Managing Epidural and Spinal Failures Ki Jinn Chin, MBBS (Hons), MMed, FRCPC Associate Professor Toronto Western Hospital University of Toronto
How often do we fail?
How common is failure? Incidence varies by technique Incidence varies by definition Spinal anesthesia Epidural lumbar Epidural - thoracic Technical Failure Failure to locate / enter correct space Therapeutic Failure Complete absence of block Inadequate block height Inadequate block intensity ( patchy block ) Inadequate block duration
How common is spinal failure? Failure of surgical anesthesia after LA injection into CSF Encompasses inadequate block height & duration Contemporary studies = 2.7% 3.2% Bupivacaine and lidocaine Community and teaching hospitals LSCS and non-obstetric settings USA, Switzerland, France Trainees and consultants < 0.1% 0.1-1% 1-3% 3-5% > 5% Total failure is not that uncommon 0.2% (6/2600) 8.4% of all failures 1 1.9% (23/1218) 59% of all failures 2 1. Steiner et al. BJA 2009;102:839-844. 2. Fuzier et al. RAPM 2011;36(4):322-6. 3. Pan et al. IJOA 2004;13:227-33
How common is spinal failure? Failure of surgical anesthesia after LA injection into CSF Encompasses inadequate block height & duration Contemporary studies = 2.7% 3.2% Bupivacaine and lidocaine Community and teaching hospitals Trainees and consultants LSCS and non-obstetric settings USA, Switzerland, France Total failure is not that uncommon 0.2% (6/2600) 8.4% of all failures 1 1.9% (23/1218) 59% of all failures 2 1. Steiner et al. BJA 2009;102:839-844. 2. Fuzier et al. RAPM 2011;36(4):322-6. 3. Pan et al. IJOA 2004;13:227-33
How common is epidural failure? Lumbar epidural / CSE Ready et al = 27% 26 000+ cases, teaching hospital, retrospective Pan et al = 12% 12 500 labor epidurals / CSE, teaching hospital, retrospective 6.8% had failure subsequent to successful initial placement and analgesia Thoracic epidural Ready et al = 32% 26 000+ cases, teaching hospital, retrospective Tran et al = 23-24% 2 RCTs of conventional LOR vs waveform analysis, teaching hospital Williams et al = 26-32% RCT of different catheter depths, teaching hospital Auyong et al = 21.6% RCT of conventional vs US-assisted, teaching hospital Ready et al. RAPM 1999;24:499-505. Pan et al. IJOA 2004;13:227-33. Tran et al. RAPM 2016;41:309-13. Auyong et al. RAPM 2017. Epub. Williams et al. CJA 2016;63:691-700
Why do we fail?
How do we prevent failure? Failure is Success, if we learn from it. Malcolm S. Forbes
Technical Failure
Technical Failure Spinal & Epidural Cannot locate intrathecal / epidural space with needle Challenging anatomy Suboptimal technique
Preventing Failure Optimize Basic Technique Effective needle handling Control skin movement Redirect in small increments Avoid deviation in trajectory Anesth Analg 1995;81:630 633 Effective use of tactile feedback Feel of different tissues paraspinal muscle vs interspinous ligament, ligamentum flavum, etc Mapping the bony contours Mental visualization of underlying bony anatomy 18G Tuohy = 3.1 4.0 mm 22G Quincke = 4.1 4.7 mm 25G Whitacre = 0.6 1.2 mm
Preventing Failure Visualize Spinal Anatomy Ultrasound Pre-procedural Skin marking Depth estimation US now almost ubiquitous Learning curve Fluoroscopy Real-time insertion Visualization of catheter and epidural spread Specialized equipment required Radiation exposure Learning curve
Ultrasound increases procedural success Perlas A, Chaparro LE, Chin KJ. Reg Anesth Pain Med 2016;41(2):251-60. 49% reduction in risk of a failed procedure NNT = 34
Ultrasound reduces epidural failure 10% 8% Incomplete analgesia Need to replace epidural More than halved by use of ultrasound 6% 4% Pre-procedural US Landmarks only 2% 0% Vallejo 2010 Grau 2002 n = 370 n = 300 Vallejo MC. Int J Obs Anesth 2010;19:373-8 Grau T. J Clin Anesth 2002;14:169-75
N=70, TEA at T10 or higher 6 thoracic, 57 upper abdominal Time taken for marking US = 85 sec (69-113 sec) Palpation = 35 sec (27-51 sec) Time taken to place epidural US = 189 sec (73 515 sec) Palpation = 242 sec (87 627 sec) No. of needle passes US = 2 (1-5) Palpation = 3 (2-7) No Difference
EASY MOD DIFF EASY MOD DIFF Number of skin punctures US Palpation 1 23 (70%) 22 (60%) 2 8 (24%) 2 (5%) 3 or more 2 (6%) 12 (32%) Failed 0 1 NRS pain score in PACU (p=0.015) US vs palpation = 3.0 (2.8) vs 4.7 (2.8) Therapeutic failure Superior efficacy? Palpation US vs palpation = 4 (12.1%) vs 8 (21.6%) Ultrasound
N=100 TEA for thoracotomy Landmark-guided vs fluoroscopic guidance Prone position, on special fluoro table Intermittent imaging used to guide needle LOR to air-saline to detect entry into space Intermittent imaging to guide catheter insertion to a T4- T6 tip position 5mL contrast injected to confirm adequate position 5mL contrast injected in both groups to obtain epidurogram http://eorthopod.com/epidural-steroid-injections/
Catheters within epidural space Fluoroscopy-guided = 98% (technical failure in 1 pt) Landmark-guided = 74% Block performance time not reported No difference in pain scores or opioid consumption between groups No difference in 48h morphine consumption between correctly-positioned catheters and malpositioned catheters Worth the effort?
Dry Taps Causes Elderly patient Dehydration Spinal stenosis Narrowed IT space Clumping of nerve roots Epidural lipomatosis Narrowed IT space Solutions Re-insert stylet and withdraw again (pumping maneuver) Rotate bevel up to 360 degrees Gentle cough or Valsalva In lateral position, put into a reverse Trendenlenburg position Repeat spinal at a higher level Epidural fat collections
Therapeutic Failure of Spinal Anesthesia
Causes of Spinal Failure after injection Adequate dose fails to reach intrathecal space Spillage of LA Epidural injection Subdural injection Maldistribution of LA Reina et al. RAPM 2011; 36(6):537-41.
Prevention of Failure Optimize Basic Technique Solution: improve technique Handling of syringe and needle minimize displacement Pencil-point needle rotation through 360 Dural Flap Fettes et al. British Journal of Anaesthesia 102 (6): 739 48 (2009)
LA Maldistribution LA maldistribution LA spreads unevenly within CSF LA concentration in lumbar CSF is unrelated to height of block Rostral spread above conus is essential Injection Bupivacaine CSF concentrations plotted against block height BJA 2009; 102: 832-8. Neal JM et al, Reg Anesth Pain Med 2015;40:506-525 Neal and Rathmell. Complications in Regional Anesthesia and Pain Medicine
Spinal failure To repeat or not to repeat? Total absence of block vs inadequate height Presumptive cause? Technical error? Maldistribution? Main concerns Selection of appropriate second dose LA neurotoxicity in event of maldistribution Drasner et al. Anesthesiology 1991;75:713-14. Abouleish. Anesthesiology 1992 Mar;76(3):476-7. Hirabayashi Y, Konishi R, Shimizu R. Neurologic symptom associated with a repeated injection after failed spinal anesthesia, Anesthesiology, 1998, vol. 89 (pg. 1294-5.
Spinal failure To repeat or not to repeat? Aspirate at end of injection Helps rule out technical error and facilitates decision making Evaluate sacral dermatomes, especially if hyperbaric solution used Allow >10-15 min to elapse before declaring failure Modify 2 nd technique Different (higher) interspace Different LA baricity Different patient positioning Do not exceed maximum acceptable dose in total Drasner et al. Anesthesiology 1991;75:713-14. Abouleish. Anesthesiology 1992 Mar;76(3):476-7. Hirabayashi Y, Konishi R, Shimizu R. Neurologic symptom associated with a repeated injection after failed spinal anesthesia, Anesthesiology, 1998, vol. 89 (pg. 1294-5.
Other Causes of Spinal Failure
Causes of Failure after LA injection Lack of pharmacological potency ( bad batch ) Returned samples are almost always within product specification
Causes of Failure after LA injection LA resistance ( rachi-resistance ) a peculiar idiosyncrasy which renders the nerve roots of certain individuals insensitive or resistant to anaesthetic (Sebrechts J. Spinal anaesthesia. Br J Anaesth 1934; 12: 4 27) Mutations in voltage-gated Na+ channel are described Sheets et al. Nav1.7 channel mutation associated with hereditary erythromelalgia contributes to neuronal hyperexcitability and displays reduced lidocaine sensitivity. J Physiol 2007; 581: 1019 31
Causes of Spinal Failure after injection Spinal ligament (Tarlov) cysts Meningeal cysts containing CSF Occur in 1.5-4.5% of population Usually arise in sacral spinal canal Often lateral to midline Journal of Spinal Disorders & Techniques. 18(1):29-33, February 2005 Often invoked, but unlikely to be a significant cause
Therapeutic Failure of Epidural Analgesia
Causes of Epidural Catheter Failure Mis-identification of epidural space False-positive LOR Catheter migration Lies in subdural space Not advanced far enough / secured - falls out Advanced too far - exits the space (transforaminal escape) Collier CB. IJOA 1996;5:19-31. Anatomic barrier obstructing spread Dorsomedian and transverse connective tissue bands Blockage of catheter orifices (blood) Motamed et al. A&A 2006 Oct;103(4):1026-32. Reina et al. RAPM 2011; 36(6):537-41. Dye
Confirming correct epidural position
Why is LOR unreliable? Cysts in interspinous ligament Gaps in ligamentum flavum Mid-thoracic = 4-18% Low thoracic = 18-35% Lumbar = 9-11% Anesth Analg 2016;122:903 7
Why is LOR unreliable Cysts in interspinous ligament Gaps in ligamentum flavum Unrecognized entry into Paravertebral muscles TPVB Pleural space Midline 5-10 Paramedian approach = Paraspinous Within 1cm of midline Keep angle to 5-10 Back
Alternatives / Adjuncts to LOR
LA Test Dose To rule out intrathecal and intravascular placement 3ml rapid-onset LA + 5 mcg/ml epi HR 10 bpm, SBP 15 mmhg good PPV in non-pregnant / children Poor PPV in pregnant women and may reduce uterine blood flow IT lidocaine 45mg in pregnant women can lead to high spinal, hypotension, emergency LSCS To rule in epidural placement 3mL 2% mepivacaine + 5 mcg/ml epi (1 st test dose) 3mL 2% mepivacaine + sufentanil 10mcg + 2mL saline (2 nd test dose 5 min later) 37% had block after 5 min (10 min) 94% had block after 10 min (15 min) 98% had block after 15 min (20min) Guay. Anesth Analg 2006;102:921 9. Bolden et al. RAPM 2016;41:169 174 Larsson et al. Acta Anaes Scand. 2010;54:761 763.
Epidural stimulation Stimulation of spinal nerve roots via epidural catheter Conducting catheter (stylet) Epidural space and catheter primed with saline Current of 1-10mA elicits a motor response Threshold after LA injected No change if intravascular Motor response at current <1mA Unilateral - <1cm from nerve root Uni-/Bilateral subarachnoid Many segments subdural Cable connector Priming line Stylet Pain Res Manage 2006;11(3):173-180.
Epidural waveform analysis Obtain LOR with air or saline Inject 5ml saline and connect to pressure transducer +ve = pulsatile waveforms Inject further 2.5ml if waveform absent Epidural needle Sterile tubing STRONG MODERATE WEAK Pressure transducer set RAPM 2015;40(6):694-697 ABSENT RAPM 2015;40(6):694-697
Epidural waveform analysis Obtain LOR with air or saline Inject 5ml saline and connect to pressure transducer +ve = pulsatile waveforms Inject further 2.5ml if waveform absent RAPM 2015;40(6):694-697 STRONG Arnuntasupakul et al. RAPM 2016;41:368-373. RCT, N=100 thoracic epidurals, EWA vs conventional Primary failure 2% vs 24% Time taken 11.2 (6.2) vs 8.0 (4.6) min EWA resulted in 40% having re-attempts at 2 nd or 3 rd level MODERATE WEAK ABSENT
LOR air or saline? Prevention of Epidural Failure Optimize Basic Technique
LOR Air vs Saline Saline Superior tactile endpoint Fewer dural punctures (?) Fewer intravascular catheters (?) Fewer patchy blocks (?) Air bubbles on nerve roots Air Improved ability to identify CSF In CSE In accidental dural puncture No conclusive evidence for increased risk of complications or failure vs saline Low-quality evidence from 7 studies and 800+ patients Dalens et al. Epidural bubbles as a cause of incomplete analgesia during epidural anesthesia. A&A 1987;66:679-83. Antibas et al. Cochrane Database Syst Rev. 2014;18;(7):CD008938.
LOR air or saline? Prevention of Epidural Failure Optimize Basic Technique Midline or paramedian approach?
Midline or paramedian approach? Paramedian Wider interlaminar space Avoids midline gaps in ligamentum flavum Anesth Analg 2016;122:903 7) Causes less dural tenting and catheter passes cephalad more reliably (cadavers) Less paresthesia on catheter insertion
Midline or paramedian approach? Paramedian More patient discomfort Requires effective 3D mental visualization More complex computation of trajectory and redirection Harder to learn?
LOR air or saline? Prevention of Epidural Failure Optimize Basic Technique Midline or paramedian approach? How far to advance an epidural catheter?
Epidural catheter advancement Too far Transforaminal exit Coiling or knotting Not far enough Migration out of space 1. Beilin et al. A&A 1995;81:301-4. 2. Hermanides et al. BJA 2012;102:144-54. 3. Williams et al. CJA 2016 Jun;63(6):691-700. Optimal distance for lumbar epidural = 4-5cm 1,2 Collier CB. IJOA 1996;5:19-31. 3cm - 31.4% failure 5cm 6.3% failure 7cm 33.3% failure Optimal distance for thoracic epidural = 5cm? 7cm? 3 24h failure equivalent in 3cm (40%) vs 5cm (32%) vs 7cm (32%) groups
LOR air or saline? Prevention of Epidural Failure Optimize Basic Technique Midline or paramedian approach? How far to advance an epidural catheter? Not more than 3-4 cm to prevent transforaminal escape Optimal method(s) of catheter fixation?
Preventing Dislodgement Suturing Requires time and dexterity May increase site inflammation Tunneling Patient discomfort Risk of difficulty with removal Not shown to be superior to fixation devices Specific fixation device Reduces but does not eliminate migration Cost
Causes of Epidural Catheter Failure Anatomic barriers obstructing LA spread Epidural fat compartment is discontinuous Dorsomedian (plica median dorsalis) and transverse connective tissue bands have been described LA bolus administration can usually overcome this Hogan. Anesthesiology 1991:75:767-75. Dura Blomberg et al. A&A 1986;65:747-52. Savolaine et al. Anesthesiology 1988.68:217-220.
Prevention of Failure Optimize Dosing Epidural Concentration Volume Infusion regimen PCEA is ideal Reduces total LA dose, motor block, and breakthrough pain Programmed intermittent bolus? LA adjuncts Opioids Epinephrine Spinal Baricity and positioning Mass of LA LA Adjuncts Opioids Increase efficacy No direct evidence that it reduces failure Consider side-effects
Summary Failure of neuraxial blockade is not uncommon Good technique is essential Training, experience, and attention to detail is important Imaging of anatomy can be helpful Ultrasound vs fluoroscopy Adjuncts to confirm epidural catheter location Feel is fallible and difficult to master Modify technique if repeating the block Consider LA maldistribution in spinals