Transcript Novel Techniques for Post Caesarean Analgesia

Novel Techniques for Post
Caesarean Analgesia
Dr Nolan McDonnell FANZCA MClinRes
School of Women’s and Infants Health and
School of Medicine and Pharmacology
University of Western Australia
Introduction
• A number of options for post
caesar pain relief available
– Method chosen depends on a
number of factors:
• Mode of anaesthesia
– 92% performed under regional
anaesthesia in Australia
• Local resources
• Maternal contra-indications
and requests
Introduction
• Post caesarean pain is:
– Multifactorial in origin
– Difficult to predict degree
• Tendency to over treat
– A significant cause of persistent
post surgical pain
– A subject of considerable
ongoing research
What is “novel”?
• Novel definition:
– “new or unusual in an
interesting way”
– “fresh: original, of a kind
not seen before”
• What is “novel” depends
on perspective
Options for Analgesia at KEMH
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Oral/IV Paracetamol
Oral/IV Anti-inflammatories
Oral/IV Tramadol
Oral Oxycodone
Intrathecal:
– Intrathecal morphine and/or clonidine
– Continuous spinal analgesia
• Epidural
– Pethidine PCEA
– Epidural morphine (single shot and PRN)
– Continuous infusions plus PCEA
• TAP Blocks/Rectus sheath blocks
• Intravenous PCA (Morphine or fentanyl)
Plan
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4.
TAP Blocks
Primary oral opioid
Neuraxial magnesium
“Worth a mention”
– Extended Release Epidural morphine
– Gabapentin
5. Worth a mention but won’t have time.....
– Neuraxial neostigmine
– IV Ketamine
British Medical Journal Christmas 2001
Transversus Abdominis Plane Blocks
• Landmark technique first
published in 2007 by McDonnell
– Led to significant interest and
research
• Concerns have been expressed
secondary to:
– Potential for bowel and liver injury
– High plasma levels of local
anaesthetic
• Ultrasound guidance now
widely recommended
TAP Blocks
• First obstetric study published in 2008 by McDonnell
• Single experienced operator
– 50 patients, 25 per group
– Landmark technique
– 1.5 mg/kg ropivacaine per side (max 150 mg per side) vs
saline control
– Rectal diclofenac and paracetamol
– IV Morphine PCA
McDonnell et al Anesth Analg Jan 2008
McDonnell et al Anesth Analg Jan 2008
McDonnell et al Anesth Analg Jan 2008
• Multiple operators
– Ultrasound guided
– Ropivacaine 0.5% 20 ml per side
– Placebo (saline) control group
– IV Morphine PCA plus paracetamol/ibuprofen
Belavy et al BJA 103 (5) 2009
• Associated with in the TAP block group:
– Improved satisfaction
• Median VAS 96 vs 77 (p=0.008)
– Decreased nausea and antiemetic use (p=0.03)
Belavy et al BJA 103 (5) 2009
Comments:
• The TAP block, in addition to multimodal
analgesia including IV PCA opioid, appeared to
have significant benefits for post CS analgesia
• But the place of the TAP block when
compared to IT morphine still needed
investigation
– Is the TAP block as effective as IT morphine?
– Does the TAP block, in addition to IT morphine,
have any benefit?
`
• 2 investigators, US guided, blinded
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100 women
Spinal anaesthesia with 100 mcg IT morphine (all patients)
20 ml Ropivacaine 0.375% or saline placebo per side
Regular paracetamol/diclofenac
Morphine on request (IV and oral)
Costello et al Reg Anest Pain Med Nov/Dec 2009
• No additional benefit of TAP block in
conjunction with IT morphine
– Less patients needed supplemental opioid in first
6 hours post surgery in TAP group
– No difference in VAS scores with rest and
movement at 6, 12, 24 and 48 hours
– No difference in satisfaction
Costello et al Reg Anest Pain Med Nov/Dec 2009
• 3 investigators, all experienced, US guided
– 2 groups:
• IT Morphine 200 mcg and placebo TAP
• IT saline and 20 ml 0.375% bupivacaine/adrenaline per
side
– Rectal diclofenac and IV paracetamol
– Breakthrough pain managed with IV tramadol
Kanazi et al Anesth Anal August 2010
Median time 4 vs 8 hours
(p=0.01)
Kanazi et al Anesth Anal August 2010
Kanazi et al Anesth Anal August 2010
Where does this leave the TAP block?
• Little evidence to support it’s use in addition
to IT morphine
• As an adjunct to IV opioids
– When IT morphine not appropriate
– GA caesarean deliveries
• Beware of potential for toxicity and
bowel/liver injury
Oral Analgesia
• Primary oral opioid
administration is in use in a
number of units across
Australia, New Zealand and
the UK
• Audit data suggests that
efficacy and maternal
satisfaction is high
• Limited number of RCTs
available
• Double blind, placebo controlled, 120 subjects
– ITM group: 100 mcg IT Morphine
– Oral oxycodone: 20 mg SR oxycodone in recovery
followed by 10 mg IR oxycodone every 6 hours
– All subjects had regular paracetamol and
diclofenac
– Breakthrough pain managed with tramadol
McDonnell et al IJOA Jan 2010
McDonnell et al IJOA Jan 2010
Oral analgesia
• Regimens still need significant refining
– Regular opioid administration in conjunction with
PRN dosing for breakthrough recommended
• Offers a number of advantages for staff and
patients
– Particularly in resource limited environments
– Midwifery staff in particular are attracted to the
ease of administration
Neuraxial Magnesium
Neuraxial Magnesium
• Naturally occurring NMDA
receptor antagonist
– Modulation important in both
acute and chronic pain states
• IV administration has been
shown to have efficacy, but
results have been limited
– Central (CNS) levels change
little with IV administration
– CSF levels appear tightly
regulated
Neuraxial Magnesium
• To date there have been 6 obstetric and 7 non
obstetric studies published using epidural or
intrathecal magnesium
– All from relatively lesser known centres
• A number of issues surrounding design and conduct
– 12 (of 13) have had positive results
– FDA/TGA approval required for studies to be
conducted and published in the USA and Australia
• Conventional spinal anaesthesia
• Randomised to three groups:
– IT Morphine 100 mcg
– IT Magnesium 100 mg
– IT Morphine and Magnesium
Ghrab et Al Ann Fr Anesth Reanim May 2009
Results
• Time to first analgesic request (p<0.01):
– 28 +/- 8 hours Group MMg
– 19 +/- 6 hours Group M
– 7 +/- 6 hours Group Mg
• Improved satisfaction in Group MMg
Ghrab et Al Ann Fr Anesth Reanim May 2009
Ghrab et Al Ann Fr Anesth Reanim May 2009
Neuraxial Magnesium
• Words of caution
– Safety record appears good
• Numerous animal neurotoxicity studies conducted
– Only one study showed potential evidence of toxicity
• Magnesium is naturally occurring in the CSF
– DBL MgSO4 contains no preservatives, only same pH
adjusters as heavy bupivacaine and IT morphine
– Further data is needed before widespread
recommendations can be made
Techniques worth a mention…..
Extended Release Epidural Morphine
• Morphine encapsulated in lipofoam
– Lipofoam slows release of morphine
– Prolongs drug delivery into second post op day
– Beneficial in patients in whom post op epidural may be
risky-eg febrile patients, severe pre-eclampsia
Extended Release Epidural Morphine
(Depodur)
• 2 Obstetric studies to date:
– Confirms prolonged analgesia
• Downsides:
– Cost: Approx $200 per dose (10 mg)
– Lipofoam may become unstable in the presence of local
anaesthetic agents
– Not readily available in Australia presently
Gabapentin
• One obstetric study to date
– N=46
VAS with Movement
• 600 mg pre op Gabapentin
– 1 hour prior to surgery
– IT Morphine in both groups
• Significant improvement in
post op pain
– Improved satisfaction
– But: 19% had “severe”
sedation (vs 0% in control)
Moore et al Anesth Anal Jan 2011
Gabapentin
Moore et al Anesth Anal Jan 2011
Conclusions
• A large body of research continues to be conducted into
post caesarean pain relief
– Increased awareness of persistent post caesarean pain
– Future studies should examine the impact on persistent pain
• “Scott’s Parabola” should be born in mind when
reviewing potentially new techniques
– The role of the TAP block is now relatively well defined
– Oral opioid techniques require further refining at a local level
– Neuraxial magnesium and oral gabapentin both appear to
have significant potential
Neuraxial Neostigmine
• Muscarinic receptors are present in the dorsal horn
of the spinal cord
– Stimulation produces analgesia in humans which is
reversed by atropine
• Intrathecal neostigmine produces dose dependant
nausea and vomiting
– Essentially precludes its use by this route
• Numerous studies of epidural neostigmine outside of
caesarean analgesia
– Generally promising results, especially when combined
with neuraxial morphine
Neuraxial Neostigmine
• Only one post
caesarean study:
– Kaya et al 2004
– Conventional CSE with
bupivacaine/fentanyl
• Epidural neostigmine 75,
150, 300 mcg or placebo
Kaya et al Anesthesiology Feb 2004
• 70 patients
• Epidural solution 15 mins post CSE
• Neostigmine 500 mcg + Clonidine 75 mcg
• 9 vs 2 delivered before first request for
additional analgesia
Van de Velde IJOA 2009
• 10 mg IV ketamine post delivery
• No difference in initial post op analgesia
– 35% were symptomatic with ketamine bolus
• BUT:
– Women in the ketamine group reported less pain
at 2 weeks post-operatively
– Needs further investigation
Bauchat et al IJOA Jan 2011