General Anaesthesia forCaesarean Section:

Delivering Best Practice

Robin RussellNuffield Department of Anaesthetics

John Radcliffe HospitalOxford

Editor in Chief International Journal of Obstetric Anesthesia

Hamer Hodges et al. Br J Anaesth 1959

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1980 1985 1990 1995 2000 2005 2010

UK trends in caesarean section

Caesarean section rate

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20

40

60

80

100

1980 1985 1990 1995 2000 2005 2010

UK trends in caesarean section

Caesarean section rate

General anaesthesia rate

Drivers for change• Maternal mortality• Airway problems• Aspiration of stomach contents• Awareness• Uterine relaxation• Effects on the baby• Maternal preference

GA non-GA

Deaths associated with anaesthesia

CEMD / CEMACH / CMACE / MBRRACE

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General vs. neuraxial anaesthesia

Hawkins et al. Obstet Gynecol 2011

Case Fatality Rates*

Year of death GA Neuraxial Rate Ratios

1979-1984 20.0 8.6 2.3 (95% CI 1.9-2.9)

1985-1990 32.3 1.9 16.7 (95% CI 12.9-21.8)

1991-1996 16.8 2.5 6.7 (95% CI 3.0-14.9)

1997-2002 6.5 3.8 1.7 (95% CI 0.6-4.6)

*Deaths per million GA or neuraxial anaesthetics

Case fatality rates and rate ratios of anaesthesia-relateddeaths during caesarean delivery in USA

Indications for general anaesthesia

• Urgency

• Refusal

• Contraindication

• Inadequate neuraxial block

Current controversies

• Intubation

• Awareness

• Induction agents

• TIVA

• Neonatal effects

• Oxygen

Accidental awareness in obstetric anaesthesia

Patient• Female• Younger age• Obese• Difficult airway• Maternal anxiety• ↑ Cardiac output

Organisational• Trainee• Out-of-hours• Emergency• Induction – incision• Follow-up

Factors related to accidental awareness

Anaesthetic• Induction agent• Fixed doses• Rapid sequence• Neuromuscular block• Effect on baby• Uterine tone

“Mind The Gap”

Recommendations1. Risk & consent2. Dose of induction agents3. Additional doses if airway problem4. Adequate end tidal volatile levels5. Use of nitrous oxide6. Use of opioids7. Use of uterotonic agents8. Drug errors

Thiopental Propofol Other

• 2011 OAA survey• 56% response rate• 93% thiopental• Historic• Awareness• Neonate• 58% would use propofol

Author Journal n Thiopental Propofol Assessment Outcome

Celleno J Clin Anesth1993

60 5 mg/kg 2.4 mg/kg EEG “Light anaesthesia” in 50% of propofol group

Lee Korean J Anesth2007

45 4 mg/kg 2 mg/kg BIS BIS significantly lower from 0-9 min in propofol group

Mercan M E J Anesth2012

82 5 mg/kg 2.5 mg.kg BIS BIS significantly lower at uterine incision & delivery in propofol group

Cakirtekin Turk J Anaesth Reanim2015

70 5 mg/kg 2 mg/kg BIS BIS significantly lower from 0-8 min in propofol group

Thiopental vs. Propofol: Awareness

Punjasawadwong et al. 2014

Author Journal n Thiopental Propofol Assessment Outcome

Celleno Br J Anaesth1989

40 5 mg/kg 2.8 mg/kg ApgarENNS

↓ 1 & 5 min Apgar scores and ENNS with propofol

Gregory Can J Anaesth1990

30 4 mg/kg 2 mg/kg+ infusion

ApgarNACS

pH

Apgar scores & pH similar; NACS poorer with propofol

Capogna Int J Obstet Anesth1991

56 4.8 mg/kg 2.3 mg/kg ApgarNACS

pH

↓ 1 min Apgar score with propofol; other outcomes similar

Celleno J Clin Anesth1993

40 5 mg/kg 2.8 mg.kg ApgarNACS

pH

↓ 1 min Apgar score & ↓ 1 & 4 h NACS with propofol; other outcomes similar

Tumukunde BMC Anaesthesia2015

150 4 mg/kg 2 mg/kg ApgarNICU

Apgar score similar↑ NICU admissions with propofol

Thiopental vs. Propofol: Neonate

• Maternal haemodynamics• Airway reflexes• Drug errors• Storage• Cost• Familiarity• Availability

Thiopental vs. Propofol: Other Outcomes

Hessen et al. Acta Anesthesiol Scand 2013

Remifentanil & pressor response

Hessen et al. Acta Anesthesiol Scand 2013

Remifentanil & pressor response

• 10 patients non-emergency CS• Remifentanil bolus 0.5 µg/kg

infusion 0.2 µg/kg/min• Propofol TCI 5 µg/mL

2.5 µg/mL post intubation• Suxamethonium 1.5 mg/kg• End tidal CO2 3.7-4.0 kPa• FiO2 0.5• Hypotension 20%• Awareness Not reported• Haemorrhage Not reported• 1 min Apgar <5 60%• 5 min Apgar <5 Nil• UA pH > 7.20 100%• Mask ventilation 60%• NICU admission Not reported

Reynolds & Seed Anaesthesia 2005

Umbilical artery pH & base deficit: spinal vs GA

• Cohort study• 5320 deliveries 1976 – 1982• CS = 497• GA = 193 vs RA = 304• Hazard ratio ↓ RA (P=0.017)• Limitations: unrandomised

low CS ratedrug usagemissing data

• 20 women• Elective caesarean section• Supine• 5 L/min• 10 L/min• 15 L/min• Circle breathing system• ≥10 L/min optimal• Air entrainment in 22%

Hignett et al. Anesth Analg 2011

Non-pregnant Control Group Caesarean section Group

Supine(n=10)

Head-up(n=10)

Supine(n=10)

Head-up(n=10)

Age (years) 31.2 ± 2.9 32.7 ± 5.9 29.5 ± 4.5 28.6 ± 6.2

Weight (kg) 65.2 ± 9.1 61.9 ± 11.6 70.9 ± 12.8* 72.4 ± 7.0*

Pre-op SpO2 (%) 98.1 ± 1.5 98.5 ± 0.94 97.5 ± 1.3 97.9 ± 0.77

Time to SpO2 95% (s) 243 ± 7.4 331 ± 7.2* 173 ± 4.8* 156 ± 2.8*

Baraka et al. Anesth Analg 1992

“The anaesthetist should consider attaching nasal cannulae with 5 l.min-1 oxygen flow before starting pre-oxygenation to maintain bulk flow of oxygen during intubation attempts.”

Umbilical vein Umbilical artery

GA for caesarean section

• Awareness

• Induction agents

• TIVA

• Neonatal effects

• Oxygen