Mechanisms and Management of
an Incomplete Epidural Block for
C-Section
DUKE UNIVERSITY
APRIL SCHMIDT, RN, BSN
What have I been up to?
St. John
Baseball and Swimming
Objectives
 1) Describe the physiologic changes in the epidural
space in the parturient.
 2) Be able to list and discuss four major categories of
potential causes for inadequate lumbar epidural
anesthesia during C-Section.
 3) Describe the steps to manage the anesthetic for a
parturient with failed or inadequate epidural block
during C-Section.
Epidural Anatomy Review
 Potential space, surrounds the dura mater
posteriorly, laterally, and anteriorly.
 Spinal Cord ends at L1 in adults
 Nerve roots travel as they exit laterally through the
foramen and course outward to become peripheral
nerves.
 Contents: nerves, fatty connective tissue,
lymphatics, venous plexus
Epidural Anatomy
Factors Affecting Epidural Block
 Volume: 1-2 ml of LA for each segment to be blocked
 Lidocaine: amide LA with rapid onset (5-15 min)
DOA (1-3 hrs) Max dose: 5mg/kg (plain) or 7mg/kg
(w/ epi)
 Epinephrine added to Lidocaine: vasoconstricts
slowing absorption and extends length of block
 Na+ Bicarb increases speed of onset (more
nonionized portion to get into cell quicker)
Parturient: Changes in the Epidural Space
 Venous engorgement
-more likely to puncture a vessel
 Compression of the epidural space by increased
intra-abdominal pressure
-higher block with less volume
 Increased sensitivity to anesthetics
-increased progesterone and endorphins
 Increased curvature of the spine
Case Presentation
 28 yo, G1P0, 39+3 gest., 74 kg, Ht 5’0”
 Hx: Mixed Connective Tissue Disorder
 Labor Epidural placed 11 hrs prior-pt comfortable
with high dose Pitocin going
 C/S indicated for “Failure to Progress” (72 hrs)
 Epidural loaded incrementally with a total of 25 ml
of Lido 2% with 1:200,000 Epi
 T4 level achieved, (-) Alyce test
Case Presentation
 Tolerated abdominal and uterine incision without




any pain.
Post-delivery pt began to C/O severe pain
Tx: Ketamine 15 mg, Versed 2 mg, Duramorph 5 mg
per epidural, N20 50%, Propofol boluses (200 mg
total)
Maintained respirations
Recall of pain
Questions
 Could I have predicted that the epidural was going to fail?
 What could I have done differently?
 Should I have converted to GETA to avoid pain recall?
 Theories:
1. Change in pressure in the epidural space
redistributing the Lidocaine?
2. Related to Mixed Connective Tissue Disorder?
Efficacy of Extending Labor Epidural for C-Section
 Tortosa et al, 2003
 Retrospective study n=194 pts whose labor epidurals
used for C/S
 5/194 (2.6%) required GETA
 27/194 (13.9%) required supplemental
analgesia/sedation
 Confirms efficacy in using epidural vs GETA which
has a higher mortality rate
Efficacy of Extending Labor Epidural for C-Section
 Halpern et al, 2008
 Prospective study n=501 pts whose labor epidural




used for C/S
30/501 (5.9%) had an inadequate block
21/501 (4%) required GETA
15/21 requiring GETA occurred intraopertively
Linked factors: Maternal ht and number of
unscheduled clinician top-ups.
Incidence of Failed or Inadequate Extension of Labor
Epidural
 Epidurals are used for 29-44% of abdominal
deliveries in the U.S.
 Incidence of failed/inadequate block is quite variable
amongst studies d/t variability of definition of
“failed” and “inadequate”.
 Up to 20% require supplementation or GETA
 Closed claims data shows intraop pain during C/S
results in more litigation than non-OB sx
4 Major Categories of Potential Factors for Failed
Block
Anatomic: septum, large spinal nerve roots
2) Technique/Equipment: catheter misplacement or
migration, defects, air used for LOR, inadequate vol.,
uniport catheter
3) Pt/Sx related: BMI>30, extremes of ht, labor >6hr, hx
of spinal sx, exteriorizing uterus, over stretching of
round ligaments, sub-diaphragmatic blood
4) Skill level: experience, psychomotor aptitude
(Portnoy et al, 2003)
1)
Predicting Block Failure
 Important to predict block failure because little can
be done when becomes apparent intraop
1) Slow surgeon
2) High parity
3) Advanced gestation
4) Several top-ups required during labor
5) High pain scores in last 1-2 hrs
Preventing Epidural Block Failure
 Saline for LOR (less unblocked segments)
 Multi-holed catheter
 Catheter 2-4 cm in epidural space (prevents
unilateral spread)
 Using epidural adjuncts has not been proven to
decrease block failure but opioids decrease the
amount of LA needed allowing reserve if repeat dose
is needed.
Management of Inadequate Block Apparent “Preop”
 T4 level needed for adequate analgesia for C/S
 Be patient
 Additional LA or opioid (Fentanyl)
 Position changes
 Pull catheter until 2 cm left in epidural space (prior
to administering LA-helps 46% of the time)
 Valsalva or cough may help spread cephalad
 “EVE”-Epidural Vol. Ext. with NS and dilute LA
Management of Inadequate Block Apparent “Preop”
1) SAB: wait at least 30 min post epidural bolus AND
2)
3)
4)
5)
6)
decrease dose by 30-40% to prevent high/total
spinal
CSA: small incremental doses, PDPH risk
CSE: decrease dosing, epidural for supplement
Replace Epidural: risk of local toxicity
GETA: emergency or regional failure
Caudal injection for unblocked sacral segments
Mechanisms of Inadequate Block Presenting “Intraop”
 Exteriorization of the uterus
 Overstretching round ligaments
 Rough handling of viscera
 Subdiaphragmatic irritation by blood or amniotic
fluid (innervated by C3-C5)
 Tachyphylaxis to Lidocaine
 Venous air embolism
Management of Inadequate Block Presenting “Intraop”
 Emotional support
 Local infiltration by surgeon
 Swabbing peritoneal cavity 0.5% Lido (Know MAX
doses)
 MAC: Versed/Valium, Opioids, Ketamine, Propofol,
N20 50%
*Must maintain airway*
 GETA with RSI: AFOI if problematic airway
Questions??? Comments?
 Has anyone else experienced an inadequate
extension of a labor epidural for C/S?
 When did it present? Preop? Intraop?
 How did you manage it?
References
 Halpern, S.H., Soliman, A., Yee, J., Angle, P., &
Isocovich, A. (2008). Conversion of epidural labour
analgesia to anaesthesia for Cesarean section: a
prospective study of the incidence and determinants
of failure. British Journal of Anaesthesia, 102 (2),
240-243.
 Morgan, G.E., Mikhail, M.S., & Murray M.J. (2006).
Clinical Anesthesiology, 4th ed. New York: NY;
McGraw-Hill.
References
 Portnoy, D. &Vadhera, R.B. (2003). Mechanisms
and management of an incomplete epidural block for
cesarean section. Anesthesiology Clinics of North
America, 21, 39-57.
 Tortosa, J.C., Parry, N.S., Mercier, F.J., Mazoit, J.X.,
& Benhamou, D. (2003). Efficacy of augmentation
of epidural analgesia for Caesarean section. British
Journal of Anaesthesia, 91 (4), 532-535.
 Vercauteren, M. (2006). Failed epidural and spinal:
Why do they and what to do? Timisoara, 86-90.