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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
0
20
40
60
80
100
1980 1985 1990 1995 2000 2005 2010
UK trends in caesarean section
Caesarean section rate
0
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
0
5
10
15
20
25
30
35
40
45
50
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