conversion of epidural analgesia to surgical anaesthesia
TRANSCRIPT
Conversion of labour epidural analgesia to surgical anaesthesia for emergency
Caesarean section
Dr. A. Patil
Consultant Anaesthetist
University Hospitals Coventry and Warwickshire
Anaesthetic involvement : 61% of total deliveries
Caesarean section: 30%
2018 -2019: Emergency LSCS under epidural : 25.9%
• Common practice to ‘top-up’ existing labour epidural to provide surgical anaesthesia for emergency LSCS
• Injection of concentrated local anaesthetic solution + adjuncts
• Successful neuraxial anaesthesia is measure of quality of care:• Successful labour analgesia• Limits the use of general anaesthesia
• RCOA recommendation • Decision to delivery time in > 90% cases
• Cat1 LSCS < 30min and Cat2 LSCS < 75min• Conversion from neuraxial to GA
• Cat 1 LSCS < 15% and Cat 1-3 < 5%
• Online OAA survey, 2017• Decision to top-up epidural for Cat 1and 2 LSCS• Response rate 41% (n=710)
• Consultants: 79.3%• Associate specialists: 1.4%• Staff grades: 4.4%• Trainees: 4.9%
• Factors influencing the decision to ‘top-up’ the epidural• Effectiveness of epidural for labour analgesia(99%),Category of LSCS(73%), Level of
blockade(61%)
• Factors influencing further management in case of failed top-up• Category of LSCS, dermatomal level of blockade, maternal airway
• Choice of further management: repeat epidural/CSE/ spinal/GA• Spinal anaesthesia was the commonest choice
• If repeat regional: What dose?• Reduced dose if the block is high
• Principles for safe conversion of epidural analgesia to surgical anaesthesia
Is the epidural good enough for top-up?(Assessment of the quality of block)
• Speak to the patient and midwife
• Is it providing adequate analgesia? Looks comfortable
• Is she still using Entonox?
• Breakthrough pain
• Epidural boluses given: Dose, frequency, time
• Was the epidural re-sited?
• Assess the block: Missed segments, Unilateral block
• Displacement, disconnection, pooling of solution under dressing
• In the delivery room before decision of em LSCS • Early recognition of poorly functioning epidural: manipulation or resiting
• Slow progress or concerns about CTG: anaesthetist must evaluate the effectiveness of epidural
• In theatre after decision to proceed to LSCS• Inspection of the site of epidural catheter
• If sufficient time is available: test the function by administering 1/4th -1/3rd LA dose: test every 3-5min, density and level of block
• In absence of evidence progression of block: DO NOT administer more than ½ of the LA solution
Reducing the risk of failure of epidural top-up(BJA education)
Where should I do the top-up?
• Labour room Vs Theatre
• Top-up in the room may decrease decision to delivery time
• Top-up in theatre allows continuous monitoring of mother and foetus and early identification of complications
• Follow the local Trust policy
• Be safe
• Always stay with the patient after top-up of epidural.
Should I use a test dose?(Confirmation of the correct location of epidural catheter)
• Area of controversy
• Important to confirm the location of epidural catheter • Avoid intravascular injection and LA systemic toxicity
• Injection into CSF resulting in high or total spinal anaesthesia
• Multi-compartmental block.
• Gentle aspiration of catheter for examining CSF or blood
• Test dose: LA +/- adrenaline (quick onset of block, hypotension, tachycardia)
• Need of test dose balanced against the delay for LSCS to commence.
• Follow local policy
What LA should I use for top-up?(Choice of LA and adjuncts)
• Choice of LA focuses on the need of• Speed of onset• Quality of block
• Mixture of• Local anaesthetic +/- adrenaline (Lidocaine, levobupivacaine, ropivacaine)• Opioid• +/- Bicarbonate
• Quickmix: 20mls of 2% lidocaine +1ml of 8.4% sodium bicarbonate + 0.1ml of 1:1000 adrenaline
• DO NOT exceed the maximum dose for the patient
• Local anaesthetic• Lidocaine + adrenaline has fastest onset of surgical anaesthesia• Ropivacaine: lowest need for intra-op supplementation• Bupivacaine and levobupivacaine: least effective solutions
• Opioids• Fentanyl: 50-100mcg• Decrease the time of onset of block• Increase the density of block
• Bicarbonate• Facilitates alkalinisation, increased concentration of unionised LA, easily cross the
neuronal membranes, quick onset• Possibly increases lipid solubility of fentanyl• Should NOT be added to bupivacaine, levobupivacaine and ropivacaine
• Adrenaline• Vasoconstriction: Decreases systemic absorption of LA, increases duration of action
Is it working enough?(Evaluation of adequacy of neuraxial blockade)
• Pelvic organs innervation: T10-L1
• Intra-abdominal plexus and greater splanchnic nerves upto T5
• Sensory Blockade:• Upper level
• National survey in 2010
• Common practice: Loss of sensation to cold and pinprick below T4 (sensitivities of 12% and 55%).
• Cold > Pinprick > Touch
• Lower level: S5
• Motor Block: Bromage Score
What do I do when the block is inadequate after top-up?Management of failed epidural top-up
• Inform the patient/ partner• Communicate to theatre staff and
obstetrician ?On LW if cat 2
• Is there time? • CTG?• Ask for help
What do I do when the block is inadequate after top-up?Management of failed epidural top-up
• Block not high enough or unilateral? Is it slow to come up?• Head low/ lateral tilt, more LA if maximum dose not reached
• If above is not suitable/ fails:
• Re-site or manipulate epidural
• CSE
• Spinal
• General anaesthesia
Drawbacks and risks (BJA education)
Manipulation or re-site epidural
• Time consuming
• Potential LA systemic toxicity with further administration of LA
CSE
• Time consuming
• Potential LA toxicity
• Difficult to choose optimal intrathecal dose
• Untested epidural catheter
Drawbacks and risks
Spinal
• Difficulty in obtaining CSF
• Difficult to select optimal intrathecal dose
• Failed spinal if low dose used
• Potential high or total spinal
General anaesthesia
• All the complications of GA : (separate topic)
What do I do when the patient complains of pain during surgery?
• Is it at incision, fundal pressure, exteriorisation of uterus, closure?
• Ask what sensation is she experiencing?• Sharp pain/ pressure/ touch
• Reassure if it’s pressure/ touch
• Offer GA
• Consider further topping-up epidural if time permits
• Document
Post-operative management
• Analgesia• Epidural diamorphine + oral analgesics
• Remove epidural catheter unless need for continuing with infusion
• Document the removal
• Prescribe appropriate thromboprophylaxis
• Post-op destination
Remember
• Team brief
• WHO checklist
• NRFit equipment
• Keep IV and epidural drugs separate
• Confirm that you are injecting LA into Epidural Catheter and NOT IV line
Epidural Top-up and COVID-19
• Important to assess the block to avoid GA
• Early re-site if not working
• Follow local policy for a theatre case (PPE, donning, doffing)
• If in doubt, do spinal
• Have help available