Anaesthesia for Obstetric Surgical Procedures
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Transcript of 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