Anaesthesia for Obstetric Surgical Procedures

Anaesthesia for Obstetric Surgical Procedures

September 2010

Retained placenta

• Sensory block to T10 required

• Spinal/existing epidural

• Patient potentially hypovolaemic

Repair of perineal tear

• Spinal/existing epidural

• Good quality saddle block required

• Potentially hypovolaemic patient

Anaesthesia for Cervical Suture

• 1st/2nd trimester

• Spinal/GA

• If GA– Avoid prolonged exposure to nitrous oxide

• Potentially teratogenic in first trimester

– Avoid hypotension/hypercarbia – fetal acidosis

Introduction

• NHS maternity statistics 2008-09: UK c/section rate = 24.6%

• RJMH c/section rate = 36.2%• NOAD 2007: anaesthesia for c/section

– Spinal – 59.6%– Epidural top-up – 22.1%– GA – 10.1%– CSE – 7.2%– De novo epidural – 0.8%

RCOA Audit Standards

• Elective c/section > 95% RA

• Emergency c/section> 85% RA

• Elective c/section <1% RA to GA

• Emergency c/section < 3% RA to GA

Elective c/section

• Common indications:– Maternal request!– Breech presentation– Previous c/section– Placenta praevia– Significant medical conditions

Choice of Anaesthetic

• Patients preference

• Patients physical profile, health considerations, pregnancy factors

• Anticipated surgical difficulties

• Experience and speed of surgeon

Preparation for Anaesthesia

• Preop assessment• Informed consent• Antacid prophylaxis• Fully prepared anaesthetic room/theatre

– Checked anaesthetic machine– Monitoring equipment– Tilting operating table– Resuscitation equipment

• Trained anaesthetic assistant• Large bore I.V. access

Spinal Anaesthesia

• Used >90% elective LSCS

• Incidence of PDPH approx 1:400 due to small gauge PP needles

• Technically simple

• Consistent, dense quality of block

• Failure rate approx 1%

Spinal Anaesthesia

• Standard technique– PP needle, no larger than 25G to minimise

PDPH risk– Injection at, or below L3/L4 interspace to

avoid damage to conus– Diamorphine 300mcg– Injection performed in sitting position, then

moved immediately to L tilted supine position on completion

– Phenylephrine ivi to prevent hypotension

Spinal Anaesthesia

• Hyperbaric Bupivicaine 0.5% - most used LA in UK

• Recommended doses vary

• Surgery requires sensory blockade to T4

• Patient factors influencing dose– Height– Abdominal size

Intrathecal Opiates

• Fentanyl – Highly lipid soluble– Reduced intraop discomfort– Provides no post op analgesia

• Morphine– Long duration of action– Little intraop effect due to poor lipophillicity

• Diamorphine– Rapid onset– Long duration of action

• Side Effects:– PONV approx 30%– Pruritus

Spinal induced hypotension

• Can cause fetal distress

• Symptoms: dizziness, N&V

• Should be treated aggressively– Approp positioning– Fluid preloading– Use of Phenylephrine ivi

• Titrated to maternal BP• Higher fetal pH than Ephedrine

Spinal after epidural

• Technique most likely to lead to high/total spinal anaesthesia. ? Dural sac compression by epidural fluid

• No formula for reducing spinal dose. NB inadequate block

• Precautions– Warn patient of risk of conversion to GA– Assess airway– Perform spinal in approp environment– Reduction of spinal dose– Consider leaving epidural catheter in situ

Epidural ‘top-up’

• Category 2 LSCS with epidural in situ

• Slow onset anaesthesia

• Inferior anaesthesia to spinal during surgery

• L-Bupivicaine 0.5%; Ropivicaine 0.75%; supplemental Diamorphine.

CSE

• 3 approaches1. ‘Full’ dose spinal with epidural back up if inadequate

block height/duration

2. Reduced dose spinal with supplemental epidural top-ups

3. Epidural volume extension-low dose spinal extended by dural sac compression using epidural saline

• ‘Needle through needle’• Separate needle, separate interspace

CSE

1. Used to reduce incidence of spinal failure– Tall patients– IUGR– Prolonged surgery

2. Reduces haemodynamic changes by more gradual onset anaesthesia; reduced risk of excessive block height– Cardiac patients– Short patients

3. Short duration of blockade esp motor blockade

Continuous Spinal

• Niche role• ‘Difficult’ equipment• PDPH• Careful titration of dose• Haemodynamic stability

– Cardiac disease– Extremely small stature– Severe skeletal deformity

• Extended period of anaesthesia

Pain during LSCS

• Leading cause of litigation– Closed claims analysis 1995-2007

• Pain during surgery - 31% (57)

• Informed consent• Give adequate doses of drugs including opioid• Produce and document adequate sensory and motor

block• Management

– Alfentanil 250mcg iv– Entonox

• Conversion to GA– NB. Clear documentation of management esp if patient refuses

GA

GA

• Indications– Refusal of RA– Contraindications eg. Coagulopathy– Insufficient time to establish RA– Serious haemorrhage anticipated– Failed RA

GA

• Reliable and safe if– Aspiration prophylaxis– Trained anaesthetic assistance– Meticulous pre-oxygenation– Well rehearsed failed intubation drill– Approp drug regimen to reduce incidence of

awareness– Awake extubation

Drugs used for GA

• RSI with cricoid pressure• Thiopentone/Propofol?

– Propofol• Poorer neonatal profile• Shorter duration of amnesia• Longer time to recovery of spontaneous ventilation

• Suxamethonium/Rocuronium?– Inadequate doses assoc with difficult intubations

• NB 1.5mg/kg; Increased Vd

– Prolonged action of Rocuronium• NB. Sugammadex

Perioperative Drugs

• Opiates at induction and post op analgesia

• On delivery of neonate– Syntocinon 5IU and IVI – Prophylactic antibiotics

• Thromboprophylaxis

Complications

• Failed intubation (1 in 300)– Increased fatty tissue– Complete dentition– Increased pharnygeal and laryngeal oedema– Incorrect drug dosages– Large tongue– Large breasts– Increasing obesity

• Aspiration (1 in 400-600)• Awareness• Increased intaop blood loss• PONV

Post op pain relief

• Introp: – Diclofenac 100mg PR– Intrathecal Diamorphine– IV Morphine and TAP blocks

• Post op:– Diclofenac 50mg PO TID– Paracetamol 1g PO QID– Codeine 30-60mg PO QID

Emergency LSCS

• Grades of urgency – category 1 to 4

• Nationally accepted classification

• ‘Continuum of risk’

• Facilitates audit

• Improves multidisciplinary communication

• Individual, ‘case by case’ approach to decision to delivery interval

Emergency LSCS

• Category 1 & 2• In utero fetal resuscitation

– Syntocinon off– Position full L lateral– Oxygen– I.V fluids– Low BP – vasopressors– Tocolysis: GTN 400mcg/B2 agonist

• Choice of anaesthesia• Post op analgesia• Post op care