General Anesthesia for General Anesthesia for Cesarean SectionCesarean Section

Dr. Imam Ghozali., SpAn.,MKes

IntroductionIntroduction

Cesarean-section (CS) deliveries have accounted for nearly 1 million of approximately 4 million annual deliveries in US.

Approximately 15% of CS was performed under general anesthesia in US (Anesthesiology Hawkins, JL 1997). Majority of CS were done under urgent or emergent situations.

Indications for General Anesthesia Indications for General Anesthesia

Fetal distressSignificant coagulopathyAcute maternal hypovolemia and

Homodynamic instability Sepsis or local skin infection failed regional anesthesiaMaternal refusal of regional anesthesia

Preoperative Preparation for Preoperative Preparation for General Anesthesia General Anesthesia

History & Examination, LABsAirway evaluationAspiration prophylaxisBasic machine and monitor preparation

Factors may complicate Factors may complicate endotracheal intubationsendotracheal intubations

Weight gain Oropharynx edema Enlarged breasts Obesity with short neck Full dentitionMallampati IV and mamdibular recessionHistory of difficult airway

Airway evaluationAirway evaluation

Anticipation of difficult endotracheal intubation (1 in 300 in OB and 1 in 2000 all patients)

Thorough examination of neck, mandible, dentition, and Oropharynx

Training and experience (Hawthorne L. Br J. Anesth 1996; 76: 680-684)

Sniffing position

Airway evaluationAirway evaluation

Moderate head elevation, extension of atlanto-occipital, and flexion of the lower portion of the cervical spine

sniffing position

Preparation and PreventionPreparation and Prevention

2-3 different blades, ie MAC 3&4 Miller 2 6 to 7 mm ETT tubes with styletsLMAs sizes 3 and 4Emergency airway cart ready in the OR Fiberoptic bronchoscope Possible surgical airway equipment

Aspiration prophylaxis Aspiration prophylaxis

Pulmonary aspiration: 1 in 400-500 in OB versus 1 in 2000 in all surgical patients

No agent or combination of agents can guarantee that a parturient will not aspirate or develop pneumonitis following failed intubations

Factors increase the risk of aspiration

Decrease in gastric and intestinal motilitydelayed gastric emptying by anxiety and

painRelaxation of lower esophageal sphincter

toneIncrease in abdominal pressure Increase gastric acid secretionPatients not fasting

Prevention of Aspiration-Prevention of Aspiration-Pharmacological agentsPharmacological agents

PO 30 ml 0.3 M sodium citrate 15-30 minute prior to induction

H2 blocker, ranitidine 50 mg IVMetoclopramide 10 mg IV, at least 5

minute prior to inductionOmeprazole 40 mg the night before and the

AM of surgery for high risk patientsOndansetron 4-8 mg IV

Prevention of AspirationPrevention of Aspiration

Cricoid pressure Adequate oxygenation of patientTreat hypotension promptlyEfficient and timely intubationOrogastric or nasogastric tube Awake extubation

Basic Machine and Monitor Basic Machine and Monitor PreparationPreparation

Monitors: esp. capnographSuction tubing functional Airway equipments ready and functionalLMAs: 2nd line of defense of difficult

airwayOthers: ie. meds

IntraoperativeIntraoperative Management of Management of Parturient Parturient

PositioningOxygenationMonitorsInduction of general anesthesiaMaintenance of general anesthesia Emergence from general anesthesia

IntraoperativeIntraoperative Management-Management-PositioningPositioning

OR bed should be allowing trendelenburg and reversed positions

Sniffing positionPatients in supine position with a wedge

under the right hipHead and back up position if preparing

awake fiberoptic intubation

IntraoperativeIntraoperative Management-Management-DenitrogenationDenitrogenation

Denitrogenation with O2 as soon as patient on OR bed

Seal mask to achieve 100% O23-5 minutes or 4 VC breaths of 100%

O2 O2 saturation drops faster during apnea

(increase VO2 and decrease FRC)

IntraoperativeIntraoperative Management-Management-MonitorsMonitors

Pulse oximeter probeRight size BP cuffElectrocardiographic electrodescapnographTemperature monitor readily available Urinary output

IntraoperativeIntraoperative ManagementManagement

Communicate with surgeons and nursing staffs while pt is prepared and draped for surgery

Final check for your READINESS FOR INDUCTION of general anesthesia

Induction of general anesthesia Induction of general anesthesia

Rapid sequence inductionCricoid pressure maintained until

endotracheal tube cuff inflated and tube placement confirmed

Agents:Thiopental/Ketamine/Propofol/Etomidate/Succinylcholine

Induction Agents-ThiopentalInduction Agents-ThiopentalThiopental (STP) 2-5 mg/kg IVFast and reliableNegative inotrope and vasodilatorCross placenta; STP concentration rarely

exceed the threshold for fetal depression with dose less than 4 mg/kg

No evidence of adverse effect of STP on fetus even the induction-to-delivery (ID) interval is prolonged; keep incision to delivery time less than 4-7 minutes

Induction Agents-PropofolInduction Agents-Propofol Propofol 1-2.5 mg/kg IV Rapid induction and rapid awakening Negative inotrope and vasodilator May inhibit oxytocin induced uterine contraction Can be rapidly cleared from neonatal circulation Dose greater than 2.8 mg/kg may result in lower

apgar scores and lower neurobehavioral scores at 1 hour after delivery comparing with STP, but similar neurobehavioral scores by 4 hours after delivery (Celleno D. Br J Anesth 1989; 62:649-54)

Induction Agents-KetamineInduction Agents-Ketamine Ketamine 1-2.0 mg/kg IV Modest hemorrhage or parturient asthma Provide rapid analgesia, hypnosis, and amnesia May depress myocardium and reduce CO and BP

in severe hypovolemic patients Avoid in hypertensive patients More than 2 mg/kg may associate with fetal

depression Maternal psychotropic profiles: dreaming,

dysphoria, hallucination during emergence (benzodiazepine reduce the side effects)

Induction Agents-EtomidateInduction Agents-Etomidate

Etomidate 0.2-0.3 mg/kg IVCause little CV depression-for HD

unstable parturientNeonatal adrenal suppression?pain at injection siteMyoclonus

Induction Agents-Succinylcholine Induction Agents-Succinylcholine

Succinylcholine (SUX) 0.3 to 1.5 mg/kg IV

Spontaneous ventilation may resume in 2-3 minutes with low dose SUX (0.3-0.5 mg/kg), but peak time delayed by about 10-15 seconds

3rd line of defense of difficult airwayRecovery from intubation dose of SUX is

unchanged in the pregnant patients

Maintenance of General Maintenance of General Anesthesia Anesthesia

PREDELIVEY50% O2/50%N2O/0.5% Isoflurane100% O2/1-1.5% Isoflurane

POSTDELIVERY50-70% N2O/30-50%O2/0.5% Isoflurane/NarcoticsMinimize volatile agents to prevent

postpartum hemorrhage; 0.5 MAC does not significantly increase maternal blood loss

Maintenance of General Maintenance of General AnesthesiaAnesthesia

Succinylcholine bolus when neededNondepolarizing agents accordingly ie.

Nimbex, Vecuronium, Rocutonium.*Oxytocin 10-40 U IV infusion*Antibiotics of choice

Emergence from General Emergence from General AnesthesiaAnesthesia

Stomach emptied via an OG tubeUpper airway suctionedNondepolarizing agents reversed adequatelyOpioids for pain reliefExtubation when patients regain protective

reflexes; are able to maintain airway; respond appropriately to verbal commands; and are hemodynamically stable

Awareness during General Awareness during General Anesthesia Anesthesia

High incidence between induction of anesthesia and delivery of the fetus

Administration of only 50% N2O in oxygen without other agents results in maternal awareness in 12-26% of cases (Warren TM Anesth Analg 1983; 62:516-20; Crawford JS Br J anesth 1971; 43:179-82 Abboud

TK et al Acta Anesthesiol Scand 1985; 29: 663-8)

Awareness during General Awareness during General AnesthesiaAnesthesia

Ketamine or combine ketamine and thiopental for induction

Minimize of induction to delivery interval

50%N2O/O2 with following AGENTS reduce awareness to less than 1 %

0.6% isoflurane1% sevoflurane3% desflurane

Fetus Consideration during Fetus Consideration during Emergency Cesarean SectionEmergency Cesarean Section

Decision to Incision or interval: 30 minutes?Uterine Incision to Delivery (UD) interval

should be less than 3 minutes (Datta et al Obstet & Gynecol

1981; 58:331-335. Crawford JS. Et al. Br J. Anesth 1973; 45:726-732)

Neonates delivered after 3 minutes following uterine incision had lower apgar and acidotic blood gas

Ultimate neonatal outcome? (Ong BY. Et al Anesth Analg 1998;

68:270-5)

Factors Cause Uterine Artery Factors Cause Uterine Artery Spasm Spasm

Uterine incisionContraction of myometrial

musclesVasoconstrictors: prostaglandin

released from fetus and placentaMaternal catecholamine release

Post Anesthesia CarePost Anesthesia Care

Transport to PACU with O2Hypoxemia: airway obstruction and

hypoventilationHypotensionPain controlNausea and VomitingShivering and hypothermia

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