Labor Epidural Analgesia

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Labor Epidural Analgesia

• Dmitry Portnoy, MD
• Anesthesiology Department

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The Physiology of Pain in Labor

• 1st stage of labor mostly visceral
• Dilation of the cervix and distention of the
  lower uterine segment
• Dull, aching and poorly localized
• Slow conducting, visceral C fibers, enter spinal
  cord at T10 to L1
• 2nd stage of labor mostly somatic
• Distention of the pelvic floor, vagina and
  perineum
• Sharp, severe and well localized
• Rapidly conducting A-delta fibers, enter spinal
  cord at S2 to S4

T10
L1
S2
S4
http//www.manbit.com/oa/oaindex.htm
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The Intensity of Pain in Labor
http//www.manbit.com/oa/oaindex.htm
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Boundaries of the Epidural Space

• Superior - the foramen magnum
• Inferior limit - the sacral hiatus and
  sacro-coccygeal membrane
• Anterior - the posterior longitudinal ligament
  covering the bodies of the vertebrae and the
  intervertebral discs
• Posterior - periosteum of laminae of the
  vertebrae and the ligamenta flava
• Lateral periosteum of the pedicles and
  intervertebral foraminae

From Cousins, Neural Blockade
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Spread of Epidurally Injected Solutions

• Epidurally administered drugs must travel
  through
• dura matter arachnoid matter
• CSF pia matter
• white matter gray matter
• Rapid access via dural cuff
• Competing pathways
• Uptake into epidural epidural fat
• Uptake into systemic circulation

From Cousins, Neural Blockade
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Indications for LEA

• PAIN EXPERIENCED BY A WOMAN IN LABOR
• When medically beneficial to reduce the stress of
  labor
• ACOG and ASA stated
• in the absence of a medical contraindication,
  maternal request is a sufficient medical
  indication for pain relief
• Points of controversy
• When?
• Who?
• How?

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Contraindications for LEA

• ABSOLUTE
• Patients refusal
• Inability to cooperate
• Increased intracranial pressure 2 mass lesion
• Infection at the site of needle placement
• Frank coagulopathy
• Severe hypovolemia
• Inadequate training

• RELATIVE
• Systemic maternal infection
• Preexisting neurological deficiency
• Mild or isolated coagulation abnormalities
• Relative (and correctable) hypovolemia
• Poor communication

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We are All ReadyNow What? - Last Check!

• Obstetrician is consulted and confirmed LEA
• Preanesthetic evaluation is performed/verified
• Pts (and only patients) desire to have LEA is
  reconfirmed
• Pts understanding of risks of LEA is
  reconfirmed
• Fetal well-being is assessed and reassured
  (obstetrician?, midwife?, yourself?)
• Supporting personal is available and present
• Resuscitation equipment and drugs are immediately
  available in the area where LEA placed

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Standard Technique of LEA

• Pre epidural check list is completed
• Aspiration prophylaxis (?) UTMB 30 cc Bicitra
• Intravenous hydration (What? When? How?)
• Monitoring
• BP every 1 to 2 min for 20 min after injection of
  drugs
• Continuous maternal HR during induction ( e.g.,
  pulse oximetry)
• Continuous FHR monitoring
• Continual verbal communication
• Maternal position ( sitting or lateral?)
• Sterile technique not negotiable

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Standard Technique of LEA (cont.)

• 7. Loss-of-resistance technique of your choice
• Catheter is threaded 3 to 5 cm into the space
• Secure taping (sponge? tegaderm? loop? tape?)
• Testing the catheter
• Aspiration test (say NO to big syringe!)
• Test dose (what? when? how?)
• 11. Inducing LEA ( Treat every bolus as a test
  dose!)
• 12. Assessment of LEA (sensory, motor, autonomic)
• 13. Repeat assessment every 1 to 2 hours

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Etiology and Contributing Factors in
Unsatisfactory Epidural Block
Unsatisfactory epidural block
Patient and surgical factors
Performance factor
Anatomical considerations
Methodology and equipment
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Etiology and Contributing Factors (Anatomical
considerations)

• Midline epidural structures
• plica mediana dorsalis (dura matris) - Luyendijk
  , 1963, epidurography
• midline adhesion of dura mater - Singh, 1967
• epidural plica mediana dorsalis - Savolaine, 1988
  using CT
• dorsomedian connective tissue band - Blomberg,
  1986, epiduroscopy
• median epidural septum
• Connective tissue plane on both dorsolateral
  compartments of the epidural space - Gallart,
  1990
• Spinal nerve root diameter - Galindo, 1975

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Etiology and Contributing Factors (Technique,
methodology and equipment)

• Initial catheter misplacement - incorrect
  placement
• Malposition in anterior or paravertebral
  (lateral) epidural space
• Transforaminal escape
• Increased skin-to-epidural space distance
• Catheter related
• Catheter migration after initial proper placement
• The distance of insertion inside the epidural
  space
• Uniport versus multiport epidural catheters
• Catheter malfunction and catheter defects
• Air for loss-of-resistance technique
• Method of injecting local anesthetic
• Patients position

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Etiology and Contributing Factors(Patient-related
and other risk factors)

• Inherited and acquired anatomical features
• Morbid obesity and body mass index greater than
  30
• Short and tall individuals
• Previous spinal surgery and a variety of
  musculoskeletal disorders
• History of a previous placement of epidural
  catheter
• Radicular pain during epidural placement
• Posterior presentation of the fetus
• Inadequate analgesia from the initial dose
• Duration of labor more than 6 hours
• Technical skills, or performance factor

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Unsatisfactory Labor Epidural AnalgesiaManagement
Options

• Catheter manipulation
• Additional volume of local anesthetic
• Patients position manipulation
• Replacement of the epidural catheter
• A single shot spinal anesthesia
• Continuous spinal anesthesia
• Combined spinal-epidural anesthesia
• Placement of an additional epidural catheter
• Supplementation with intravenous medications

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Management of Unsatisfactory Epidural
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Management of Unsatisfactory Epidural
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Labor Epidural Pearls (Humble Suggestions)

• Not always epidural is worth its risks
• Do not insist unless medically indicated
• Consider other pain control options when LEC
  placement is risky
• No epidural analgesia with instant onset (not
  even close to)
• Realistic expectations and labor dynamics
• Constant communication during procedure
• Treat every dose as a test dose
• The longer skin-to-epidural distance, the deeper
  catheter inside the space
• Do not allow the level to recede

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Avoiding Epidural Disasters (made ridiculously
simple)

• Maintain constant verbal contact with patient
• Always aspirate before each injection
• Observe for passive return through the catheter
• Do not inject more than 4 ml of LA at a time
• Observe the patient at least 1.5-2 min between
  boluses
• If in doubts, repeat test dose. Still in doubts?
  Replace it
• After all, be mentally prepare to treat
• Convulsions
• Total spinal
• Cardiovascular collapse and arrest