3 Outline C-section – a unique psychosocial surgery How the OB anesthetist should behave.Evolution of techniquesNeuraxial block physiology and managementGA physiology and management.Management of common problems
4 C-section – a unique psychosocial surgery Psychological / interpersonal aspectsUnique surgery, happy event gone awry.Strike a balance between “happy event” and “risky surgery”.Most patients are awake– and want to be.Team approach (patient, family, nursing, OB, anesthesia)Support person present in OR.Family members in the labor room (face them).Discretion about medical info– JW, drug use, previous abortions, etc.
5 Anticipate and be available Know every patient on the floor. Introduce yourself early.Be accessible to OBs and nurses.Get informed early about potential problems (airway, obesity, coagulopathy JW, congenital heart disease)Remember the basics (IV access, airway)
6 Anticipate and be available We need a certain knowledge of OB to know what is going to happen. Try to think one or two steps ahead.“Placenta isn’t out yet in room 7”“The lady in 6 has a pretty bad tear.”“Strip review in 3, please.”“We can’t get an IV on the lady in 4.”“Can you give us a whiff of anesthesia in 8? We don’t need much.”
7 Evolution of technique Last 30 years: decreasing use of GA, now about 5% of cases. Was 20-30% in 70’s at UCSD.Epidural was “all the rage” in 70’s and 80’s.SAB (or epidural) are now preferred anesthetics.
8 Anesthesia for C/S— basic interventions Happy event (sort of)Gastric acid neutralizationLeft uterine displacementFluid loadingSupplemental oxygenSupport person in room (regional only)
10 C/S red flags“I don’t feel so good…I think I’m going to throw up…” (Hypotension until proven otherwise).“Doc, I feel like I’m not getting enough to breathe…”The “floppy arm sign.”The “shaking head sign.”
11 Spinal-- advantages Uniquely appropriate in C/S (happy event). Really amazing when you think about it.Awake and smiling.Arms and hands are normal.Major surgery inside the abdomen.Quick, solid, simple, reliable, pretty safe.LA + narcotic gives great block.Can give long-acting analgesia (intrathecal MS)
12 Regional anesthesia for c/s in Turkey (SOAP outreach)
13 Spinal-- disadvantages Fixed duration (unless continuous spinal).Rapid onset of sympathectomy or high block.Small chance of PDPH.
14 SAB– absolute contraindications Patient refusalUncorrected hypovolemiaClinical coagulopathyInfection at site of injection
15 SAB– obsolete contraindication Severe pre-eclampsia—Not associated with increased chance of severe hypotension with neuraxial block.Show me the literature if you disagree.
16 SAB– relative contraindications Spinal cord, LE nerve disease.Spinal deformity, instrumentationBack problems / fear of blockLaboratory coagulopathyBacteremia
18 Basic C/S monitoring Talk with the patient! Does her face display anxiety?“Take a deep breath!”Have her squeeze your fingersWhat is her hand temperature?Are the hand veins dilated?“Do your hands feel normal or do they feel a little numb?”
19 SAB / epidural cause sympathectomy Dilation of capacitance vessels (70-80% of blood volume)May cause drop in CODilation of resistance arterioles ( mm diameter).Drop in SVR
22 SAB / epidural cause sympathectomy rfumsphysiology.pbwiki.com/Characteristics+of...
23 38 y.o. female, repeat c/s, 420 #, gestational hypertension, continuous spinal: fall in SVR, rise in CO with onset of block. Increased SVR with phenylephrine.
24 When is sympathectomy (low SVR) bad? BP = CO x SVRWhenever you can’t increase CO!Uncorrected hypovolemiaIVC compressionStenotic valve lesionsPulmonary hypertension
25 Aortic stenosis at rest Pulmonary capillariesLV dilation / hypertrophyTricuspidAortic stenosisMitralPulmonicAortic stenosis at restCardiac output not sufficient to cause critically high LV intracavitary pressure / LV failure.Resistance arterioles
26 Pulmonary capillaries (edema) LV failure / ischemiaTricuspidAorticStenosisPulmonicMitralAortic stenosis with SAB: increased cardiac output / arteriolar vasodilation:Decreased SVR Fall in systemic BP and / or increase in LV intracavitary pressure ischemia or LV failure.Resistance arterioles– decreased SVR
27 38 y. o. female, repeat c/s, 420#, continuous SAB 38 y.o. female, repeat c/s, 420#, continuous SAB. Delivery with increased CO at 17, oxytocin 3 U bolus at 18, phenylephrine at 19
28 When is sympathectomy (low SVR) bad? With bolus of other vasodilator (oxytocin)
30 Both delivery and oxytocin cause increase in cardiac output. Delivery of babyOxytocin 5U IV pushPhenylephrine bolus for hypotensionC/S under epidural in pt with previous peripartum cardiomyopathy (May 30, 2007)
31 When is sympathectomy (low SVR) bad? When drop in SVR could exacerbate R > L shunt.ASDVSDPDA
32 Decompensated patient with REAL RL shunt. LALVDecreased SVR desaturationAoPAIncreased pulmonary vascular resistance desaturationRARVDecompensated patient with ASD, VSD or PDA-- Decreased SVR or increased pulmonary vascular resistance increased RL shunt and increased arterial desaturation.
33 38 y.o. female, repeat c/s, 420 #, gestational hypertension, continuous spinal: fall in SVR, rise in CO with onset of block. Increased SVR with phenylephrine.
34 Compensated patient with POTENTIAL RL shunt. LALVHigh SVR,Minimal RL shuntAoPARARVLow pulmonary vascular resistanceNormal, compensated patient with ASD, VSD or PDA-- high SVR and low pulmonary vascular resistance minimal RL shunt.
35 JW with previa / accreta for c-hyst. GA JW with previa / accreta for c-hyst. GA. Induction at 7, 8, intubation before 9, incision after 9. Note rise in SVR and fall in CO with GA.
36 How to prevent a sympathectomy from being a problem Keep the SVR up with a vasopressor like phenylephrine.
37 Preventing or treating hypotension from sympathectomy: augment venous return (CO). Trendelenburg (empty capacitance vessels into central thoracic veins)LUD (get pressure off vena cava)Fluid loading (fill capacitance vessels)CrystalloidHetastarchArteriolar constrictors (inc SVR)Ephedrine, phenylephrineVenous constrictors (inc venous return)
38 Hypotension with SAB or epidural Pre-load does not prevent reliably.500 mL hetastarch better than 1500 mL crystalloid.First symptom is nausea or “I don’t feel so good.”
39 Hypotension Use phenylephrine (neosynephrine) if tachycardia. Use ephedrine if bradycardia.Use atropine if severe bradycardia.Glycopyrolate works slowly.
53 www.siumed.edu/~dking2/erg/images/placenta.jpg from Google images
54 )Normal placental function: fetal and maternal circulations separated by thin membrane (syncytiotrophoblast).Umbilical artery (UA)Umbilical vein (UV)Fetus“Lakes” of maternal bloodFetal capillaries in chorionic villiPrecariously oxygenated environmentMomUterine veinsUterine arteriesArcher TL 2006 unpublished
55 Placenta blood flow (O2 delivery) = Ohm’s Law of the placenta: O2 delivery = Placental blood flow = (P1 – P2) / RAorto-caval compression decreases P1 (“aorto”) and increases P2 (“caval”)Therefore, aorto-caval compression decreases O2 delivery to fetus.R = placental resistance (fixed in short term)P1 = uterine artery pressurePlacenta blood flow (O2 delivery) =(P1 – P2) / RP2 = uterine vein pressureArcher TL 2006
56 General anesthesia-- advantages FastReliable (if you get the tube in).Doesn’t cause sympathectomyDuration is flexiblePatient is not awake (to experience problems).Can be given despite coagulopathy
57 General anesthesia-- disadvantages Patient not awake for birth.Unprotected airway.Possible “can’t intubate, can’t ventilate” scenario.Nausea, post-op pain, sore throat.
58 Functional residual capacity (FRC) is our “air tank” for apnea. from Google images
59 Pregnant Mom has a smaller “air tank”. Non-pregnant woman
60 GA for C/S— Thorough pre-oxygenation Cricoid pressure Small tube ( )RSI50% N2O until delivery MAC volatile.60-70% N2O after delivery + midazolam + narcotic.Small dose non-depolarizing NMB, if needed.
61 General anesthesia-- advantages SVR is maintained high (no need to increase CO)HypovolemiaStenotic cardiac valve lesionPulmonary hypertensionPotential R>L shunt
62 JW with previa / accreta for c-hyst. GA JW with previa / accreta for c-hyst. GA. Induction at 7, 8, intubation before 9, incision after 9. Note rise in SVR and fall in CO with GA.
64 High block– patient can’t breathe Move to anesthesia mask and circle system early. Don’t fuss around “assessing” the patient!Reassure patient, tell them this happens, and tell them you will help them breathe.You usually don’t have to intubate.Sometimes patients will panic and shake head back and forth to get the mask off of their face.Assume accompanying hypotension. Give ephedrine or neo as you reach for the mask.
65 High block– patient can’t breathe If patient becomes unresponsive, you probably should intubate– BUT VENTILATE FIRST AND DON’T PANIC.Assistant can give cricoid pressure– but VENTILATE, above all!May not need relaxant to intubate.Respiratory paralysis usually does not last long (5-15 minutes).
66 Failed regional anesthesia Be honest with yourself– recognize failure.Move on to plan B.
67 Aspiration16 y.o. WF, “Crystal”, +Hx substance abuse, C/S for failure to progress.Epidural, patchy block, supplemented with ketamine, fentanyl, diazepam.I was vigilant with breath sounds (precordial stethoscope era).Baby OK. Mother OK in PACU at 4PM.
68 AspirationCalled at home next AM: Pt SOB, transferred to ICU and intubated.I go to hospital, review nurses’ notes.Nauseated during the night, got MS several doses. Lying flat during the night.SOB at 4AM. Aspiration? When? My fault?Died 10 days later of progressive ARDS, hypoxia.
69 Aspiration Not only during GA! Use “triple Rx” freely (on everybody?) Beware withHigh spinalHeavy supplementation for bad block“Never turn your back on a spinal.”
70 “STAT C/S” Often “a flail”. “We’ve got to go. NOW!” Egos and emotions run high.Does the patient know what is happening?Talk to patient. Informed consent.Don’t endanger the mother to “save” the baby.Know when and how to say “no” to the OB.Stay calm.Cover the basics (H&P, IV access, airway, informed consent, patient asleep before incision.)
71 A stat C/S, once upon a time… Fetal decelsRush to the ORAnesthesiologist is sure he can get the tube in fastHe skips the pre-O2.He can’t intubate or ventilatePatient arrests.Code blue called, staff intubates.Post op seizures, hypoxic encepalopathy.Patient recovers after several days.
72 SummaryRegional anesthesia is elegant and uniquely suited to C-section.GA still has its place, and its dangers.Early warning, good communications and equanimity under pressure promote good outcomes.