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 cm2) 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

PARAMEDIANIn 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 DOSE1) 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 LAUsing 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)

++ EPINEPHRINEUseful effect: 1) Vasoconstriction2) Antinociceptive properties Delayed absorption of LA into

systemic circulation, with higher effect-site & lower plasma concentrations

2) Antinociceptive propertiesMediated 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

DOSINGPCEA 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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