. But if really bleeding, can just run prop TIVA and work in some ketamine.* Ketamine has some uterotonic properties, will provide deeper anesthetic, great pain relief, and will not affect respiratory drive for extubation.]
10. UTERINE INCISION & DELIVERY – START PITOCIN.
11. ANTIBIOTICS (if not yet administered)
12. VERSED 2mg as soon as cord is clamped. (^^ risk of awareness in OB GA) and can work in some narcotic (I use 100mcg fent, and wait until they come back breathing to titrate any more)
13. Ask about tone – check Sevo % – can convert to just prop gtt & N₂O if necessary.
14. No need for rocuronium (if succs used) to maintain paralysis. Can give 100 fent with the 2 versed right after cord clamp, place bite block then let succs wear off, get pt back breathing, then titrate in narcotics to RR. (fent/dilaudid)
    • Careful using dilaudid in OSA patients. Pregnancy exacerbates decreased FRC.
    • Pt WILL come back breathing – propofol pushes and a little fent usually do the trick without needing to paralyze. For a normal C/S, it’s still a pretty quick case.
15. BITE BLOCK ASAP – either soft or oral airway – she won’t stay paralyzed for long – she CANNOT bite tube, huge fluid shift after delivery puts pt at baseline risk for pulmonary edema, NPPE would be a mess. 
16. *****Can use propofol pushes for periods of stimulation to keep them a little deeper – reduces risk of over-narcotizing before they have a return of resp drive, and prop is quick on and off.
17. OGT (full stomach) NO NASOGASTRIC tubes in pregnant pts.
18. Pain control:
    • Normal post-op anesthesia order set w/ post-op IV narcotic
    • +/- TAP BLOCK/ilio-inguinal block/regional combos
    • INCISIONAL LOCAL on closing
      • If pt has no neuraxial onboard, this is just general surgery
      • If neuraxial on board, the Neuraxial post-op order set is needed.
19. Check & document TOF prior to extubation – reduced pseudocholinesterase activity in pregnancy can prolong succs, and magnesium can prolong NMBDs.
20. AWAKE EXTUBATION.
    • Portable SpO2 probe. Don’t leave OR until pt is awake and able to maintain solid airway and good SpO2. The OB PACU is not used to managing resp emergency, and this is a baseline swollen airway. A large % of maternal morbidity from airway compromise is post-extubation!!
21. Post-op GA* order set with IV narcotics – if she has no neuraxial opioids onboard – this is just general surgery and needs more pain control.

Antibiotics

• Ancef: Always (prevents surgical site infection)
  • If actual allergy to CEFAZOLIN itself (anaphylaxis, angioedema, resp distress, or urticaria) they’ll give 900mg clindamycin and 5 mg/kg aminoglycoside
• If Membranes Ruptured:
  • ADD Azithromycin 500 IV in 100-250mL NS slow gtt over > 1hr.

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Conversion to GA Post-delivery

(ex: hemorrhage and HD instability)

• No longer a fetus to consider, but uterine tone is still considered, and dangerous intubation and extubation.
• May not tolerate propofol with hypovolemia in unstable hemorrhage – etomidate/ketamine may be better choice
  • (etomidate good for pre-delivery GA too in unstable bleeding pts eg: abruption. Ketamine pre-delivery in the high induction doses – probably better to use just etomidate and wait until after delivery and work ketamine in.)
• Same principles of good pre-oxygenation, if possible, and suction ready.
• RSI still 2/2 full stomach, but don’t need to dramatically announce when you’re through the cords.
• Maintain same principles outlined above of 1/2 Mac sevo, with versed bc we’re still not going full MAC sevo (uterine tone) and want to ensure no recall with lower sevo%.
• Can use propofol pushes for periods of stimulation to keep them a little deeper – spares some IV narcotic and it’s quick on and off – of course this depends on pt HD stability. Ketamine is good as well to minimize sevo% without over-narcotizing.
  • (you’re double dosing narcotic if both intrathecal and long-acting IV given, which can bite you since the neuraxial morphine has a biphasic response and can cause late respiratory depression.)
• HH Neuraxial order set still ok bc intrathecal opioids are still active (if received).
• BITE BLOCK!! as succs quickly wears off by the time you’ve gotten her settled.
  • May or may not need to maintain paralysis (depends on length of case/reason for GA conversion – once we had to convert to GA to maintain paralysis for a really difficult closure in an obese pt with complicated hx of multiple abdominal surgeries)
• Get them back breathing first WITH A BITE BLOCK IN PLACE, THEN titrate small narcotic doses to RR (you have intrathecal narcotics in place as well)