FAILED EPIDURAL: CAUSES & MANAGEMENT
PRESENTER : MEI YINMODERATOR: DR TUAN NORIZAN BT TUAN MAHMUD
REVIEW ARTICLES
Failed epidural anaesthesia / analgesia
is more frequent than generally recognized.
Occurs up to 30% in clinical practice.In heterogeneous cohort of 2140 surgical pt, failure rated of 32% for thoracic & 27% for lumbar epidural.
The definitions cover a spectrum ranging from insufficient analgesia
to catheter dislodgement to any
reason for early discontinuation of
epidural analgesia.
DEFINITIONS & RATES OF FAILED
EPIDURAL ANESTHESIA / ANALGESIA
Type of surgery
Failure definition Failure rate
Thoracic/Lumbar
Eappen & colleagues
Parturients receiving epidural analgesia @ anaesthesia for delivery
Any reason requiring catheter replacement after the catheter was secured to the back with adhesive tape, a greater than 3 dermatomal segment discrepancy between analgesic level as assessed by T ( ice) sensation in pt complaining of pain after the initial bolus of epidural bupivacaine
550/4240( 13.1%)
Lumbar
Ready All surgical pt Any condition during the course of tx that requires epidural catheter replacement or addition of another major modality such as i.v. PCA
n= 2140Thoracic ( 32%)Lumbar (27%)
Thoracic:lumbar ?/?
Type of surgery
Failure definition Failure rate
Thoracic/Lumbar
McLeod & colleagues
Major esophageal, gastric, small & large bowel surgery / aortic aneurysm repair
Apparent inability to deliver LA /opioid solution to the epidural space due to occlusion, dislodgement or leakage or poor spread within the epidural space resulting in patchy or unilateral block
83/640 ( 13%)
Thoracic
Rigg & colleagues
Major abdominal op/oesophagectomy
Could not be inserted, removed before leaving OT, removed before 72hr
203/431( 47.1%)
Thoracic:lumbar ?/?
Neal Oesophagectomy
Catheter dislodgement 8/46( 14.2%)
Thoracic
Type of surgery
Failure definition Failure rate
Thoracic/Lumbar
Pan & colleagues
Obstetric neuraxialanalgesia
Epidural / CSE procedures resulting in inadequate analgesia / no sensory block after adequate dosing / any time after initial placement, inadvertent dural puncture with the epidural needle / catheter, iv epidural catheter, or any technique requiring replacement or alternative mx
1099/7849( 14%)
Lumbar
Motamed & colleagues
Major elective abdominal surgery for CA
Interruption of epidural analgesia before 48h for any reason. A VAS score that exceeded 30mm at rest & persisted for 45 min after rescue 5ml epidural 0.125% bupivacaine injection & 1 g PCM i.v, were administered
31/125 ( 24.8%)
Thoracic
Type of surgery
Failure definition Failure rate
Thoracic/Lumbar
Pratt & colleagues
Pancreatoduode-nectomy
Aborted before anticipated (4th POD) because of haemodynamic compromise, inadequate analgesia, or both
49/158 ( 31%)
Thoracic
Kinsella Anaesthesia for C-sec
Loss of cold sensation, using ethyl chloride spray, from T4 ( the nipples) down to S1 ( the buttocks)& anaesthesia ( no feeling)to 19G needle inserted @ several points along the line of surgical incision @ T12
302/1286(23.55)
Thoracic:Lumbar?:?
Konigsrai-ner & colleagues
Thoraco-abdominal surgery,upper abdominal surgery , colorectal surgery & other
Motor weakness, catheter dislodgement , insufficient analgesic
124/300( 41.4%)
Thoracic: lumbar241:59
CAUSES OF
FAILED EPIDURAL
TECHNICAL- EQUIPMENT
- ANATOMY
PHARMACOLOGICAL- DRUGS- DOSES
CAUSES OF
FAILED EPIDURAL
TECHNICAL PHARMACOLOGICAL
In imaging study
50 % Incorrect catheter placement
50% Suboptimal analgesia
Correctly placed catheter
This review summarizes technical factors known to influence block success & gives an overview of the pharmacological strategies
available to optimize epidural anaesthesia & analgesia.
TECHNICAL FACTORS INFLUENCING BLOCK
SUCCESS
1) Anatomical Catheter Location2) Pt Position3) Puncture Site4) Midline Vs Paramedian5) Localization Of Epidural Space6) Catheter Insertion & Fixation7) Test Dose8) Equipment
ANATOMICAL CATHETER LOCATION
Epidural catheters may primarily be
placed incorrectly , OR become dislodged during the course of treatment.
1o misplacement can happens in ~ paravertebral space, ~ pleural cavity & ~ i.v.
Even when epidural space correctly
identified, the catheter may leave the
epidural space through intervertebral
foramen at levels above @ belowinsertion site.
Factors contribute to 20 migration of
epidural catheters :
1) Pt’s normal movement - may be displaced by cm
2) Changes in epidural pressures3) CSF oscillations
In 60 pt undergoing surgery
with thoracic epidural, with CXR taken
before & after operation, the catheter
had migrated > 1 vertebral level in24%.
PATIENT POSITION
Lateral
Affects the needle placement by changing the relationship of
osseous &soft tissues.
Flexed position + head downresult in (A) movement ofspinal cord at thoracic level & (P) at lumbar.
Spinal cord is flexible attached within
dural sac & changes in position according to gravity.
Sitting position Shorter insertion times
( no applied to CSE in C-sec) Higher accuracy at 1st attempt Cost of more vagal reflexes Leads to epidural venous plexus distension,
the risk of vascular puncture, esp in parturients
Comparable final success rates with lateral
position
Lateral positioning
the distances from skin to epidural space.
More difficulty in CSE anesthesia for
C-sec.
PUNCTURE SITE
Most studies show that there is a tendency for the site to be more cranial than intended.
MIDLINE VS PARAMEDIAN
PARAMEDIAN
In cadavers using epiduroscopy, paramedian
catheters cause less stenting & pass more cephalad more reliably.
In pt faster catheter insertion times. Less dependent upon spine
flexion.
MIDLINE
Higher incidence of paraesthesia & bloody puncture in non-pregnant
adult.
In parturients, the risk of vascular puncture was not associated with lumbar midline OR paramedian techniques.
LOCALIZATION OF EPIDURAL SPACE
Correct placement requires correct identification of epidural space.
Variety method are used to confirm
epidural needle position:* LOR using saline ( most widely
used)* LOR to air* Hanging drop
Meta- analysis 2009comparing LoR with saline vs air, included 5 RCTs ( total 4422 pts) : 4 in obstetric population & 1 in general pt population
significance difference in any
outcome was found, other than 1.5%
reduction in PDPH when using saline.
Study comparing CSE punctures using
air / saline found no difference in success rate / adverse events.
A recent retrospective study of 929 obstetric epidurals found that
using air for LoR, significantly >> attempts were needed compared with saline
with comparable final success.
Subgroup analyses showed that the use
of the “ preferred technique” ( i.e. the
technique used by a practitioner > 70%
of the time) resulted in significantly
- fewer attempts, - lower incidence of paraesthesia - & fewer dural headaches.
Hanging drop technique depends on
-ve pressure within the epidural space.
Recent experimental study evidence
suggests that –ve pressure is poor reliably detecting the epidural
space & is useful only in sitting position.
Of note, identification of the epidural
space was reported 2mm deeper for
hanging drop technique when compared with LoR, possibly
indicating increase risk of dural perforation.
There is growing evidence-base for USG in obese pt & infants.
USG is a useful educational tool & can
enhance the learning curve for epidural
anaestheisa.pre-assessment of lumbar
epidural space depth shown to correlate well with actual puncture depth in obese parturients.
In children, UGS allows identifications
for the neuraxial structures, particularly
neonates.
< 3m.o. , only the vertebral bodies are
ossified, enabling detailed visualization
of spinal structures.
Only 1 RCT conducted, found that use of USG lead to :
<< bony contact, shorter time to block success decreased supplemental opioid
requirements.
CATHETER INSERTION & FIXATION
Optimal depth of insertion in adults is
~ 5 cm
Methods of fixation :
1) Tunnelling of epidural catheter2) Suturing 3) Catheter fixation device
Tunneling the epidural catheter for 5cm
in cohort of 82 pts a/w less motion of
catheter but the % of catheters maintaining original position was
not statistically different.
Placement Of Tunnelled Caudal Epidural Catheter
Epidural catheter (approximately 6–10 cm) is threaded through the epidural insertion needle to reach a thoracic dermatomal level of T10–12.
Sacro-coccygeal ligament
The tunneling needle (17- or 18-gauge styletted Crawford or Tuohy needle) is inserted near the posterior superior iliac crest
The tunneling needle emerges at the epidural needle insertion (1). The epidural insertion needle is not removed and is left in place to protect the catheter.
Cut the residual skin & subcutaneous tissue bridge between 2 needles using scalpel blade 11.
The epidural insertion needle is removed leaving the catheter in place, depicted as dashed line.
The stylette from the tunneling needle is removed & the distal end of epidural catheter is thread into the tunneling needle.
The tunneling needle is removed. The subcutaneous portion of the epidural catheter is depicted with a dashed line
The primary insertion site and the final catheter exit site are secured with Steri-Strips® & covered with transparent adhesive dressings. A loop is placed in the catheter to prevent accidental dislodgement
In > 200 pt undergoing either thoracic/ lumbar epidural
anaesthesia, tunnelling led to significantly catheter migration, with a modest clinical net result of 83%
functioning catheter after 3/7, compared with
67% without tunneling.
In retrospective observational study >500 children, tunnelling a caudalepidural catheter reduced the risk of bacterial colonization to levels comparable with untunelled lumbar catheters.
may be related to the fact that tunneling places the catheter entry point above diaper.
The advantages must be weighed against the increased incidence of erythema @ the puncture site, potentially linked to increased risk
of bacterial colonization.
Suturing of the epidural catheter was
similarly a/w less migration but at the
cost of increased inflammation at the
puncture site.
Catheter fixation devices may significantly reduce rates of
analgeisc failure.
No studies comparing modern dressing
devices with tunneling techniques with
respect to migration,analgesic failure or
infection.
TEST DOSE
1) Lidocaine
to detect intrathecal placement
2) Epinephrine
to detect intravascular placement recommended in pt without CI
EQUIPMENT The orifice of catheter can lie
laterally or anteriorly in the epidural spaceputting the LA more to one side & producing an unilateral block.
Multi- orifice catheters are considered
better than single -orifice.
Manufacturing errors may occur, e.g.
faulty markings on the epidural catheter which can lead to wrong
depth of placement.
Debris in the catheter / disconnection
may cause epidural failure.
important preventable cause of
obstruction of epidural infusion system
is air lock , of as little as 0.3- 0.7ml of
air, in the bacterial filter.
Knotting of catheter internally or externally can cause obstruction.
1
Only 13% of lumbar catheter insertedIn a group of 45 men were advanced > 4cm without coiling, & coiling
occurred at a mean insertion of 2.8cm.
Based on 18 case reports, the frequency of knotted epidural
catheters is estimated to be 1: 200 000-300
000 epidurals with 87% knots occurring <
3cm from tip of catheter & 28% a/w loop
in the catheter.
PHARMACOLOGICAL OPTIMIZATION OF
EPIDURAL ANAESTHESIA
1) LA dose vs volume2) Choice of LA3) Addition of Opioids4) Addition of Epinephrine5) Bolus vs Continuous dosing
LA Dose vs Volume
With continuous infusion , DOSEis the primary determinant of
epidural anaesthesia quality, with volume & concentration playing a lesser role.
The effect of volume is more pronounced during bolus
application.
E.g. the no. of dermatomes blocked during labour analgesia
was higher in a high volume bupivacaine group than low volume group when same total dose was given.
CHOICE OF LA
Using equipotent doses, the difference in clinical effect
between bupivacaine & the newer isoforms levobupivacaine & ropivacaine
appears minimal.
++ OPIOIDS
Allows reduction in LA Improves the quality of
analgesia. May have spinal or supraspinal action.
Epidural fentanyl was a beneficial adjuvant to LA for surgical
anesthesia, improving pain therapy & with a
low incidence of nausea & pruritus.( meta- analysis 1998)
++ EPINEPHRINE
Useful effect:
1) Vasoconstriction2) Antinociceptive properties Delayed absorption of LA into
systemic circulation, with higher effect-site & lower plasma concentrations
2) Antinociceptive properties
Mediated via α-2 adrenoreceptorsDecreased presypnatic transmitter
release & post synaptic hyperpolarization within substantia gelatinosa of spinal cord dorsal horn.
full effect only observed when catheter
place above L1.
The effect of epinephrine on LA & opioid
are additive.
Minimum LA concentration of bupivacaine reduced by 29% in labouring parturients.
Adding epinephrine to low dose thoracic epidural infusion of ropivacaine & fentanyl improved pain relief & reduced nausea
Suggested concentrations 1.5 - 2mcg/ml
BOLUS VS CONTINUOUS
DOSING
PCEA requirement determined by site of surgery , surgery for malignant dz,
pt weight & age.
In labour analgesia, meta-analysisdemonstrated that obstetric pt
using PCEA needed:
LESS co-analgesic interventions LESS LA Decreased likelihood of motor block
Demand- only PCEA resulted in lower
LA requirement, but more breakthrough
pain, higher pain scores & lower maternal satisfaction.
Best method for postoperative analgesia:
PCEA + background infusion
THANK YOU !!!
REFERENCES
REVIEW ARTICLES FAILED EPIDURAL : CAUSES & MANAGEMENT J.Hermanides, M.W.Hollmann, M.F. Stevens & P. Lirk- BJA. Advance Access publication 26 June
2012
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