“Success going from failure to failure without loss of enthusiasm”

Failure of neuraxial analgesia: factors within & beyond our control

…tips, trick & solutions

…science, evidence & guidance

Dr Matt Wilson

“Failed epidural”

Definition?

Frequency?

Outcome measure?

Spectrum

Insufficient analgesia

Ineffective anaesthesia

Discontinuation

Dislodgement

Commoner than we care to admit…Incidence and characteristics of failures in obstetric neuraxial analgesia and anesthesia: a retrospective analysis of 19,259 deliveries P.H. Pan, T.D. Bogard, M.D. Owen

International Journal of Obstetric AnesthesiaVolume 13, Issue 4 , Pages 227-233, October 2004

12% “inadequate or no sensory block”

6.8% failure after initial effective analgesia

Other estimates..

Eapen & colleagues

Parturients

Catheter replacement (any)

Kinsella

Anaesthesia

Caesarean Section

Ready

All surgical patients

• 550/4240 (13.1%)

• 302/1286 (23.5%)

• Thoracic 32%

• Lumbar 27%

Technical factors

Anatomical dislocation

Primary misplacement

Paravertebral

Intra-spinous

Subdural

Intravascular

Intra-thecal

Dislodgement

Migration

Epidural catheter exiting through the transforaminal passage

Hermanides J et al. Br. J. Anaesth. 2012;bja.aes214

© The Author [2012]. Published by Oxford University Press on behalf of the British Journal of

Anaesthesia. All rights reserved. For Permissions, please email:

journals.permissions@oup.com

Asymmetric block

Unilateral/Missed segment/Dermatomal sparing

Epidural anatomical studies

Resin injection

Epiduroscopy

CT

“Dorsal Median Connective Tissue Band”

Rare

Incomplete

Radiographic Findings of Unilateral Epidural Block Asato, Fumio; Goto, Fumio

Anesthesia & Analgesia. 83(3):519-522, September 1996.

Catheter migration

Maternal movement

Posture at placement

CSF dynamics

Tunnelling

Fixation devices

Hamilton CL et al. Anesthesiology 1997; 86: 778-84

Copyright © 2013 Anesthesiology. Published by Lippincott Williams & Wilkins. 12

Hamilton, Catherine L.; Riley, Edward T.; Cohen, Sheila E.

Anesthesiology. 86(4):778-784, April 1997.

Changes in Position of Epidural Catheters Associated with Patient Movement

Catheter insertion

≥4cm in space

>5cm?

Coiling?

The effect of the Lockit® epidural catheter clamp on epidural migration: a controlled trial

Anaesthesia Volume 56, Issue 9, pages 865-870

Equipment

Multi vs. Single orifice

Manufacturing error

Air-lock

Bacterial filter

0.3-0.7 ml

Maternal position at insertion

Sitting

↓ insertion time

↑ 1st success

Vagal reflexes

? Venous distension

Lateral

↑ LOR Skin distance

↑ technical difficulty

Puncture site

Estimation inaccuracy

Cranial “Creep”

USS?

Accuracy in estimating the correct intervertebral space level during lumbar, thoracic and cervical epidural anaesthesia

Acta Anaesthesiologica ScandinavicaVolume 48, Issue 3, pages 347–349, March 2004

Localisation (LORS/A)

WETS DRYS

“Drys” vs. “Wets”

“Like being savaged by a dead sheep…”

“It is rather like sending your opening batsmen to the crease only for them to find, the moment the first balls are bowled, that their bats have been broken before the game by the team captain.”

Rt. Hon. G. Howe. 1990

Epidural Space Identification: A Meta-Analysis of Complications After Air Versus Liquid as the Medium for Loss of ResistanceSchier et al. Anesthesia & Analgesia. 109(6):2012-2021, December 2009.

5 RCTs (4 Obstetric)

4422 subjects

No differences:

Difficult catheter insertion

Paresthesia

i.v. catheter

ADP

PDPH

Partial block

Copyright © 2013 Anesthesiology. Published by Lippincott Williams & Wilkins. 23

Grondin, Lydia S.; Nelson, Kenneth; Ross, Vernon; Aponte, Orlando; Lee, Sherman; Pan, Peter H.Anesthesiology. 111(1):165-172, July 2009.

“Preferred” technique associated with

• Fewer attempts (median [interquartile range], 1 [1–1] vs 1 [1–2], P < 0.001).

• Fewer paresthesias (8.7% vs 18.5%, OR = 0.42, P= 0.007).

• Fewer unintentional dural punctures (1.0% vs 4.4%, OR = 0.23, P = 0.03).

Copyright © 2013 International Anesthesia Research Society. Published by Lippincott Williams & Wilkins. 24

A Retrospective Effectiveness Study of Loss of Resistance to Air or Saline for Identification of the Epidural Space

Segal, Scott; Arendt, Katherine W.Anesthesia & Analgesia. 110(2):558-563, February 2010.

Ultrasound localisation

USS guidance

Pre-puncture localisation

Midline c/f Obesity & Scoliosis

Skin-to-space distance

Angle of insertion

Real-time?

Paramedian insonnation

Teaching tool

Pharmacological optimisation

Dose vs. Volume

Local anaesthetic

Bupivacaine

Ropivacaine

Levo-bupivacaine

Opioids

Bolus vs. continuous

PCEA +/- background +/- IMB

PCEA

↑Satisfaction

↓Workload

↓LA consumption

↓Motor-block

Number of women requiring “No unscheduled intervention”

Local anaesthetic dose

Outcomes

Proportion of PCEA+AMB and PCEA+BCI parturients who did not self-bolus after induction of CSE.

Sia A T et al. Anesth Analg 2007;104:673-678

©2007 by Lippincott Williams & Wilkins

Automated Mandatory Bolus

Same volume/hr, superior analgesia

Infusion/PCEA vs. PCEA & AMB

↓LA consumption

↓Breakthrough/Intervention

Driving pressure

Uniformity LA spread

Multiorifice catheters

Spinal translocation

Immovable obstacles:

Weight watchers

Obesity a risk factor for adverse pregnancy outcomes.

UK parturient population:

33% BMI>25

23% BMI>30

Linear association between maternal BMI and risk of caesarean section in term deliveries

BJOG: An International Journal of Obstetrics & GynaecologyVolume 113, Issue 10, pages 1173-1177, 13 SEP 2006

Irresistible forces: pharmacogenetics

118 OPRM1 Gene (Opioid μ receptor)

Response to neuraxial opioids

ED50 spinal fentanyl

Hz 304A:6.8 μg vs. Htz 304G:17.7 μg

Modulation of pain perception

ADRβ2

Labour progress

Clinical implications?

Minimising failure

Find the epidural space!

Use saline or air

Leave a catheter in 4-5cm

Fix it

Dilute LA + Opioid

PCEA (+ INF/AMB)

Be realistic!

Recognise & replace!

Learning from our mistakes

“Experience” is simply the name we give our mistakes.

Oscar Wilde